Table 1.

Bi- and tricyclic proline-based DKP with simple side chains.

Entry	Structure	Name	Cell Line	Activity IC50 [μM]	Reference
1.	1	cyclo(l-Phe-l-Hyp)	U87-MG	5.8 ± 1.7	[105]
			U251	18.6 ± 0.1	[105]
			HCT-116	>25 1	[106]
			OVCAR-8	>25 1	[106]
			SF-295	>25 1	[106]
2.	2	cyclo(l-Leu-l-Hyp)	U87-MG	14.5 ± 1.6	[105]
			U251	29.4 ± 1.3	[105]
3.	3	cyclo(l-Leu-l-Pro)	U87-MG	1.3 ± 0.1	[105]
			U251	19.8 ± 0.8	[105]
			ECA-109	55 2	[107]
			HeLa-S3	41 2	[107]
			PANC-1	14 2	[107]
			HCT-116	16 1	[108]
			HepG2	≥50 1	[108]
			MCF7	30 1	[108]
4.	4	cyclo(d-Leu-l-Pro)	ECA-109	44 2	[107]
			HeLa-S3	52 2	[107]
			PANC-1	55 2	[107]
5.	5	cyclo(l-Ile-l-Pro)	ECA-109	50 2	[107]
			HeLa-S3	45 2	[107]
			PANC-1	56 2	[107]
			HCT-116	22 1	[108]
			HepG2	≥50 1	[108]
			MCF7	27 1	[108]
6.	6	cyclo(l-Ile-l-Hyp)	ECA-109	54 2	[107]
			HeLa-S3	47 2	[107]
			PANC-1	42 2	[107]
7.	7	cyclo(4-S-hydroxy-d-Pro-d-Ile)	SF-268	>295 3	[109]
			MCF-7	204 3	[109]
			H460	234 3	[109]
			HT-29	270 3	[109]
			CHO-K1	>295 3	[109]
8.	8	cyclo(l-Phe-l-Pro)	HCT-116	21.4 1	[106]
			OVCAR-8	18.3 1	[106]
			SF-295	16.0 1	[106]
			ECA-109	42 2	[107]
			HeLa-S3	36 2	[107]
			PANC-1	50 2	[107]
9.	9	cyclo(l-Phe-d-Pro)	HCT-116	38.9	[110]
			HepG2	≥50	[110]
			MCF-7	102.0	[110]
10.	10	cyclo(d-Phe-d-Pro)	HCT-116	94.0	[110]
			HepG2	≥50	[110]
			MCF-7	114.0	[110]
11.	11	Penicillatide B	HCT-116	23.0	[110]
			HepG2	≥50	[110]
			MCF-7	≥50	[110]
12.	12	cyclo(l-Phe-2OH-d-Pro)	HCT-116	30 1	[108]
			HepG2	≥50 1	[108]
			MCF7	30 1	[108]
13.	13	cyclo(l-Val-l-Pro)	HeLa	33.3 4	[111]
			K562	n.a.	[111]
			HL-60	n.a.	[111]
			BGC-823	n.a.	[111]
			MCF-7	n.a.	[111]
14.	14	Bacillusamide B	HCT-116	25 1	[108]
			HepG2	≥50 1	[108]
			MCF7	27 1	[108]
15.	15	Brevianamide F, cyclo(l-Trp-l-Pro)	HCT-116	>25 1	[106]
			OVCAR-8	11.9	[106]
			SF-295	>25 1	[106]
16.	16	cyclo(l-Trp-l-Hyp)	HL-60	64.34	[112]
17.	17	cyclo(d-Leu-2-OH-Pro)	HL-60	98.49	[112]
18.	18	Penicimutide	HeLa	39.4 5	[111]
			K562	n.a.	[111]
			HL-60	n.a.	[111]
			BGC-823	n.a.	[111]
			MCF-7	n.a.	[111]
19.	19	cyclo(l-Pro-l-Pro)	ECA-109	30 2	[107]
			HeLa-S3	40 2	[107]
			PANC-1	34 2	[107]

¹ IC₅₀ [μg/mL]; ² the inhibitory effect at 20 μM, inhibition rate (%); ³ GI₅₀ (μM); ⁴ inhbition rate [%] at at 100 μg/mL (510.2 μM); ⁵ IR % at at 100 μg/mL (480.8 μM); n.a.—not active.