Evaluation of the antimicrobial activity of Acalypha monostachya Cav. (Euphorbiales: Euphorbiaceae)

Acalypha monostachya (Euphorbiaceae) is used by the inhabitants of San Rafael and Zapotitlan Salinas, Puebla, Mexico, to alleviate illnesses of bacterial and fungal origin. We analyzed the antimicrobial activity of A. monostachya and some of its chemical features. The extracts were obtained by percolation. The antibacterial and antifungal activities were examined through the disc-diffusion method. The general toxicity was carried out by using Artemia salina. The quenching of free radicals by extracts was evaluated by the decolouration of a methanol solution of DPPH∙. Total phenols were determined by Folin Ciocalteu reagent. Gram-positive and negative bacteria were sensitive to methanol and hexane extracts. The methanol extract had a bactericidal effect on Vibrio cholera Tor (MIC = 1000 µg/mL). The fungi strain most sensitive to this extract was T. mentagrophytes (LC50 = 430 µg/mL). The methanol extract showed inhibition of DPPH∙ radical (SC50 = 3.45 µg/ml), 43.4% of total phenolics and was toxic against A. salina (LC50 = 4.5 µg/mL). The methanol extract showed a variety of phenolic compounds, while hexane extract showed different fatty acids methyl ester. The bacterial, antifungal, antioxidant activities and a qualitative chemical characterization of A. monostachya’s extracts are reported here for the first time.   Key words: Acalypha monostachya, antimicrobial activity, medicinal plants, chemical characterization, plant extracts analysis.