RESUMO:A planta Plinia glomerata (Myrtaceae), popularmente conhecida como cabeludinha ou "jabuticaba-amarela", ocorre amplamente no sul do Brasil e é cultivada como ornamental e frutífera comestível. O presente trabalho avaliou as propriedades antimicrobianas dos extratos, frações e substâncias puras isoladas da planta contra bactérias e fungos patogênicos. As concentrações inibitórias mínimas (CIM) foram determinadas através do método de diluição em ágar. As frações acetato de etila (AE) e fração aquosa (AQ) demonstraram a melhor atividade contra Staphylococcus aureus. A fração AQ também foi efetiva contra Escherichia coli. As substâncias puras, ácido 3,4,3'-trimetóxi-fl avelágico-4'-O-glicosídeo e ácido 3,4,3'-trimetóxi-fl avelágico foram inativas até a concentração de 500 g/mL contra os microrganismos testados. Em relação aos resultados antifúngicos, os extratos metanólico (EM) e acetônico (EA) e a fração aquosa (AQ) mostraram boa atividade somente contra dermatófi tos. Os resultados obtidos permitem concluir que a Plinia glomerata possui princípios ativos com ação antimicrobiana, sugerindo que outras substâncias da planta estão agindo contra os microrganismos indicados ou a existência de efeitos sinérgicos.Unitermos: Plinia glomerata, atividade antimicrobiana, ácido 3,4,3'-trimetóxi-fl avelágico-4'-O-glicosídeo, ácido 3,4,3'-trimetóxi-fl avelágico.ABSTRACT: "Evaluation of the antimicrobial effects of Plinia glomerata (Myrtaceae)". Plinia glomerata, commonly known as "yellow jaboticaba" or "cabelluda" occurs widely in south of Brazil. This work evaluated the antimicrobial properties of the extracts, fractions and isolated compounds of this plant against pathogenic microorganisms, bacteria and fungi. The minimal inhibitory concentration (MIC) was determined through the method of dilution in agar. The ethyl acetate (EtOAc) and aqueous fractions demonstrated the best activity against Staphylococcus aureus. The aqueous fraction also exhibited good activity against Escherichia coli. The pure substances 3,4,3'-trimethoxy-fl avellagic-4'-O-glucose acid and 3,4,3'-trimethoxy-fl avellagic acid were inactive up to 500 g/mL. Regarding results against fungi, EA and EM extracts as well as AQ fraction showed good activity only against dermatophytes. The results suggest that P. glomerata produces active principles with antimicrobial activity, suggesting that other substances from the plant are acting against the microorganisms or the existence of synergic effects.

The chemical study of Heterothalamus alienus gave rutin, spathulenol (1), (1R,7S)-germacra-4(15),5,10(14)-trien-1beta-ol (2), sakuranetin (3), padmatin 3-acetate (4), (2R,3R)-dihydroquercetin-7,3',4'-trimethyl ether (5), (2R,3R)-dihydroquercetin-7,4'-dimethyl ether (6), (2R,3R)-3-acetoxy-5,7,4'-trihydroxyflavanone (7), as the main components of an antifungal extract of the aerial parts of the plant. Compound 2 showed moderate activity, with Epidermophyton floccosum being the most susceptible species (MIC = 100 microg/mL); compound 3 showed the best antifungal behavior having a broad spectrum of action and the lowest MICs. This flavanone along with flavanolol 5 showed very good activity against standardized (MIC = 31.2 microg/mL) as well as clinical isolates of Trichophyton rubrum and T. mentagrophytes (MIC ranges 31.2-62.5 microg/mL and 31.2-125 microg/mL, respectively) and demonstrated not only fungistatic but also fungicide properties. Flavanolol 6 was active against all the dermatophytes tested with MICs of 62.5-250 microg/mL. Rutin, spathulenol (1) and the 3-acetylated flavanones 4 and 7 were inactive or marginally active against the fungal panel.

Epidendrum mosenii is a Brazilian medicinal plant, traditionally used to treat infections and pains. This study reports on the chemical composition and microbiological properties of different parts and in different seasons of this plant. Results demonstrate that 4,3',5'-trihydroxy-3-methoxy-dihydrostilbene (1), 4,5-dihydroxy-3,3-dimethoxy-dihydrostilbene (2) and pholidotin (3) were mainly present in the roots in all seasons, and the yield of mass extract increased their recovery in other parts, such as the stem and leaves for compounds (2) and (3), in summer and winter, respectively. The antifungal results indicate that compounds (1) and (2) have interesting activity against Cryptococcus neoformans, Microsporum gypseum, Trychophyton rubrum and Trychophyton mentagrophytes with MIC values between 62.5 and 125 µg/mL. Taken together, these results strongly suggest that the antifungal properties of E. mosenii are related, at least in part, to the presence of dihydrostilbenes 1 and 2, and this is useful for quality control of phytopreparations based on this plant, justifying the popular use of this plant to treat infections.