Abstract

MARTINEZ AGUILAR, Yordan et al. Secondary metabolites and in vitro antibacterial activity of extracts from Anacardium occidentale L. (Cashew tree) leaves. Rev Cubana Plant Med [online]. 2012, vol.17, n.4, pp. 320-329. ISSN 1028-4796.

Introduction: the leaves of Anacardium occidentale L. (cashew tree) have optimal contents of nutrients and have been used as antidiarrheal and nutraceutical in animals; however, the phytochemical characterization and antimicrobial of the extracts are insufficient. Objective: to determine secondary metabolites and in vitro antimicrobial activity of Anacardium occidentale L. leaf extracts. Methods: fluid extract and 20% tincture were initially obtained from powdered leaves of Anacardium occidentale L. Phytochemical screening and quality testing of pharmaceuticals were performed. The antibacterial activity was determined (Escherichia coli, Staphylococcus aureus Bacillus subtilis, Salmonella enteric and Shigella sp.) in three dilutions of the dry extract (50, 100, and 200 mg/mL) from the 20 %, tincture and from the n-hexane, chloroform and ethyl acetate extracts (Escherichia coli, Staphylococcus aureus, Shigella sp., Salmonella enteric, Pseudomonas aerugiosa and Enterobacter aerogenes), with subsequent phytochemical characterization. Results: high content of coumarins and other metabolites such as saponins, flavonoids, reducing sugars, free aminoacids, triterpenes and/or steroids, phenols and/or tannins were detected in the fluid extract and the 20 % tincture. The refractive index, the density, the pH and the total solids showed similar results for the fluid extract and for the 20 % tincture. Besides, no significant differences were found in these parameters six months after the study. The dry extract showed antibacterial activity against Staphylococcus aureus, with the largest inhibition zones for dilution of 200 mg/mL. Furthermore, the ethyl acetate extract indicated the slowest growth of this bacterial pathogen, according to inhibition hales. In the chloroform and ethyl acetate extracts, abundant coumarins and reducing sugars were found. Conclusions: the fluid extract and the 20% tincture from Anacardium occidentale leaves contained mostly coumarins and their quality remained the same six months afterwards. N-hexane, chloroform and ethyl acetate extracts disclosed staphylococcal activity in vitro whereas reducing sugars and coumarins were detected in the last two extracts.

Keywords : cashew; tree; antibacterial; plant extracts; phytochemical screening.

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