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Ginkgo biloba seeds are wildly used in the food and medicine industry. It has been found that 4′-O-methylpyridoxine (MPN) is responsible for the poisoning caused by G. biloba seeds. The objective of this study was to explore and optimize the extraction method of MPN from G. biloba seeds, and investigate its toxic effect on human gastric epithelial cells (GES-1) and the potential related mechanisms. The results showed that the extraction amount of MPN was 1.933 μg/mg, when extracted at 40 °C for 100 min, with the solid–liquid ratio at 1:10. MPN inhibited the proliferation of GES-1 cells, for which the inhibition rate was 38.27% when the concentration of MPN was 100 μM, and the IC50 value was 127.80 μM; meanwhile, the cell cycle was arrested in G2 phase. High concentration of MPN (100 μM) had significant effects on the nucleus of GES-1 cells, and the proportion of apoptotic cells reached 43.80%. Furthermore, the Western blotting analysis showed that MPN could reduce mitochondrial membrane potential by increasing the expression levels of apoptotic proteins Caspase 8 and Bax in GES-1 cells. In conclusion, MPN may induce apoptosis in GES-1 cells, which leads to toxicity in the human body.

Morchella protein hydrolysate (MPH) and its glycosylated derivative (G-MPH) may possess the potential as natural antioxidants. However, knowledge about the protective effects of MPH and G-MPH on cellular oxidative damage is limited. This study evaluated whether MPH and G-MPH protected Caco-2 cells from H2O2-induced oxidative injury and explored the potential mechanisms of protection. The results showed that, under H2O2 stress, both MPH and G-MPH significantly increased cell viability, suppressed intracellular ROS and MDA production, increased cellular antioxidant capacity, and activated Nrf2 signaling pathway. More importantly, MPH and G-MPH significantly inhibited the H2O2-induced apoptosis via restoring the loss of mitochondrial membrane potential and regulating the protein expressions of Bax, Bcl-2, and caspase-3. These data indicate that MPH and G-MPH can protect Caco-2 cells against oxidative injury by improving cellular antioxidant responses and inhibiting apoptosis. Therefore, MPH and G-MPH can have a broad application potential as promising ingredients of nutraceutical products or functional foods. [ABSTRACT FROM AUTHOR]