Morusalbanol A, a neuro-protective Diels–Alder adduct with an unprecedented architecture from Morus alba

Morusalbanol A (1), a neuro-protective Diels–Alder adduct with a new carbon skeleton, was isolated from the bark of Morus alba. Compound 1 showed evidence of interesting astropisomerism, and resulted in the absence of a number of key proton and carbon signals in the NMR spectra. Its structure was thus elucidated by spectroscopic analysis of its peracetylated derivative (2) and its absolute configuration established as 1S,3S,4R,5S via experimental and calculated ECD spectra of 1. In a neuro-protective assay, morusalbanol A (1) significantly attenuated the H2O2-induced cell damage in a dose-dependent manner.