Antimicrobial, antioxidant and cytotoxic activites and chemical profile of species of Miconia Ruiz Pav., Clidemia D. Don and Tibouchina Aubl. (Melastomataceae)

The resistance of microorganisms to current antimicrobials, and the deleterious effects caused by the excessive free radical manufacturing in the human body and their relationship with increasing global incidence of cancer, has led to a continuous search for new chemical agents that can contribute to the fight against these ills. The objective of the present work was to evaluate the antimicrobial, antioxidant and cytotoxic activities and determine the chemical profile of ethyl acetate extract of ten species of the family Melastomataceae. Antimicrobial activity was assessed by the methods of disk diffusion in agar and microdilution in broth (MIC-µg/mL). Antioxidant activity was measured by DPPH free radical capture assay while toxicity was evaluated with Artemia salina Leach. Cytoxicity was evaluated by in vitro tests with THP-1-cells. Identification of the classes of metabolites was performed using chemical reagents, while quantification of total phenols (EGA/g) and total flavonoids (EQ/g) was done by spectrophotometry. The extract of Clidemia capitellata exhibited activity against Micrococcus luteus with MIC = 62.5-μg/mL. The extract of C. hirta had the highest sequestering activity of DPPH free radicals (63.54-%). The toxicological assay revealed high toxicity for Miconia alborufescens extract (CL50 61.6-μg/mL). Cytotoxic activity of extracts for THP-1-cells was observed through visualization of apoptotic bodies and cell death. Phytochemical analysis detected the presence of condensed tannins, terpenes, steroids and polyphenols, and the absence of alkaloids. The assays performed provided promising results, suggesting the continuation of new chemical-pharmacological evaluations and the isolation of the active principle of the extracts. Key words: Bacteria, Artemia, total phenols, THP-1 cells, toxicity.