Potential of TPC and TFC as Free Radical Scavengers and Microbial Growth Inhibitors in Himalayan Endemic Artemisia sieversiana Ehrhl Ex Willd. (Asteraceae) Plant from Northeastern, Pakistan

Abstract

In various microorganisms, various defense mechanisms have evolved against the commercially available antimicrobial agents with increased resistance. Natural antimi-crobial agents of plant origin are better alternatives when an infectious disease arises due to resistant microbial strains. Here, we have evaluated the efficacy of total phenolics and total flavonoids with antioxidant and antimicrobial potential of Artemisia sieversiana Ehrhl Ex Willd. plant extracted with methanol, ethyl acetate, ethanol, n-hexane, and chloroform using soxhlet procedures The evaluation of TPC was achieved with Folin-Ciocalteu’s reagent method and quanti-tative estimation of TFC was done with the aluminum chloride colorimetric method. The antioxi-dant activities were estimated using FRSA-DPPH and TAC methods. The inhibitory activities of five solvent extracts of A. sieversiana against 2 gram-positive and 2 gram-negative pathogenic bac-terial strains (B. subtilis, P. aerogenosa, S. aureus, and E. coli) were evaluated using the well dif-fusion technique. The highest percentage yields of A. sieversiana extracts were obtained in ethanol (4.8 g, 12.1%) and methanol (4.01 g, 10%), while minimum extract yield was obtained in n-hexane (0.53 g, 1.34%). Both phenolics and flavonoids were higher in ethanol, methanol, and ethyl acetate ex-tracts while minimal in n-hexane extracts. Ethanol extract has shown maximum (69%) DPPH ac-tivity with a lower IC50 value (181 μg/ml), while the highest IC50 values of 330 and 325μg/ml were recorded for n-hexane and ethyl acetate extracts. The ethyl acetate and chloroform extracts dis-played overall highest TAC values. All the tested extracts of A. sieversiana exhibited variable in-hibitory effects in a dose-dependent manner against the tested bacterial strains with minimum 9.08 ± 0.23 to maximum 21.23 ± 7.04 mm inhibition zones. Methanol and ethyl acetate extracts at 2 to 4 mg/ml showed greater MIC results against P. aeruginosa in comparison to the B. subtilis strain. The extracts of A. sieversiana have been found to be rich in TPC and TFC with re-markable antibacterial and antioxidant efficacies, and the plant extracts could be employed as pos-sible alternatives to synthetic drugs in various nutraceutical and pharmaceutical industries.