Sterubin: Enantioresolution and configurational stability, enantiomeric purity in nature, and neuroprotective activity in vitro and in vivo

Alzheimer´s disease (AD) is a neurological disorder with still no preventive or curative treatment. Flavonoids are phytochemicals with potential therapeutic value. Previous studies described the flavanone sterubin isolated from the Californian plant Eriodictyon californicum as a potent neuroprotectant in several in vitro assays. Herein, we describe the resolution of synthetic racemic sterubin (1) into its two enantiomers, (R)-1 and (S)-1, on a chiral chromatographic phase and their stereochemical assignment online, by HPLC-ECD coupling. (R)-1 and (S)-1 showed comparable neuroprotection in vitro with no significant differences. While the pure stereoisomers were configurationally stable in methanol, fast racemization was observed in the presence of culture medium. We also established the occurrence of extracted sterubin as its pure (S)enantiomer. Moreover, we investigated the activity of sterubin (1) for the first time in vivo, in an AD mouse model. Sterubin (1) showed a significant positive impact on short- and long-term memory at low dosages.