In Vivo Evaluation of Analgesic Activities of Dioscorea dumetorum (Kunth) Pax and Tragia benthamii Bak

Abstract

An analgesic is any member of the group of drugs used to achieve analgesia, relief from pain without loss of consciousness. Pain is one of the devastating health problems commonly treated with medicinal plants. Dioscorea dumetorum (Kunth) Pax (Family Dioscoreaceae) is one of the popular species of yam, usually found in Africa and mostly consumed in West Africa. Tragia benthamii Bak. is an herbaceous twining or trailing plant which belongs to the Euphobiaceae family. The plant is indigenous to Ivory Coast extending wide spread across Africa including Nigeria. This study investigated the analgesic activities of Dioscorea dumetorum and Tragia benthamii leaves’ methanol extract on mice. Acetic acid-induced writhing method was engaged. Thirty-two (32) healthy and energetic mice were grouped into eight (8) of four (4) mice. Indomethacin (25 mg/kg) was administered to the positive control group, negative control group received distilled water (10 ml/kg) while each extract treatment groups received 50, 100, 200 mg/kg respectively. Analgesic activities of the plants’ extract were assessed by counting the number of writhes for 30 minutes after a latency period of 5 minutes. Reduction in the number of writhes as compared to the control groups was considered as evidence for analgesic potential of the plants. In this study, the positive control (Indomethacin), D. dumetorum and T. benthamii significantly decreased the mean number of abdominal constrictions or writhes in a dose dependent manner following the order of 200>100>50 mg/kg. The result showed that the potency of the two plants’ extract was superior to that of Indomethacin but T. benthamii (200 mg/kg) exhibited higher analgesic activity. Values of reduction time in writhing were significantly different (P<0.05) among the treatments. This research revealed effective potential analgesic effects of D. dumetorum and T. benthamii which could be attributed to the presence of phytochemicals in them. Therefore, further studies to explain their mechanisms of action should be conducted to aid the discovery of new therapeutic agents for the treatment of pains.