Hibiscus sabdariffa extractivities on cadmium-mediated alterations of human U937 cell viability and activation

To investigate the effect of the anthocyanin-rich extract of Hibiscus sabdariffa (H. sabdariffa) calyx on the viability of cadmium-treated U937 cells and cadmium-mediated activation of U937-derived macrophages.

The macrophage cell line U937 was treated with cadmium (0.1 μ mol/L) and later incubated with the anthocyanin-rich extract and cell viability was assessed via trypan blue staining. In the other experiment, the U937 cells were transformed to the macrophage form by treatment with phorbol 12, myristate 13, and acetate and incubated with cadmium (10 μ mol/L). The anthocyanin-rich extract was added to the cells later and subsequently, the supernatant of each cell culture was analysed for the production of tumour necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), nitric oxide, and catalase activity as indices for the activation of macrophages.

It revealed that the anthocynanin-rich extract significantly (P < 0.05) increased the viability of the cells which was suppressed by cadmium when compared to quercetin dihydrate. The extract also reduced the cadmium-mediated production of the markers of macrophage-activation when compared to quercetin dihydrate. In both experiments, the activity of the extract was concentration-dependent (P < 0.05).

The findings show that H. sabdariffa possesses significant immunoprotective effect. These corroborate the immense reported antioxidant and medicinal potential of the calyces of the plant which could be exploited for pharmacological and neutraceutical advantages.