The study was to investigate the phytochemical composition, antioxidant activities and the immunomodulatory effects on cyclophosphamide-induced (cy-induced) immunosuppressed mice of purple red rice bran pigment extracts (PRBP). The phytochemical composition of total anthocyanins, total phenolic and total flavonoid contents were evaluated. Moreover, UV-Vis, FT-IR and UPLC-ESI-QTOF-MS spectra analysis identified for the first time the presence of seventeen anthocyanins in PRBP, including five anthocyanin aglycones and twelve acetylated anthocyanins, suggesting that PRBP were a highly acylated anthocyanin profile. The DPPH, ABTS+, hydroxyl radical scavenging activity and FRAP assays showed that PRBP had excellent antioxidant activities. Further, the results of animal experiments showed that PRBP alleviated immune organ damage and recovered damaged immune function, such as preventing the reduction of body weight, spleen and thymus organ indexes, and significantly increasing the levels of TNF-α, IL-6 and IL-1β in spleen which indicated that PRBP alleviated immunosuppression in Cy-induced mice. The immunomodulatory activity of PRBP was reflected by the upregulation of MAPK signaling pathways after gavage. Taken together, these results suggest that PRBP possessed a certain antioxidant and immunomodulatory abilities. These findings will lead to a better understanding of the biological properties of PRBP and broaden its utilization in food processing.
Keywords: Anthocyanin; Antioxidant; Immunomodulatory; Purple red rice bran pigment extracts; UPLC-ESI-QTOF-MS.
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