Anti-Alzheimer's flavanolignans from Ceiba pentandra aerial parts.

Four flavanolignans, ceibapentains A (1) and B (2) and cinchonains Ia (3) and Ib (4), were isolated for the first time from an ethyl acetate extract of Ceiba pentandra (L) (Bombacaceae) aerial parts. The ceibapentains A (1) and B (2) are new compounds and their structures, including the absolute configurations, were determined by HRESIMS, 1D and 2D NMR, and electronic circular dichroism analyses, then compared with reported data. Compounds 1 – 4 were tested for their anti-Alzheimer's activity via an assessment of their inhibitory effect on amyloid β 42 aggregation using a thioflavin T assay. The results revealed that cinchonain Ia (3) showed a higher inhibitory effect (91%) than the standard curcumin (70%). Compounds 1 , 2 , and 4 exhibited moderate activity, with inhibition ratios of 43%, 47%, and 58%, respectively. A molecular docking study on the binding mode of 3 and curcumin with an amyloid β 1–40 peptide fibril structure indicated a high affinity of cinchonain 1a (3) towards amyloid β 1–40 peptide, in agreement with the experimental results. Unlabelled Image • Isolation of two new and two known flavanolignans from Ceiba pentandra • Investigation of the anti-Alzheimer's activities of the isolated compounds • Assessment of their inhibitory effect on amyloid β 42 aggregation • Molecular docking study on the binding mode of compounds with amyloid β 1–40 [ABSTRACT FROM AUTHOR]