Estudo fitoquímico e avaliação da atividade antibacteriana de Macrolobium acaciifolium (Benth.) Benth. (Fabaceae)

Abstract

The Chemistry of Natural Products has provided the discovery of new biologically active molecules, which are extracted from plant species with diversified uses for humans and animals. One of these species is Macrolobium acaciifolium, a large tree belonging to the Fabaceae family, subfamily Caesalpinioideae, present not only in the Amazon, but in other states of Brazil, besides other countries in Central and South America. This project aimed to carry out a phytochemical study and evaluation of the antibacterial activity of M. acaciifolium. The leaves and branches of the plant were grounded and extracted with hexane and methanol. The phytochemical study of M. acaciifolium extracts allowed the isolation and identification of 18 substances, 15 of which are reported for the first time in this species. From the methanolic extract of the leaves, the flavonoids luteolin-3'-O-α-L-rhamnoside (1), neoastilbin (2), astilbin (3), neoisoastilbin (4), isoastilbin (5), quercetin-3-O-α-L-rhamnoside (6), quercetin-3-O-rutinoside (7), kaempferol-3-O-rutinoside (8), quercetin-3-O-glisoside (9) and kaempferol-7-O-rutinoside (10) and the methanolic extract of branches, the flavonoids chrysoeryol (13), apigenin (14), 7,4'-dihydroxyflavone (16), eriodictyol (17) and luteolin (18), in addition to the phenylpropanoids 3,4-dihydroxybenzoic acid (11), 3-methoxy,4-hydroxybenzoate (12) and methyl 3,4-dihydroxybenzoate (15). From the leaves hexane extract were isolated triterpenes lupeol (19), β-amyrin (20) and 24-methylenecycloartanol (21) and from branches hexane extract, mixture of triterpene friedelin (22) and xanthone lichexanthone (23). The β-sitosterol (24) and stigmasterol (25) steroids were isolated as mixture in both hexane extracts. The structural identification of the compounds was established by 1H NMR, 13C, HSQC, HMBC and COSY analyses. EtOAc phase of branches and hydromethanolic phase of leaves showed antimicrobial activity against Staphylococcus aureus and Morganela morganii at a concentration of 1000 μg/mL. Hexane extract leaves showed antimicrobial activity against Aeromonas hydrophila at 1000 μg/mL. These results corroborate the importance of M. acaciifolium as a source of secondary metabolites.