Immunomodulatory potential and toxicological assessment of methanol extract and fractions of Cryptolepis sanguinolenta root

Purpose: To evaluate the paramunity induction potentials of crude methanol extract (CME) and methanol fractions (MF) of Cryptolepis sanguinolenta (CS) root (Fam. Periplocaceae). Method: A total of forty (40) albino rats were divided into two sets of four groups, with five animals per group. Groups 1 - 3 of both animal sets were orally administered 200, 300 and 500 mg/kg bw of CME and MF, respectively once daily for 14 days. Furthermore, Group 4 of both sets served as negative control. The effect of extracts on early-type hypersensitivity (ETH), delayed-type hypersensitivity (DTH), leukocyte count and haemagglutinin titer using sheep red blood cell (SRBC) as antigen were evaluated. Results: Significant (p < 0.05) body weight gains were recorded in the animal groups treated with the ME while no changes were observed in the relative organ weight of all the animals in all the groups. Acute toxicity studies yielded no adverse effect. The CME and MF elicited significant (p < 0.05) increases and decreases in ETH and DTH, respectively, at all doses. They showed a significant (p < 0.05) dose-dependent, stimulatory effect on primary and secondary antibody titer across the treated groups. Packed cell volume and red blood cell count increased significantly (p < 0.05), while a dose- dependent increase occurred in neutrophil counts in rats receiving CME, but the MF-treated rats had significantly decreased (p < 0.05) neutrophil counts at 300 mg/kg compared to control. Both CME and MF did not affect lymphocyte counts. Conclusion: Cryptolepis sanguinolenta extract and MF produce significant stimulatory effects on humoral immunity (antibody) with non-significant impact on cellular and innate immunity. Future studies will require isolation and characterization of the bioactive compounds in the plant extracts.