Naturally Occurring Asterric Acid Analogs: Chemistry and Biology.

Asterric acid and its analogs belong to diphenyl ethers (DPEs) with multiple substitutions on A/B aromatic rings. This member of DPEs originates from the polyketide pathway and displays a wide range of biological effects. Though the structures of asterric acid analogs are not complex, there were only more than 50 asterric acid analogs found in nature from 1960 to 2023. In this review, the structures, bioactivities, and biosynthesis of asterric acid analogs are summarized. More importantly, the empirical rule about the shielding effect of B-ring on H-6 is suggested, and this provides a convenient and useful way to analyze the NMR spectral data of asterric acid analogs, based on which the chemical shift values of the A-ring in some asterric acid analogs are revised.