Phytochemical Analysis of Ethanol Leaf Extract of Nymphaea lotus and the Possible Mechanism of Its Anti-inflammatory Activity Using Rats

Abstract

Inflammation is a natural defense mechanism triggered by harmful stimuli, including tissue damage and pathogenic infections. Nymphaea lotus, a medicinal plant indigenous to tropical Africa and belonging to the Nymphaeaceae family, has been traditionally employed in African folk medicine to treat various ailments, including inflammatory disorders. This study aimed to investigate the anti-inflammatory effects of the ethanol leaf extract of Nymphaea lotus (ELENL), providing a scientific basis for its traditional use. Standard methods were used for the analysis of the phytochemical composition of the ELENL.The anti-inflammatory effect of ELENL was assessed using egg albumin-, Carrageenan-, and Formalin-induced inflammation models in an in vivo assay. For the inflammatory studies, rats were divided into five groups (n=6 per group): Group 1 (control): received normal saline (10 ml/kg), Groups 2-4: received ELENL at doses of 200, 400, and 800 mg/kg, respectively. Group 5 (standard): received diclofenac (10 mg/kg) For mechanism of action studies, rats were assigned to three groups (n=6): Group 1 received either 0.01 μg/ml Prostaglandin E2 or 5% w/v Arachidonic acid; Groups 2 and 3 received ELENL at 400 and 800 mg/kg, respectively. The phytochemical analysis of the leaf extract of Nymphaea lotus revealed the presence of tannins, flavonoids, alkaloids, terpenoids, and glycosides. Dose-dependent inhibition of carrageenan- and formalin-induced paw edema was observed, indicating significant anti-inflammatory activity. Egg albumin-induced oedema was significantly inhibited (p < 0.05) by 65.9% at 800 mg/kg. The extract significantly reduced prostaglandin E2-induced paw edema (44.5% at 400 mg/kg and 72.5% at 800 mg/kg) and inhibited paw edema by 69.8%. The findings of this study show that the ethanol leaf extract of Nymphaea lotus has notable anti-inflammatory properties. The results of this studies indicate that the extract exerts a dual action, effectively inhibiting both pathways of arachidonic acid metabolites.