Evaluation of in vitro antioxidant activity, phytochemical screening of selected medicinal plants of Nepal and in vitro anti-inflammatory Activity of Morus alba L. and Colebrookea oppositifolia J.E. Smith

Abstract

Introduction: Oxidative stress and inflammation are pathophysiological condition of mammalian tissues in response to infectious organisms, toxic chemical substances, physical injury or tumor growth, and leading to local accumulation of plasma fluid and blood cells. The main aim of the present study was to evaluate in vitro antioxidant and in vivo anti-inflammatory activity of Morus alba L., Imperata cylindrica (L.) Beauv, Colebrookea oppositifolia J.E. Smith and Crinum amoenum Roxb. Materials and Methods: Phytochemical screening of the entire sample was carried out by different chemical tests. The in vitro antioxidative activity was evaluated by 2,2’-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity method. Free radicals and reactive oxygen species are also implicated in inflammatory diseases. Therefore, two most potent plants extract, showing best free-radical scavenging activity, that is, M. alba (82%) and C. oppositifolia (79%) at 100 μg/mL concentration were chosen for in vivo anti-inflammatory analysis using 1% w/v carrageenan induced rat paw edema model. Diclofenac sodium was used as a standard drug at the concentration of 50 mg/kg of body weight. Aqueous and ethanolic leaves extract at the concentration of 100 mg/kg and 250 mg/kg were used as test drugs. Standard drug and all the extracts were administered 60 min before carrageenan injection. The paw volume was measured at 1, 2, 3, and 4 h after carrageenan injection, using a plethysmometer. Results: The phytochemical screening of all four plant species revealed that they contain terpenoids, saponins, alkaloids, and flavonoids. The ethanolic extract of M. alba root bark and C. oppositifolia leaves exhibited dose-dependent DPPH radicals inhibition with IC50 value of 51.37 μg/mL and 55.81 μg/mL, respectively, showing comparable potency with ascorbic acid (IC50: 5.47 μg/mL). Both plant extract suppressed rat paw edema significantly (P < 0.05) in a dose-dependent manner, compared to the negative control group. The ethanolic extract of Morus alba and Colebrookea oppositifolia exhibited highest  57.87% and 50.68% inhibition of paw edema volume, respectively, almost similar to the inhibitory effect of the standard drug

Diclofenac sodium (63.39%). Conclusion: Thus, the root bark extract of M. alba and leaves extract of C. oppositifolia possess
potent in vitro antioxidant effect and in vivo anti-inflammatory effect in carrageen induced Wistar rat model.