Protective effect of a rosmarinic acid-rich extract from cold-pressedPerilla frutescensseed flour on oxidative hepatotoxicity in vitro and in vivo

Abundant phenolic compounds, including rosmarinic acid (RA), caffeic acid, and their derivatives, are present in cold-pressed Perilla frutescens seed flour (CP-PFSF) after oil extraction. In this study, the in vitro antioxidant and hepatoprotective activities of the major phenolic components of CP-PFSF were assessed and compared. RA showed the highest antioxidant and hepatoprotective activities. An RA-rich extract was prepared and its hepatoprotective effects were assessed in vitro and in vivo. In vitro, treatment with RA-rich extract markedly reduced H2O2-induced cytotoxicity, significantly prevented H2O2-induced lipid peroxidation and glutathione depletion, inhibited H2O2-induced apoptosis by regulating the expression of Bcl-2/Bax, caspase 9, and caspase 3, which are involved in the mitochondrial apoptosis pathway. In vivo, oral administration of RA-rich extract significantly reduced the levels of aspartate aminotransferase and alanine aminotransferase, and hepatocyte degeneration and neutrophilic infiltration induced by tert-butylhydroperoxide (t-BHP). Therefore, an RA-rich extract from CP-PFSF showed potential protective effects against oxidative hepatic damage. Practical applications Perilla (Perilla frutescens) seed is extensively cold pressed for extraction of cooking oils. However, abundant phenolic compounds still exist in the cold-pressed Perilla seed flour (CP-PFSF), which was usually considered useless after oil extraction. In this study, the in vitro antioxidant and hepatoprotective activities of the major phenolic components from CP-PFSF, including rosmarinic acid (RA), caffeic acid (CA), and their derivatives, were assessed and compared. RA showed the highest antioxidant and hepatoprotective activities. Then, an RA-rich extract was prepared and its hepatoprotective effects were assessed in vitro and in vivo. The results indicated that RA-rich extract of CP-PFSF showed potential hepatoprotective activities, which would broaden our knowledge about the bioactivities of phenolic components in CP-PFSF, and facilitate the development of CP-PFSF as candidate functional dietary supplements in food industries.