Pharmacological Evaluation of Anti-Inflammatory Activity of Aqueous Extract of the Root Bark of Capparis Erythrocarpos

Abstract

Background: Capparis erythrocarpos is a medicinal plant that is used extensively in folklore medicine in Ghana to manage various inflammatory conditions. Previous pharmacological study showed that an ethanolic extract of the roots of Capparis erythrocarpos may have anti-inflammatory activity. However, no attempt has been made to investigate the basis of the effect(s), if any, of the aqueous extract on the inflammatory processes or ascertain its safety. Aim: The aim of this study was to verify claims in folklore medicine that the aqueous extract of the root bark of Capparis erythrocarpos has anti-inflammatory activity, as well as to ascertain its safety in animal models. Methodology: The extract was prepared by extraction of the pulverized root of C. erythrocarpos with water in a Soxhlet extractor. Reaction time, volume of paw oedema, weight of section of mouse pinna, and white blood cells (WBC) count in inflammatory exudates, were used as measurable indicators of the inflammatory processes, namely, perception of pain, increased capillary permeability, vasodilation and recruitment of white blood cells. In each of the respective inflammation studies, 25 rats (150 - 230 g) or mice (24 - 30 g) of both sexes were randomly selected and assigned to 5 treatment groups of 5 rats each (cohort). One group received normal saline (control) whiles two other treatment groups received specified dose levels of the extract (20 – 80 mg/kg). In all cases, an internal standard (morphine, indomethacin or celecoxib) was employed. The animals were subjected to the appropriate stimulus, the individual responses were measured and the mean responses of the cohorts determined. Plasma prostaglandin E2 (PGE2) concentration of indomethacin-, celecoxib- and extract-treated rats was also determined using Enzyme-Linked Immunosorbent Assay (ELISA). The mean plasma PGE2 concentration of a treatment group was compared to that of control, and the percent inhibition caused by a treatment determined. The toxicity of the extract was studied in rats given the extract orally for a period of 28 days, followed by histopathological examination of the liver and kidneys under light microscope. Results: The extract (20 – 80 mg/kg), like indomethacin, significantly increased pain perception threshold, reduced paw oedema and inhibited PGE2 biosynthesis (p˂0.05) in the animal models of acute pain and inflammation used in this study, though not in a dose-dependent manner. The aqueous extract was also found to inhibit recruitment of inflammatory cells to the site of injury, which contributes to the validation of its anti-inflammatory activity. The extract (50 – 200 mg/kg) did not cause any significant alteration in the histoarchitecture of the liver and kidneys of extract-treated rats compared to controls when the extract was administered orally over a period of 28 days. Conclusion: The results indicate that the aqueous extract of the root of C. erythrocarpos exhibited significant analgesic and anti-inflammatory properties. The extract, at the stated dose range, was neither hepatotoxic nor nephrotoxic in rats over the 28-day observation period. The findings support ethnomedical claims of therapeutic efficacy of the extract in management of pain and inflammatory conditions.

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Thesis (MPhil)

Keywords

Anti-Inflammatory, Root Bark, Medicinal Plant, Pharmacology, Ghana

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