Neuroprotective neolignan glycosides from the pseudobulbs of Bletilla striata

Four undescribed neolignan glycosides, bletineosides A-D (1-4) were isolated from the pseudobulbs of Bletilla striata. Their structures with absolute configurations were elucidated on the basis of spectroscopic analyses, along with acidic hydrolysis reactions and ECD experiments. All isolates were evaluated for their neuroprotective activities against glutamate-induced PC12 cell injury. Compound 3 and 4 showed significantly neuroprotective effects at the concentration of 10 μM when compared with the model group. Compounds 1-4 represented the first examples of neolignan glycosides from the genus Bletilla. This study disclosed the potency of Bletilla striata as a new source of anti-neurodegenerative agents.