Analgesic effects of Capsicum frutescens Linn. (Solanaceae) fruit aqueous extract in mice

Jolayemi AT¹* and Ojewole JAO²

¹Department of Anaesthesia and ICU, Goulburn Base Hospital and Senior Lecturer Australia National University (ANU) Goulburn Campus, Goulburn City NSW Australia

²Department of Pharmacology Faculty of Health Sciences, University of KwaZulu Natal Durban.

*Corresponding Author E-mail:  adebayoj@hotmail.com

Accepted 20 October, 2014

Abstract

The analgesic property of Capsicum frutescens LINN. (SOLANACEAE) extract-CFE (98% Capsaicin by NMR) of South African origin in mice (20-30 g), using ‘hot plate’ and ‘acetic acid’ methods was investigated. In the hot plate test, twelve mice in each of 5 groups were administered intraperitoneal (i.p.) CFE or synthetic capsaicin (Fluka Biotechnika-CF) at 0.5-8 mg/kg and at hourly intervals; at 40 C, the mean reaction time (MRT) was estimated. In the ‘acetic acid’ test method, CFE or CF was administered i.p. at various doses (0.5- 8 mg/Kg) at hourly intervals following single treatment using 0.2 mls of 3 % v/v acetic acid-induced writhing responses, or non treated (n=12). Separate groups of rats (n=12) were pre-treated with 100-mg/kg diclofenac (DIC) or morphine (MPN) 10 mg/kg i.p. to evaluate the peripheral analgesic effects and central analgesia, respectively. Data obtained were pooled and analysed by the student’s T-test. The ‘hot plate’ and ‘acetic acid’ test methods showed significant (p<0.0001) prolongation of the MRT and inhibition of writhing responses, respectively, compared to the control. Similar results with a Pearson correlation of 0.999 were obtained in the CF subgroups. This study shows that capsaicin has superior central analgesia compared to equipotency doses of MPN or DIC and comparable peripheral analgesia to either MPN or DIC.

Keywords: Capsicum frutescens, ‘chili’, ethylacetate extract, capsaicin, analgesia, ‘hot plate’ test, ‘acetic acid’ test, analgesiometer, writhings.