Antibacterial activity, cytotoxicity, antioxidant capacity and phytochemicals of Rheum australe rhizomes of Nepal

Abstract

Rhizome of Rheum australe D. Don of Nepalese origin was evaluated for its antibacterial, cytotoxic and antioxidant efficacies. The plant extracts significantly inhibited the growth of Gram-positive and Gram-negative bacteria tested. Cytotoxicity of the methanolic and aqueous extracts was tested on the brine-shrimp nauplii and the LC50 value was determined to be 194.98 and 18.28 I¼g/ml, respectively. The aqueous extract contained a higher amount of total phenolics than the methanolic extract and the result was in correlation with their Fe (III) reducing power ability as well. However, the methanolic extract contained more potent DPPH free radical scavengers than the aqueous extract. Two anthraquinones namely chrysophanol and emodin were isolated from the hexane extract.