Synthesis and activity of amides of tripeptides as potential urokinase inhibitors

Figures & data

Table 1.  Structures of obtained peptides: H-d-Ser-Ala-Arg-NH-X.

Compound	X
1	(CH2)2-NH2
2	(CH2)3-NH2
3	(CH2)4-NH2
4	(CH2)5-NH2
5	(CH2)6-NH2
6	(CH2)7-NH2
7	(CH2)8-NH2
8	(CH2)9-NH2
9	(CH2)2-OH
10	(CH2)3-OH
11	(CH2)4-OH

Table 2.  Analytical data of the synthesized compounds.

Compound	Yield (%)	MW	[M + H]^+	Retention time (min)
1	47	374	375	17.1
2	46	388	389	17.3
3	48	402	403	17.2
4	42	416	417	16.5
5	43	430	431	18.1
6	39	444	445	16.9
7	21	458	459	17.3
8	45	472	473	20.1
9	44	375	376	17.9
10	39	389	390	17.9
11	40	403	404	18.1

Table 3.  Inhibition of H-d-Ser-Ala-Arg-NH-X on the amidolytic activity of enzymes.

No.	X	Ki (μM)
		Urokinase S-2444	Thrombin S-2238	Trypsin Bzl-l-Arg-pNA·HCl	Plasmin S-2251
1	(CH2)2-NH2	n.i.	n.i.	n.i.	n.i.
2	(CH2)3-NH2	n.i.	n.i.	n.i.	n.i.
3	(CH2)4-NH2	n.i.	n.i.	n.i.	n.i.
4	(CH2)5-NH2	6.3 ± 0.5	n.i.	n.i.	37 ± 3
5	(CH2)6-NH2	n.i.	n.i.	2.5 ± 0.2	181 ± 14
6	(CH2)7-NH2	244 ± 19	n.i.	30 ± 2	364 ± 28
7	(CH2)8-NH2	87 ± 7	0.24 ± 0.02	10 ± 0.7	n.i.
8	(CH2)9-NH2	293 ± 22	n.i.	5 ± 0.4	90 ± 7
9	(CH2)2-OH	n.i.	n.i.	n.i.	727 ± 54
10	(CH2)3-OH	n.i.	n.i.	15 ± 1.2	1090 ± 81
11	(CH2)4-OH	n.i.	n.i.	10 ± 0.7	545 ± 45
	2-phenethyl-SO2-d-Ser-Ala-Arg-al	IC50 = 3.1 nM^16 Ki = 3nM^15	—	—	IC50 = 367 nM^16 —
	i-Boc-d-Ser-Ala-Arg-al	IC50 = 23.1 nM^16 Ki = 28 nM^15	—	—	IC50 = 1460 nM^16 —

Note. n.i., no inhibition was observed in maximum concentration (0.02M).

Figure 1.  Lineweaver–Burk analysis of compound 4 inhibition of urokinase was performed in amidolytic assays with S-2444 as described in “Enzymatic investigations.” S-2444 substrate concentration was 3 mM. Compound 4 concentration was 2 mM. Data represent the means of triplicate determinations.