Avaliação dos constituintes químicos de Guarea convergens, G. scabra, G. silvatica (voláteis) e G. humaitensis (fixos e voláteis) e atividade sobre Aedes aegypti

Abstract

The Meliaceae family has pantropical occurrence and include around 700 species distributed in 50 genus. The main secondary metabolites of the family are limonoids, terpenoids, steroids e and flavonoids. The Guarea genus found in Tropical America and Africa contains about 50 species, of which around 10 species have chemical studies. The studies showed that sesqui-, di-, triterpenes and limonoids are the main constituents. This work aimed to evaluate the chemical constituents of Guarea convergens, G. scabra, G. silvatica (volatile) and G. humaitensis (volatile and non-volatile) and the activity against Aedes aegypti, the main species transmitter of the dengue. In this manner, vegetal samples collected in the Ducke Reserve were submitted to hydrodistillation to obtain essential oil and/or macerated to obtain the organic extract. The essential oils obtained showed the predominance of sesquiterpenes. In the branches of G. convergens the majority components were α-santalene (26.26%), α-copaene (14.61%), drim-7,9 (11)-diene (6.85%) and β-santalene (6.32%), and in the oil of G. humaitensis branches predominated the caryophyllene epoxide (40.91%), humulene epoxide II (14.43%) and β-bisabolene (8.36%). In leaves of G. scabra, the majority components were cis-caryophyllene (33.37%) and α-trans-bergamotene (11.88%), and in G. silvatica, caryophyllene epoxide (36.54% leaves; 8.57% branches), espatulenol (14.34% branches and 4.17% leaves) and β-elemene (6.20% leaves), further the kaurene diterpene in leaves (15.61%). The phytochemical study of extracts of leaves and branches of G. humaitensis lead to obtaining a mixture of sesquiterpenes caryophyllene epoxide and humulene epoxide II, mixture of steroids β-sitosterol and stigmasterol, a new limonoid of the mexicanolide type, 2-deoxygrandifolide A, the coumarin scopoletin and the triterpene cycloart-23-ene-3β,25-diol. Among essential oils tested against the larvae of. A. aegypti, the oil of the G. humaitensis branches presented the best larvicidal activity (49,0 CL50= μg.mL-1).