Advanced Biomedical Research (Jan 2020)
In vitro evaluation of the antimicrobial activity of leaf extracts of Litsea iteodaphne against a selected group of bacteria including methicillin-resistant Staphylococcus aureus
Abstract
Background: The quest for scientific endorsement of new drugs from plants continues due to the rising antibiotic resistance against pathogenic bacteria. Litsea iteodaphne is used in Sri Lanka in the treatment of infectious diseases. Therefore, in vitro antibacterial activity of L. iteodaphne plant extracts were evaluated against selected human pathogenic bacteria. Materials and Methods: Antibacterial activity of 400, 40, and 4 mg/ml concentrations of hexane, ethanol, and aqueous leaf extracts of L. iteodaphne were evaluated against Staphylococcus aureus, Psedomona s aeruginosa, Klebsiella pneumoniae, Escherichia coli, and methicillin-resistant S. aureus (MRSA) clinical isolates using disc diffusion method. Minimum inhibitory concentration (MIC) was identified, and phytochemical screening was carried out. Results: Significant zones of inhibition ranging from 5.7 mm to 8.1 mm, 7.1 mm to 8.0 mm, and 7.6 mm were obtained for ethanol, hexane, and aqueous extracts at 400 mg/ml, respectively, against above four bacteria. For MRSA clinical isolates, zones of inhibition ranging from 6.1 mm to 10.9 mm, 6.7 mm to 10.8 mm, and 6.4 mm to 8.6 mm were obtained for ethanol, hexane, and aqueous extracts at 400 mg/ml, respectively. Ethanol extract of L. iteodaphne showed the lowest MIC value (0.0256 mg/ml). Phytochemical screening revealed the presence of tannins, cardiac glycosides, reducing sugars, phenolic compounds, saponins, and flavonoids. Conclusions: L. iteodaphne crude leaf extracts showed promising antibacterial activity against Gram-positive and Gram-negative bacteria and clinical isolates of MRSA. Further investigations toward fractionation and the identification of an active compound will enhance the antimicrobial potential of L. iteodaphne.
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