Identification of two novel prenylated flavonoids in mulberry leaf and their bioactivities.

Mulberry leaf is a vegetable used in daily diet. It can bring delicious taste and multiple health benefits. However, the chemicals responsible for these health benefits remain unveiled. In this work, two novel prenylated flavonoids were isolated from mulberry leaf. Their structures were identified and named as morachalcone D and morachalcone E. The protective effects of these two compounds were investigated, against endogenous oxidative damage (oxytosis/ferroptosis) induced by glutamate and erastin in HT22 cells. The results revealed that morachalcone D was much more potent in preventing from glutamate- and erastin-induced cell death than morachalcone E. The neuroprotective effect of morachalcone D was related to the prevention of ROS production, glutathione depletion, and iron accumulation. Morachalcone D upregulated the expression of genes involved in antioxidant defense, including GPx4, CAT, SOD2, Nrf2, HMOX1 and SLC7A11. These findings indicated that morachalcone D was responsible for the health benefits of mulberry leaf, and could be a potent neuroprotective agent for use in dietary supplements and functional foods.