Biological Activities and Phytochemical Profile of Hawm Gra Dang Ngah Rice: Water and Ethanolic Extracts

Hawm Gra Dang Ngah rice (HDNR) is a red rice variety cultivated in Thailand's southern border region, yet its biological properties have not been extensively studied. This study investigates the effects of HDNR extracts on bioactive constituents, spectral fingerprints, and antioxidant capacities. We evaluated the inhibitory effects of aqueous (HDNR-W) and ethanolic (HDNR-E) extracts on monoamine oxidase (MAO), α-glucosidase, and HMG-CoA reductase activities, as well as their cytotoxicity in normal and cancer cells. The results demonstrated that HDNR-E contained significantly higher concentrations of phenolic compounds, flavonoids, and anthocyanins compared to HDNR-W. In contrast, HDNR-W exhibited greater amino acid content than HDNR-E. FT-IR analysis revealed solvent-specific interactions that influenced compound solubility, highlighting distinct extraction efficiencies. Antioxidant assays showed HDNR-E to be markedly more potent, with superior performance in DPPH, ABTS, metal chelation, and FRAP assays, as evidenced by its lower IC₅₀ values relative to HDNR-W. Furthermore, HDNR-E displayed significantly stronger inhibitory activity against both MAO and α-glucosidase compared to HDNR-W. Conversely, HDNR-W demonstrated greater inhibitory efficacy toward HMG-CoA reductase than HDNR-E. Furthermore, HDNR-E exhibited significant antiproliferative effects against A549 lung cancer and MCF-7 breast cancer cells without affecting normal cells. These results highlight the potential of HDNR-E as a valuable source of bioactive compounds and underscore the importance of solvent selection in enhancing the health benefits of rice extracts.