Bioactive chemical constituents and comparative antimicrobial activity of callus culture and adult plant extracts from Alternanthera tenella.

Crude extracts of a callus culture (two culture media) and adult plants (two collections) from Alternanthera tenella Colla (Amaranthaceae) were evaluated for their antibacterial and antifungal activity, in order to investigate the maintenance of antimicrobial activity of the extracts obtained from plants in vivo and in vitro. The antibacterial and antifungal activity was determined against thirty strains of microorganisms including Gram-positive and Gram-negative bacteria, yeasts and dermatophytes. Ethanolic and hexanic extracts of adult plants collected during the same period of the years 1997 and 2002 [Ribeirão Preto (SP), collections 1 and 2] and obtained from plant cell callus culture in two different hormonal media (AtT43 and AtT11) inhibited the growth of bacteria, yeasts and dermatophytes with inhibition halos between 6 and 20 mm. For the crude extracts of adult plants bioassay-guided fractionation, purification, and isolation were performed by chromatographic methods, and the structures of the isolated compounds were established by analysis of chemical and spectral evidences (UV, IR, NMR and ES-MS). Steroids, saponins and flavonoids (aglycones and C-glycosides) were isolated. The minimum inhibitory concentration (MIC) of the isolated compounds varied from 50 to 500 microg/mL.

Evaluation of the antimicrobial activity of crude extracts and isolated constituents from Chresta scapigera

Crude extracts and eight isolated compounds from Chresta scapigera were evaluated for antibacterial and antifungal activities by the agar-well diffusion method. Twenty strains, including Gram-positive and Gram-negative bacteria and yeasts were used in the bioassay. Hexane extracts presented the best results while ethanol extracts did not indicate inhibition of the microbial growth. Amongst the evaluated compounds b-amyrin acetate, tiliroside and luteolin showed the strongest antimicrobial effect.

Os extratos brutos e oito constituintes isolados de Chresta scapigera foram avaliados para as atividades antibacteriana e antifúngica, utilizando o método de difusão em ágar. Vinte cepas indicadoras, incluindo bactérias (Gram-positivas e Gram-negativas) e leveduras, foram utilizadas no bioensaio. Os melhores resultados foram obtidos para os extratos hexânicos, enquanto os extratos etanólicos não inibiram o crescimento microbiano. Acetato de b-amirina, tilirosídeo e luteolina foram os mais eficazes dentre os constituintes avaliados.

Avaliação da atividade antimicrobiana e citotóxica de extratos de Gochnatia polymorpha ssp floccosa / Evaluation of antimicrobial and cytotoxic activitiy of extracts from Gochnatia polymorpha (Less) ssp floccosa

Neste estudo procedeu-se a avaliação da atividade antimicrobiana e citotóxica de extratos de Gochnatia polymorpha ssp floccosa, espécie empregada na medicina popular contra doenças respiratórias. Folhas, cascas do tronco e ramos foram extraídos com hexano, diclorometano e etanol, sucessivamente, sendo obtidos os respectivos extratos brutos. A atividade antimicrobiana foi determinada pelo método de difusão em ágar utilizando-se bactérias Gram-positivas, Gram-negativas e fungos. A avaliação da citotoxicidade foi realizada empregando-se o ensaio de letalidade contra Artemia salina. Nenhum dos extratos mostrou atividade citotóxica. Os extratos das folhas apresentaram uma fraca atividade antimicrobiana frente a algumas cepas de Staphylococcus aureus e Streptococcus mutans, enquanto o extrato em diclorometano dos ramos e o extrato em etanol das cascas foram ativos contra Micrococcus luteus, Staphylococcus aureus e S. epidermidis. A maior atividade antimicrobiana foi observada para o extrato em diclorometano das cascas, que inibiu o crescimento de Micrococcus luteus, Staphylococcus aureus, S. epidermidis, Streptococcus mutans, Enterococcus faecalis e Candida albicans. Esta atividade parece estar relacionada à presença de diterpenos no extrato. Nenhum dos extratos estudados (a 5,0 mg/mL) mostrou atividade frente a cepas de bactérias Gram-negativas. Esses resultados demonstram o potencial dessa planta como fonte de compostos antibacterianos e justificam, parcialmente, seu uso popular.

The antimicrobial and cytotoxic activities of Gochnatia polymorpha ssp floccosa, a medicinal plant used against respiratory diseases, were evaluated. Successive petroleum ether, dichloromethane and ethanol extracts of dried leaves, trunk bark and stems were used in the brine shrimp lethality bioassay and tested against 22 strains of microorganisms (Gram-positive and Gram-negative bacteria and fungi) by the well-diffusion agar method. None of the extracts showed cytotoxicity on the brine shrimp bioassay. The extracts of leaves showed a mild activity against some strains of Staphylococcus aureus and Streptococcus mutans. The ethanol extracts of trunk bark and dichloromethane extract of stems also showed activity against Micrococcus luteus, Staphylococcus aureus and S. epidermidis. The highest activity was found in the dichloromethane extract of trunk bark, which showed significant antibacterial and antifungal activities against Micrococcus luteus, Staphylococcus aureus, S. epidermidis, Streptococcus mutans, Enterococcus faecalis and Candida albicans. Diterpenes are present in this extract and could be responsible for the activity. All the screened extracts were shown to be inactive (at 5.0 mg/mL) against strains of Gram-negative bacteria tested. These results indicate the potential of G. polymorpha ssp floccosa as a source of antibacterial compounds and partly support the use of this plant in folk medicine.

Antibacterial screening of anthocyanic and proanthocyanic fractions from cranberry juice.

The effect of anthocyanin- and proanthocyanidin-rich fractions isolated from cranberry juice was studied for their antibacterial activity against nine bacterial strains. Activity was assessed by the agar diffusion assay. Staphylococcus aureus ATCC 6538 was the only strain to exhibit some susceptibility to four out of 10 anthocyanin-rich fractions tested. A variable susceptibility of S. aureus, Enterococcus faecalis ATCC 10541, and Micrococcus luteus ATCC 9341 to proanthocyanidin- rich fractions was also observed. Streptococcus mutans strains as well as Escherichia coli ATCC 10538 and Pseudomonas aeruginosa ATCC 27853 were not susceptible to any of the cranberry juice samples or fractions at the tested concentrations. There was no clear correlation between Gram-positive or Gram-negative bacterial susceptibility to cranberry juice. In this work, the role of cranberry juice anthocyanic and proanthocyanic fractions upon bacterial viability is discussed.

Comparative study of antibacterial and antifugal activity of callus culture and adult plants extracts from Alternanthera maritima (Amaranthaceae)

Neste estudo procedeu-se a avaliação da atividade antibacteriana e antifúngica dos extratos brutos de Alternanthera maritima (Amaranthaceae) planta in natura de duas coletas distintas e obtidos por cultura de células buscando-se averiguar a manutenção da atividade antimicrobiana dos extratos obtidos da planta in vivo e in vitro. A ação antibacteriana e antifúngica foi determinada pelo método de difusão em ágar (técnica do poço) utilizando-se trinta cepas de microrganismos indicadores (bactérias Gram-positivas e Gram-negativas, leveduras e dermatófitos). Todos os extratos obtidos com solventes orgânicos avaliados apresentaram-se bioativos com halos de inibição de 6 a 20 mm. Os extratos da planta in natura das duas coletas (Restinga de Marica (RJ), verão de 1995 e 1998) inibiram o desenvolvimento de diferentes microrganismos (bactérias, leveduras e dermatófitos). Os extratos obtidos da cultura de calos desenvolvidos em duas condições de cultivo diferentes, também se mantiveram bioativos. Assim, os resultados obtidos encorajam a realização de novos estudos com esta espécie vegetal para se determinar quais as substâncias presentes nos extratos e que contribuem para a atividade biológica, como também para entender seu mecanismo de ação e avaliar sua toxicidade, visando uma possível aplicação farmacêutica.

A new heptasubstituted (E)-aurone glucoside and other aromatic compounds of Gomphrena agrestis with biological activity.

A new aurone 1 and two known substances, aurantiamide acetate (2) and tiliroside (3), were isolated from the ethanolic extract of Gomphrena agrestis. The structural determination of 1 was based on spectroscopic and spectrometric data. The substance was defined as (E)-3'-O-beta-D-glucopyranosyl-4,5,6,4'-tetrahydroxy-7,2'-dimethoxyaurone. Biological activity of the ethanolic crude extract and isolated compounds against bacteria, fungi and Leishmania amazonensis amastigotes was evaluated. This appears to be the first report documenting aurone and aurantiamide compounds in the Amaranthaceae family. In the evaluation of biological activity the ethanolic extract of G. agrestis and compounds 1, 2, and 3 were shown to be active mainly against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa.