Abstract

Modulatory effects of the seed extracts and fractions of Garcinia kola Heckel (Clusiaceae) on the immune responses

Author(s): Chukwuemeka S. Nworu, Peter A. Akah, Charles O. Esimone

Garcinia kola has versatile application in folk medicine and is believed to increase immunity and general resistance to infections, but there are no scientific data on the effect of G.kola on the immune system. In this study, the immunomodulatory activities of the methanol seed extract of G.kola seed (ME) and its fractions were studied on some antigen-specific and non-antigen specific components of the immune system such as the delayed- type hypersensitivity response (DTHR), primary and secondary humoral responses, phagocytic activity of polymorphonuclear neutrophils (PMNs), haemolytic activity of complement, and in vivo leucocytes mobilization. The methanol extract,ME (250 and 500mg/kg) produced a doserelated and significant (P<0.05) inhibition ofDTHRinduced by Sheep Red Blood Cells (SRBCs) in rats by 44 and 68%, respectively. DTHR was also significantly (P<0.05) inhibited byEF (250 and 500mg/kg) and CF (500mg/ kg) by 52, 64 and 24%, respectively. Bioactivity study on the column fractions shows that the flavonoid-rich fraction, F3 exhibited the highest inhibitory activity of DTHR of 46.15%. Sheep erythrocytes-specific antibody synthesis, especially the secondary humoral response was significantly (P < 0.05) increased byME (250 and 500mg/kg) and EF (500mg/kg) by 26.09, 34.74 and 21.74%, respectively.At a dose of 500mg/kg,ME and EF caused an increase in total leucocytes mobilization up to 62.66 and 17.72% into the peritoneal perfusates when compared to the untreated group. The ME and column fraction, F3 also showed significant (P<0.05) inhibition of complement-induced haemolysis of SRBC up to 26.27 and 29.66%, respectively. The results of this study establish cellular and humoral immunomodulatory properties of G.kola extract and justify its inclusion as immune adjuvant in dietary supplements.