Phytochemical Screening and Evaluation of Pharmaceutical Activity of Nymphaea nouchali

Abstract

Nymphaea nouchali is a species of perennial aquatic flowering plants with large, round and mostly floating leaves and rhizomes. For generations, this plant has been used in traditional medicinal practices in Southern Africa for various conditions including management of inflammatory conditions and dysmenorrhea. However, the biosafety and efficacy of the plant species native to Zimbabwe with regards to common pharmacological endpoints has never been systematically, scientifically validated. The aim of this present study therefore was to qualitatively determine the pharmacologically relevant metabolites prevalent in N. nouchali, to confirm the biosafety using laboratory animals as well as to determine the antioxidant activity, as well as its anti-inflammatory activities. The metabolomic screening was carried out using classical wet chemistry techniques, OECD guidelines were used to determine the acute oral toxicity profile of the plant. The egg albumin denaturation assay was used to determine anti-inflammatory activity with diclofenac as a standard. The anti oxidancy was evaluated with ascorbic acid as a standard using the DPPH assay method. The phyto-screening confirmed the presence of numerous biomedically relevant secondary metabolites including phenols alkaloids and flavonoids. The biosafety studies using rat models confirmed that N. nouchali is nontoxic with an LD50 above 5000 mg/kg body weight. The lyophilized hydroethanolic extract demonstrated significant anti-inflammatory activity approximately 50% of diclofenac at all concentrations and high antioxidant activities (87.77% DPPH scavenging activity) comparable to ascorbic acid. It was therefore concluded that the plant is nontoxic to humans, possesses numerous relevant bioactive secondary metabolites and has significant  antioxidant and anti-inflammatory activity. Our results support the continued use of plant extracts as an adjunct therapy for managing inflammatory conditions in traditional medical practices in Southern Africa.