Contribuição ao conhecimento químico de plantas do gênero Tephrosia: investigação química e ensaios biológicos de Tephrosia egregia Sandwith (Fabaceae)

Abstract

The present work describes the chemical study of leaves, stems and roots of the Tephrosia egregia Sandwith (Fabaceae) species, through the analysis of the volatile and nonvolatile constituent of the specie. The determination of the volatile chemical composition of leaves and stems of T. egregia showed the predominance of sesquiterpenes, with some monoterpenes and trisnor-sesquiterpenes. The comparison between identified constituents in the leaves (16; 88.75%) and stems (13; 85.22%) showed a similarity between the samples, although the trisnor-sesquiterpenes geijeren and pregeijeren were the major constituents in both the essential oils. From the chromatographic investigation of the essential oil of leaves, the trisnor-sesquiterpene dictamnol was isolated for the first time in the Tephrosia genus. The chromatographic investigation of the roots of T egregia yields pongachalcone and praecansone B, of pongaflavone, of 6a,12a-dehydrorotenone and 12a-hydroxyrotenone, the mixture of sitosterol and stigmasterol, and their glucosylated foul's, and the maackiain. From its leaves were isolated p-coumaric acid and ferulic acid. This two compounds had been isolated for the first time in the genus. The assays with extracts and isolated substances of T. egregia showed that the studied specie has very important larvicidal activity against Aedes aegypti and allelopathic activity, with best result for the ethanolic extract of the roots. In other hand, the bioassays of antimicrobial activity against of S. aureaus, E. coli, P. aeruginosa, S. choleraesuis and C. albicans, and the nematicidal activity on Meloidogyne incognta not shown significant results.