Differential Effects of In Vitro Simulated Digestion on Antioxidant Activity and Bioaccessibility of Phenolic Compounds in Purple Rice Bran Extracts.

Pigmented rice varieties are abundant in phenolic compounds. Antioxidant activity and bioaccessibility of phenolic compounds are modified in the gastrointestinal tract. After in vitro simulated digestion, changes in antioxidant activity and bioaccessibility of phenolic compounds (phenolic acids, flavonoids, and anthocyanins) in purple rice brans (Hom Nil and Riceberry) were compared with undigested crude extracts. The digestion method was conducted following the INFOGEST protocol. Antioxidant activity was determined using the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assays. The bioaccessibility index (BI) was calculated from the ratio of digested to undigested soluble phenolic content. Overall results showed that the in vitro simulated digested rice brans had lower antioxidant activity and lower total phenolic, flavonoid, and anthocyanin contents. However, the concentration of sinapic acid was stable, while other phenolic acids (gallic, protocatechuic, vanillic, ρ-coumaric, and ferulic acids) degraded after the oral, gastric, and intestinal phases. The BI of sinapic, gallic, vanillic, and ferulic acids remained stable, and the BI of quercetin was resistant to digestion. Conversely, anthocyanins degraded during the intestinal phase. In conclusion, selective phenolic compounds are lost along the gastrointestinal tract, suggesting that controlled food delivery is of further interest.

Comprehensive Analysis of Antioxidant and Phenolic Profiles of Thai Medicinal Plants for Functional Food and Pharmaceutical Development.

Medicinal plants, are resources of traditional medicines, have played a significant role in human culture throughout history. The connect of traditional knowledge with contemporary scientific findings, display the potential of these plants for nutritional and pharmaceutical applications. This study aimed to investigates the antioxidant activity and phenolic compositions of seven medicinal plants (Kaempferia parviflora, Hibiscus sabdariffa, Phyllanthus emblica, Terminalia chebula, Terminalia bellirica, Gynostemma pentaphyllum, and Stevia rebaudiana) from Kalasin Province, Thailand. 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays were used to evaluate the the antioxidant activities. The qualitative method was used for the phytochemical screening. Additionally, reverse-phase high-performance liquid chromatography (RP-HPLC) analysis reveals their phenolic compositions. Results revealed that phenols, flavonoids, and terpenoids were found in all medicinal plants studied, with flavonoids and phenols most predominant. Notably, P. emblica and T. bellirica show significant antioxidant properties and high levels of phenolics and flavonoids. P. emblica had the highest phenolic acid concentrations, with ρ-coumaric (79.43 µg/g), chlorogenic (45.22 µg/g), and ferulic acid (29.58 µg/g) being dominant. The research emphasizes the value of these plants in developing functional foods and pharmaceuticals, underlining the importance of conserving biodiversity and traditional knowledge for future health product innovation.