In Vitro and in Vivo Pharmacological Activities of the Extracts of Rheum Nobile Hook. F. & Thomson Rhizomes

Rheum nobile Hook. f. & Thomson (family Polygonaceae) is extraordinary, unexploited, and vulnerable Himalayan rhubarb with high ethnomedicinal values. Traditionally in Nepal, its rhizomes are used to relieve pain, swelling, and in bone fractures. In this study, several in vitro and in vivo assays of the rhizome extracts were carried out. The hexane, dichloromethane, ethyl acetate and butanolic extracts obtained after fractionation of 95 % ethanolic extract showed potentially cytotoxicity against Artemia salina nauplii and antibacterial effect. The 80 % ethanolic extract displayed sedative effect in mice (ED50 = 100.32 mg/kg). The same extract inhibited 66.60 and 81.49 % of acetic acid-induced writhes in mice at doses 250 and 400 mg/kg, respectively (p <0.0001). The extract could increase the reaction latency up to 774.59 % in the Eddy's hot plate assay (p <0.0001). A high anti-inflammatory effect was observed in the Albumin-induced paw edema assay. The extract also exhibited hypoglycemic activity by lowering blood glucose level in normoglycemic rats, and antifertility activity in pregnant rats. CNS depressant and antifertility activities are observed for the first time in genus Rheum.