Evaluation of In vitro Antioxidant, Antimicrobial and Cytotoxicity Activities of Orthosiphon Pallidus Royle

Abstract

Objective: The objective of present research work was to evaluate the in vitro antioxidant, antimicrobial and cytotoxicity activity of Orthosiphon pallidus Royle. Methods:  Total phenolic and flavonoid content of hydroalcoholic extract (50:50) of Orthosiphon pallidus Royle hydroalcoholic extract (OPRHE) was estimated and the in vitro antioxidant activity was determined using ABTS radical scavenging assay and metal chelating assay.  Antimicrobial activity was investigated by agar well diffusion method and MIC was determined. Cytotoxic assay was measured by the SRB method against breast cancer cell lines (MDA-MB-231 and MCF-7) using Rapamycin as standard drug.  Results: The total phenolic and flavonoid content of the hydroalcoholic extract of OPRHE was estimated and the In vitro antioxidant activity was determined using the ABTS radical scavenging assay and metal chelating assay.  Antimicrobial activity was investigated by the agar well diffusion method and MIC was determined. The cytotoxic assay was measured by the SRB method against breast cancer cell lines (MDA-MB-231 and MCF-7) using Rapamycin as standard drug. The total phenolic and flavonoid content of OPRHE was found to be 228.86±0.19 mg gallic acid equivalents/ g plant extract, and 735.86±1.09 mg quercetin equivalents/ g plant extract, respectively. The IC50 value was found to be 59.22±1.28 µg/ml for extract, and that of standard compound gallic acid & BHT was 1.12±0.42 µg/ml and 3.25 ±1.12µg/ml. OPRHE showed a maximum metal chelating effect of 81.21 % at 600 µg/ml. Antimicrobial activity showed the bacterial strain showed the highest zone of inhibition when compared to the fungal strain. The percentage of cytotoxicity was increasing with the increase in concentration steadily up to 7.5 µg/ml on both the cell lines and the CTC50 value of MCF-7 and MDA-MB-231 cell lines was 153.64 & 213.056 μg/ml while rapamycin standard drug showed a CT50 value of 3.86 & 4.091 μg/ml caused 50 % cytotoxicity.  Conclusion: The results of the present investigation demonstrated significant variations in the antioxidant, antimicrobial and cytotoxic effects of hydro alcoholic extract. These data could be helpful in isolation of pure potent compounds with good biological activities from the extract of plant.