Antibacterial activity and mutagenicity of leaves of <i>Indigofera tinctoria</i> Linn

Abstract

Objective: Indigofera tinctoria Linn was traditionally been used in the ancient herbal medicine in India/China for epilepsy, nervous disorders, bronchitis, and liver ailments; and also used as an anticardiovascular, but there was no literature evidence substantiating its antibacterial activity. The purpose of this study is to determine the antibacterial and mutagenic properties of an extract prepared from the leaves of I.tinctoria, commonly known as indigo plant. Methods: Minimum inhibitory concentrations (MICs) of the extract are determined with respect to bacterial species by agar dilution as per Clincial and Laboratory Standard Institute and mutagenicity of the extract is determined by Ames test. Results: The respective MICs of the methanol extract of I.tinctoria were methicillin sensitive Staphylococcus aureus 0.125 µg/ml, methicillin resistant S.aureus 0.25 µg/ml, coagulase negative S.aureus 0.25-0.5 µg/ml, vancomycin sensitive Enterococcus faecalis 0.5 µg/ml, vancomycin resistant Enterococcus species 0.125-0.5 µg/ml, Moraxella 2 µg/ml, Streptococcus species 0.125-0.25 µg/ml, Haemophilus influenzae 2-4 µg/ml and against anaerobes is 1-2 µg/ml. Time kill assay were analyzed for methanol extract of I.tinctoria and it showed bacteriostatic and nonmutagenic activity up to 5 mg per plate in Ames test both in the presence and absence of S9 fraction. Conclusion: Methanol extract of I.tinctoria exhibited antibacterial activity, which was more active than that of standard linezolid, against a variety of clinically important bacteria isolated from near by selected hospitals in India and was found to be nonmutagenic up to 5 mg/plate in Ames test.