Ethanol extracts from Cinnamomum camphora seed kernel: Potential bioactivities as affected by alkaline hydrolysis and simulated gastrointestinal digestion

The aim of the study was to evaluate the changes of potential bioactivities of ethanol extracts (EE) from Cinnamomum camphora seed kernel (CCSK) after alkaline hydrolysis and simulated gastrointestinal digestion. A total of 13 compounds in EE, mainly phenolics and saponins were tentatively identified using HPLC-ESI-QTOF-MS2 analysis. The total phenolic and total flavonoid contents in EE decreased by 30.6%, 1%, 33% and 11.8% after hydrolysis and digestion, respectively. The total saponins content decreased by 17% after hydrolysis while increased by 48% after digestion. The total condensed tannin contents increased by 70.3% and 17.2% after hydrolysis and digestion, respectively. The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), cupric ion reducing activity (CUPRAC), ferric reducing antioxidant power (FRAP) and metal chelating activity (MCA) were used to determine antioxidant activity. Overall, the changes of antioxidant activities by hydrolysis and digestion were consistent with the changes of their total phenolic and flavonoid contents. The alpha-amylase and alpha-glucosidase inhibitory activities in EE increased by 817% and 33.3% after digestion while decreased by 12.3% and 19% after hydrolysis, respectively. Although the inhibitory activities of cholinesterase, tyrosinase and xanthine oxidase were decreased by hydrolysis and digestion, most of these activities were retained. These results showed that CCSK ethanol extracts had strong bioactivities and were reasonably stable to alkali and digestive enzymes.