Anti-inflammatory action of a novel peptide, SEK-1005, isolated from a Streptomyces

The pharmacological activity of a novel cyclic peptide (SEK-1005: C(45)H(70)N(8)0(13)) isolated from Streptomyces nobilis was studied in rats during the development of inflammation. SEK-1005 (0.1-0.5 mg/kg, i.p.) suppressed the passive Arthus reaction and the carrageenin-induced oedema. A steroidal anti-inflammatory drug, prednisolone (10 mg/kg, i.p.), also was effective on both inflammations. However, indomethacin (5 mg/kg, i.p.), a cyclooxygenase inhibitor, was less effective on the passive Arthus reaction. Also interesting was that the SEK-1005 effect showed its maximum level after a 24-h lag period and that its effect, as well as the prednisolone effect, was reduced by the treatment with a protein synthesis inhibitor, cycloheximide. SEK-1005 and prednisolone also showed marked protection against the adjuvant-induced arthritis, but failed to prevent the tuberculin response. These findings indicate that SEK-1005 is a new type of non-steroidal anti-inflammatory agent with an action similar to that of prednisolone.