Immunosuppressive activity of hymenistatin I

Hymenistatin I (HS-I), a cyclic octapeptide [c-(-Pro-Pro-Tyr-Val-Pro-Leu-Ile-Ile-)], was synthesized by the solid-phase peptide synthesis method and examined for its immunosuppressive activity in the humoral and cellular immune responses. The peptide activity was tested on cell lines producing various cytokines. The results are compared with the activity of the well-known immunosuppressive agent cyclosporin A (CsA). It was found that hymenistatin I exerts immunosuppressive effect (both in the humoral and cellular immune responses) comparable with that of CsA. Comparison of the influence of HS-I and CsA on cytokines production suggests that the mechanisms of the interaction with the immunological system are substantially different for the two compounds tested.