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Molecules 2012, 17(5), 5385-5395; doi:10.3390/molecules17055385

Free Radical Scavenging, Antimicrobial and Immunomodulatory Activities of Orthosiphon stamineus

Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
Institute of Biological Science (ISB), Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
Department of Biological Science, Faculty of Biosciences and Bioengineering, Universiti Teknologi Malaysia, UTM Skudai, Johor 81310, Malaysia
Department of Chemistry, Faculty of Science, University Malaya, Kuala Lumpur 50603, Malaysia
Department of Microbiology, Faculty of Medicine and Health Sciences, Sana’a University, Sana’a, Yemen
Authors to whom correspondence should be addressed.
Received: 12 March 2012 / Revised: 10 April 2012 / Accepted: 17 April 2012 / Published: 8 May 2012
(This article belongs to the Section Natural Products)
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Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC50 9.6 µg/mL, whereas the IC50 for the ethanol extract was 21.4 µg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.
Keywords: antibacterial; minimum inhibitory concentration; peripheral blood mononuclear cells (PBMCs); DPPH antibacterial; minimum inhibitory concentration; peripheral blood mononuclear cells (PBMCs); DPPH
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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MDPI and ACS Style

Alshawsh, M.A.; Abdulla, M.A.; Ismail, S.; Amin, Z.A.; Qader, S.W.; Hadi, H.A.; Harmal, N.S. Free Radical Scavenging, Antimicrobial and Immunomodulatory Activities of Orthosiphon stamineus. Molecules 2012, 17, 5385-5395.

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