Studies on o-methylflavinantine

The antinociceptive effects of O-methylflavinantine (OMF), a morphinandienone alkaloid, were investigated in the mouse hot plate and abdominal constriction tests (nociceptive agents: 5-Hydroxytryptamine, acetylcholine, bradykinin, prostaglandin, E (1) (PGE (1), formic acid and phenylquinone). The potency of OMF in the hot plate test was approximately 10 times less than that of morphine and the effect was naloxone reversible. In the abdominal constriction test, morphine was 78-650 times more potent than OMF, depending on the nociceptive agent used, but a higher dose of naloxone was necessary to reverse the response to formic acid. Pretreatment of mice with reserpine (1 mg/kg, s.c., 24 h) reduced and alpha-methyl-p-tyrosine (200 mg/kg, i.p., 3 h) potentiated the antinociceptive effects of both morphine and OMF in the hot plate test. The results are considered to indicate that OMF possesses centrally mediated antinociceptive activity which is similar to that of morphine.