An evaluation of antibacterial activities of Psidium guajava (L.)

The present study was designated to evaluate the antibacterial activities of aqueous and ethanol:water extracts from leaves, roots and stem bark of Psidium guajava L. The antibacterial activities of the extracts against bacteria were tested by using both microdilution assay. The aqueous extracts of...

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Bibliographic Details
Published in:	Brazilian archives of biology and technology Vol. 48; no. 3; pp. 429 - 436
Main Authors:	Sanches, Neviton Rogério(Departamento de Farmácia e Farmacologia), Garcia Cortez, Diógenes Aparício(Departamento de Farmácia e Farmacologia), Schiavini, Michelle Simone(Universidade Estadual de Maringá Departamento de Análises Clínicas), Nakamura, Celso Vataru(Universidade Estadual de Maringá Departamento de Análises Clínicas), Dias Filho, Benedito Prado(Universidade Estadual de Maringá Departamento de Análises Clínicas)
Format:	Journal Article
Language:	English
Published:	Tecpar 01-05-2005 Instituto de Tecnologia do Paraná (Tecpar)
Subjects:	alpha- and beta-amyrin antibacterial activities beta-sitosterol flavonoids Psidium guajava
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Summary:	The present study was designated to evaluate the antibacterial activities of aqueous and ethanol:water extracts from leaves, roots and stem bark of Psidium guajava L. The antibacterial activities of the extracts against bacteria were tested by using both microdilution assay. The aqueous extracts of P. guajava leaves, roots and stem bark were active against the gram-positive bacteria Staphylococcus aureus (MICs=500, 125 and 250 µg/ml, respectively) and Bacillus subtilis (MICs=500 µg/ml), and virtually inactive against the gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa (MICs >1000 µg/ml). The ethanol:water extracts showed higher antimicrobial activity as compared to aqueous extracts. Based on this finding, the ethanol:water extract of P. guajava leaves was fractionated on silica gel column chromatography in a bioassay-guided fractionation affording flavonoid mixture, triterpenes (alpha- and beta-amyrin) and sterol (beta-sitosterol). Flavonoid mixture showed good activity on S. aureus with MIC of 25 µg/ml. beta-sitosterol was inactive for all the bacteria tested. O presente estudo foi conduzido para avaliar a atividade antibacteriana dos extratos etanol:água e aquoso das folhas, raízes e casca do caule de Psidium guajava L. As atividades antibacterianas dos extratos contra as bactérias foram testados usando o ensaio de microdiluição em caldo. O extrato aquoso das folhas, raízes e casca do caule de P. guajava foram ativos contra as bactérias Gram-positivas Staphylococcus aureus (CIMs=500, 125 e 250 µg/ml, respectivamente) e Bacillus subtilis (CIMs=500 µg/ml), e foram inativas contras as bactérias Gram-negativas Escherichia coli e Pseudomonas aeruginosa (CIMs >1000 µg/ml). Os extratos etanol:água apresentaram maior atividade quando comparados com os extratos aquosos. Com base nestes resultados, o extrato de folhas de P. guajava foi fracionado em cromatografia em coluna de sílica gel em um bioensaio de fracionamento direcionado, produzindo uma mistura de flavonoides, uma mistura de alfa e beta-amirina e beta-sitosterol. A mistura de flavonoides mostrou boa atividade sobre S. aureus com CIM de 25 µg/ml. O beta-sitosterol foi inativo para todas as bactérias testadas.
Bibliography:	10.1590/S1516-89132005000300014 http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132005000300014
ISSN:	1516-8913 1516-8913 1678-4324
DOI:	10.1590/S1516-89132005000300014