Bio-active secondary metabolites from two Malaysian Clusaceae: Calophyllum flavo-ramulum and C. wallichianum
Résumé
Calophyllum species (Clusiaceae) are known as a rich source of various secondary metabolites and prenylated phenolic derivatives [1] are very common among them. As part of our continuing phytochemical investigation on Calophyllum species from Malaysia [2] we report here our results on the fractionation of different crude extracts obtained from two endemic species -Calophyllum flavo-ramulum and C. wallichianum- which exhibited significant anti-oxidant activities. This study mainly resulted in the identification of phenolic derivatives among which prenylated xanthones and biflavonoids (amentoflavone) appeared as the active principles. The structure of flavoramulone, a new xanthone exhibiting a quite unusual α-dimethyl β-hydroxy tetrahydropyrane was determined through extensive NMR studies.