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.

Marigold flower-powder exhibits significant potential to inhibit lipid oxidation in rice bran tea.

We supplemented marigold flower-powder (MFP) in rice bran tea at different proportions as a source of natural antioxidant compounds. Changes of phenolic compounds, antioxidant activity, fatty acid composition and lipid oxidation in the rice bran tea with MFP after 30 days of storage were investigated, comparing results with the initial data. Adding MFP in rice bran tea resulted in an increased content and composition of phenolics and flavonoids along with enhanced antioxidant activities, which were increased in a dose-dependent manner. As a result, MFP supplementation of rice bran tea was able to retard the lipid oxidation as determined by the peroxide value (PV), due to the protection of essential fatty acids during 30 days of storage. The PVs were strongly negatively correlated (p < 0.01) with phenolic compounds, total phenolic content (TPC) and total flavonoid content (TFC), but were positively correlated with tocopherols and γ-oryzanol contents. We also found that the PV was positively correlated with the PUFA (poly unsaturated fatty acid) content but adverse results were found for SFA (saturated fatty acid) and MUFA (mono unsaturated fatty acid) contents. These findings suggest that MFP could be used as a natural antioxidant in foods for preventing lipid oxidation as well as extending the shelf-life of food products.

Effects of different treatments on the antioxidant properties and phenolic compounds of rice bran and rice husk.

We investigated the changes of antioxidant activity and bioactive compounds in bran, rice husk and ground rice husk after three different treatments, namely hot-air, far-infrared radiation (FIR), and cellulase, compared with raw samples. Overall, FIR-treated group showed a higher DPPH radical scavenging activities, ferric reducing antioxidant power (FRAP), and total phenolic content (TPC) than did hot-air and cellulase treatments for all samples. A significant increase in α- and γ-tocopherols was found in FIR irradiated rice bran compared to raw bran, while α- and γ-tocopherols in hot-air and cellulase treated rice bran were remained unchanged. Cellulase significantly increased the amount of vanillic acid; however a dramatic decrease of ferulic acid was observed. The contents of γ-oryzanol in cellulase treated ground rice husk were significantly increased. Decreasing particle size in the husk was found to work positively for enhancing antioxidant activities, γ-oryzanol and phenolic compounds.