Anti-inflammatory, Antipyretic, and Safety Assessment of Aqueous and Ethanolic Leaf Extracts of Pistia stratiotes Linn (Araceae)

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2012
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Abstract
Pistia stratiotes Linn has been reported to have therapeutic effect on arthritis, conjunctivis, and iritis. Thus, this study sought to determine the efficacy of aqueous and ethanolic leaf Pistia stratiotes leaf extracts on acute and chronic inflammatory disorders and to establish its safety for use. Carrageenan-induced paw edema, adjuvant and formalin-induced arthritis, endotoxin-induced uveitis and other mediator-induced inflammation using PGE2, serotonin, bradykinin, and histamine was induced in Sprague-Dawley rat. Antipyretic, acute and delayed and ocular toxicity assessment were also performed. The extracts significantly reduced (P ≤ 0.05-0.001) paw thickness in all the models of acute inflammation except the 300 mg/kg doses. In adjuvant-induced arthritis, the extracts, except the 300mg/kg ET PSE doses, caused significant (P ≤0.05–0.001) reduction in ipsilateral paw swelling, similar to the effects of methotrexate, dexamethasone, and diclofenac. White blood cell number, erythrocytes sedimentation rate and C- reactive proteins decreased significantly (P ≤0.05–0.01) in arthritic rats treated with the 30 mg/kg dose of aqueous extract and those treated with methotrexate. Histopathological assessment confirmed the efficacy of 30mg/kg dose of the aqueous extract in the management of arthritis in rats. There was significant reduction (P ≤ 0.05-0.01) in paw thickness of formalin-induced arthritic animals treated with both aqueous and ethanolic leaf extracts with effects comparable to the reference drugs. Lipopolysacharride-induced fever in rats was also significantly reduced (P ≤ 0.05-0.01) at all doses of the extract treated animals similar to that of acetaminophen. The extracts significantly reduced protein exudation, inflammatory cell infiltration and vasodilation of the iris vessels (P ≤ 0.05-0.01) associated with uveitis in endotoxin-induced uveitis in rats. Safety assessment showed that the aqueous extract caused reduction in the number of red blood cells (hemolysis and presence of urobilinogen in urine), proteinuria and microalbuminuria indicating possible acute kidney impairment. But the topical application of the extracts directly into the the conjunctival sac did not show any toxic effect on the ocular tissues.
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A Thesis Submitted In Fulfilment of the Requirement for the Award of Master of Philosophy (Pharmacology) Degree in the Department of Pharmacology
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