Investigação química das folhas e galhos de Guarea convergens (Meliaceae).

Abstract

The Meliaceae family comprises has about 50 genus and approximately 700 species, generally arboreus, occurring in regions Pantropical. The predominant metabolites in the family are triterpenoids with cycloartane, dammarane, tirucallane and apotirucallane skeleta, further degraded triterpenoids (limonoids and steroids). The genus Guarea possesses about 50 species however chemical studies are limited to ten species, whose reports are sesquiterpenes, diterpenes and triterpenes (cycloartane, tirucallane lanostane and apotirucallane), further limonoids. Although the occurrence of approximately 30 species of Guarea in Amazon have few relates on chemical studies, this acted as stimulus for our investigation about Guarea convergens T.D. occurrent in Amazon. Thus, leaves and branches collected in the Adolpho Ducke Forest Reserve were submitted to maceration to obtain the organic extracts. The chromatographic fractionning of the CH2Cl2 and MeOH leaves extracts led to the isolation of apotirucallane triterpenes: the 24R-acetoxy,25-hydroxy-3,7-dioxo-apotirucalla-14-en-21,23- olide (1) and the 7a,24R,25-trihydroxy-3-oxo-apotirucalla-14-en-21,23-olide (4), steroids: ergosta-5,24-diene-3 ,4 ,22S-triol (2) and ergosta-5,24-diene-3 ,7 -21-triol (3). The compounds 1, 3 and 4 are being reported for first time. The CH2Cl2 branches extract yielded a mixture of steroids (b-sitosterol and stigmasterol, 5) and the tirucallane triterpenes namely melianone (6) and melianodiol (7). This is the first chemical study effected with species G. convergens whose isolated and identified compound provide contributions to knowledge of the chemosystematic of the Rutales order.