(P)/(M)-corinepalensin A, a pair of axially chiral prenylated bicoumarin enantiomers with a rare C-5[sbnd]C-5′ linkage from the twigs of Coriaria nepalensis.

A pair of undescribed bicoumarin enantiomers, ( P )/( M )-corinepalensin A, two undescribed prenylated coumarins, corinepalensins B and C, along with ten known coumarins were isolated from the twigs of Coriaria nepalensis . ( P )/( M )-corinepalensin A feature a rare C-5 C-5′ axially chiral linkage between two prenylated coumarin monomers. Their structures were determined by a combination of spectroscopic methods, single crystal X-ray diffraction, and ECD calculations. All isolates were evaluated for the inhibitory activity against phosphodiesterase-4 (PDE4), which is a drug target for the treatment of asthma and chronic obstructive pulmonary disease. Compounds ( P )-corinepalensin A, ( M )-corinepalensin A, corinepalensin B, norbraylin, braylin, and nepalin C exhibited significant inhibition with IC 50 values ranging from 0.43 to 7.15  μ M. [ABSTRACT FROM AUTHOR]