Table 1.

Src kinase inhibitory activity of peptides.

Entry	Peptide	IC50a (µM)
1	Cyclic [KF]4	1567.6
2	Cyclic [KA]4	≥300
3	Cyclic [RFEF]2	≥300
4	Cyclic [KE]4	≥300
5	Cyclic [RE]4	52.6
6	Cyclic [RF]4	31.3
7	Cyclic [RW]4	21.5
8	Cyclic [RW]3	25.0
9	Cyclic [RW]5	2.8
10	Cyclic [KW]5	46.9
11	Linear (RW)5	7.1
12	Linear (KW)5	69.1
13	Staurosporine	0.6
14	PP2	0.5

^aThe concentration of the compounds that inhibited the enzyme activity by 50%. All the experiments were carried out in triplicate.