Evaluation of Inhibition of Prostaglandin E2 Level by Psychotria sarmetosa Leaves used in Traditional Porridge in Sri Lanka

Abstract

Prostaglandin E2 (PGE2) is a mediator associated with physiological and pathological conditions. Although it has various physiological roles at normal level, alterations in PGE2 are associated with pathological conditions such as inflammatory diseases. Psychotria sarmentosa (“Gonica” in Sinhala) leaves are consumed in the form of a traditional porridge. Indigenous healers prescribe an aqueous extract of these leaves for individuals who have been physically assaulted, indicating that it may possess potent analgesic and/or antiinflammatory activity. Our previous studies have also shown that aqueous extract of these leaves has significant anti-inflammatory activity in rats. As PGE2 is an inflammatory marker, an attempt has been made to evaluate inhibition of PGE2 level on adjuvant-induced arthritis rat model, in the present study. Healthy adult male Wistar rats (150-200 g) were used for the experiment (n=6/ group). The negative and positive control groups were orally administered with 1.0 ml of distilled water and celecoxib (20 mg/kg b.w.) respectively. The test group received a dose of 100 mg/kg b.w.of aqueous extract of P. sarmentosa leaves (AEPL) which was found to be the most effective dose during the studies on acute anti-inflammatory activity. The oral treatments were started on day 14 and continued to day 28. This results showed that the treatment with 100 mg/kg b.w.of AEPL significantly (p ≤ 0.05) inhibited the PGE2 level as compared to the negative control. It was 436±85 pg/l in AEPL group whereasit was 792±158 pg/l for negative control. The PGE2 level for celecoxib treated group was 294±54 pg/l. Hence, the present study has demonstrated that the aqueous extract of P. sarmentosa leaves has PGE2 inhibitory activity which may be contributing to its antiinflammatory effect and it justifies the traditional use of this plant in the treatment of various types of inflammation.