Narjatamanins A and B, a pair of novel epimers possessing a 2,3-seco-iridoid skeleton with an unusual 1,10-oxygen bridge from Nardostachys jatamansi and evaluation of their effects on worm paralysis in AD C. elegans

Narjatamanins A (1) and B (2), a pair of epimers possessing a novel 2,3-seco-iridoid skeleton with an unusual 1,10-oxygen bridge, were isolated from the whole plants of Nardostachys jatamansi. Their structures were elucidated by a combination of various spectroscopic methods, including HRESIMS, IR and 1D and 2D NMR techniques. The absolute configurations of 1 and 2 were established by electronic circular dichroism (ECD) calculations. The pharmacological activities of 1 and 2 to alleviate AD-like symptoms were also evaluated using the Caenorhabditis elegans Alzheimer's disease (AD) pathological model, and narjatamanins A (1) and B (2) showed statistically significant delay in the worm paralysis phenotype of AD-like symptoms.