Phytochemical Screening and HMG-CoA Reductase Inhibitory Activity of Black Rice Extract as a Potential Treatment for Hypercholesterolemia

Abstract

Hypercholesterolemia is a significant risk factor for cardiovascular diseases, and the search for effective and natural alternatives to conventional treatments is crucial. Black rice, a pigmented rice variety, has gained attention for its potential health benefits, including its ability to modulate lipid metabolism. This study aimed to investigate the phytochemical profile and HMG-CoA reductase inhibitory activity of local black rice, called Tadong (TBR), evaluating its potential as a treatment for hypercholesterolemia. Methanol (80% v/v) and water were used to extract the phytochemicals from TBR. Qualitative phytochemical screening of TBR was conducted to screen the presence of saponins, tannins, alkaloids and steroids. Total phenolic content (TPC) was also measured using the Folin-Ciocalteu method. The HMG-CoA reductase inhibitory activity of the extract was assessed using an in-vitro enzymatic assay.  Qualitative phytochemical screening revealed the presence of tannins, alkaloids, and steroids in the methanol extract. In contrast, these compounds were not detected in the water extract. The methanol extract (0.421 mg GAE/g extract) exhibited a significantly higher TPC when compared to the water extract (0.101 mg GAE/g) (p<0.05). The methanol extract (0.230±0.007 ng/ml) also demonstrated a potent inhibitory effect on HMG-CoA reductase activity, compared to the water extract (0.311±0.005 ng/ml) (p<0.05) indicating its potential as a natural cholesterol-lowering agent. The TBR's phytochemical profile and its ability to inhibit HMG-CoA reductase indicate its promising role as a natural and effective alternative for the management of hypercholesterolemia.