Evaluation of Sub-chronic Toxicity Effect of n-Hexane fraction of Cannabis sativa Leaves in Mice

Abstract

Background: Cannabis sativa (Cannabaceae) has been cultivated for centuries in different parts of the world for its psychoactive property. However, despite the pharmacological potential and economic prospects, there is a dearth of information on the toxicity profile of Nigerian Cannabis.  This study aims at evaluating the subchronic toxicity of the n-hexane fraction of C. sativa leaves (nHCS) in mice.  

Method: The n-hexane fraction was obtained from the methanol extract of C. sativa.

Oral median lethal dose (LD₅₀) of nHCS was determined in mice following the OECD 423 method. Forty mice were divided into four groups (n=10); Group 1 (Vehicletreated group), received 10 ml/kg while groups 2 – 4 received nHCS (200, 400 and 800 mg/kg respectively) orally for 28 days.  Five mice in each group (n=5 per group) were selected for recovery, and the remaining were sacrificed for collection of blood, brain, liver, kidney and oviduct. After 21-days of recovery, the remaining animals were subjected to the same procedure. Haematological parameters were determined using a standard procedure while the biochemical assays were carried out on the liver enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and kidney functional parameters (urea and creatinine). Histopathology assessment was done on essential organs such as liver, kidney, brain and fallopian tube using H & E. Data obtained were analyzed using descriptive statistics and ANOVA at ?_0.05.

Results: The LD₅₀ of nHCS was found to be above 2000 mg/kg per oral. The 28-day repeated dose administration results showed that there was no significant alteration in most of the haematological parameters. However, both platelet and lymphocyte counts were significantly increased at the dose of 200 mg/kg while the white blood cell count was significantly increased at the doses of 400 and 800 mg/kg (8.80±1.50, 9.40 ± 1.20 vs 4.40 ± 0.70   x10³/µL), when compared with control. The biochemical results revealed that only urea level was significantly increased at dose of 200 and 400 mg/kg and this effect was reversed during the recovery period. Histopathological results showed that there was a dose-dependent deleterious effect on the liver, kidney, brain cortex and fallopian tube that was reversed back to normal during the recovery period.  Conclusion: Our findings suggest that the LD₅₀ is greater than 2,000 mg/kg and Cannabis sativa n-hexane extract exhibited no toxicity at low dose level (200 mg/kg, p.o.), but there was evidence of neuronal, hepatic, renal and reproductive toxicities at higher doses (400 and 800 mg/kg, p.o) suggesting the need to exercise caution when used subchronically.