Chemical composition analysis and antioxidant activity of black rice pigment

The purpose of this research was conducted to determine anthocyanin constituent from the grains of Purple black rice No. 6. Moreover, the in vitro antioxidant activity of black rice pigment (BRP) was evaluated. The crude extract of black rice was isolated and purified by silica gel thin layer chromatography. Anthocyanins were elucidated using ultraviolet visible spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and high-performance liquid chromatography. Meanwhile, salicylic acid Fenton system, superoxide radical system, H₂ O₂ scavenging system, DPPH-free radical scavenging system, and Prussian blue method were used to determine the free radical scavenging ability and total reducing ability of BRP. Overall results suggest that the main component of BRP is cyanidin-3-glucoside, which is a kind of anthocyanins. It also had significant scavenging capacity to OH, O₂^- , H₂ O₂ , DPPH, and its scavenging rate and reducing ability increased with the increase in pigment concentration.