Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.
Molecules. 2012 May 8;17(5):5385-95. doi: 10.3390/molecules17055385.
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 50 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.
越南肾茶被认为是一种重要的传统民间药物。本研究评估了越南肾茶的乙醇和水提取物的体外抗氧化、抗菌以及对人外周血单核细胞（PBMC）的免疫调节特性。采用 DPPH 自由基清除法测定抗氧化活性，采用圆盘扩散法和最小抑菌浓度（MIC）法测定四种细菌（革兰氏阳性和革兰氏阴性）的抗菌效果。此外，还通过 MTT 测定法研究了提取物的免疫调节潜力。越南肾茶水提取物具有显著的自由基清除活性，IC₅₀为 50.96 µg/mL，而乙醇提取物的 IC₅₀为 21.4 µg/mL。越南肾茶水提取物对金黄色葡萄球菌表现出最佳的抗菌活性，抑菌圈为 10.5 mm，MIC 值为 1.56 mg/mL。此外，MTT 测定结果表明，两种植物提取物均能以浓度依赖的方式刺激 PBMCs 体外增殖，但水提取物对 PBMCs 具有显著的活性。这些发现表明，越南肾茶具有较高的抗氧化活性，可作为免疫调节剂。
