Design, synthesis and biological evaluation of marine naphthoquinone-naphthol derivatives as potential anticancer agents

Yujuan Li; Luyou Yelv; Xiaoqiu Wu; Ning Liu; Yamin Zhu

doi:10.1080/14756366.2024.2412865

. 2024 Oct 15;39(1):2412865. doi: 10.1080/14756366.2024.2412865

Design, synthesis and biological evaluation of marine naphthoquinone-naphthol derivatives as potential anticancer agents

Yujuan Li ^a, Luyou Yelv ^a, Xiaoqiu Wu ^a, Ning Liu ^a,^b,^c,^d,^e,^✉, Yamin Zhu ^a,^b,^c,^d,^e,^✉

PMCID: PMC11486183 PMID: 39404032

Abstract

1’-Hydroxy-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (compound 5), a secondary metabolite recently discovered in marine fungi, demonstrates promising cytotoxic and anticancer potential. However, knowledge regarding the anticancer activities and biological mechanisms of its derivatives remains limited. Herein, a series of novel naphthoquinone-naphthol derivatives were designed, synthesised, and evaluated for their anticancer activity against cancer cells of different origins. Among these, Compound 13, featuring an oxopropyl group at the ortho-position of quinone group, exhibited the most potent inhibitory effects on HCT116, PC9, and A549 cells, with IC₅₀ values decreasing from 5.27 to 1.18 μM (4.5-fold increase), 6.98 to 0.57 μM (12-fold increase), and 5.88 to 2.25 μM (2.6-fold increase), respectively, compared to compound 5. Further mechanistic studies revealed that compound 13 significantly induced cell apoptosis by increasing the expression levels of cleaved caspase-3 and reducing Bcl-2 proteins through downregulating the EGFR/PI3K/Akt signalling pathway, leading to the inhibition of proliferation in HCT116 and PC9 cells. The present findings suggest this novel naphthoquinone-naphthol derivative may hold potential as an anticancer therapeutic lead.

Keywords: Naphthoquinone-naphthol derivatives, marine, anticancer activities, EGFR

GRAPHICAL ABSTRACT

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Introduction

Cancer poses a persistent threat to human health, with rising morbidity and high mortality rates¹^,². Over the past decades, numerous anticancer drugs have been developed through combinatorial synthesis and molecular docking studies for chemotherapy³. However, the substantial side effects induced by anticancer drugs, along with the potential for tumour resistance and recurrence, continue to pose a formidable challenge⁴^,⁵. Consequently, there is an urgent imperative to discover innovative anticancer drugs.

To date, over 60% of approved and pre-new drug application (NDA) chemotherapeutic candidates are derived from or closely related to natural products⁶. Marine natural products (MNPs) stand out for their diverse chemical structures and remarkable pharmacological activities, shaped by the unique environmental conditions of marine ecosystems, including high pressure, salt, low oxygen, and limited light⁷. Among these, secondary metabolites from marine fungi have garnered attention, not only leading to new cytotoxic chemicals but also providing insights for refining structures to develop improved chemotherapeutic drugs⁸. For example, plinabulin, a ketopyrazine compound derived from marine Aspergillus, is currently undergoing Phase III clinical trials for non-small cell lung cancer (NSCLC) and shows promise in preventing chemotherapy-induced neutropenia⁹. Additionally, varioloid A and B¹⁰, scopararane I¹¹, physcion¹², and others^13–15 are isolated from various marine fungi, demonstrating potent cytotoxic activity against a wide range of cancer cell lines.

In our ongoing exploration for novel small-molecule anticancer agents with distinct structures from MNPs, our focus shifted to 1′-hydroxy-4′,8,8′-trimethoxy-[2,2′-binaphthalene]-1,4-dione (5), isolated from the marine fungus Hypoxylon rubiginosum FS521 in 2020¹⁶. This compound features a unique naphthoquinone-naphthol skeleton, while also demonstrating promising cytotoxic activity. Despite reports on the structure and cytotoxic activity of compound 5, there is still limited understanding of its derivatives, including their anticancer activity and biological mechanisms. Thus, in this study, a structure-activity relationship (SAR)-based synthetic strategy was employed to synthesise structurally refined analogues towards potential MNP-derived anticancer agents. In fact, the naphthoquinone moiety, widely found in naturally occurring and biologically active compounds, has been associated with the pharmacological properties of some known anticancer agents¹⁷. Naphthoquinone derivatives, such as napabucasin (BBI-608), sepantronium bromide (YM-155), and menadione (vitamin K3), have demonstrated significant anticancer effects against metastatic colorectal carcinoma, lymphoma, and liver cancer, respectively, both as monotherapies and in combination with other anticancer agents¹⁸. Notably, napabucasin has advanced to Phase III clinical trials, while sepantronium bromide has reached Phase II clinical trials¹⁹. Dinaphthoquinone (6), bearing two naphthoquinone rings, was initially designed but showed a significant decrease in effect. Thereby, the naphthoquinone-naphthol scaffold was identified as responsible for the anti-proliferative activity, which led to further structure modifications. Notably, compound 13, featuring an oxopropyl group at the ortho-position of the quinone group, was found to exhibit the most potent inhibitory effects (HCT116, IC₅₀ = 1.18 μM; PC9, IC₅₀ = 0.57 μM; A549, IC₅₀ = 2.25 μM), with activity increases of 4.5-fold, 12-fold, and 2.6-fold, respectively, compared to compound 5. The intriguing activity of compound 13 stimulated us to conduct further studies on its biological mechanisms.

Results and discussion

Chemistry

Compound 5 was synthesised via a streamlined four-step procedure for the initial evaluation of its anti-proliferative activity (Scheme 1). Commercially available 1,5-dihydroxynaphthalene (1) underwent methylation with dimethyl sulphate and K₂CO₃ in acetone, yielding 1,5-dimethoxynaphthalene (2). Then, a Vilsmeier-Haack reaction was conducted by adding compound 2 to a mixture of phosphorus oxychloride (POCl₃) and N,N-dimethylformamide (DMF) in CHCl₃, producing 4,8-dimethoxy-1-naphthaldehyde (3). This compound underwent Baeyer-Villiger oxidative rearrangement with 3-chloroperoxybenzoic acid (m-CPBA), followed by hydrolysis with K₂CO₃ to obtain 4,8-dimethoxynaphthalene-1-ol (4). A one-step oxidative coupling of compound 4 with p-chloranil in CH₂Cl₂ produced naphthoquinone-naphthol (5) with a good yield, differing from the reported two-step sequence involving oxidative dimerisation and monodemethylation.

To examine the importance of the naphthol moiety²⁰ and two methoxy groups²¹ for the anticancer efficacy of the entire structure, we initially designed dinaphthoquinone (6) and demethoxylated naphthoquinone-naphthol (9). Compound 6 was prepared by oxidising compound 5 with cerium ammonium nitrate (CAN) in CH₃CN. Commercially available compound 7 underwent oxidative dimerisation with p-chloranil in CH₂Cl₂ to produce compound 8, followed by monodemethylation using SnO₂ in CH₂Cl₂ to obtain compound 9 (Scheme 2).

Scheme 2. — Synthesis of dinaphthoquinone 6 and naphthoquinone-naphthol derivative 9. Reagent and conditions: (a) CAN, CH₃CN, H₂O, 0 °C, 45 min, 85%; (b) p-chloranil, CH₂Cl₂, r.t., 24 h, 90%; (c) SnO₂, CH₂Cl₂, r.t., 24 h, 69%.

Subsequently, compound 5 underwent esterification with various carboxylic acids using 4-dimethylaminopyridine (4-DMAP), 3-(((ethylimino)methylene)amino)-N,N-dimethylpropan-1-amine hydrochloride (EDCI), and 3H-[1,2,3]triazolo[4,5-b]pyridin-3-ol (HOAt) in CH₂Cl₂, yielding 10a-10k. Additionally, nucleophilic substitution with alkyl bromides led to the synthesis of ether derivatives 11a-11b (Scheme 3).

Scheme 3. — Synthesis of naphthoquinone-naphthol derivatives **10a–10k** and **11a–11b**. Reagent and conditions: (a) EDCI, 4-DMAP, HOAt, CH₂Cl₂, r.t. or reflux, 7–12 h, 40%–98%; (b) K₂CO₃, acetone, reflux, 10–14 h, 51%–75%.

Finally, the ortho-position of the quinone group (3-position) was explored by using two strategies (Scheme 4). Compound 5 underwent oxidative cyclisation with p-chloranil, resulting in the formation of the five-fused-ring structure (12). Alternatively, ortho-substitution with an oxopropyl group was achieved in the presence of bromoacetic acid, Cs₂CO₃ and KI, yielding compound 13. Further esterification or etherification of compound 13 generated compound 14 or 15, respectively. Remarkably, both 14 and 15 featured two substituent groups: an oxopropyl group at the ortho-position in the naphthoquinone moiety, along with either an indole ester group or a phenyl ether group replacing the free phenolic hydroxyl group in the naphthol moiety.

In vitro antiproliferative activity and SAR

Building upon the initial cytotoxic activity observed in compound 5, we assessed the antiproliferative effects of naphthoquinone-naphthol derivatives against colon cancer (HCT116) and NSCLC (PC9, A549) cell lines using the CCK-8 assay. As illustrated in Table 1, compound 5 demonstrated remarkable inhibitory effect across all three cancer cell lines, with 72 h IC₅₀ values ranging from 5.27 to 6.98 μM. It was included as a positive reference compound for further investigation.

Table 1.

Antiproliferative activities of compounds 5–15.

Compd.	Antiproliferative Activity (IC₅₀ ± SD, μM)^a
Compd.	HCT116	PC9	A549
5	5.27 ± 0.56	6.98 ± 0.50	5.88 ± 0.31
6	>20	>20	>20
9	>20	19.00 ± 0.85	>20
10a	>20	>20	>20
10b	4.34 ± 0.32	3.64 ± 0.19	17.90 ± 1.63
10c	5.66 ± 0.46	>20	>20
10d	>20	>20	>20
10e	8.57 ± 7.37	4.56 ± 0.53	16.87 ± 1.27
10f	12.75 ± 1.59	6.22 ± 0.24	3.11 ± 0.40
10g	5.37 ± 0.37	7.47 ± 0.41	>20
10h	3.07 ± 0.22	4.24 ± 0.39	>20
10i	10.99 ± 0.97	5.26 ± 0.67	3.01 ± 0.45
10j	8.19 ± 0.40	7.50 ± 0.36	8.22 ± 0.16
10k	5.99 ± 0.33	9.60 ± 0.22	3.85 ± 0.73
11a	9.61 ± 0.24	8.57 ± 0.33	12.54 ± 1.09
11b	>20	>20	>20
12	>5^b	>5^b	>5^b
13	1.18 ± 0.09	0.57 ± 0.16	2.25 ± 0.27
14	>20	>20	>20
15	>20	>20	>20

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^{^a}

Cells were treated with different concentrations of compounds for 72 h to obtain the IC₅₀ values. Data are shown as the mean ± SD (n = 3).

^{^b}

Due to its poor solubility, the maximum measured was 5 μM.

As discussed in the chemistry section, modifying compound 5 to compound 6, characterised by two linked naphthoquinone rings, resulted in a complete loss of inhibitory activity against all three cancer cell lines at a concentration of 20 μM (Table 1). This is consistent with previous studies, where binaphthoquinone (BQ) exhibited cytotoxicity against A549 with IC₅₀ values of >10 μM²². Compound 9, lacking two methoxy groups at 8 and 8′ positions, also exhibited a significant decrease in effect, with all IC₅₀ values > 19 μM across the three cancer cell lines. These findings highlight the critical role of the naphthoquinone-naphthol skeleton with two methoxy groups in anticancer activity, prompting further synthesis efforts to modify the phenolic hydroxyl group through esterification or etherification.

In the esterification study, we synthesised various compounds, including benzoate esters (10a–10c), cinnamate ester (10d), heteroaromatic esters (10e–10h), and non-aromatic esters (10i–10k). Compound 10a, featuring an electron-donating 4-OEt substituent, showed no effect on three cancer cell lines at a concentration of 20 μM. Compound 10b, designed with a 4-F substituent, displayed comparable antiproliferative activity to compound 5 against HCT116 and PC9 but exhibited a 3-fold activity loss against A549 cells, despite the known pharmacological benefits of fluorine atoms in drug design²³. Compound 10c, with an electron-withdrawing 4-NO₂ group, only exhibited similar antiproliferative activity to compound 5 against HCT116 (IC₅₀ = 5.66 μM), but had no effect on PC9 and A549 cells at 20 μM. Compound 10d, derived from a naturally-occurring cinnamic acid and containing α, β-unsaturated carbonyl groups conducive to binding to hydrophobic pockets in drug modification scenarios²⁴, strikingly showed no inhibitory activity on three cancer cells. Substituting the phenyl ring with heteroaromatic rings, such as pyridine (10e), pyridazine (10f), thiophene (10g) and indole (10h) rings, generally maintained potent inhibitory activity against HCT116 and PC9, with IC₅₀ ranging from 3.07 to 12.75 μM. However, against A549, compound 10f showed a smaller improvement with an IC₅₀ value of 3.11 μM, while compounds 10e, 10g, and 10h showed varying activity loss. Non-aromatic esters were then introduced with a morpholine ring (10i), a cyclopropyl group (10j), and an n-heptyl group (10k), but no obvious enhancement in effect was observed. Further exploration of phenolic hydroxyl group modification involved synthesising ether derivatives 11a–b. Benzyl ether (11a) slightly decreased the inhibitory activity against the three cancer cells compared to the parent compound 5, while propenyl ether (11b) showed no activity against three cancer cells at 20 μM.

Compound 12, with its five-fused-ring structure, exhibited compromised activity due to poor solubility (maximum measured: 5 μM). However, compound 13, featuring an oxopropyl group at the ortho-position, surprisingly displayed superior antiproliferative activity against all three cancer cell lines. It demonstrated a 4.5-fold increase in effect on HCT116 (IC₅₀ = 1.18 μM), a 12-fold increase on PC9 (IC₅₀ = 0.57 μM), and a 2.6-fold increase on A549 cell lines (IC₅₀ = 2.25 μM) compared to the positive control, compound 5. Additionally, its activity is more potent than several reported natural products derived from marine fungi. For instance, purpuride G from Talaromyces sp. ZZ1616 showed an IC₅₀ of 2.1 μM against PC9 cells²⁵, chlorotrinoreremophilane sesquiterpene from Penicillium sp. (PR19N-1) had an IC₅₀ of 12.2 μM against A549 cells, and apochalasin V from Aspergillus sp. exhibited an IC₅₀ of 39.2 μM against HCT116 cells²⁶. Since ortho-substitution was preferred, compounds 14 and 15, with two substituents at both the ortho-position and the free phenolic hydroxyl group site, respectively, were further crafted. Regrettably, both exhibited lower activity than compound 5, showing no inhibitory activity at 20 μM against all three cancer cell lines. Together, compound 13 demonstrated the best potent and well-balanced antiproliferative activity against three cancer cells, prompting further investigation into its biological mechanisms.

The structure-activity relationship (SAR) derived from the above discussion is depicted in Figure 1. The entire naphthoquinone-naphthol scaffold emerged as pivotal for antiproliferative activity, with the presence of two methoxy groups proving beneficial. Regarding derivations of the phenolic hydroxyl group, compounds such as 4-F benzoate ester, heterocyclic esters, aliphatic esters, and benzyl ether were found to be optimal, though only exhibiting activity comparable to the parent 5. Notably, the ortho-substitution of the quinone group with an oxopropyl group (compound 13) significantly enhanced the effect against all three cancer cell lines. However, combining ortho-substitution with phenolic hydroxyl group esterification or etherification weakened the effect considerably. In summary, compound 13, featuring an oxopropyl group at the ortho-position of the quinone group, demonstrated the most potent antiproliferative activity against the three cancer cell lines (IC₅₀ = 1.18 μM in HCT116 cells, 0.57 μM in PC9 cells, and 2.25 μM in A549 cells).

Compound 13 suppressed the proliferation of both HCT116 and PC9 cells

In vitro antiproliferation experiments have demonstrated the efficacy of compound 13 in inhibiting the proliferation of both colon cancer and NSCLC lines (Figure 2A,B). To further elucidate its mechanism, colony formation assays were performed to evaluate the impact of compound 13 on HCT116 and PC9 cells. Compared to compound 5, treatment with compound 13 at indicated concentrations significantly reduced colony formation rates in both HCT116 and PC9 cells after 14 days. Compound 13 exhibited a dose-dependent decrease in the colony-forming ability of these two cancer cell lines. Particularly noteworthy, treatment with 2 μM of compound 13 nearly completely suppressed colony formation in HCT116 cells, reducing both the number and size of the colonies (Figure 2C,D). Similarly, in PC9 cells, obvious inhibition of colony formation was observed at a concentration of 0.5 μM, with almost no colonies forming at 1 μM (Figure 2E,F).

Figure 2. — The antiproliferation effects of compound 5 and 13. (A) HCT116 and PC9 were treated with the indicated concentrations of compound 5 and 13 (0.01, 0.1, 0.25, 0.5, 1, 2.5, 5, 10 and 20 μM) or DMSO for 72 h. Cell viability was evaluated using CCK-8 assay and shown as relative viability compared to the untreated control. Each test was performed in triplicate. (B) The IC₅₀ values of compound 5 and 13 in HCT116 and PC9 cells were assessed after 72 h of incubation. (C) Compound 5 and 13 dose-dependently inhibited colony formation in HCT116 cells. Colony formation was assessed after treatment at concentrations of 0.5, 1, 2, and 4 μM for 14 days, and images of crystal violet-stained colonies were depicted. (D) The statistical result of (C). (E) Compound 5 and 13 dose-dependently inhibited colony formation in PC9 cells. Colony formation was assessed after treatment at concentrations of 0.2, 0.5, 1 and 2 μM for 14 d, and images of crystal violet-stained colonies were depicted. (F) The statistical result of (E). All data are shown as mean ± SD, n = 3, t test, *p < .05, **p < .01, ***p < .001, ****p < .0001.

Compound13 inhibited the EGFR/PI3K/Akt signalling pathway in both HCT116 and PC9 cells

The physiological function of the Epidermal Growth Factor Receptor (EGFR) is essential in various cellular processes and is often aberrantly activated in cancers, contributing to tumour occurrence and progression²⁷. Its downstream PI3K/Akt signalling pathway plays a pivotal role in many cancers, controlling essential aspects such as cell survival, metastasis, and metabolism²⁸. Inspired by the remarkable effect of compound 13 against HCT116 and PC9 cell lines, we investigated its effect on EGFR phosphorylation and its downstream signalling transduction in both cell lines using Western blotting analysis. As illustrated in Figure 3, both compounds 5 and 13 dose-dependently inhibited the phosphorylation of EGFR, PI3K, and Akt proteins in both HCT116 and PC9 cells. Remarkably, compound 13 exhibited a stronger inhibitory effect, surpassing that of compound 5 at comparable concentrations. Furthermore, we explored the apoptosis-inducing effects of compound 13 on HCT116 and PC9 cells. Compared to compound 5, compound 13 increased the expression of cleaved-caspase-3 by activating caspase-3 and reduced the expression of the anti-apoptotic factor Bcl-2 in a dose-dependent manner, which demonstrated that compound 13 inhibited the survival of HCT116 and PC9 cells by inducing apoptosis. These results suggest that compound 13 emerged as a potent EGFR inhibitor, suppressing cell proliferation by inducing cell apoptosis through the EGFR/PI3K/Akt pathway.

Figure 3. — Western blot assay of compound 5 and 13. (A) Western blot assay of EGFR phosphorylation (p-EGFR), PI3K phosphorylation (p-PI3K), Akt phosphorylation (p-Akt), caspase-3, cleaved-caspase-3, and Bcl-2 after treatment of HCT116 cells with 2 μM and 4 μM concentrations of compound 5 and 13 for 24 h. (B) The statistical result of (A). (C) Western blot assay of EGFR phosphorylation (p-EGFR), PI3K phosphorylation (p-PI3K), Akt phosphorylation (p-Akt), caspase-3, cleaved-caspase-3, and Bcl-2 after treatment of PC9 cells with 2 μM and 4 μM concentrations of compound 5 and 13 for 24 h. (D) The statistical result of (C). All data are shown as mean ± SD, n = 3, t test, *p < .05, **p < .01, ***p < .001, ****p < .0001.

Conclusion

In summary, a series of novel naphthoquinone-naphthol derivatives, inspired by compound 5 of marine origin, were designed and synthesised with the aim of developing potential anticancer agents. Among them, the preferred compound 13 emerged as the most promising candidate, demonstrating potent and well-balanced antiproliferative activity against three human cancer cell lines (HCT116: IC₅₀ = 1.18 μM; PC9: IC₅₀ = 0.57 μM; A549: IC₅₀ = 2.25 μM). Notably, compound 13 showed significant improvements of 4.5-fold, 12-fold, and 2.6-fold compared to the parent 5 across these cell lines, respectively. The SAR analysis highlighted the importance of ortho-position substitution of the quinone group for enhancing activity. Biological mechanistic studies revealed that compound 13 effectively inhibited colony formation of HCT116 and PC9 cancer cells at concentrations of 0.5 μM and 1 μM, respectively. Additionally, compound 13 induced the apoptosis of HCT116 and PC9 cells by significantly increasing the expression of cleaved-caspase-3 and decreasing the expression of Bcl-2. Mechanistically, compound 13 also downregulated the phosphorylation of EGFR, PI3K, and Akt proteins in HCT116 and PC9 cells in a dose-dependent manner. Further studies are needed to explore its pharmacokinetic properties, evaluate its in vivo anti-tumour activity, and assess its toxicology to develop it into an anti-tumour drug. Overall, the marine-derived compound 13 with its novel scaffold holds promise for the development of anticancer agents.

Experimental

General chemistry

Compounds 1 and 7 were purchased from Shanghai Macklin Biochemical Technology Co., Ltd. All other commercially available reagents and solvents were sourced from Energy Chemical (Shanghai, China) and Shanghai Macklin Biochemical Technology Co., Ltd., and were used without further purification. Reaction progress was monitored via thin layer chromatography (TLC), employing silica gel (300–400 mesh) for column chromatography. Spot visualisation was achieved using ultraviolet light or alkaline potassium permanganate. For spectroscopic analysis,¹H NMR and ¹³C NMR spectra were acquired using a Bruker 400 MHz spectrometer, with CDCl₃ and DMSO-d₆ as solvents (chemical shifts reported in ppm). Tetramethylsilane (TMS) served as the internal standard, with CDCl₃ and DMSO-d₆ as references. High-resolution mass spectrometry (HRMS) was performed using an Orbitrap Exploris mass spectrometer (Thermo Scientific, USA) in the ESI mode. Known compounds underwent analysis using a Waters tandem quadrupole liquid chromatography-mass spectrometer. The melting points of all compounds were determined using an SGW X-4 micro melting point instrument without correction.

Synthesis of 1’-hydroxy-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (5)

To a solution of compound 4 (0.25 mmol, 1 equiv.) in CH₂Cl₂ (6 ml) was added p-chloranil (0.54 mmol, 2.16 equiv.) at room temperature. The mixture was vigorously stirred at room temperature for 3 d. After completion, the reaction solution was concentrated under vacuum, and the resulting residue was purified via silica gel column chromatography to give compound 5. Black solid; yield: 84%.¹H NMR (400 MHz, CDCl₃)δ 9.42 (s, 1H, OH), 7.86 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.76 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.67 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.38 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.31 (d, J = 8.5 Hz, 1H, naphthoquinyl-1H), 7.04 (s, 1H, naphthoquinyl-1H), 6.86 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.72 (s, 1H, naphthol-1H), 4.01 (d, J = 6.8 Hz, 6H, OCH₃), 3.95 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.54, 183.45, 159.75, 156.56, 151.10, 147.92, 146.44, 134.59, 134.56, 134.49, 129.03, 126.50, 121.23, 118.76, 117.89, 116.08, 115.45, 114.99, 107.17, 105.71, 56.63, 56.26, 56.06. MS (ESI): m/z 391.1 [M + H]⁺.

Synthesis of 8,8’-dimethoxy-[2,2’-binaphthalene]-1,1’,4,4’-tetraone (6)²⁹

Compound 5 (0.13 mmol, 1 equiv.) was dissolved in 10 ml of acetonitrile in an ice bath. A solution of ammonium cerium nitrate (2.5 equiv.) was prepared by dissolving it in 0.6 ml of water, then slowly added to the reaction mixture. The reaction stirred for 45 min at 0 °C. After completion, 10 ml of water was added to the reaction mixture, followed by extraction with CH₂Cl₂ (10 ml × 3). The organic phase underwent washing with brine, drying with Na₂SO₄, and concentration under vacuum. The resulting residue was purified via silica gel column chromatography to give compound 6. Yellow solid; yield: 85%. ¹H NMR (400 MHz, CDCl₃) δ 7.72 (m, 4H, naphthoquinyl-4H), 7.31 (d, J = 8.2 Hz, 2H, naphthoquinyl-2H), 6.95 (s, 2H, naphthoquinyl-2H), 3.99 (s, 6H, OCH₃). MS (ESI): m/z 397.0 [M + Na]⁺.

Synthesis of 1’-hydroxy-4’-methoxy-[2,2’-binaphthalene]-1,4-dione (9)

To a solution of compound 8 (0.15 mmol, 1 equiv.) in CH₂Cl₂ (15 ml) was added SnO₂ (5 g). The mixture was vigorously stirred at room temperature for 24 h. After filtration, the residue was washed with CH₂Cl₂. The filtrate was then concentrated under vacuum, and the resulting residue was purified via silica gel column chromatography to give compound 9. Black solid; yield: 69%. ¹H NMR (400 MHz, CDCl₃) δ 8.49 (s, 1H, OH), 8.45–8.36 (m, 1H, naphthol-1H), 8.29–8.10 (m, 3H, naphthol-1H, naphthoquinyl-2H), 7.89–7.76 (m, 2H, naphthoquinyl-2H), 7.57–7.59 (m, 2H, naphthol-2H), 7.14 (s, 1H, naphthoquinyl-1H), 6.56 (s, 1H, naphthol-1H), 3.99 (s, 3H, OCH₃). MS (ESI): m/z 329.1[M-H]^–.

Synthesis of ester derivatives 10a–10k

To a solution of different carboxylic acids or acyl chlorides (0.26 mmol, 2 equiv.) in dry CH₂Cl₂ (3 ml) at 0 °C was added HOAt (0.13 mmol, 1 equiv.), EDCI (0.325 mmol, 2.5 equiv.), 4-DMAP (0.25 mmol, 1 equiv.), and the mixture was stirred at room temperature for 15 min. Subsequently, compound 5 (0.13 mmol, 1 equiv.) was added to the reaction mixture, which was vigorously stirred at room temperature or reflux for 7–12 h. The reaction mixture was quenched by H₂O (5 ml), and extracted with CH₂Cl₂ (5 ml × 3). The combined organic phase was washed with brine, dried with Na₂SO₄, and concentrated under vacuum. The resulting residue was then purified by silica gel column chromatography to obtain the pure target compounds 10a–10k.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-ethoxybenzoate (10a)

Black solid; yield: 73%; m.p. 267.1 °C–267.5 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.09–8.04 (m, 2H, phenyl-2H), 7.90 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.69–7.60 (m, 2H, naphthoquinyl-2H), 7.41 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.24 (d, J = 8.1 Hz, 1H, naphthoquinyl-1H), 7.04 (s, 1H, naphthoquinyl-1H), 6.86 (m, 3H, naphthol-1H, phenyl-2H), 6.76 (s, 1H, naphthol-1H), 4.07 (q, J = 7.0 Hz, 2H, CH₂), 4.02 (s, 3H, OCH₃), 3.96 (s, 3H, OCH₃), 3.52 (s, 3H, OCH₃), 1.43 (t, J = 7.0 Hz, 3H, CH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.98, 183.06, 165.40, 162.85, 159.55, 155.77, 152.75, 149.42, 137.93, 134.93, 134.68, 134.24, 132.35, 128.99, 126.81, 124.46, 122.16, 120.60, 119.65, 118.71, 117.79, 114.82, 113.92, 107.32, 105.31, 63.70, 56.42, 55.88, 55.67, 14.70. HRMS (ESI) calc’d for C₃₂H₂₆O₈ [M + Na]⁺ 561.1525, found 561.1531.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-fluorobenzoate (10b)

Red solid; yield: 84%; m.p. 243.6 °C–243.9 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.15 (dd, J = 8.6, 5.6 Hz, 2H, phenyl-2H), 7.91 (d, J = 9.4 Hz, 1H, naphthol-1H), 7.65 (m, 2H, naphthoquinyl-2H), 7.43 (t, J = 8.0 Hz, 1H, naphthol-1H), 7.25 (d, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.09 (t, J = 8.6 Hz, 2H, phenyl-2H), 7.03 (s, 1H, naphthoquinyl-1H), 6.86 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.76 (s, 1H, naphthol-1H), 4.02 (s, 3H, OCH₃), 3.95 (s, 3H, OCH₃), 3.51 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.92, 182.95, 167.08, 164.61, 159.55, 155.59, 152.97, 149.34, 137.57, 134.98, 134.79, 134.22, 132.89, 132.80, 129.01, 126.90, 126.24, 124.42, 120.53, 119.41, 118.76, 117.83, 115.55, 115.34, 114.95, 107.42, 105.24, 56.40, 55.90, 55.66. HRMS (ESI) calc’d for C₃₀H₂₁FO₇ [M + Na]⁺ 535.1169, found 535.1177.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-nitrobenzoate (10c)

Yellow solid; yield: 89%; m.p. 252.2 °C–252.7 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.29 (q, J = 8.5 Hz, 4H, phenyl-4H), 7.93 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.71–7.61 (m, 2H, naphthoquinyl-2H), 7.45 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.27 (d, J = 8.1 Hz, 1H, naphthoquinyl-1H), 7.02 (s, 1H, naphthoquinyl-1H), 6.88 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.76 (s, 1H, naphthol-1H), 4.00 (d, J = 24.2 Hz, 6H, OCH₃), 3.51 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.79, 182.76, 163.70, 159.58, 155.30, 153.27, 150.61, 149.12, 137.10, 135.37, 135.11, 134.97, 134.15, 131.34, 128.99, 127.03, 124.38, 123.48, 120.36, 119.05, 118.84, 117.95, 115.14, 107.60, 105.18, 56.45, 55.95, 55.72. HRMS (ESI) calc’d for C₃₀H₂₁NO₉ [M + Na]⁺ 562.1114, found 562.1118.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl cinnamate (10d)

Red solid; yield: 84%; m.p. 242.3 °C–242.9 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.91 (dd, J = 8.5, 1.0 Hz, 1H, naphthol-1H), 7.79 (d, J = 16.0 Hz, 1H, CH), 7.72 (dd, J = 7.6, 1.2 Hz, 1H, naphthoquinyl-1H), 7.64 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.52 (m, 2H, phenyl-2H), 7.43 (t, J = 8.0 Hz, 1H, naphthol-1H), 7.40–7.36 (m, 3H, phenyl-3H), 7.24 (d, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.02 (s, 1H, naphthoquinyl-1H), 6.89 (dd, J = 7.9, 1.0 Hz, 1H, naphthol-1H), 6.74 (s, 1H, naphthol-1H), 6.58 (d, J = 16.0 Hz, 1H, CH), 4.01 (s, 3H, OCH₃), 3.93 (s, 3H, OCH₃), 3.78 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.00, 183.03, 165.78, 159.69, 155.73, 152.84, 149.29, 145.96, 137.48, 135.07, 134.77, 134.42, 134.32, 130.46, 128.95, 128.92, 128.18, 126.85, 124.43, 120.53, 119.55, 118.82, 117.90, 117.59, 114.90, 107.39, 105.28, 56.47, 55.96, 55.88. HRMS (ESI) calc’d for C₃₂H₂₄O₇ [M + Na]⁺ 543.1420, found 543.1427.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl isonicotinate (10e)

Brown solid; yield: 36%; m.p. 251.9 °C–252.3 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.79 (s, 2H, phenyl-2H), 7.91–7.97 (m, 3H, naphthol-1H, phenyl-2H), 7.71–7.60 (m, 2H, naphthoquinyl-2H), 7.44 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.25 (d, J = 8.1 Hz, 1H, naphthoquinyl-1H), 7.01 (s, 1H, naphthoquinyl-1H), 6.87 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.76 (s, 1H, naphthol-1H), 4.03 (s, 3H, OCH₃), 3.94 (s, 3H, OCH₃), 3.52 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.81, 182.80, 164.06, 159.52, 155.33, 153.28, 150.54, 149.24, 137.21, 137.10, 135.05, 134.92, 134.16, 129.01, 127.04, 124.33, 123.42, 120.44, 119.06, 118.81, 117.87, 115.10, 107.59, 105.14, 56.35, 55.94, 55.70. HRMS (ESI) calc’d for C₂₉H₂₁NO₇ [M + Na]⁺ 518.1216, found 518.1224.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 6-methoxypyridazine-3-carboxylate (10f)

Brown solid; yield: 89%; m.p. 152.9 °C–153.4 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.17 (d, J = 9.1 Hz, 1H, pyrazinyl-1H), 7.93 (dd, J = 8.5, 1.0 Hz, 1H, naphthol-1H), 7.71–7.61 (m, 2H, naphthoquinyl-2H), 7.44 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.25 (d, J = 8.1 Hz, 1H, naphthoquinyl-1H), 7.06–7.00 (m, 2H, naphthoquinyl-1H, pyrazinyl-1H), 6.88 (d, J = 8.1 Hz, 1H, naphthol-1H), 6.77 (s, 1H, naphthol-1H), 4.21 (s, 3H, OCH₃), 4.02 (s, 3H, OCH₃), 3.93 (s, 3H, OCH₃), 3.56 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.88, 182.86, 165.92, 162.55, 159.66, 155.44, 153.03, 148.66, 147.66, 137.23, 135.26, 134.81, 134.22, 130.77, 128.95, 126.98, 124.34, 120.49, 119.17, 118.80, 117.96, 116.68, 115.09, 107.73, 105.48, 56.44, 55.97, 55.93, 55.53. HRMS (ESI) calc’d for C₂₉H₂₂N₂O₈ [M + Na]⁺ 549.1274, found 549.1281.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl thiophene-2-carboxylate (10g)

Orange solid; yield: 71%; m.p. 268.1 °C–268.4 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.93–7.87 (m, 2H, naphthol-1H, thienyl-1H), 7.70 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.64 (t, J = 7.9 Hz, 1H, naphthoquinyl-1H), 7.56 (dd, J = 5.0, 1.3 Hz, 1H, thienyl-1H), 7.42 (t, J = 8.2 Hz, 1H, naphthol-1H), 7.27 (d, J = 8.2 Hz, 1H, naphthoquinyl-1H), 7.09 (dd, J = 5.0, 3.7 Hz, 1H, thienyl-1H), 7.05 (s, 1H, naphthoquinyl-1H), 6.87 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.75 (s, 1H, naphthol-1H), 4.01 (s, 3H, OCH₃), 3.95 (s, 3H, OCH₃), 3.58 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 184.98, 182.91, 160.97, 159.67, 155.67, 152.89, 148.98, 137.29, 135.13, 134.73, 134.27, 133.40, 132.90, 128.92, 127.64, 126.90, 124.52, 120.56, 119.54, 118.75, 117.87, 114.84, 107.42, 105.35, 56.39, 55.90, 55.76. HRMS (ESI) calc’d for C₂₈H₂₀O₇S [M + Na]⁺ 523.0827, found 523.0833.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 1-methyl-1H-indole-3-carboxylate (10h)

Black solid; yield: 67%; m.p. 297.8 °C–298.0 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.18 (d, J = 7.7 Hz, 1H, indolyl-1H), 7.93–7.86 (m, 2H, naphthol-1H, indolyl-1H), 7.64 (d, J = 7.5 Hz, 1H, naphthoquinyl-1H), 7.58 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.41 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.34–7.27 (m, 2H, naphthoquinyl-1H, indolyl-1H), 7.20–7.23 (m, 2H, indolyl-2H), 7.09 (s, 1H, naphthoquinyl-1H), 6.85 (d, J = 7.7 Hz, 1H, naphthol-1H), 6.77 (s, 1H, naphthol-1H), 4.02 (s, 3H, OCH₃), 3.89 (s, 3H, OCH₃), 3.81 (s, 3H, OCH₃), 3.51 (s, 3H, NCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.03, 183.05, 163.56, 159.59, 156.10, 152.60, 149.52, 137.86, 137.14, 135.98, 135.07, 134.57, 134.30, 128.98, 126.84, 126.74, 124.67, 122.71, 122.16, 121.91, 120.67, 120.18, 118.80, 117.91, 114.77, 109.54, 107.45, 106.71, 105.45, 56.44, 55.91, 55.89. HRMS (ESI) calc’d for C₃₃H₂₅NO₇ [M + Na]⁺ 570.1529, found 570.1536.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl morpholine-4-carboxylate (10i)

Orange solid; yield: 98%; m.p. 253.8 °C–254.3 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.88 (d, J = 8.4 Hz, 1H, naphthol-1H), 7.79 (d, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.72 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.41 (t, J = 8.2 Hz, 1H, naphthol-1H), 7.34 (d, J = 8.2 Hz, 1H, naphthoquinyl-1H), 7.05 (s, 1H, naphthoquinyl-1H), 6.90 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.72 (s, 1H, naphthol-1H), 3.99 (s, 6H, OCH₃), 3.89 (s, 3H, OCH₃), 3.60 (m, 8H, CH₂). ¹³C NMR (100 MHz, CDCl₃) δ 185.03, 182.95, 159.53, 155.91, 153.84, 152.71, 149.55, 137.94, 134.95, 134.93, 134.33, 129.01, 126.77, 124.47, 120.54, 120.03, 118.90, 117.90, 114.92, 107.46, 105.21, 66.80, 66.64, 56.42, 56.00, 55.87, 44.74, 44.05. HRMS (ESI) calc’d for C₂₈H₂₅NO₈ [M + Na]⁺ 526.1478, found 526.1484.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl cyclopropanecarboxylate (10j)

Red solid; yield: 89%; m.p. 80.1 °C–80.7 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.87 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.79 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.72 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.41 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.34 (d, J = 8.3 Hz, 1H, naphthoquinyl-1H), 6.96 (s, 1H, naphthoquinyl-1H), 6.89 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.70 (s, 1H, naphthol-1H), 3.99 (d, J = 9.7 Hz, 6H, OCH₃), 3.90 (s, 3H, OCH₃), 1.76 (m, 1H, CH), 1.07 (m, 2H, CH₂), 0.89 (m, 2H, CH₂). ¹³C NMR (100 MHz, CDCl₃) δ 184.94, 182.79, 172.58, 159.79, 155.63, 152.77, 149.41, 137.40, 135.06, 134.88, 134.26, 128.89, 126.74, 124.26, 120.41, 119.56, 118.82, 117.98, 114.95, 107.39, 105.23, 56.44, 55.99, 55.86, 34.27, 31.40, 28.96, 24.73, 22.33, 14.04. HRMS (ESI) calc’d for C₃₁H₃₂O₇ [M + Na]⁺ 481.1263, found 481.1269.

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl octanoate (10k)

Brown solid; yield: 84%; m.p. 205.2 °C–205.6 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.89 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.77 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.71 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.42 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.33 (d, J = 8.3 Hz, 1H, naphthoquinyl-1H), 6.98 (s, 1H, naphthoquinyl-1H), 6.89 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.70 (s, 1H, naphthol-1H), 3.99 (d, J = 7.6 Hz, 6H, OCH₃), 3.86 (s, 3H, OCH₃), 2.44 (t, J = 7.6 Hz, 2H, CH₂), 1.54 (q, J = 7.6 Hz, 2H, CH₂), 1.34–1.03 (m, 8H, CH₂), 0.78 (t, J = 6.9 Hz, 3H, CH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.04, 182.96, 173.62, 159.81, 155.72, 152.62, 149.00, 137.44, 135.08, 134.88, 134.31, 128.86, 126.77, 124.25, 120.45, 119.62, 118.82, 118.00, 114.83, 107.28, 105.36, 56.47, 55.85, 55.71, 29.72, 13.01, 8.31. HRMS (ESI) calc’d for C₂₇H₂₂O₇ [M + Na]⁺ 539.2046, found 539.2042.

Synthesis of ether derivatives 11a–11b

A mixture of compound 5 (0.13 mmol, 1 equiv.), K₂CO₃ (1.3 mmol, 10 equiv.) and acetone (3 ml) were stirred at room temperature for 15 min. 3-bromopropylene or benzyl bromide (0.65 mmol, 5 equiv.) was introduced, and the mixture vigorously stirred at 45 °C for 10–14 h. After evaporating the acetone under reduced pressure, 5 ml of water was added, and the solution was extracted with CH₂Cl₂ (5 ml × 3). The organic phase was washed with brine, dried with Na₂SO₄, and concentrated under a vacuum. The residue was purified via silica gel column chromatography to obtain the pure target compounds 11a–11b.

1’-(Benzyloxy)-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (11a)

Brown solid; yield: 75%; m.p. 223.2–223.9 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.92 (d, J = 8.4 Hz, 1H, naphthol-1H), 7.71 (d, J = 7.7 Hz, 1H, naphthoquinyl-1H), 7.66 (t, J = 7.9 Hz, 1H, naphthoquinyl-1H), 7.45 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.25 (d, J = 8.1 Hz, 1H, naphthoquinyl-1H), 7.11–7.14 (m, 2H, phenyl-2H), 7.07–7.03 (m, 3H, phenyl-3H), 6.95 (d, J = 7.8 Hz, 1H, naphthol-1H), 6.90 (s, 1H, naphthoquinyl-1H), 6.68 (s, 1H, naphthol-1H), 4.80 (s, 2H, CH₂), 3.99 (s, 3H, OCH₃), 3.92 (d, J = 4.7 Hz, 6H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.16, 183.62, 159.43, 156.33, 151.31, 150.62, 146.69, 137.63, 134.73, 134.41, 134.25, 129.65, 128.18, 128.00, 127.52, 126.69, 125.18, 121.12, 120.54, 118.50, 117.67, 114.91, 107.13, 105.75, 56.36, 55.98, 55.84. HRMS (ESI) calc’d for C₃₀H₂₄O₆ [M + Na]⁺ 503.1471, found 503.1477.

1’-(Allyloxy)-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (11b)

Black solid; yield: 51%; m.p. 98.2 °C–98.5 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.91 (dd, J = 17.9, 8.5 Hz, 1H, naphthol-1H), 7.78 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.70 (t, J = 7.9 Hz, 1H, naphthoquinyl-1H), 7.43 (t, J = 8.1 Hz, 1H, naphthol-1H), 7.32 (d, J = 8.4 Hz, 1H, naphthoquinyl-1H), 7.07 (d, J = 4.2 Hz, 1H, naphthoquinyl-1H), 6.93 (d, J = 7.7 Hz, 1H, naphthol-1H), 6.68 (d, J = 4.5 Hz, 1H, naphthol-1H), 5.95–5.83 (m, 1H, CH), 5.16 (d, J = 15.9 Hz, 1H, CH), 5.00 (d, J = 10.4 Hz, 1H, CH), 4.26 (d, J = 5.6 Hz, 2H, CH₂), 3.99 (d, J = 8.6 Hz, 6H, OCH₃), 3.95 (s, 3H, OCH₃). ¹³C NMR (100 MHz, CDCl₃) δ 185.22, 183.98, 159.62, 156.27, 151.18, 150.34, 146.72, 135.21, 134.63, 134.36, 134.32, 129.44, 126.63, 124.89, 120.97, 120.62, 118.69, 117.84, 116.69, 114.86, 107.10, 105.83, 76.20, 56.45, 56.01, 55.84. HRMS (ESI) calc’d for C₂₆H₂₂O₆ [M + Na]⁺ 453.1314, found 453.1320.

Synthesis of 1,5,8-trimethoxydinaphtho[1,2-b:2’,3’-d]furan-7,12-dione (12)

To a solution of compound 5 (0.13 mmol, 1 equiv.) in toluene (7 ml) was added p-chloranil (1.14 mmol, 1.1 equiv.), and the mixture was stirred at 120 °C for 2 d. Then, the mixture was concentrated under vacuum, and the residue was purified by silica gel column chromatography to yield compound 12. Black solid; yield: 88%. ¹H NMR (400 MHz, CDCl₃) δ 7.97 (dd, J = 7.1, 2.0 Hz, 2H, naphthoquinyl-2H), 7.74–7.68 (m, 2H, phenyl-1H, naphthoquinyl-1H), 7.57 (t, J = 8.2 Hz, 1H, phenyl-1H), 7.35 (d, J = 8.2 Hz, 1H, phenyl-1H), 7.11 (d, J = 7.9 Hz, 1H, phenyl-1H), 4.17 (s, 3H, OCH₃), 4.09 (d, J = 1.8 Hz, 6H, OCH₃). MS (ESI): m/z 389.1[M + H]⁺.

Synthesis of 1’-hydroxy-4’,8,8’-trimethoxy-3–(2-oxopropyl)-[2,2’-binaphthalene]-1,4-dione (13)

To a solution of compound 5 (0.13 mmol, 1 equiv.) in acetone (9 ml) was added Cs₂CO₃ (0.65 mmol, 5 equiv.), KI (0.13 mmol, 1 equiv.), bromoacetic acid (0.65 mmol, 5 equiv.), and the mixture was stirred at room temperature for 17 h. After evaporating the acetone, 10 ml of water was added, and the solution was extracted with CH₂Cl₂ (10 ml × 3). The organic phase was washed with brine, dried with Na₂SO₄, and concentrated under a vacuum. The residue was purified via silica gel column chromatography to obtain compound 13. Black solid; yield: 67%; m.p. 224.5 °C–225.2 °C. ¹H NMR (400 MHz, DMSO-d₆) δ 9.18 (s, 1H, OH), 7.83 (t, J = 8.0, 8.4 Hz,1H, naphthoquinyl-1H), 7.73 (d, J = 8.4 Hz, 1H, naphthol-1H), 7.66 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.58 (d, J = 8.4 Hz, 1H, naphthoquinyl-1H), 7.46 (t, J = 8.0 Hz, 1H, naphthol-1H), 7.08 (d, J = 8.0 Hz, 1H, naphthol-1H), 6.63 (s, 1H, naphthol-1H), 4.01 (s, 3H, OCH₃), 3.90 (s, 3H, OCH₃), 3.81 (s, 3H, OCH₃), 3.68 (d, J = 17.0 Hz, 1H, CH), 3.40 (d, J = 17.0 Hz, 1H, CH), 2.12 (s, 3H, CH₃). ¹³C NMR (100 MHz, CDCl₃) δ 204.85, 159.95, 156.42, 147.74, 144.94, 134.67, 126.09, 119.25, 118.01, 116.12, 107.11, 105.60, 77.16, 56.59, 56.26, 56.00, 43.39, 30.51. HRMS (ESI) calc’d for C₂₂H₂₆O₇ [M + Na]⁺ 469.1263, found 469.1256.

Synthesis of 4,8,8’-trimethoxy-1’,4’-dioxo-3’-(2-oxopropyl)-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 1-methyl-1H-indole-3-carboxylate (14)

To a solution of 1-methyl-1H-indole-3-carboxylic acid (0.13 mmol, 1 equiv.) in dry CH₂Cl₂ (3 ml) at 0 °C was added HOAt (0.13 mmol, 1 equiv.), EDCI (0.275 mmol, 2.5 equiv.), 4-DMAP (0.11 mmol, 1 equiv.), and the mixture was stirred at room temperature for 15 min. Subsequently, compound 13 (0.11 mmol, 1 equiv.) was added to the reaction mixture, which was vigorously stirred at reflux for 72 h. The reaction mixture was quenched by H₂O (5 ml), and extracted with CH₂Cl₂ (5 ml × 3). The combined organic phase was washed with brine, dried with Na₂SO₄, and concentrated under vacuum. The resulting residue was then purified via silica gel column chromatography to obtain compound 14. Orange solid; yield: 40%; m.p. 290.2 °C–290.5 °C. ¹H NMR (400 MHz, CDCl₃) δ 8.12 (d, J = 7.8 Hz, 1H, indolyl-1H), 7.90 (d, J = 8.5 Hz, 1H, naphthol-1H), 7.82 (s, 1H, indolyl-1H), 7.64 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.56 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.40 (t, J = 8.2 Hz, 1H, naphthol-1H), 7.27 (d, J = 10.6 Hz, 2H, indolyl-2H), 7.18 − 7.21 (m, 2H, naphthoquinyl-1H, indolyl-1H), 6.85 (d, J = 8.0 Hz, 1H, naphthol-1H), 6.67 (s, 1H, naphthol-1H), 3.92 (s, 3H, OCH₃), 3.87 (d, J = 17.7 Hz, 1H, CH), 3.77 (s, 3H, OCH₃), 3.69 − 3.59 (m, 3H, OCH₃), 3.51 (s, 3H, CH₃), 3.46 (d, J = 9.4 Hz, 1H, CH), 2.19 (s, 3H, CH₃). ¹³C NMR (100 MHz, CDCl₃) δ 205.07, 184.75, 182.21, 159.68, 156.06, 152.81, 137.11, 135.97, 134.45, 134.06, 129.92, 129.60, 128.93, 128.68, 126.85, 126.42, 126.04, 125.80, 124.41, 122.68, 122.01, 121.85, 120.37, 120.23, 119.19, 117.94, 114.75, 109.59, 107.51, 106.55, 56.52, 55.99, 55.86, 43.23, 33.38, 30.42. HRMS (ESI) calc’d for C₃₆H₂₉NO₈ [M + Na]⁺ 626.1791, found 626.1796.

Synthesis of 1’-(benzyloxy)-4’,8,8’-trimethoxy-3–(2-oxopropyl)-[2,2’-binaphthalene]-1,4-dione (15)

A mixture of compound 13 (0.11 mmol, 1 equiv.), K₂CO₃ (1.1 mmol, 10 equiv.) and acetone (4 ml) were stirred at room temperature for 15 min. Following this, benzyl bromide (0.55 mmol, 5 equiv.) was introduced, and the mixture vigorously stirred at 45 °C for 14 h. After evaporating the acetone, 5 ml of water was added, and the solution was extracted with CH₂Cl₂ (5 ml × 3). The organic phase was washed with brine, dried with Na₂SO₄, and concentrated under a vacuum. The residue was purified via silica gel column chromatography to obtain compound 15. Orange solid; yield: 75%; m.p. 178.2 °C–178.7 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.91 (d, J = 8.4 Hz, 1H, naphthol-1H), 7.74 (d, J = 7.6 Hz, 1H, naphthoquinyl-1H), 7.66 (t, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.44 (t, J = 8.0 Hz, 1H, naphthol-1H), 7.27 (d, J = 8.0 Hz, 1H, naphthoquinyl-1H), 7.15–7.19 (m, 2H, phenyl-2H), 7.11–7.06 (m, 2H, phenyl-2H), 6.95 (d, J = 8.0 Hz, 1H, naphthol-1H), 6.60 (s, 1H, naphthol-1H), 4.88 (d, J = 11.2 Hz, 1H, CH), 4.70 (d, J = 11.2 Hz, 1H, CH), 3.92 (d, J = 3.9 Hz, 6H, OCH₃), 3.89 (s, 3H, OCH₃), 3.83 (d, J = 17.0 Hz, 1H, CH), 3.31 (d, J = 17.0 Hz, 1H, CH), 2.13 (s, 3H, CH₃). ¹³C NMR (100 MHz, CDCl₃) δ 204.57, 184.90, 183.37, 159.57, 156.20, 151.20, 148.42, 145.70, 140.70, 138.08, 134.51, 134.05, 129.24, 128.02, 127.68, 127.30, 126.38, 124.35, 120.64, 120.54, 119.05, 117.80, 114.89, 107.05, 106.00, 56.39, 56.00, 55.83, 43.24, 30.48. HRMS (ESI) calc’d for C₃₃H₂₈O₇ [M + Na]⁺ 559.1733, found 559.1740.

Cell culture

The HCT116 and A549 cell lines were acquired from the American Type Culture Collection (ATCC, CCL-247, CCL-185), and the PC9 cell line was purchased from the European Collection of Authenticated Cell Cultures (ECACC, 90071810). All cell lines were regularly tested to confirm that they were free of Mycoplasma. HCT116 and PC9 cell lines were cultured in the RPMI-1640 medium (Gibco, USA), while A549 cell lines were cultured in DMEM medium (Gibco, USA). All culture media were supplemented with 10% FBS, 100 U/mL penicillin, and 100 μg/mL streptomycin, and maintained at 37 °C in a 5% CO₂ atmosphere. Cells were used at low passages (3–5 passages) upon receipt from the suppliers³⁰.

In vitro anti-proliferative activity assay

In vitro anti-proliferative activity of the derivatives was evaluated using the CCK-8 assay against lung cancer cells (PC9 and A549) and colon cancer cells (HCT116). Cells were seeded in 96-well plates at a density of 5 × 10³ cells per well and allowed to adhere overnight. Compounds at various concentrations, with DMSO as the vehicle control, were then added. After 72 h of incubation, CCK-8 solution was introduced, followed by further incubation at 37 °C for 1 h. Absorbance at 450 nm was measured using a microplate reader (Spectramax Plus 384, Molecular Devices, Sunnyvale, CA, USA). IC₅₀ values were determined using GraphPad Prism 9.0 software.

Colony formation assay

To evaluate the long-term effects of compounds on HCT116 and PC9 cell growth, a colony formation assay was conducted. Cells were seeded at a density of 1000 cells per well in 6-well plates and allowed to adhere for 24 h. Following this, cells were treated with varying concentrations of compound 5 and 13. The culture media were refreshed every other day, and cells were continuously incubated in fresh media for 14 d. After removing the media, cells were washed with cold PBS, fixed with 4% paraformaldehyde (PFA) at room temperature, stained with crystal violet for 15 min, and photographed using a camera. Macroscopic colonies in each well were then counted.

Western blotting

Western blot analysis was performed as in our previous reports³¹. Cells were exposed to varying doses of compound 5 and 13 (0, 2, and 4 μM) for 24 h, followed by protein sample preparation using RIPA lysis buffer containing protease and phosphatase inhibitors. Equal amounts of total protein were then suspended in a sample buffer, boiled at 100 °C for 10 min, and separated by 10%-15% sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The proteins were transferred onto PVDF membranes (Merck Millipore, #IPFL00010, Germany). The membranes were blocked with 5% skim milk at room temperature for 1 h, followed by overnight incubation at 4 °C with specific primary antibodies. Subsequently, the membranes were washed three times for 5 min each with 1× TBST to remove unbound primary antibodies. They were then incubated at room temperature for 1 h with secondary antibodies conjugated to horseradish peroxidase (HRP) (1:10,000). After three washes with 1× TBST for 5 min each, the immunoblots were visualised using the Bio-Rad ChemiDoc XRS system and quantified using ImageJ software.

Supplementary Material

Supplementary_data CLEAN.docx

IENZ_A_2412865_SM5865.docx^{(3.8MB, docx)}

Original Image for Figure 3A and 3C.tif

IENZ_A_2412865_SM5864.tif^{(40.3MB, tif)}

Original Image for Figure 2C and 2E.tif

IENZ_A_2412865_SM5863.tif^{(43.7MB, tif)}

Funding Statement

This work was financially supported by Natural Science Foundation of Shanghai (No. 21ZR1427300) and Shanghai Frontiers Research Centre of the Hadal Biosphere.

Authors contributions

Yamin Zhu conceived and designed the chemistry aspect of the study, while Ning Liu led the design of the biology section. Yujuan Li and Luyou Yelv synthesised all compounds and performed SAR analysis. Yujuan Li and Xiaoqiu Wu conducted colony formation and Western blotting assays. Yamin Zhu and Ning Liu prepared the initial manuscript draft. All authors critically reviewed the manuscript, contributed to its revision, approved the fininal version, and take full responsibility for the work. Furthermore, all authors have confidence in the integrity of their co-authors’ contributions.

Disclosure statement

The authors report no conflicts of interest.

Data availability statement

The data presented in the current study are available from the corresponding author upon reasonable request.

References

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25.Ge H, Shi M, Ma M, Lian X-Y, Zhang Z.. Evaluation of the antiproliferative activity of 106 marine microbial metabolites against human lung cancer cells and potential antiproliferative mechanism of purpuride G. Bioorg Med Chem Lett. 2021;39:127915. [DOI] [PubMed] [Google Scholar]
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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary_data CLEAN.docx

IENZ_A_2412865_SM5865.docx^{(3.8MB, docx)}

Original Image for Figure 3A and 3C.tif

IENZ_A_2412865_SM5864.tif^{(40.3MB, tif)}

Original Image for Figure 2C and 2E.tif

IENZ_A_2412865_SM5863.tif^{(43.7MB, tif)}

Data Availability Statement

The data presented in the current study are available from the corresponding author upon reasonable request.

[CIT0001] 1.Lu Z, Chen Y, Liu D, Jiao X, Liu C, Wang Y, Zhang Z, Jia K, Gong J, Yang Z, et al. The landscape of cancer research and cancer care in China. Nat Med. 2023;29(12):3022–3032. [DOI] [PubMed] [Google Scholar]

[CIT0002] 2.Siegel RL, Giaquinto AN, Jemal A.. Cancer statistics, 2024. CA Cancer J Clin. 2024;74(1):12–49. [DOI] [PubMed] [Google Scholar]

[CIT0003] 3.Tropsha A, Isayev O, Varnek A, Schneider G, Cherkasov A.. Integrating QSAR modelling and deep learning in drug discovery: the emergence of deep QSAR. Nat Rev Drug Discov. 2024;23(2):141–155. [DOI] [PubMed] [Google Scholar]

[CIT0004] 4.Yang W, Zhang B, Tan Q, Chen Y, Chen T, Zou G, Sun B, Wang B, Yuan J, She Z, et al. 4-Hydroxy-2-pyridone derivatives with antitumor activity produced by mangrove endophytic fungus Talaromyces sp. CY-3. Eur J Med Chem. 2024;269:116314. [DOI] [PubMed] [Google Scholar]

[CIT0005] 5.Fralish Z, Chen A, Khan S, Zhou P, Reker D.. The landscape of small-molecule prodrugs. Nat Rev Drug Discov. 2024;23(5):365–380. [DOI] [PubMed] [Google Scholar]

[CIT0006] 6.Demain AL, Vaishnav P.. Natural products for cancer chemotherapy. Microb Biotechnol. 2011;4(6):687–699. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0007] 7.Zhang Z, Sun Y, Li Y, Song X, Wang R, Zhang D.. The potential of marine-derived piperazine alkaloids: sources, structures and bioactivities. Eur J Med Chem. 2024;265:116081. [DOI] [PubMed] [Google Scholar]

[CIT0008] 8.Wang H-N, Sun S-S, Liu M-Z, Yan M-C, Liu Y-F, Zhu Z, Zhang Z.. Natural bioactive compounds from marine fungi (2017-2020). J Asian Nat Prod Res. 2022;24(3):203–230. [DOI] [PubMed] [Google Scholar]

[CIT0009] 9.Millward M, Mainwaring P, Mita A, Federico K, Lloyd GK, Reddinger N, Nawrocki S, Mita M, Spear MA.. Phase 1 study of the novel vascular disrupting agent plinabulin (NPI-2358) and docetaxel. Invest New Drugs. 2012;30(3):1065–1073. [DOI] [PubMed] [Google Scholar]

[CIT0010] 10.Zhang P, Li X-M, Mao X-X, Mándi A, Kurtán T, Wang B-G.. Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291. Beilstein J Org Chem. 2016;12(1):2012–2018. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0011] 11.Liu H, Zhang L, Chen Y, Li S, Tan G, Sun Z, Pan Q, Ye W, Li H, Zhang W, et al. Cytotoxic pimarane-type diterpenes from the marine sediment-derived fungus Eutypella sp. FS46. Nat Prod Res. 2017;31(4):404–410. [DOI] [PubMed] [Google Scholar]

[CIT0012] 12.Wijesekara I, Zhang C, Van Ta Q, Vo T-S, Li Y-X, Kim S-K.. Physcion from marine-derived fungus Microsporum sp. induces apoptosis in human cervical carcinoma HeLa cells. Microbiol Res. 2014;169(4):255–261. [DOI] [PubMed] [Google Scholar]

[CIT0013] 13.Sun H-F, Li X-M, Meng L, Cui C-M, Gao S-S, Li C-S, Huang C-G, Wang B-G.. Asperolides A-C, tetranorlabdane diterpenoids from the marine alga-derived endophytic fungus Aspergillus wentii EN-48. J Nat Prod. 2012;75(2):148–152. [DOI] [PubMed] [Google Scholar]

[CIT0014] 14.Kamat S, Kumari M, Sajna KV, Jayabaskaran C.. Endophytic fungus, Chaetomium globosum, associated with marine green alga, a new source of Chrysin. Sci Rep. 2020;10(1):18726. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0015] 15.Liang X, Zhang X-Y, Nong X-H, Wang J, Huang Z-H, Qi S-H.. Eight linear peptides from the deep-sea-derived fungus Simplicillium obclavatum EIODSF 020. Tetrahedron. 2016;72(22):3092–3097. [Google Scholar]

[CIT0016] 16.Zhang J, Chen Y, Liu Z, Guo B, Gao X, Liu H, Zhang W.. Cytotoxic secondary metabolites from a sea-derived fungal strain of Hypoxylon rubiginosum FS521. Chin J Org Chem. 2020;40(5):1367. [Google Scholar]

[CIT0017] 17.Ahmadi ES, Tajbakhsh A, Iranshahy M, Asili J, Kretschmer N, Shakeri A, Sahebkar A.. Naphthoquinone derivatives isolated from plants: recent advances in biological activity. Mini Rev Med Chem. 2020;20(19):2019–2035. [DOI] [PubMed] [Google Scholar]

[CIT0018] 18.Angulo-Elizari E, Henriquez-Figuereo A, Morán-Serradilla C, Plano D, Sanmartín C.. Unlocking the potential of 1,4-naphthoquinones: a comprehensive review of their anticancer properties. Eur J Med Chem. 2024;268:116249. [DOI] [PubMed] [Google Scholar]

[CIT0019] 19.Tolcher AW, Quinn DI, Ferrari A, Ahmann F, Giaccone G, Drake T, Keating A, de Bono JS.. A phase II study of YM155, a novel small-molecule suppressor of survivin, in castration-resistant taxane-pretreated prostate cancer. Ann Oncol. 2012;23(4):968–973. [DOI] [PubMed] [Google Scholar]

[CIT0020] 20.Zhang Y, Xie J.. Induction of ferroptosis by natural phenols: A promising strategy for cancer therapy. Phytother Res. 2024;38(4):2041–2076. [DOI] [PubMed] [Google Scholar]

[CIT0021] 21.Chiodi D, Ishihara Y.. The role of the methoxy group in approved drugs. Eur J Med Chem. 2024;273:116364. [DOI] [PubMed] [Google Scholar]

[CIT0022] 22.Dai F, Yan W-J, Fu X, Zheng Y-L, Du Y-T, Bao X-Z, Kang Y-F, Jin X-L, Zhou B.. Designing dichlorobinaphthoquinone as a prooxidative anticancer agent based on hydrogen peroxide-responsive in situ production of hydroxyl radicals. Eur J Med Chem. 2018;159:317–323. [DOI] [PubMed] [Google Scholar]

[CIT0023] 23.Liu J, Xie S, Shao X, Xue S, Du P, Wu H, Xu S, Chen Z-S, Yang D-H, Xu J, et al. Identification of new potent anticancer derivatives through simplifying the core structure and modification on their 14- hydroxyl group from oridonin. Eur J Med Chem. 2022;231:114155. [DOI] [PubMed] [Google Scholar]

[CIT0024] 24.Liu Y, Kong L-J, Li N, Liu Y-H, Jia M-Q, Liu Q-G, Zhang S-Y, Song J.. Design, synthesis and biological evaluation of novel 2,4-diaminopyrimidine cinnamyl derivatives as inhibitors of FAK with potent anti-gastric cancer activities. Bioorg Chem. 2023;141:106895. [DOI] [PubMed] [Google Scholar]

[CIT0025] 25.Ge H, Shi M, Ma M, Lian X-Y, Zhang Z.. Evaluation of the antiproliferative activity of 106 marine microbial metabolites against human lung cancer cells and potential antiproliferative mechanism of purpuride G. Bioorg Med Chem Lett. 2021;39:127915. [DOI] [PubMed] [Google Scholar]

[CIT0026] 26.Deshmukh SK, Prakash V, Ranjan N.. Marine fungi: a source of potential anticancer compounds. Front Microbiol. 2017;8:2536. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0027] 27.Sigismund S, Avanzato D, Lanzetti L.. Emerging functions of the EGFR in cancer. Mol Oncol. 2018;12(1):3–20. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0028] 28.He Y, Sun MM, Zhang GG, Yang J, Chen KS, Xu WW, Li B.. Targeting PI3K/Akt signal transduction for cancer therapy. Signal Transduct Target Ther. 2021;6(1):425. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0029] 29.Takeya T, Doi H, Ogata T, Okamoto I, Kotani E.. Aerobic oxidative dimerization of 1-naphthols to 2,2′-binaphthoquinones mediated by SnCl₄ and its application to natural product synthesis. Tetrahedron. 2004;60(41):9049–9060. [Google Scholar]

[CIT0030] 30.Yan S, Zhang B, Feng J, Wu H, Duan N, Zhu Y, Zhao Y, Shen S, Zhang K, Wu W, et al. FGFC1 selectively inhibits erlotinib-resistant non-small cell lung cancer via elevation of ROS mediated by the EGFR/PI3K/Akt/mTOR pathway. Front Pharmacol. 2021;12:764699. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0031] 31.Duan N, Hu X, Qiu H, Zhou R, Li Y, Lu W, Zhu Y, Shen S, Wu W, Yang F, et al. Targeting the E2F1/Rb/HDAC1 axis with the small molecule HR488B effectively inhibits colorectal cancer growth. Cell Death Dis. 2023;14(12):801. [DOI] [PMC free article] [PubMed] [Google Scholar]

PERMALINK

Design, synthesis and biological evaluation of marine naphthoquinone-naphthol derivatives as potential anticancer agents

Yujuan Li

Luyou Yelv

Xiaoqiu Wu

Ning Liu

Yamin Zhu

Abstract

GRAPHICAL ABSTRACT

Introduction

Results and discussion

Chemistry

Scheme 1.

Scheme 2.

Scheme 3.

Scheme 4.

In vitro antiproliferative activity and SAR

Table 1.

Figure 1.

Compound 13 suppressed the proliferation of both HCT116 and PC9 cells

Figure 2.

Compound13 inhibited the EGFR/PI3K/Akt signalling pathway in both HCT116 and PC9 cells

Figure 3.

Conclusion

Experimental

General chemistry

Synthesis of 1’-hydroxy-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (5)

Synthesis of 8,8’-dimethoxy-[2,2’-binaphthalene]-1,1’,4,4’-tetraone (6)29

Synthesis of 1’-hydroxy-4’-methoxy-[2,2’-binaphthalene]-1,4-dione (9)

Synthesis of ester derivatives 10a–10k

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-ethoxybenzoate (10a)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-fluorobenzoate (10b)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 4-nitrobenzoate (10c)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl cinnamate (10d)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl isonicotinate (10e)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 6-methoxypyridazine-3-carboxylate (10f)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl thiophene-2-carboxylate (10g)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 1-methyl-1H-indole-3-carboxylate (10h)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl morpholine-4-carboxylate (10i)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl cyclopropanecarboxylate (10j)

4,8,8’-Trimethoxy-1’,4’-dioxo-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl octanoate (10k)

Synthesis of ether derivatives 11a–11b

1’-(Benzyloxy)-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (11a)

1’-(Allyloxy)-4’,8,8’-trimethoxy-[2,2’-binaphthalene]-1,4-dione (11b)

Synthesis of 1,5,8-trimethoxydinaphtho[1,2-b:2’,3’-d]furan-7,12-dione (12)

Synthesis of 1’-hydroxy-4’,8,8’-trimethoxy-3–(2-oxopropyl)-[2,2’-binaphthalene]-1,4-dione (13)

Synthesis of 4,8,8’-trimethoxy-1’,4’-dioxo-3’-(2-oxopropyl)-1’,4’-dihydro-[2,2’-binaphthalen]-1-yl 1-methyl-1H-indole-3-carboxylate (14)

Synthesis of 1’-(benzyloxy)-4’,8,8’-trimethoxy-3–(2-oxopropyl)-[2,2’-binaphthalene]-1,4-dione (15)

Cell culture

In vitro anti-proliferative activity assay

Colony formation assay

Western blotting

Supplementary Material

Funding Statement

Authors contributions

Disclosure statement

Data availability statement

References

Associated Data

Supplementary Materials

Data Availability Statement

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Synthesis of 8,8’-dimethoxy-[2,2’-binaphthalene]-1,1’,4,4’-tetraone (6)²⁹