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 (CL 50 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.

Plants possess a renewable source of metabolites with enormous chemical structural diversity, which may have potential therapeutic relevance. Furthermore, this chemical diversity favors the possibility of finding new and different chemical constituents with antimicrobial, antioxidant and anti-tumor activities. This work analyzed preliminary phytochemical profiles and evaluated the antimicrobial, antioxidant and cytotoxic activities of hexane extracts of leaves of ten species of the family Melastomataceae. Phytochemical screening was performed using staining methods while total phenols and flavonoids were quantified by spectrophotometry. Antimicrobial activity was evaluated using the disk diffusion method. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazil (DPPH) method. Toxicity was recorded using the lethality test with Artemia salina Leach (1819). Cytotoxic activity of the extracts was assessed in vitro with acute monocytic leukemia cells (THP-1). Phytochemical analysis detected the presence of tannins, terpenes, steroids, polyphenols and flavonoids and the absence of alkaloids. Clidemia capitellata (Bonpl.) D. Don had the greatest amount of polyphenols (205.95 mg/g ± 4.14) while Clidemia hirta (L.) D. Don had the highest content of total flavonoids (143.99 mg/g ± 4.18). The hexane extracts did not show antimicrobial activity nor toxicity against Artemia salina. The extract of Tibouchina francavillana Cogn. was the most active in sequestering the DPPH radical. The extracts showed cytotoxicity in THP-1 cells with the appearance of apoptotic bodies and cell death. The extracts of Miconia amoena, Clidemia sericea and Clidemia capitellata are non-toxic against Artemia salina and induce the formation of apoptotic bodies and cell death of the THP-1 lineage.

O mel de abelhas vem sendo utilizado na medicina popular para o tratamento de infecções e contra danos oxidativos. Entretanto, a composição do mel é bastante variável, pois depende da composição do néctar da espécie vegetal, da espécie de abelha produtora, das condições ambientais, da coleta e processamento. O presente estudo objetivou avaliar a atividade antibacteriana, antioxidante, teor dos compostos fenólicos totais e flavonoides totais do mel de Nannotrigona testaceicornis L. A atividade antibacteriana foi realizada pelo método de difusão em discos e concentração inibitória mínima. A capacidade antioxidante foi investigada através do ensaio de captura do radical livre 2,2-difenil-1-picrilhidrazila. O teor total de fenóis totais e flavonoides totais foi quantificado por espectrofotometria. As amostras dos meses de maio e junho/2013 inibiram o crescimento bacteriano para todas as bactérias analisadas. Todas as amostras de mel apresentaram ação antibacteriana frente a Pseudomonas aeruginosa. O teste ANOVA mostrou que houve diferença estatisticamente significante entre os meses para as bactérias Pseudomonas aeruginosa; Escherichia coli; Micrococcus luteus e Staphylococcus aureus. No ensaio de determinação da concentração inibitória mínima, as amostras de maio/2013, março/2014 e junho/2014 foram mais ativas frente a Micrococcus luteus. A capacidade antioxidante acima de 60% foi observada na amostra de maio/2013. As amostras de janeiro/2014 e maio/2103 se destacaram na quantificação de fenóis totais e flavonoides totais, respectivamente. Houve correlação positiva entre a ação antioxidante e flavonoides totais. O mel in natura de Nannotrigona testaceicornis L. apresenta potencial antimicrobiano e capacidade sequestradora de radicais livres.