PHARMACOLOGICAL EVALUATION OF THE ANTI-EPILEPTOGENIC, ANXIOLYTIC AND ANTI-INOCICEPTIVE POTENTIALS OF STRYCHNOS INNOCUA DEL. (LOGANACEAE) ETHANOLIC LEAF EXTRACT IN MICE USING ISONIAZIDE-INDUCED SEIZURE, ELEVATED ZERO MAZE AND TAIL FLICK MODELS

According to WHO, about 80% people globally make use of plants for their basic health care need. Among the various plant species used in traditional medicine for different medicinal purposes is Strychnos innocua. It is commonly used in Nigerian traditional medicine for nutritional and ethnomedicinal purposes. However, there are a limited scientific evidences for such usage. Hence, this study was aimed at investigating the antiepileptic, anxiolytic and analgesic properties of Strychnos innocua ethanoic extract (SIEE) using acknowledged animal models.Qualitative phytochemical analysis of SIEE was carried-out using standard procedures. Furthermore, the bioactive compounds present in the extract was evaluated using GC-MS analytical method. Oral acute toxicity test was carried-out on SIEE using Lorke’s method. The anti-epileptogenic activity of SIEE was evaluated using isoniazide-induced seizure model in mice. Graded SIEE doses (250, 500, 1000 mg/kg body weight) was used for the test, diazepam (0.5 mg/kg) served as the standard drug, while control group was given distilled water. The anxiolytic effect of SIEE was ascertained usingtheelevated zero maze model. Graded SIEE dose (250, 500, 1000 mg/kg body weight) was used for the test, the standard drug used was diazepam (0.5 mg/kg), while the negative group was administered distilled water. The phytochemical screening results indicated the presence of several phytochemicals including alkaloids, phenols and flavonoids. GC-MS analysis showed the presence of 40 compounds including salicyclic acid, n-Hexadecanoic acid and phytol. Result from acute toxicity test indicated that the LD50 of S.innocua was greater than 5000mg/kg. Result from the isoniazide-induced seizure study revealed that SIEE elongated the survival time of the treated animals in a non-dose related order. The SIEE 500 and 1000 mg/kg increased the survival time by 14.4 and 16.3 % respectively, while SIEE 250 mg/kg which had the highest effect in the study had 53.3 % increase compare3de to the control group. Observations from the elevated zero maze study revealed that all test doses of SIEE (250 – 1000 mg/kg) increased the time spent in the open arm compared to the control group. This increase was in a dose dependent trend. In the tail flick test model, the result revealed that there was decrease in reaction time throughout the study in the control group when compared to baseline. However, all test doses of SIEE (250 1000 mg/kg body weight) increased the reaction time of the treated animals during the study when compared to baseline reaction time. This effect was non-dose dependent as SIEE 250 mg/kg had the highest extract effect, and was significant (P ˂ 0.05) at 30, 60 and 120 minutes respectively. The control drug dihydrocodeine had the highest effect which was significant (P ˂ 0.05) throughout the study. The study demonstrated that Strychnos innocua ethanoic leaf extract has potent antiepileptogenic, anxiolytic and analgesic activities in mice thus, may be worthy of further investigation for possible therapeutic application.