Appraisal of Thai glutinous rice husk for health promotion products

Rice husks of the RD 6 variety were refluxed with water for 30, 60 and 120 min. The longest extraction time resulted in the greatest yield (0.089 ± 0.008%), radical scavenging activity (IC₅₀ = 37.203 ± 0.421 μg/ml), and total phenolic and flavonoid contents (7.512 ± 0.008 g GAE/100 g extract and 36.886 ± 0.004 g QE/100 g extract). Fatty acids of cosmetic importance, such as hexanoic, heptatonic, octanoic, nonanoic, stearic, palmitic, oleic and linoleic acids, were quantified using the best antioxidant extract (166.004 mg/kg). The total phenolic content was related to the antioxidant activity and total fatty acid content (r = 0.997 and 0.864) in linoleic acid (r = 0.989), which displayed antioxidant properties (r = 0.996). The extract was non-cytotoxic in vero cells. Furthermore, it was compatible and stable in cosmetic formulations. Therefore, rice husks should be further studied for use in health promotion products.