Abstract

The aim of this study is to investigate phytochemical composition and antibacterial activity of four species of Cnidoscolus [Cnidoscolus infestus Pax and K. Hoffman, Cnidoscolus pubescens Pohl, Cnidoscolus quercifolius Pohl and Cnidoscolus urens (L.) Arthur] used as ethnopharmacologicals in Caatinga. The qualitative phytochemical composition was analyzed by thin layer chromatography using eluent and specific revealing. Antimicrobial activity was evaluated using the agar diffusion method and determining the Minimum Inhibitory Concentration (MIC). The phytochemicals present in all samples were coumarins, phenolic compounds and terpenoids, however, alkaloids and naphthoquinones were not observed. The extract of the barks of C. quercifolius was active against Staphylococcusstrains, with a MIC between 250 and 500 µg/ml and its dichloromethane fraction had MIC between 62.5 and 250 µg/ml against methicillin-resistant Staphylococcus aureus (MRSA). The antimicrobial activities of the bark of C. quercifolius indicated that the mechanism of multidrug resistance of Staphylococcus to current antibiotics does not confer resistance to the compounds present in samples. Thus, identification of the chemical constituents responsible for the antimicrobial activities of C. quercifolius may lead to the identification of new antimicrobial drugs against these pathogens.

Key words: Antimicrobial, Caatinga, multidrug resistance, phytochemistry,Staphylococcus, urtiga.