Some bioactive potentials of two biflavanols isolated from Garcinia kola on cadmium-induced alterations of raw U937 cells and U937-derived macrophages

Objective:To investigate the abilities of two flavonoids - Garcinia hiflavanol-1(GB-1) and Garcinia biflavanol-2(GB-2) from Garcinia kola(G.kola) in reducing cadmium-induced effects on raw U937 cells and 11937-derived macrophages.Methods:Macrophage U937 cells were incubated with cadmium followed by treatment with the flavonoids and cell viability assessed via trypan blue staining.In the other experiment,the U937 cells were transformed to the macrophage form and treated with cadmium in order to activate them.The cells were later incubated with the flavonoids and finally the supernatant of each cell culture was analysed for the secretion of nitric oxide,catalyse activity,and the release of tumour necrosis factor-alpha,interleukin-1 and interleukin-2 as indices of macrophage activation.Quercetin(a flavonol) was used as the reference flavonoid in all experiments.Results:It revealed that the flavonoids significantly increased the viability of the cells and also reduced the cadmium-induced activation of the macrophage cells in a concentration-dependent manner.The flavanols GB-1 and GB-2 possessed higher activities than quercetin in all cases(P<0.05).Garcinia biflavanol-2 possessed a higher bioactivity than GB-1 significantly(P<0.05).Conclusions:In addition to corroborating the several reported importance of G.kola as a potential neutraceutical and pharmacological condiment,the study also clearly indicates the role hydroxylation especially at the 3’- position of polyphenols could play in enhancing bioactivities of flavonoids.