Antinociceptive properties of morusin, a prenylflavonoid isolated from Morus nigra root bark.

The antinociceptive effects of morusin (1), the main prenylflavonoid present in the Morus nigra root barks have been investigated in classical models of pain in mice. The results showed that 1 exhibits a promising antinociceptive or analgesic profile by the intraperitoneal route, being more potent than some standard drugs used as reference. The mechanism by which the morusin exerts antinociceptive activity still remains undetermined, but our results strongly suggest that it involves the participation of the opioid system.