Leaf extract of Crinum bulbispermum has antinociceptive activity in rats

In Sri Lankan folk medicine, the leaves of Crinum bulbispermum Burm. (Family: Amaryllidaceae) are claimed to be useful for earache, which is suggestive of antinociceptive activity. The aim of this study was to examine scientifically the antinociceptive activity of Crinum bulbispermum leaves. One of three doses (1000, 1500 and 3000 mg/kg, N = 6/group) of aqueous leaf extract (ALE) or 1 ml of distilled water (DW) (vehicle) (N = 6) was orally administered to male rats and antinociceptive activity was determined using three models of nociception (tail flick, hot plate and formalin tests). In the hot plate test, slight (18-42%) but significant (P < 0.05) overall prolongation of reaction time was evident up to 4 h. In the hot plate test, reaction time was markedly (84-121%) and significantly increased by the high dose up to 3 h. In contrast, in the formalin test, the high and mid doses significantly impaired the number of lickings and time spent on licking at both phases, whilst the lower dose impaired only the time spent on licking at the late phase. Collectively these results suggest that the antinociception is mediated both spinally and supraspinally and is effective against phasic and continuous non-inflammatory/inflammatory pain. Additionally, the ALE had antihyperalgesic activity. The antinociception of the ALE appear to results from opioid mechanisms, sedation and antioxidant activities. Unfortunately, ALE is mild to moderately toxic.