Table 4. Inhibitory effects and IC₅₀ of series I peptide-like ligand binding rhNRP-1 (chemiluminescence detection).

Compound	AA2–AA3 fragment	Inhibition of NRP-1/VEGF-A165 binding [%]							IC50 [μM]
		100 μM	50 μM	25 μM	10 μM	5 μM	2.5 μM	1 μM
2	Pro–Pro	77.0 ± 1.0	67.9 ± 1.4	54.1 ± 1.0	37.1 ± 1.0	—	—	—	20.9 ± 0.3 40
5	Hyp–Hyp	71.7 ± 0.6	63.1 ± 0.2	56.8 ± 0.7	36.7 ± 0.6	—	—	—	21.3 ± 0.6 a
6	Aze–Aze	59.9 ± 0.3	53.6 ± 0.2	41.9 ± 1.8	30.0 ± 1.1	—	—	—	48.6 ± 1.7 b
7	ΔPro–ΔPro	79.3 ± 0.8	72.2 ± 0.6	61.3 ± 0.5	45.4 ± 0.5	—	—	—	14.0 ± 0.1 c
8	Oic–Oic	83.6 ± 0.3	77.6 ± 0.2	68.2 ± 0.2	53.4 ± 1.4	47.8 ± 2.3	42.1 ± 2.6	32.9 ± 2.1	7.2 ± 1.3 d
9	Piz–Piz	70.8 ± 1.0	63.3 ± 1.7	58.7 ± 0.9	45.0 ± 1.9	—	—	—	16.0 ± 0.9 e
10	Tic–Tic	45.2 ± 0.3	40.7 ± 1.1	31.4 ± 0.9	24.7 ± 1.1	—	—	—	>100

^alog IC₅₀ = –4.67 ± 0.06.

^blog IC₅₀ = –4.31 ± 0.08.

^clog IC₅₀ = –4.85 ± 0.05.

^dlog IC₅₀ = –5.14 ± 0.10.

^elog IC₅₀ = –4.80 ± 0.09. R² was between 0.93–0.98. Results are presented as the mean ± SEM.