I3-naringenin-II8-4 '-OMe-eriodictyol - a new potential analgesic agent isolated from Rheedia gardneriana leaves

This paper describes the isolation, identification and analgesic activity o f a new biflavonoid from Rheedia gardneriana leaves, which correspond to I3 -naringenin-II8-4'-OMe-eriodictyol (GB-2a-II-4'-OMe) (1), with a methoxyl g roup in position 4 of ring-II. Its structure was determined by spectroscopi c data and confirmed by an alkaline hydrolysis. Its analgesic effect was ev aluated in a writhing test and a formalin test in mice. It was found that t his compound exhibits potent and dose-related analgesic action in both expe rimental models, with ID50'S values of 4.5 mu mol/kg against the writhing t est and 8.2 and 6.8 mu mol/kg against the first and second phase of the for malin test, respectively. It was several times more potent than some well-k nown analgesic drugs used as reference.