Hibiscus tiliaceus: A possible immunomodulatory agent

Objective

The objective of the study is to evaluate the immunomodulatory effect of methanolic leaf extract of Hibiscus tiliaceus (MLHT) in pyrogallol induced immunosuppressed Wistar rats.

Methods

The methanolic extract of leaves of H. tiliaceus was administered orally at the dosage levels of 250 mg/kg/day and 500 mg/kg/day b.w in Wistar rats for 28 days. The assessment of immunomodulatory activity, humoral and cellular immunity was studied by hemagglutination antibody (HA) titer, delayed type hypersensitivity (DTH), Neutrophil adhesion test and carbon clearance test. In order to induce immunosuppression in rats pyrogallol (100 mg/kg/day, p.o.) is used and septilin syrup (1ml/100 g/day, p.o.) used as standard as it is immunostimulating agent. Hematological and biochemical were estimated by standard methods.

Results

Oral administration of MLHT showed a significant increase in the production of circulating antibody titer in response to sheep red blood cells (SRBCs). A significant (P < 0.001) increase in both primary and secondary HA titer was observed when compared to control group, whereas in H. tiliaceus showed significant (P < 0.001) increase in HA titer. MLHT significantly (P < 0.001) potentiated the DTH reaction by facilitating the footpad thickness response to SRBCs in sensitized rats. Also MLHT evoked a significant (P < 0.001) increase in percentage neutrophil adhesion to nylon fibers and phagocytic activity. It also enhanced the production of RBC, WBC and hemoglobin. It does not much affect the biochemical parameters.

Conclusion

An oral administration of the MLHT showed immunomodulatory effect in Wistar rats in a dose dependent manner. From the results obtained and reported phytochemical studies H. tiliaceus has a significant effect on both humoral and cellular immunity in experimental animals, this may be attributed to the polyphenols and flavonoid content of the plant extract.