In vitro evaluation of antioxidant and antimicrobial activities of the root of Rheum tanguticum

Abstract

Rheum tanguticum, belonging to the family Polygonaceae, is one of the most important Traditional Chinese Medicines (TCM) which have been used for centuries. The roots, stems, and rhizomes have been reported to contain active pharmacological components that are of biological importance. The rhizomes and roots of Rheum species have been one of the most important and abundant ingredients used in TCM and have been used in the prevention of many diseases since prehistory. It has been reported to possess various pharmacological activities such as anticancer, antifungal, antiviral, antibacterial, purgative, hepatoprotective, anti-inflammatory, anti-platelet aggregation, anticoagulant, etc. An In vitro antioxidant activity of the DPPH Radical Scavenging Activity of ethanol, methanol, ethyl acetate, and water extracts of the root of R. tanguticum was found to be concentration-dependent and had an IC50 of 17.327 µg/mL, 18.848 µg/mL 19.769 µg/mL, and 49.639 µg/mL respectively as compared to the standard, L-ascorbic acid of 7.4 µg/mL. The crude extract was highest in methanol (42.25%), followed by ethanol (30.59%), water (25.55%), and ethyl acetate (10.40%) extracts. The antimicrobial activity of the root of R. tanguticum of ethanol, methanol, ethyl acetate, and water extracts was determined using the paper disc and agar well diffusion methods and exhibited a range of activity against Staphylococcus aureus, Pseudomonas aeruginosa, Pseudomonas solanacarum, and Xanthomonas oryzae as compared to the positive control, neomycin. The high phenolic content, antioxidant and antimicrobial activities exhibited by the root of R. tanguticum is an indication of the widely used of the plant as one of the main ingredients in TCM and could be used as a prototype in developing natural cost-effective antibiotics against a wide range of pathogenic microorganisms and oxidative-related diseases.