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. 2023 Feb 15;14(4):680–691. doi: 10.1039/d2md00427e

Synthesis and anti-proliferative activity of dehydroabietinol derivatives bearing a triazole moiety†

Mingjun Zhu a,‡, Jinchuan Sun a,‡, Yaju Wu a, Xianli Ma a, Fuhou Lei b, Qian Li a,✉, Caina Jiang a,✉, Fangyao Li a,✉
PMCID: PMC10131649  PMID: 37122546

Abstract

In search of more efficacious antitumor agents, a series of novel dehydroabietinol derivatives containing a triazole moiety was synthesized, and evaluated for cytotoxicity against four human cancer cell lines. Many exhibited superior cytotoxic profiles compared to the parent molecule, dehydroabietic acid. In particular, compounds 5g, 5i and 5j exhibited promising cytotoxicity with IC50 values ranging from 4.84 to 9.62 μM against all the test cell lines. Cell clone formation and migration tests of compound 5g showed that it not only effectively inhibited the formation of MGC-803 cell colonies but also inhibited the MGC-803 cell migration and invasion. Additionally, the preliminary pharmacological mechanism indicated compound 5g induced apoptosis, arrested the mitotic process at the G0/G1 phase of the cell cycle, reduced the mitochondrial membrane potential, and increased the intracellular ROS and Ca2+ levels.

In search of more efficacious antitumor agents, a series of novel dehydroabietinol derivatives containing a triazole moiety was synthesized, and evaluated the cytotoxicity and preliminary pharmacological mechanism.graphic file with name d2md00427e-ga.jpg

1. Introduction

Natural products have always played a prominent role in drug discovery for various diseases.1,2 It is reported that approximately 60% of clinically used antitumor drugs originated from natural products.3 However, sometimes natural molecules may suffer from insufficient efficacy, unacceptable pharmacokinetic properties, undesirable toxicity, or poor availability, which impede their direct therapeutic application.4 Therefore, natural products often serve as lead templates and are subjected to structural optimization to generate clinically useful structures.5,6

Dehydroabietic acid (DHA), the main component of the traditional Chinese medicine rosin, is a naturally occurring tricyclic diterpene aromatic abietane with excellent biocompatibility and biodegradability.7,8 DHA and its derivatives exhibit a broad range of biological activities, including antimicrobial,9,10 anti-inflammatory,11 antioxidant,12 and vasodilator13 activity. Many DHA derivatives possess potent cytotoxicity in various types of human cancers, and they were shown to exert anti-tumor effects by directly inhibiting tumor cell growth, arresting the cell cycle and inducing apoptosis.14,15

Heterocyclic compounds are an important class of organic compounds that have been widely used for many important medicinal and synthetic chemistry applications.16–19 In particular, the privileged 1,2,3-triazole scaffold has drawn considerable attention due to its favourable properties, such as moderate dipole character, hydrogen bonding capability, rigidity and stability under in vivo conditions.20 1,2,3-Triazole derivatives display a variety of pharmacological properties such as antibacterial,21,22 antimalarial,23 antitubercular24 and antiviral25 activity. Moreover, numerous studies reported the antitumor potency of 1,2,3-triazole-containing compounds (Fig. 1). Among them, erythrina derivatives bearing a 1,2,3-triazole moiety A as PARP-1 inhibitors showed potent inhibitory activity against A549 cells (IC50 = 0.23 μM).26 Isatin-triazole hydrazones B were potent MARK4 inhibitors and displayed antiproliferative activity in MCF-7, MDA-MB-435s and HepG2 cell lines.27 Therefore, 1,2,3-triazole derivatives are privileged scaffolds for the development of novel drugs.

Fig. 1. 1,2,3-Triazole derivatives with antitumor activity reported.

Fig. 1

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Molecular hybridization is an attractive structural modification strategy to design novel molecules with better pharmacophoric properties based on the combination of two or more bioactive compounds or pharmacophoric units. It is believed that hybrid molecules not only have synergistic biological effects but also enhance their ability to inhibit more than one biological target.28 To our excitement, some anticancer hybrids have reached clinical trials. For example, estramustine, a hybrid of estradiol and nitrogen mustard, is in clinical trials for various solid cancers.

We were inspired by the pharmacological implications of both the moieties and the data based on our own previous study to find novel bioactive compounds.29–32 We designed and synthesized a series of dehydroabietinol derivatives containing the 1,2,3-triazole unit as potential anticancer agents. The cytotoxicity of the target compounds was evaluated against human normal liver cells (LO2) and various cancer cell lines (MGC-803, A549, T24 and HepG2), and the possible mechanisms of cell proliferation inhibition were studied.

2. Results and discussion

Chemistry

The natural product dehydroabietic acid, an abietane diterpene resin acid, was easily obtained from Pinus. It is well known that the carboxyl group and the benzene ring are the main sites of dehydroabietic acid that tolerate structural modification. The present study focused on the –COOH group at a C-18 position for the attachment of the triazole moiety on dehydroabietic acid. As shown in Scheme 1, dehydroabietic acid (1) was subjected to a reduction reaction using lithium aluminium hydride (LAH) in the presence of anhydrous THF to form dehydroabietinol (DHO) (2). Subsequently, (2) reacted with chloroacetyl chloride in anhydrous THF at room temperature to provide chloroacetate (3) in good yield. The chloride was converted to an azide (4) in the presence of sodium azide, which was subsequently reacted with propargyl-containing compounds to afford 1,2,3-triazole derivatives via a [3 + 2] cycloaddition reaction. The structures of all the derivatives were confirmed by IR, 1H NMR, 13C NMR and HRMS, and the related spectra can be found in ESI.† In the 1H NMR spectra, The protons on the saturated carbon linked to acyl showed single or double peak at about 5.10 ppm. The protons on the methylene bonded to the O atom displayed signals at about 4.10 ppm.

Scheme 1. Synthetic route for the dehydroabietinol-1,2,3-triazole derivatives.

Scheme 1

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Antiproliferative activity

Using the MTT assay, all target compounds were tested for their proliferative activity against various cancer cell lines (MGC-803, A549, T24 and HepG2) and non-cancerous (LO2) cells. 5-fluorouracil (5-FU) was used as the positive control. All the IC50 values are shown in Table 1.

Antiproliferative activity of compounds 5a–5y on tumor cells.

Compounds IC50a (μM)
MGC-803 A549 T24 HepG2 LO2
5a 11.56 ± 0.91 35.50 ± 4.68 47.60 ± 1.88 33.30 ± 4.23 25.61 ± 0.67
5b 7.59 ± 1.85 13.27 ± 0.41 11.46 ± 0.50 18.66 ± 4.05 35.77 ± 4.72
5c 26.19 ± 2.96 14.74 ± 0.25 16.27 ± 3.26 13.39 ± 1.46 44.69 ± 2.30
5d 13.20 ± 0.63 10.94 ± 0.35 10.43 ± 2.39 11.40 ± 1.96 35.33 ± 1.33
5e 26.04 ± 3.71 42.87 ± 1.73 39.04 ± 1.17 13.31 ± 2.71 28.73 ± 2.51
5f 25.33 ± 3.78 19.22 ± 0.09 29.56 ± 1.27 14.90 ± 0.44 29.93 ± 4.61
5g 4.84 ± 0.64 7.24 ± 0.60 7.82 ± 0.97 5.82 ± 1.79 39.12 ± 1.79
5h 16.36 ± 1.77 >50 44.92 ± 1.98 >50 >50
5i 9.92 ± 0.36 9.29 ± 1.15 9.08 ± 1.18 9.62 ± 0.46 15.88 ± 1.68
5j 6.36 ± 0.83 7.08 ± 0.58 8.76 ± 0.86 6.31 ± 1.04 28.56 ± 1.80
5k 13.87 ± 0.93 11.16 ± 1.63 9.62 ± 1.71 11.94 ± 1.32 45.17 ± 1.85
5l 43.63 ± 3.57 >50 33.60 ± 3.46 14.45 ± 1.81 41.65 ± 3.25
5m 25.66 ± 1.31 27.74 ± 0.69 23.64 ± 1.61 12.45 ± 3.58 31.43 ± 2.32
5n >50 38.55 ± 4.46 21.18 ± 0.84 15.52 ± 3.71 >50
5o 19.78 ± 0.89 15.96 ± 1.24 13.23 ± 0.45 10.25 ± 0.52 31.71 ± 2.32
5p >50 >50 >50 >50 >50
5q 25.86 ± 0.67 11.67 ± 2.24 12.65 ± 2.18 15.30 ± 0.90 38.57 ± 3.85
5r 23.73 ± 0.17 22.56 ± 3.55 13.12 ± 0.78 17.42 ± 3.75 >50
5s 19.80 ± 0.86 31.46 ± 1.34 29.08 ± 0.85 18.37 ± 1.24 >50
5t 20.85 ± 2.42 7.51 ± 1.20 9.02 ± 0.90 22.73 ± 0.96 28.34 ± 0.59
5u 26.80 ± 1.54 41.58 ± 1.44 36.57 ± 4.69 29.94 ± 1.14 >50
5v 20.87 ± 0.42 41.33 ± 0.65 26.34 ± 2.16 22.85 ± 2.60 >50
5w 18.04 ± 1.72 12.05 ± 0.50 10.59 ± 3.66 15.46 ± 0.08 26.49 ± 1.44
5x 22.12 ± 1.40 20.95 ± 3.95 20.81 ± 0.49 10.86 ± 1.15 41.54 ± 1.65
5y 21.63 ± 1.20 39.19 ± 1.39 21.32 ± 2.16 18.33 ± 2.49 20.18 ± 1.54
DHA >50 >50 >50 >50 >50
DHO 42.81 ± 2.46 44.14 ± 1.26 >50 45.70 ± 2.69 37.16 ± 2.59
5-FU 27.56 ± 2.18 27.08 ± 3.84 25.23 ± 3.65 17.57 ± 2.37 44.05 ± 4.62
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a

IC50 values are expressed as the mean ± SD (standard error of the mean) from three independent experiments.

The in vitro cytotoxicity data listed in Table 1 revealed that the parent compound DHA and key intermediate DHO displayed weak antiproliferative activity in the four cancer cell lines, but all the synthesized compounds showed strong antiproliferative activity with most IC50 values between 4.84 μM and 30 μM. Among these derivatives, compounds 5b, 5c, 5d, 5g, 5i, 5j, 5k, 5o, 5q, 5r, 5w and 5x exhibited better cytotoxic activity than the positive control 5-FU against all tested cancer cells. In particular, compounds 5g and 5j showed significant cytotoxicity with IC50 values of 4.84 and 6.36 μM against the MGC-803 cell line, 7.24 and 7.08 μM against A549 cells, 7.82 and 8.76 μM against T24 cells and 5.82 and 6.31 μM against HepG2 cells, respectively. For thioether-containing derivatives (5a–5e), compound 5d (RH is 4,5-dihydrothiazole-2-thiol) demonstrated higher proliferative inhibition than others against A549, T24 and HepG2 cell lines. Changing the 4-hydroxycoumarin unit (5f) to a 7-hydroxycoumarin unit (5g) led to a significant improvement in the activity against all the tested cell lines, indicating that the attachment point to the 1,2,3-triazole was important for inhibitory activity. However, when a methyl group was introduced at the 4-position of 7-hydroxycoumarin, the activity decreased dramatically. The presence of fluorine in the para position of the phenyl ring gave more potency than in the two other positions. In addition, when the fluorine in the para position was replaced with nitro or methyl group, antiproliferative activity decreased further.

Effects of 5g on the morphology of MGC-803 cells

After being treated with compound 5g (0 μM, 2.5 μM, 5 μM, 10 μM) for 24 h, MGC-803 cells were stained with Hoechst 33258 and observed under a fluorescence microscope. The results showed that the majority of nuclei in treated MGC-803 cells were hypercondensed (brightly stained). Some treated cells exhibited the formation of apoptotic bodies, which were visible as round or oval masses of cytoplasm with multi-fragmented nuclei.33 The number of apoptotic nuclei significantly increased along with the concentration of 5g to 10.0 μM (Fig. 2).

Fig. 2. Hoechst 33258 staining of compound 5g in MGC-803 cells.

Fig. 2

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Effects of 5g on the colony formation of MGC-803 cells

The colony formation assay, an in vitro test for cell survival, assesses the capacity of cells to multiply into a colony.34 From the colony formation results in Fig. 3, MGC803 cells treated with 5g (2.5 μM, 5 μM and 10 μM) for 12 days showed fewer colonies compared with the control. The cell viability of MGC803 cells treated with hybrid 5g at 2.5 μM, 5 μM and 10 μM was 75.11%, 47.89% and 25.78%, respectively, which indicated that compound 5g significantly inhibited the growth of MGC803 cells in a concentration-dependent manner.

Fig. 3. Effect of compound 5g on proliferation ability of MGC-803 cells.

Fig. 3

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Effects of 5g on the migration of MGC-803 cells

The migration of cancer cells is a key factor in tumor progression and metastasis.35 The effects of 5g on the migration ability of MGC803 cells were evaluated by the wound healing assay. As shown in Fig. 4, compared with the control group, 5g significantly suppressed the wound closure. After 5g treatment with different concentrations, the cell migration rates were 46.53%, 38.48%, 27.28%, 16.72% at 24 h and 68.53%, 58.00%, 28.49%, 18.10% at 48 h, respectively. Therefore, these results indicated that 5g could inhibit the migration of MGC-803 cells in a concentration and time-dependent manner.

Fig. 4. Effect of compound 5g on migration ability of MGC-803 cells.

Fig. 4

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Effects of 5g on the levels of reactive oxygen species and mitochondrial membrane potential of MGC-803 cells

ROS are important signalling molecules in every stage of cancer development, including initiation, promotion and progression and have the potential to induce apoptosis in cancer cells.36,37 To confirm whether the antiproliferation activity is related to the ROS level, the intracellular ROS levels were measured by DCFH-DA and DHE staining and photofluorography. As shown in Fig. 5, ROS accumulation increased slightly with the increasing compound concentrations and was generated in a concentration-dependent way. These results suggested that 5g considerably increased the levels of ROS, which might be also a contributing factor to cell death. The depolarization of mitochondrial transmembrane potential (Δψm) could be induced by the opening of the mitochondrial permeability transition pore when apoptosis happens. The JC-1 staining demonstrated that 5g caused a reduction in red fluorescence and an accumulation of green fluorescence, indicating a dissipation of the mitochondrial transmembrane potential (Δψm) (Fig. 6). These data demonstrate that compound 5g induces apoptosis via the mitochondrial death pathway, elevating mitochondrial superoxide generation and depolarizing mitochondrial transmembrane potential (Δψm).

Fig. 5. Effect of intracellular ROS level in MGC-803 cells treated with compound 5g for 24 h.

Fig. 5

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Fig. 6. Effect of MMP in MGC-803 cells treated with compound 5g for 24 h.

Fig. 6

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Effects of 5g on the apoptosis of MGC-803 cells

Apoptosis is an essential cellular process regulating normal growth of cells. However, it is compromised in the cancerous cells.38 To determine whether cell death and proliferation caused by compound 5g was due to increasing apoptosis, a double staining method (annexin V-FITC/propidium iodide (PI) assay) was used to measure apoptosis. Stained cells were analysed by flow cytometry, and it was found that the treatment with 5g induced apoptosis in these cells (Fig. 7). Analysis of the results suggested that treatment of 5g (2.5, 5 and 10 μM) induced apoptosis in 10.05%, 36.11% and 83.08% of MGC-803 cells, respectively, as compared to the controls.

Fig. 7. Effects of compound 5g on cell apoptosis of MGC-803 cells. The cells were treated with different concentrations of compound 5g (0 μM, 2.5 μM, 5 μM, 10 μM) for 24 h and then measured by flow cytometry.

Fig. 7

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Effects of 5g on the cycle of MGC-803 cells

The effect of compound 5g on the cell cycle progression was also measured as it can also be evidence for anticancer activity.39 Cell cycle distribution of gastric cancer cells after the treatment with different concentrations of compounds was assessed using PI (single staining) flow cytometric analysis. As shown in Fig. 8, treatment with increasing concentrations of compound 5g for 48 h increased the G0/G1 phase distribution by 15.22% (from 56.32% to 71.54%), whereas the G2/M phase distribution decreased from 17.95% to 8.95% in gastric cancer cells, which caused accumulation of the cells at the G0/G1 phase in a dose-dependent manner. These data suggested that compound 5g induced cell cycle arrest at the G0/G1 phase, delaying cell cycle progression. In summary, compound 5g induces cell cycle arrest at G0/G1 phase, thereby controlling cell proliferation.

Fig. 8. Effects of compound 5g on cell cycle of MGC-803 cells. MGC-803 cells were treated with compounds 5g (0 μM, 2.5 μM, 5 μM, 10 μM) for 48 h and then measured by flow cytometry.

Fig. 8

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Effect of intracellular Ca2+ level in MGC-803 cells

Mitochondrial Ca2+ plays an important role in apoptosis, and changes in mitochondrial Ca2+ homeostasis may lead to changes in apoptosis by affecting mitochondrial structure and function. MGC-803 cells in the control group showed weak green fluorescence. After being treated with compound different concentrations of 5g for 24 hours, the intensity of green fluorescence increased with the increase of drug concentration (Fig. 9). All these data suggest that compound 5g promoted the increase of Ca2+ level in MGC-803 cells in a concentration-dependent manner and induce apoptosis.

Fig. 9. Effect of intracellular Ca2+ level in MGC-803 cells treated with compound 5g for 24 h.

Fig. 9

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3. Experimental

Synthesis

Procedure for the synthesis of dehydroabietinol 2

Lithium aluminium hydride (1.52 g, 39.94 mmol) was added to an anhydrous THF (30 ml) solution of dehydroabietic acid 1 (10.00 g, 33.28 mmol) under ice-water cooling. The mixture was stirred at 0 °C for 30 min and then increased to 65 °C for an additional 3 h. The reaction mixture was poured into dilute sulphuric acid and extracted with EtOAc. The organic layer was successively washed with saturated aqueous NaHCO3 and NaCl and was dried over Na2SO4. After evaporation, the residue was chromatographed on a silica gel column with EtOAc : petroleum ether (10 : 1) to give a colourless oil of 2 (6.06 g, 63.6%). 1H NMR (500 MHz, CDCl3) δ 7.21 (d, J = 8.1 Hz, 1H), 7.02 (d, J = 8.1 Hz, 1H), 6.92 (s, 1H), 3.50 (d, J = 11.3 Hz, 1H), 3.26 (d, J = 10.9 Hz, 1H), 2.94–2.82 (m, 3H), 2.32 (d, J = 12.8 Hz, 1H), 1.85–1.68 (m, 5H), 1.53–1.41 (m, 3H), 1.26 (d, J = 3.0 Hz, 6H), 1.24 (s, 3H), 0.92 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 147.34, 145.54, 134.76, 126.81, 124.24, 123.80, 72.27, 43.98, 38.47, 37.86, 37.35, 35.13, 33.46, 30.11, 25.27, 24.00, 23.98, 18.88, 18.66, 17.40. HRMS-ESI (m/z): calcd for C20H30O [M + H]+: 287.2375; found: 287.2367.

Procedure for the synthesis of dehydroabietyl chloroacetate 3

To a stirred solution of dehydroabietinol (1.00 g, 3.49 mmol) in 20 mL anhydrous THF was added pyridine (0.28 g, 3.49 mmol), DMAP (0.04 g, 0.35 mmol) and chloroacetyl chloride (0.47 g, 4.19 mmol under a nitrogen atmosphere. The mixture was stirred for 2 h at room temperature. After completion of reaction, the solvent was evaporated, and the crude was extracted with EtOAc (3 × 30 mL). The organic layer was washed several times with saturated aqueous NaCl, separated and dried over Na2SO4. The residue was chromatographed on a silica gel column with EtOAc : petroleum ether (12 : 1) to afford the yellow oil of 3 (0.95 g, 75.0%). 1H NMR (500 MHz, CDCl3) δ 7.21 (d, J = 8.2 Hz, 1H), 7.03 (d, J = 9.6 Hz, 1H), 6.93 (s, 1H), 4.12 (d, J = 10.9 Hz, 1H), 4.07 (s, 2H), 3.86 (d, J = 10.9 Hz, 1H), 2.95–2.83 (m, 3H), 2.32 (d, J = 12.8 Hz, 1H), 1.80–1.66 (m, 5H), 1.49–1.41 (m, 3H), 1.27 (s, 3H), 1.25 (s, 6H), 0.99 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 167.47, 146.98, 145.71, 134.62, 126.91, 124.26, 123.96, 74.12, 44.28, 40.92, 38.24, 37.46, 37.01, 35.51, 33.45, 30.15, 25.35, 23.98, 23.96, 19.06, 18.48, 17.37. HRMS-ESI (m/z): calcd for C22H31ClO2 [M + Na]+: 385.1910; found: 385.1894.

Procedure for synthesis of dehydroabietyl azidoacetate 4

Compound 3 (0.30 g, 0.83 mmol) was dissolved in dry DMF and mixed with NaN3 (0.05 g, 0.83 mmol), and the reaction mixture was heated at 70 °C for 6 h. After completion of the reaction (monitored by monitoring TLC), the solvent was evaporated to dryness under reduced pressure, and the residue was extracted with ethyl acetate (3 × 15 mL). The combined organic extracts were washed with water (10 mL) and brine (10 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to give the colourless oil of 4 (0.25 g, 81.5%).

General procedure for synthesis of target compounds 5a–5y

Compound 4 (0.18 g, 0.49 mmol) was dissolved in dry DMF (10 mL) and treated with terminal acetylenes 5 (0.49 mmol) in the presence of CuI (0.01 g, 0.05 mmol). The mixture was stirred at 70 °C for 5–6 h until the starting materials were completely consumed. The reaction mixture was poured into water and extracted with EtOAc. The organic layer was successively washed with saturated aqueous NaCl and dried over Na2SO4. It was then purified by silica gel (100–200 mesh) column chromatography to obtain the compounds 5a–5y.

Dehydroabietyl 2-(4-(((4,6-dimethylpyrimidin-2-yl)thio)methyl)-1H-1,2,3- triazol-1-yl)acetate (5a)

Brown solid, yield 67.1%, m.p. 66.8–68.2 °C. IR(KBr) ν/cm−1: 2931, 1749, 1678, 1581, 1269 1H NMR (400 MHz, CDCl3) δ 7.52 (s, 1H), 7.09 (d, J = 8.2 Hz, 1H), 6.92 (d, J = 8.2 Hz, 1H), 6.83 (s, 1H), 6.63 (s, 1H), 5.01 (s, 2H), 4.21 (s, 2H), 3.92 (d, J = 10.9 Hz, 1H), 3.77 (d, J = 10.9 Hz, 1H), 2.80–2.62 (m, 3H), 2.32 (s, 6H), 2.20 (d, J = 12.9 Hz, 1H), 1.69–1.58 (m, 3H), 1.37 (dd, J = 11.3, 3.3 Hz, 1H), 1.27–1.19 (m, 4H), 1.14 (d, J = 6.9 Hz, 6H), 1.11 (s, 3H), 0.81 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 170.24, 167.10, 166.21, 146.85, 146.21, 145.78, 134.41, 126.91, 124.23, 124.00, 123.53, 115.84, 74.06, 50.94, 44.23, 38.24, 37.35, 36.88, 35.48, 33.46, 30.04, 25.23, 25.21, 23.98, 23.96, 23.82, 18.99, 18.37, 17.22. HRMS-ESI (m/z): calcd for C31H41N5O2S [M + H]+: 548.3059; found: 548.3050.

Dehydroabietyl 2-(4-((benzo[d]thiazol-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)acetate (5b)

White solid, yield 48.9%, m.p. 121.5–122.6 °C. IR(KBr) ν/cm−1: 2927, 1762, 1460, 1427, 1211, 995, 759; 1H NMR (500 MHz, CDCl3) δ 7.91 (d, J = 8.1 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.73 (s, 1H), 7.46 (t, J = 7.7 Hz, 1H), 7.33 (t, J = 7.6 Hz, 1H), 7.19 (d, J = 8.2 Hz, 1H), 7.03 (d, J = 8.1 Hz, 1H), 6.93 (s, 1H), 5.12 (s, 2H), 4.40 (d, J = 4.4 Hz, 2H), 4.01 (d, J = 10.9 Hz, 1H), 3.85 (d, J = 10.9 Hz, 1H), 2.93–2.75 (m, 3H), 2.30 (d, J = 12.9 Hz, 1H), 1.76–1.67 (m, 3H), 1.43 (dd, J = 12.6, 3.4 Hz, 1H), 1.37–1.31 (m, 4H), 1.24 (d, J = 6.9 Hz, 6H), 1.21 (s, 3H), 0.90 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.03, 165.92, 153.00, 146.87, 145.80, 144.74, 135.53, 134.44, 126.98, 126.10, 124.41, 124.27, 124.04, 121.50, 121.14, 73.90, 51.05, 44.00, 38.24, 37.34, 36.85, 35.42, 33.46, 30.07, 27.23, 25.24, 24.01, 23.97, 18.93, 18.38, 17.24. HRMS-ESI (m/z): calcd for C32H38N4O2S2 [M + Na]+: 597.2334; found: 597.2322.

Dehydroabietyl 2-(4-((benzo[d]oxazol-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)acetate (5c)

Yellow solid, yield 66.3%, m.p. 53.7–54.9 °C. IR(KBr) ν/cm−1: 2933, 1751, 1483, 1220, 742, 464; 1H NMR (400 MHz, CDCl3) δ 7.76 (s, 1H), 7.60 (d, J = 6.8 Hz, 1H), 7.42 (d, J = 7.1 Hz, 1H), 7.28 (td, J = 7.6, 1.4 Hz, 1H), 7.23 (td, J = 11.6, 1.2 Hz, 1H), 7.15 (d, J = 8.2 Hz, 1H), 6.99 (d, J = 8.1 Hz, 1H), 6.89 (s, 1H), 5.09 (s, 2H), 4.31 (d, J = 0.9 Hz, 2H), 3.97 (d, J = 10.9 Hz, 1H), 3.82 (d, J = 10.9 Hz, 1H), 2.87–2.66 (m, 3H), 2.26 (d, J = 12.8 Hz, 1H), 1.73–1.59 (m, 3H), 1.39 (dd, J = 11.5, 3.2 Hz, 1H), 1.33–1.25 (m, 4H), 1.21 (d, J = 6.9 Hz, 6H), 1.17 (s, 3H), 0.86 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 165.99, 164.30, 152.10, 146.88, 145.79, 144.30, 141.85, 134.43, 126.96, 124.35, 124.25, 124.22, 124.05, 124.02, 118.47, 110.02, 73.94, 51.05, 44.05, 38.24, 37.34, 36.86, 35.44, 33.46, 30.03, 26.34, 25.21, 24.00, 23.96, 18.94, 18.36, 17.22. HRMS-ESI (m/z): calcd for C32H38N4O3S [M + H]+: 559.2743; found: 559.2749.

Dehydroabietyl 2-(4-(((4,5-dihydrothiazol-2-yl)thio)methyl)-1H-1,2,3-triazol-1-yl)acetate (5d)

Yellow solid, yield 63.3%, m.p. 51.2–53.3 °C. IR(KBr) ν/cm−1: 2929, 1741, 1465, 1253, 1008, 744; 1H NMR (500 MHz, CDCl3) δ 7.66 (s, 1H), 7.19 (d, J = 8.2 Hz, 1H), 7.03 (d, J = 8.1 Hz, 1H), 6.93 (s, 1H), 5.14 (s, 2H), 4.31–4.11 (m, 4H), 4.03 (d, J = 10.9 Hz, 1H), 3.87 (d, J = 10.9 Hz, 1H), 3.42 (t, J = 8.0 Hz, 2H), 2.94–2.74 (m, 3H), 2.30 (d, J = 12.8 Hz, 1H), 1.78–1.68 (m, 3H), 1.46 (dd, J = 11.7, 2.9 Hz, 1H), 1.41–1.32 (m, 4H), 1.25 (d, J = 6.9 Hz, 6H), 1.22 (s, 3H), 0.93 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.14, 146.87, 145.78, 144.90, 134.45, 126.94, 124.26, 124.11, 124.02, 74.01, 63.99, 50.98, 44.11, 38.22, 37.36, 36.88, 35.76, 35.46, 33.47, 30.05, 26.81, 25.25, 24.02, 24.00, 18.96, 18.40, 17.28. HRMS-ESI (m/z): calcd for C28H38N4O2S2 [M + H]+: 527.2514; found: 527.2515.

Dehydroabietyl 2-(4-(((1,3,4-thiadiazol-2-yl)thio)methyl)-1H-1,2,3-triazol-1-yl)acetate (5e)

Yellow solid, yield 25.5%, m.p. 68.2–70.1 °C. IR(KBr) ν/cm−1: 2931, 1749, 1500, 1454, 1234, 1130, 744 1H NMR (500 MHz, CDCl3) δ 9.02 (s, 1H), 7.80 (s, 1H), 7.19 (d, J = 8.2 Hz, 1H), 7.02 (d, J = 8.1 Hz, 1H), 6.93 (s, 1H), 5.13 (s, 2H), 4.35 (q, J = 14.6 Hz, 2H), 4.00 (d, J = 10.9 Hz, 1H), 3.86 (d, J = 10.9 Hz, 1H), 2.93–2.73 (m, 3H), 2.30 (d, J = 12.9 Hz, 1H), 1.75–1.66 (m, 3H), 1.42 (dd, J = 11.9, 2.8 Hz, 1H), 1.37–1.27 (m, 4H), 1.24 (d, J = 6.9 Hz, 6H), 1.21 (s, 3H), 0.91 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 165.97, 165.02, 151.78, 146.90, 145.79, 143.83, 134.50, 126.99, 124.82, 124.28, 124.01, 73.81, 51.03, 43.88, 38.24, 37.34, 36.83, 35.39, 33.47, 30.04, 27.65, 25.24, 24.02, 23.98, 18.88, 18.38, 17.28. HRMS-ESI (m/z): calcd for C27H35N5O2S2 [M + H]+: 526.2310; found: 526.2313.

Dehydroabietyl 2-(4-(((2-oxo-2H-chromen-4-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5f)

Yellow solid, yield 65.8%, m.p. 82.4–83.9 °C. IR(KBr) ν/cm−1: 2935, 1741, 1612,1467, 1220, 758; 1H NMR (400 MHz, CDCl3) δ 7.80 (s, 1H), 7.74 (dd, J = 8.0, 1.5 Hz, 1H), 7.53 (ddd, J = 8.6, 7.4, 1.6 Hz, 1H), 7.31 (d, J = 7.8 Hz, 1H), 7.22 (t, J = 7.6 Hz, 1H), 7.17 (d, J = 8.2 Hz, 1H), 7.04 (d, J = 8.2 Hz, 1H), 6.91 (s, 1H), 5.77 (s, 1H), 5.22 (d, J = 1.5 Hz, 2H), 5.02 (q, J = 12.1 Hz, 2H), 4.05 (d, J = 10.9 Hz, 1H), 3.86 (d, J = 10.9 Hz, 1H), 2.91–2.68 (m, 3H), 2.28 (d, J = 12.9 Hz, 1H), 1.70–1.63 (m, 3H), 1.42 (dd, J = 10.7, 3.9 Hz, 1H), 1.37–1.25 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.19 (s, 3H), 0.92 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 165.85, 164.83, 162.53, 153.36, 146.85, 145.93, 141.96, 134.44, 132.53, 126.94, 124.80, 124.24, 124.18, 123.88, 123.12, 116.77, 115.44, 91.27, 73.94, 62.20, 51.12, 43.93, 38.33, 37.35, 36.88, 35.50, 33.43, 30.04, 25.18, 24.04, 23.91, 18.89, 18.36, 17.29. HRMS-ESI (m/z): calcd for C34H39N3O5 [M + H]+: 570.2968; found: 570.2969.

Dehydroabietyl 2-(4-(((2-oxo-2H-chromen-7-yl)oxy)methyl)-1H-1,2,3- triazol-1-yl)acetate (5g)

White solid, yield 35.8%, m.p. 146.4–147.5 °C. IR(KBr) ν/cm−1: 2929, 1747, 1566, 1462, 1263, 1018, 804; 1H NMR (400 MHz, CDCl3) δ 7.66 (s, 1H), 7.56 (d, J = 9.5 Hz, 1H), 7.30 (d, J = 8.6 Hz, 1H), 7.09 (d, J = 8.2 Hz, 1H), 6.94 (d, J = 8.2 Hz, 1H), 6.87–6.79 (m, 3H), 6.20 (d, J = 9.5 Hz, 1H), 5.11 (s, 2H), 4.92 (s, 2H), 3.97 (d, J = 10.9 Hz, 1H), 3.77 (d, J = 10.9 Hz, 1H), 2.84–2.60 (m, 3H), 2.21 (d, J = 12.9 Hz, 1H), 1.67–1.59 (m, 3H), 1.36 (dd, J = 11.3, 3.2 Hz, 1H), 1.29–1.18 (m, 4H), 1.14 (d, J = 6.9 Hz, 6H), 1.12 (s, 3H), 0.84 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 165.97, 161.24, 161.08, 155.72, 146.85, 145.84, 143.52, 143.31, 134.46, 128.88, 126.95, 124.37, 124.25, 124.09, 113.52, 112.99, 112.74, 102.17, 73.93, 61.91, 51.08, 43.95, 38.26, 37.36, 36.88, 35.47, 33.45, 30.06, 25.22, 24.02, 23.95, 18.90, 18.39, 17.30. HRMS-ESI (m/z): calcd for C34H39N3O5 [M + H]+: 570.2968; found: 570.2964.

Dehydroabietyl 2-(4-(((4-methyl-2-oxo-2H-chromen-7-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5h)

White solid, yield 62.1%, m.p. 121.3–123.8 °C. IR(KBr) ν/cm−1: 2931, 1722, 1622, 1238, 929, 821, 767; 1H NMR (500 MHz, CDCl3) δ 7.79 (s, 1H), 7.51 (d, J = 8.8 Hz, 1H), 7.18 (d, J = 8.2 Hz, 1H), 7.04 (d, J = 8.1 Hz, 1H), 6.92 (s, 1H), 6.91 (dd, J = 8.9, 2.3 Hz, 1H), 6.87 (d, J = 2.4 Hz, 1H), 6.16 (s, 1H), 5.21 (d, J = 1.9 Hz, 2H), 5.00 (d, J = 2.7 Hz, 2H), 4.06 (d, J = 10.9 Hz, 1H), 3.86 (d, J = 10.9 Hz, 1H), 2.92–2.73 (m, 3H), 2.41 (s, 3H), 2.30 (d, J = 12.8 Hz, 1H), 1.77–1.66 (m, 3H), 1.46 (dd, J = 11.5, 3.0 Hz, 1H), 1.39–1.29 (m, 4H), 1.23 (d, J = 6.9 Hz, 6H), 1.21 (s, 3H), 0.93 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.02, 161.16, 161.07, 155.10, 152.48, 146.86, 145.81, 143.52, 134.47, 126.94, 125.68, 124.47, 124.25, 124.08, 114.03, 112.43, 112.26, 102.15, 73.93, 61.85, 51.06, 43.99, 38.27, 37.36, 36.87, 35.47, 33.45, 30.06, 25.22, 24.03, 23.96, 18.91, 18.68, 18.40, 17.30. HRMS-ESI (m/z): calcd for C35H41N3O5 [M + Na]+: 606.2944; found: 606.2940.

Dehydroabietyl 2-(4-(((6-(hydroxymethyl)-4-oxo-4H-pyran-3-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5i)

White solid, yield 43.8%, m.p. 47.6–49.3 °C. IR(KBr) ν/cm−1: 2954, 1743, 1510, 1230, 1004,815; 1H NMR (500 MHz, CDCl3) δ 7.86 (s, 1H), 7.80 (s, 1H), 7.18 (d, J = 8.2 Hz, 1H), 7.02 (d, J = 8.2 Hz, 1H), 6.92 (s, 1H), 6.50 (s, 1H), 5.18 (s, 2H), 4.94 (s, 2H), 4.46 (s, 2H), 4.03 (d, J = 10.9 Hz, 1H), 3.87 (d, J = 10.9 Hz, 1H), 2.91–2.71 (m, 3H), 2.30 (d, J = 12.8 Hz, 1H), 1.79–1.68 (m, 3H), 1.47 (dd, J = 11.5, 2.9 Hz, 1H), 1.40–1.31 (m, 4H), 1.24 (d, J = 6.9 Hz, 6H), 1.21 (s, 3H), 0.93 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 174.95, 168.00, 166.11, 146.88, 146.62, 145.78, 143.17, 141.49, 134.51, 126.96, 125.46, 124.25, 123.99, 111.92, 74.02, 62.70, 60.60, 50.99, 44.05, 38.24, 37.36, 36.87, 35.45, 33.45, 30.04, 25.25, 24.01, 24.00, 18.92, 18.39, 17.30. HRMS-ESI (m/z): calcd for C31H39N3O6 [M + H]+: 550.2917; found: 550.2922.

Dehydroabietyl 2-(4-((2-acetyl-5-methoxyphenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5j)

Pink solid, yield 67.8%, m.p. 52.1–54.3 °C. IR(KBr) ν/cm−1: 2929, 1751, 1463, 1219, 1051, 744; 1H NMR (400 MHz, CDCl3) δ 7.80 (d, J = 8.5 Hz, 1H), 7.75 (s, 1H), 7.15 (d, J = 8.2 Hz, 1H), 7.00 (d, J = 8.1 Hz, 1H), 6.90 (s, 1H), 6.56–6.52 (m, 2H), 5.18 (d, J = 2.1 Hz, 2H), 5.03 (s, 2H), 4.03 (d, J = 10.9 Hz, 1H), 3.85 (s, 3H), 3.84 (d, J = 8.1 Hz, 1H), 2.90–2.65 (m, 3H), 2.50 (s, 3H), 2.27 (d, J = 12.8 Hz, 1H), 1.77–1.62 (m, 3H), 1.44 (dd, J = 11.1, 3.4 Hz, 1H), 1.36–1.26 (m, 4H), 1.21 (d, J = 6.9 Hz, 6H), 1.19 (s, 3H), 0.90 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 197.49, 166.05, 164.45, 159.51, 146.86, 145.80, 143.83, 134.47, 132.74, 126.94, 124.32, 124.22, 124.06, 121.38, 105.91, 99.64, 73.96, 62.10, 55.62, 51.04, 44.02, 38.26, 37.35, 36.87, 35.48, 33.43, 31.87, 30.04, 25.22, 24.01, 23.93, 18.92, 18.38, 17.29. HRMS-ESI (m/z): calcd for C34H43N3O5 [M + H]+: 574.3281; found: 574.3278.

Dehydroabietyl 2-(4-((4-fluorophenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5k)

White solid, yield 30.0%, m.p. 109.8–110.1 °C. IR(KBr) ν/cm−1: 2931, 1747,1500,1217, 1049,746; 1H NMR (400 MHz, CDCl3) δ 7.67 (s, 1H), 7.15 (d, J = 8.2 Hz, 1H), 6.99 (d, J = 8.6 Hz, 1H), 6.95 (d, J = 8.4 Hz, 2H), 6.90 (s, 1H), 6.88 (d, J = 4.3 Hz, 1H), 6.85 (d, J = 4.3 Hz, 1H), 5.15 (s, 2H), 4.94 (s, 2H), 4.04 (d, J = 10.9 Hz, 1H), 3.85 (d, J = 10.9 Hz, 1H), 2.91–2.70 (m, 3H), 2.28 (d, J = 12.8 Hz, 1H), 1.74–1.65 (m, 3H), 1.45 (dd, J = 11.2, 3.1 Hz, 1H), 1.37–1.27 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.19 (s, 3H), 0.91 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.08, 157.53 (d, J = 239.8 Hz), 154.24 (d, J = 2.1 Hz), 146.85, 145.80, 144.62, 134.47, 126.94, 124.25, 124.04, 115.89 (d, J = 8.1 Hz), 115.88 (d, J = 23.2 Hz), 73.98, 62.25, 51.01, 44.04, 38.24, 37.37, 36.89, 35.47, 33.46, 30.07, 25.25, 24.02, 23.97, 18.93, 18.40, 17.30. HRMS-ESI (m/z): calcd for C31H38FN3O3 [M + H]+: 520.2975; found: 520.2972.

Dehydroabietyl 2-(4-((3-fluorophenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5l)

Yellow solid, yield 59.0%, m.p. 69.1–70.7 °C. IR(KBr) ν/cm−1: 2927, 1726, 1614, 1384, 1232, 1004, 848; 1H NMR (400 MHz, CDCl3) δ 7.68 (s, 1H), 7.21 (td, J = 8.2, 6.9 Hz, 1H), 7.15 (d, J = 8.2 Hz, 1H), 7.00 (d, J = 8.1 Hz, 1H), 6.90 (s, 1H), 6.71 (dd, J = 8.5, 2.3 Hz, 1H), 6.69–6.62 (m, 2H), 5.16 (d, J = 1.9 Hz, 2H), 4.93 (s, 2H), 4.04 (d, J = 10.9 Hz, 1H), 3.84 (d, J = 10.9 Hz, 1H), 2.95–2.74 (m, 3H), 2.28 (d, J = 12.9 Hz, 1H), 1.72–1.63 (m, 3H), 1.44 (dd, J = 11.3, 3.4 Hz, 1H), 1.37–1.25 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.19 (s, 3H), 0.91 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.05, 163.56 (d, J = 246.3 Hz), 159.45 (d, J = 10.9 Hz), 146.84, 145.81, 144.27, 134.47, 130.29 (d, J = 10.0 Hz), 126.95, 124.26, 124.11, 124.07, 110.46 (d, J = 2.9 Hz), 108.09 (d, J = 21.3 Hz), 102.68 (d, J = 25.1 Hz), 73.93, 61.83, 51.04, 43.99, 38.25, 37.37, 36.88, 35.46, 33.45, 30.07, 25.25, 24.03, 23.95, 18.91, 18.39, 17.30. HRMS-ESI (m/z): calcd for C31H38FN3O3 [M + H]+: 520.2975; found: 520.2975.

Dehydroabietyl 2-(4-((2-fluorophenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5m)

Pink solid, yield 59.0%, m.p. 37.6–39.3 °C. IR(KBr) ν/cm−1: 2927, 1728, 1614, 1384, 1232,1004, 848; 1H NMR (400 MHz, CDCl3) δ 7.73 (s, 1H), 7.14 (d, J = 8.2 Hz, 1H), 7.10–7.05 (m, 2H), 7.04 (s, 1H), 6.99 (d, J = 8.2 Hz, 1H), 6.95–6.88 (m, 2H), 5.15 (d, J = 2.4 Hz, 2H), 5.04 (d, J = 5.7 Hz, 2H), 4.03 (d, J = 10.9 Hz, 1H), 3.85 (d, J = 10.9 Hz, 1H), 2.96–2.71 (m, 3H), 2.27 (d, J = 12.8 Hz, 1H), 1.73–1.65 (m, 3H), 1.44 (dd, J = 11.2, 3.4 Hz, 1H), 1.37–1.25 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.19 (s, 3H), 0.90 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.05, 152.81 (d, J = 246.6 Hz), 146.85, 146.16 (d, J = 10.7 Hz), 145.77, 144.45, 134.47, 126.94, 124.34 (d, J = 4.0 Hz), 124.25, 124.23, 124.01, 121.83 (d, J = 7.0 Hz), 116.29 (d, J = 18.3 Hz), 115.77 (d, J = 1.3 Hz), 74.00, 63.02, 51.02, 44.06, 38.23, 37.36, 36.88, 35.48, 33.45, 30.04, 25.23, 24.00, 23.97, 18.93, 18.38, 17.28. HRMS-ESI (m/z): calcd for C31H38FN3O3 [M + H]+: 520.2975; found: 520.2976.

Dehydroabietyl 2-(4-((4-nitrophenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5n)

White solid, yield 59.7%, m.p. 47.4–49.3 °C. IR(KBr) ν/cm−1: 2931, 1757, 1666, 1600, 1267, 1201, 1002, 837, 569; 1H NMR (600 MHz, CDCl3) δ 8.22 (d, J = 9.2 Hz, 2H), 7.75 (s, 1H), 7.18 (d, J = 8.2 Hz, 1H), 7.06–7.00 (m, 3H), 6.93 (s, 1H), 5.21 (q, J = 10.5 Hz, 2H), 5.05 (s, 2H), 4.07 (d, J = 10.9 Hz, 1H), 3.87 (d, J = 10.9 Hz, 1H), 2.96–2.82 (m, 2H), 2.78–2.68 (m, 1H), 2.31 (d, J = 12.8 Hz, 1H), 1.82–1.68 (m, 3H), 1.46 (dd, J = 11.9, 2.7 Hz, 1H), 1.39–1.30 (m, 4H), 1.25 (d, J = 1.1 Hz, 3H), 1.23 (d, J = 1.1 Hz, 3H), 1.21 (s, 3H), 0.93 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 165.92, 163.04, 146.87, 145.84, 143.33, 141.91, 134.47, 126.94, 125.91, 124.40, 124.26, 124.06, 114.86, 73.91, 62.04, 51.08, 43.93, 38.27, 37.37, 36.89, 35.46, 33.46, 30.06, 25.22, 24.04, 23.96, 18.89, 18.39, 17.31. HRMS-ESI (m/z): calcd for C31H38N4O5 [M + H]+: 547.2920; found: 547.2917.

Dehydroabietyl 2-(4-((p-tolyloxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5o)

Pink solid, yield 43.1%, m.p. 51.2–52.9 °C. IR(KBr) ν/cm−1: 2958, 1755, 1508, 1213, 1004, 827; 1H NMR (400 MHz, CDCl3) δ 7.65 (s, 1H), 7.15 (d, J = 8.2 Hz, 1H), 7.06 (d, J = 8.3 Hz, 2H), 6.99 (d, J = 8.1 Hz, 1H), 6.89 (s, 1H), 6.82 (d, J = 8.5 Hz, 2H), 5.11 (s, 2H), 4.95 (s, 2H), 4.02 (d, J = 10.9 Hz, 1H), 3.83 (d, J = 10.9 Hz, 1H), 2.85–2.64 (m, 3H), 2.26 (d, J = 7.1 Hz, 4H), 1.74–1.62 (m, 3H), 1.44 (dd, J = 11.1, 3.5 Hz, 1H), 1.37–1.25 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.18 (s, 3H), 0.90 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.15, 156.10, 146.87, 145.77, 145.02, 134.48, 130.47, 129.96, 126.95, 124.25, 124.04, 124.00, 114.69, 74.02, 61.82, 50.99, 44.17, 38.27, 37.39, 36.91, 35.51, 33.47, 30.07, 25.25, 24.03, 24.00, 20.50, 18.98, 18.43, 17.30. HRMS-ESI (m/z): calcd for C32H41N3O3 [M + H]+: 516.3226; found: 516.3231.

Dehydroabietyl 2-(4-((3,5-dimethoxyphenoxy)methyl)-1H-1,2,3-triazol-1-yl)acetate (5p)

Yellow solid, yield 20.6%, m.p. 38.1–39.8 °C. IR(KBr) ν/cm−1: 2956, 1716, 1394, 1222, 1093, 715; 1H NMR (500 MHz, CDCl3) δ 7.72 (s, 1H), 7.19 (d, J = 8.2 Hz, 1H), 7.04 (d, J = 9.8 Hz, 1H), 6.93 (s, 1H), 6.15 (d, J = 2.1 Hz, 2H), 6.13 (t, J = 2.1 Hz, 1H), 5.18 (d, J = 1.9 Hz, 2H), 4.98 (s, 2H), 4.07 (d, J = 10.9 Hz, 1H), 3.87 (d, J = 10.9 Hz, 1H), 3.78 (s, 6H), 2.93–2.73 (m, 3H), 2.31 (d, J = 12.8 Hz, 1H), 1.79–1.68 (m, 3H), 1.49 (dd, J = 11.6, 3.0 Hz, 1H), 1.42–1.30 (m, 4H), 1.25 (d, J = 6.9 Hz, 6H), 1.22 (s, 3H), 0.94 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.12, 161.52, 160.04, 146.83, 145.81, 144.62, 134.45, 126.95, 124.23, 124.06, 124.04, 93.71, 93.49, 74.06, 61.70, 55.36, 50.99, 44.13, 38.25, 37.37, 36.89, 35.50, 33.45, 30.06, 25.24, 24.01, 23.95, 18.96, 18.40, 17.28. HRMS-ESI (m/z): calcd for C33H43N3O5 [M + H]+: 562.3281; found: 562.3289.

Dehydroabietyl 2-(4-((10H-phenothiazin-10-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5q)

Pink solid, yield 59.9%, m.p. 160.3–161.2 °C. IR(KBr) ν/cm−1: 2964, 1751, 1261, 1095, 1020, 800; 1H NMR (400 MHz, CDCl3) δ 7.41 (s, 1H), 7.14 (d, J = 8.2 Hz, 1H), 7.11 (dd, J = 7.6, 1.5 Hz, 2H), 7.05 (td, J = 7.9, 1.5 Hz, 2H), 7.00 (d, J = 8.1 Hz, 1H), 6.92–6.87 (m, 3H), 6.75 (d, J = 8.1 Hz, 2H), 5.09 (d, J = 7.0 Hz, 2H), 5.05 (d, J = 7.2 Hz, 2H), 4.00 (d, J = 10.9 Hz, 1H), 3.81 (d, J = 10.9 Hz, 1H), 2.90–2.65 (m, 3H), 2.24 (d, J = 12.9 Hz, 1H), 1.69–1.59 (m, 3H), 1.46 (dd, J = 11.2, 3.4 Hz, 1H), 1.34–1.25 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.18 (s, 3H), 0.88 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.06, 146.85, 145.79, 145.34, 144.23, 134.48, 127.39, 127.18, 126.96, 124.25, 123.99, 123.89, 123.83, 122.84, 115.29, 74.23, 50.96, 44.70, 44.32, 38.23, 37.37, 36.88, 35.53, 33.47, 30.03, 25.21, 23.99, 18.99, 18.40, 17.26. HRMS-ESI (m/z): calcd for C37H42N4O2S [M + H]+: 607.3107; found: 607.3111.

Dehydroabietyl 2-(4-((3,4-dihydroquinolin-1(2H)-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5r)

Pink solid, yield 30.8%, m.p. 50.6–52.1 °C. IR(KBr) ν/cm−1: 2964, 1751, 1593, 1516, 1340,1257, 1111, 997, 846, 752, 688, 634; 1H NMR (400 MHz, CDCl3) δ 7.40 (s, 1H), 7.17 (d, J = 8.2 Hz, 1H), 6.99 (t, J = 7.7 Hz, 2H), 6.94 (d, J = 6.4 Hz, 1H), 6.90 (s, 1H), 6.58 (t, J = 7.7 Hz, 2H), 5.16 (d, J = 2.0 Hz, 2H), 4.43 (q, J = 11.0 Hz, 2H), 3.99 (d, J = 10.9 Hz, 1H), 3.84 (d, J = 10.9 Hz, 1H), 3.28 (t, J = 5.6 Hz, 2H), 2.95–2.75 (m, 3H), 2.73 (t, J = 6.4 Hz, 2H), 2.29 (d, J = 12.7 Hz, 1H), 1.93 (td, J = 11.6, 6.3 Hz, 2H), 1.70–1.64 (m, 3H), 1.47 (dd, J = 11.1, 3.5 Hz, 1H), 1.38–1.27 (m, 4H), 1.22 (d, J = 7.0 Hz, 6H), 1.20 (s, 3H), 0.90 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.26, 146.85, 145.97, 145.81, 144.76, 134.46, 129.26, 127.11, 126.94, 124.24, 124.04, 122.93, 122.86, 116.46, 111.20, 74.05, 50.90, 49.62, 46.93, 44.26, 38.28, 37.39, 36.87, 35.50, 33.47, 30.07, 27.97, 25.26, 23.99, 23.97, 22.34, 18.98, 18.41, 17.28. HRMS-ESI (m/z): calcd for C34H44N4O2 [M + H]+: 541.3543; found: 541.3538.

Dehydroabietyl 2-(4-(indolin-1-ylmethyl)-1H-1,2,3-triazol-1-yl)acetate (5s)

Black solid, yield 22.3%, m.p. 47.3–48.9 °C. IR(KBr) ν/cm−1: 2956, 1751, 1651, 1614, 1462, 1199, 1053, 985, 821; 1H NMR (400 MHz, CDCl3) δ 7.48 (s, 1H), 7.17 (d, J = 7.9 Hz, 1H), 7.08–6.98 (m, 3H), 6.90 (s, 1H), 6.67 (t, J = 7.3 Hz, 1H), 6.48 (d, J = 7.6 Hz, 1H), 5.08 (s, 2H), 4.26 (s, 2H), 4.01 (d, J = 10.9 Hz, 1H), 3.84 (d, J = 10.9 Hz, 1H), 3.31 (t, J = 8.3 Hz, 2H), 2.91 (t, J = 8.1 Hz, 2H), 2.86–2.69 (m, 3H), 2.29 (d, J = 12.6 Hz, 1H), 1.73–1.63 (m, 3H), 1.48 (dd, J = 14.8, 2.8 Hz, 1H), 1.38–1.24 (m, 4H), 1.22 (d, J = 6.9 Hz, 6H), 1.20 (s, 3H), 0.90 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 166.28, 151.58, 146.86, 145.82, 145.08, 134.48, 130.33, 127.29, 126.96, 124.63, 124.28, 124.08, 123.35, 118.12, 107.45, 74.02, 53.15, 50.92, 44.25, 44.18, 38.28, 37.40, 36.88, 35.48, 33.48, 30.10, 28.54, 25.30, 24.02, 18.98, 18.42, 17.31. HRMS-ESI (m/z): calcd for C33H42N4O2 [M + H]+: 527.3386; found: 527.3381.

Dehydroabietyl 2-(4-((1H-indol-1-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5t)

White solid, yield 70.6%, m.p. 63.7–65.1 °C. IR(KBr) ν/cm−1: 2956, 1751, 1598, 1469, 1201, 1153, 1064, 821; 1H NMR (400 MHz, CDCl3) δ 7.60 (d, J = 7.8 Hz, 1H), 7.27 (d, J = 7.8 Hz, 1H), 7.21–7.14 (m, 3H), 7.09 (t, J = 7.0 Hz, 1H), 7.04–6.99 (m, 2H), 6.92 (s, 1H), 6.48 (d, J = 2.6 Hz, 1H), 5.20 (q, J = 16.3 Hz, 2H), 5.00 (q, J = 17.5 Hz, 2H), 3.96 (d, J = 10.9 Hz, 1H), 3.81 (d, J = 10.9 Hz, 1H), 2.89–2.66 (m, 3H), 2.30 (d, J = 12.8 Hz, 1H), 1.72–1.63 (m, 3H), 1.41 (dd, J = 11.7, 2.8 Hz, 1H), 1.33–1.25 (m, 4H), 1.21 (d, J = 2.0 Hz, 3H), 1.20 (d, J = 2.2 Hz, 3H), 1.19 (s, 3H), 0.87 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 165.94, 146.91, 145.90, 145.43, 135.79, 134.49, 128.83, 127.84, 126.96, 124.29, 124.12, 122.92, 121.85, 121.05, 119.73, 109.45, 102.08, 73.87, 50.96, 44.07, 41.84, 38.31, 37.39, 36.85, 35.43, 33.47, 30.06, 25.24, 23.99, 23.97, 18.91, 18.37, 17.27. HRMS-ESI (m/z): calcd for C33H40N4O2 [M + H]+:525.3230; found: 525.3235.

Dehydroabietyl 2-(4-((4-phenylpiperazin-1-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5u

Yellow solid, yield 32.8%, m.p. 50.0–51.7 °C. IR(KBr) ν/cm−1: 2958, 1751, 1612, 1490, 1269, 1136, 1016, 827, 767, 678; 1H NMR (500 MHz, CDCl3) δ 7.67 (s, 1H), 7.28 (t, J = 8.0 Hz, 2H), 7.20 (d, J = 8.2 Hz, 1H), 7.04 (d, J = 8.1 Hz, 1H), 6.99–6.92 (m, 3H), 6.88 (t, J = 7.3 Hz, 1H), 5.18 (s, 2H), 4.07 (d, J = 10.9 Hz, 1H), 3.89 (d, J = 10.9 Hz, 1H), 3.64 (s, 2H), 3.22 (t, J = 4.8 Hz, 4H), 2.94–2.76 (m, 3H), 2.69 (t, J = 4.5 Hz, 4H), 2.32 (d, J = 12.8 Hz, 1H), 1.80–1.70 (m, 3H), 1.53 (dd, J = 11.2, 3.4 Hz, 1H), 1.44–1.33 (m, 4H), 1.26 (d, J = 6.9 Hz, 6H), 1.23 (s, 3H), 0.95 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.29, 151.18, 146.85, 145.78, 134.47, 129.13, 126.94, 124.31, 124.26, 124.02, 119.82, 116.13, 74.06, 52.93, 52.81, 50.92, 48.92, 44.20, 38.25, 37.40, 36.90, 35.50, 33.45, 30.10, 25.28, 24.03, 18.99, 18.42, 17.32. HRMS-ESI (m/z): calcd for C35H47N5O2 [M + H]+: 570.3808; found: 570.3802.

Dehydroabietyl 2-(4-((4-(4-fluorophenyl)piperazin-1-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5v)

Yellow solid, yield 25.2%, m.p. 46.8–48.6 °C. IR(KBr) ν/cm−1: 2958, 1751, 1504, 1462, 1382, 1257, 1201, 1049, 823, 748; 1H NMR (500 MHz, CDCl3) δ 7.69 (s, 1H), 7.20 (d, J = 8.2 Hz, 1H), 7.03 (d, J = 8.1 Hz, 1H), 6.97 (t, J = 8.7 Hz, 2H), 6.93 (s, 1H), 6.87 (dd, J = 9.1, 4.6 Hz, 2H), 5.18 (s, 2H), 4.07 (d, J = 10.9 Hz, 1H), 3.88 (d, J = 10.9 Hz, 1H), 3.65 (s, 2H), 3.14 (t, J = 5.0 Hz, 4H), 2.93–2.75 (m, 3H), 2.70 (t, J = 5.0 Hz, 4H), 2.31 (d, J = 12.8 Hz, 1H), 1.78–1.69 (m, 3H), 1.52 (dd, J = 11.2, 3.3 Hz, 1H), 1.41–1.34 (m, 4H), 1.26 (d, J = 6.9 Hz, 6H), 1.22 (s, 3H), 0.95 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 166.28, 157.25 (d, J = 239.53 Hz), 147.79 (d, J = 3.84 Hz), 146.85, 145.77, 134.47, 126.94, 124.46, 124.26, 124.02, 117.93 (d, J = 7.56 Hz), 115.54 (d, J = 22.05 Hz), 74.05, 52.82, 52.75, 50.92, 49.87, 44.16, 38.24, 37.39, 36.89, 35.49, 33.45, 30.10, 25.28, 24.02, 18.97, 18.41, 17.32. HRMS-ESI (m/z): calcd for C35H46FN5O2 [M + H]+: 588.3714; found: 588.3721.

Dehydroabietyl 2-(4-((1,3-dioxoisoindolin-2-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5w)

White solid, yield 53.4%, m.p. 68.6–70.2 °C. IR(KBr) ν/cm−1: 2955, 2364, 1751, 1587, 1483, 1278, 1001, 748; 1H NMR (400 MHz, CDCl3) δ 7.83 (dd, J = 5.3, 3.1 Hz, 2H), 7.74–7.68 (m, 3H), 7.16 (d, J = 8.2 Hz, 1H), 6.99 (d, J = 8.1 Hz, 1H), 6.91 (s, 1H), 5.11 (s, 2H), 4.79 (q, J = 10.8 Hz, 2H), 4.00 (d, J = 10.9 Hz, 1H), 3.84 (d, J = 10.9 Hz, 1H), 3.02–2.66 (m, 3H), 2.27 (d, J = 12.8 Hz, 1H), 1.86–1.57 (m, 3H), 1.46 (dd, J = 11.0, 3.5 Hz, 1H), 1.38–1.24 (m, 4H), 1.20 (d, J = 6.9 Hz, 6H), 1.17 (s, 3H), 0.88 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 167.54, 166.06, 146.89, 145.78, 143.23, 134.43, 134.07, 132.05, 126.94, 124.46, 124.23, 124.00, 123.43, 74.14, 50.93, 44.21, 38.22, 37.34, 36.86, 35.47, 33.45, 32.65, 30.02, 25.19, 23.96, 23.95, 18.98, 18.35, 17.21. HRMS-ESI (m/z): calcd for C33H38N4O4 [M + H]+: 555.2971; found: 555.2976.

Dehydroabietyl 2-(4-((2,3-dioxoindolin-1-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5x)

Red solid, yield 43.4%, m.p. 97.9–99.7 °C. IR(KBr) ν/cm−1: 2951, 1759, 1712, 1614, 1388, 1267, 1201, 1153, 1068,1010, 819; 1H NMR (400 MHz, CDCl3) δ 7.73 (s, 1H), 7.60–7.55 (m, 2H), 7.26 (d, J = 8.5 Hz, 1H), 7.17 (d, J = 8.2 Hz, 1H), 7.10 (t, J = 7.9 Hz, 1H), 6.99 (d, J = 8.2 Hz, 1H), 6.91 (s, 1H), 5.12 (s, 2H), 4.78 (s, 2H), 4.00 (d, J = 10.9 Hz, 1H), 3.84 (d, J = 10.9 Hz, 1H), 2.91–2.71 (m, 3H), 2.28 (d, J = 12.9 Hz, 1H), 1.75–1.59 (m, 3H), 1.43 (dd, J = 11.4, 3.3 Hz, 1H), 1.32–1.24 (m, 4H), 1.21 (d, J = 2.0 Hz, 3H), 1.20 (d, J = 2.0 Hz, 3H), 1.18 (s, 3H), 0.88 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 183.06, 165.90, 157.91, 150.20, 146.89, 145.79, 138.63, 134.46, 126.97, 125.31, 124.62, 124.25, 124.02, 124.01, 117.54, 111.51, 74.07, 51.13, 44.04, 38.21, 37.34, 36.86, 35.46, 35.02, 33.44, 30.03, 25.22, 24.01, 23.96, 18.95, 18.35, 17.24. HRMS-ESI (m/z): calcd for C33H38N4O4 [M + H]+: 555.2971; found: 555.2973.

Dehydroabietyl 2-(4-((5-fluoro-2,3-dioxoindolin-1-yl)methyl)-1H-1,2,3-triazol-1-yl)acetate (5y)

Red solid, yield 45.3%, m.p. 96.7–98.9 °C. IR(KBr) ν/cm−1: 2945, 1759, 1712,1612, 1388, 1271, 1203, 1143, 1062, 1008, 850; 1H NMR (500 MHz, CDCl3) δ 7.78 (s, 1H), 7.33–7.29 (m, 3H), 7.20 (d, J = 8.2 Hz, 1H), 7.02 (d, J = 8.2 Hz, 1H), 6.94 (s, 1H), 5.16 (s, 2H), 4.79 (s, 2H), 4.03 (d, J = 10.9 Hz, 1H), 3.86 (d, J = 10.9 Hz, 1H), 2.99–2.77 (m, 3H), 2.31 (d, J = 12.8 Hz, 1H), 1.75–1.67 (m, 3H), 1.46 (dd, J = 11.6, 2.7 Hz, 1H), 1.36–1.27 (m, 4H), 1.23 (d, J = 2.7 Hz, 3H), 1.22 (d, J = 2.7 Hz, 3H), 1.21 (s, 3H), 0.91 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 182.54 (d, J = 2.5 Hz), 165.90, 159.47 (d, J = 247.2 Hz), 157.64 (d, J = 1.8 Hz), 146.89, 146.26 (d, J = 2.4 Hz), 145.81, 141.92, 134.46, 126.97, 124.93 (d, J = 24.2 Hz), 124.59, 124.27, 124.04, 118.09 (d, J = 7.3 Hz), 112.92 (d, J = 7.4 Hz), 112.24 (d, J = 24.4 Hz), 73.99, 51.03, 43.95, 38.21, 37.35, 36.86, 35.43, 34.99, 33.44, 30.03, 25.23, 24.02, 23.96, 18.92, 18.36, 17.26. HRMS-ESI (m/z): calcd for C33H37FN4O4 [M + Na]+: 595.2697; found: 595.2689.

Cell culture

Cells: human liver cancer (HepG2) cells, human gastric cancer (MGC-803) cells, human bladder cancer (T24) cells, human lung cancer (A549) cells and human liver (LO2) cells were provided by the Institute of Biochemistry and Cell Biology, China Academy of Sciences. All cell lines were seeded into 70 mm cell and tissue culture dishes in DMEM (Dulbecco's modified eagle medium) medium with 10% FBS (foetal bovine serum), 100 mg mL−1 of streptomycin and 100 units per mL of penicillin, and then incubated at 37 °C with a humidified atmosphere of 5% CO2.

In vitro cytotoxicity

The in vitro cytotoxic potency of compounds 5a–5y was evaluated in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with 5-FU and DOX as the positive controls. After counting the number of cells, the cells were seeded in 96-well plates (180 μL per well at a density of 5 × 104 cells per mL) with DMEM and then incubated for 24 h at 37 °C in 5% CO2. The cells were treated with various concentrations of the synthesized compounds and positive control 5-FU, and then the plates were incubated for 24 h at 37 °C with 5% CO2. Next, 20 μL of a solution of MTT (5 mg mL−1) was added to each well. After incubation for 4 h at 37 °C, the supernatants were carefully removed, and formazan precipitates were dissolved in 150 μL of dimethyl sulfoxide (DMSO). Plates were then shaken (300 rpm) for 10 min. Finally, the absorbance was measured at 490 nm by an enzyme labelling instrument (ELx800). The final IC50 values were calculated by the Bliss method (n = 5). All the tests were repeated in at least three independent experiments.

Hoechst 33258 staining assay

MGC-803 cells were seeded on a sterile cover slip in 6-well plates and treated with compound 5g (0 μM, 2.5 μM, 5 μM, 10 μM) for 24 h. The culture medium containing compounds was removed, and the cells were fixed in 4% paraformaldehyde for 10 min. Then, the cells were washed with PBS and stained with Hoechst 33258 at 37 °C for 5 min in the dark. After being washed with PBS, the cells were observed with the fluorescence microscope.

Colony formation assay

MGC-803 cells were seeded in 6-well plates with 300 cells per well and incubated overnight. Then, the cells were treated with vehicle (0.1% DMSO) or different concentrations of 5g (2.5, 5, 10 μM) for 96 h. After every 24 h, the cell culture medium was refreshed, and the corresponding concentration of 5 g was added every 4 days until the colonies were visible. About 12 days later, the colonies were fixed with 4% paraformaldehyde (Biosharp) and stained with 0.1% crystal violet (Macklin). The pictures were taken with a digital camera, and the number of colonies was counted with ImageJ software.

Cell migration assay

MGC-803 cells (3 × 105 mL−1 per well) were seeded in 6-well plates and incubated overnight. When the confluence reached 90%, the cells were scratched with 10 μL pipette tips. Then, the cells were washed with sterilized PBS three times to remove cell debris. Subsequently, serum-free medium containing 0.1% DMSO or different concentrations of 5g (10, 5 and 2.5 μM) was added. Scratch width was recorded using an inverted microscope at 0 h, 24 h and 48 h. The results were analysed using ImageJ software.

Reactive oxygen species assay

MGC-803 cells (1 × 105 mL−1 per well) were plated in 6-well culture plates and allowed to grow for 24 h. Cells were treated with different concentrations of compound 5g (10, 5 and 2.5 μM) for 24 h. After treatment, cells were washed twice with ice-cold PBS and incubated with 0.1% DCFH-DA (1 mL) for 20 min at 37 °C in the dark. The stained cells were observed under a fluorescence microscope.

Mitochondrial membrane potential assay

MGC-803 cells were seeded in 6 well plates and treated with 0.1% DMSO and compound 5g (10, 5 and 2.5 μM) for 24 h. They were then washed with PBS and fresh medium (1 mL) and JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide) molecular probe (1 mL) were added. After a 20 min incubation at 37 °C, they were rinsed twice with PBS. Visualization of JC-1 aggregates (red fluorescence) and JC-1 monomers (green fluorescence) was done using a filter by fluorescence microscopy.

Cell apoptosis assay

Annexin-V staining was used to analyse the apoptotic potential of synthesized dehydroabietinol triazoles as described previously.27 Briefly, the cells were dosed with different concentrations of compound 5g for 24 h at 37 °C. After 24 h, the cells were collected and washed twice with PBS and then resuspended in 200 μL of 1× binding buffer. The cells were subjected to 5 μL of FITC annexin V and 5 μL propidium iodide (PI) staining using an annexin-V FITC apoptosis kit (BD, Pharmingen) and incubated for 30 min at RT (25 °C) in the dark. Then, 100 μL of 1× binding buffer was added. The apoptosis ratio was quantified using a flow cytometer (Becton-Dickinson Accuri C6), and data were analysed using the FlowJo software.

Cell cycle assay

MGC-803 cells were treated with different concentrations of compound 5g. After 24 h of incubation, cells were washed twice with ice-cold PBS, fixed and permeabilized with ice-cold 70% ethanol at 4 °C overnight. The cells were treated with 100 μg ml−1 RNase A at 37 °C for 30 min, washed with ice-cold PBS and stained with 1 mg mL−1 propidium iodide (PI) (BD, Pharmingen) in the dark at 4 °C for 30 min. The samples were analysed by a flow cytometer (Becton-Dickinson Accuri C6), and data were analysed using the ModFitLT software.

Ca2+ level assay

MGC-803 cells were seeded on a sterile cover slip in 6-well plates and treated with compound 5g (0 μM, 2.5 μM, 5 μM, 10 μM) for 24 h. The culture medium containing compounds was removed and stained with Fluo-3 AM at 37 °C for 20 min in darkness. After being washed with DMEM, the cells were observed with the fluorescence microscope.

4. Conclusions

In the present study, 25 novel dehydroabietinol derivatives bearing a triazole moiety were synthesized, and their structures were established on the basis of IR, 1H NMR, 13C NMR and HRMS. All the target compounds were assessed for anti-proliferative activity against four cancer cell lines (MGC-803, A549, T24 and HepG2) using the MTT assay. Our results showed that compound 5g inhibited MGC-803 cell lines with an IC50 value of 4.84 μM, which was 5-fold more potent than the positive control drug 5-FU, and it induced early apoptosis in MGC-803 cells and arrested the cell cycle mainly at the G0/G1 stage. Meanwhile, it also reduced the mitochondrial membrane potential of MGC-803 cells, with increasing intracellular ROS and Ca2+ levels. These experiments showed that the majority of these compounds cause apoptosis via the mitochondrial pathway. The introduction of the 1,2,3-triazole group improved the antitumor potency of parent compound, which is worthy of further study.

Conflicts of interest

There are no conflicts to declare.

Supplementary Material

MD-014-D2MD00427E-s001

Acknowledgments

This work was supported by the Guangxi Natural Science Foundation of China (2018GXNSFAA281200), Project for Science Research and Technology Development of Guilin (20210227-1), the Open Fund of Guangxi Key Laboratory of Chemistry and Engineering of Forest Products(GXFK2202), the State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources (Guangxi Normal University)(CMEMR2019-B02), Cultivation Plan of Thousands of Young and Middle-aged Backbone Teachers in Guangxi Colleges and Universities.

†

Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2md00427e

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