Bletistrosides M-X, Anti-Alzheimer’s Disease Compounds from the Tubers of Bletilla striata

Twelve new compounds, bletistrosides M-X (1-12), including five glucosyloxybenzyl 2-isobutylmalates (1-5), along with four neolignan glycosides (6-9), two phenanthrene derivatives (10-11), and one bibenzyl derivative (12), were isolated from the tubers of Bletilla striata (B. striata). The structures and absolute configurations of the undescribed compounds were elucidated on the basis of spectroscopic data analysis, experimental and calculated electronic circular dichroism data, chiroptical analysis, and chemical derivatizations. In silico, compounds 2, 3, and 12 bound well to Aβ_1-42. Compounds 2, 3, and 12 significantly delayed the paralysis phenotype in CL4176 worms compared to controls. Higher nonparalysis rates were observed in these treatment groups (5 μM for compound 2; 25, 50 μM for compounds 2, 3 and 12), suggesting their potential role in anti-Alzheimer's disease.