Depsides from <i>Origanum dictamnus</i> and <i>Satureja pilosa</i> as selective inhibitors of carbonic anhydrases: Isolation, structure elucidation, X‐ray crystallography

In this study, four depsides were isolated from Origanum dictamnus L. and Satureja pilosa Velen. medicinal plants and their structures were assessed by means of one-dimensional (1D)- and two-dimensional (2D)-nuclear magnetic resonance, high resolution mass spectrometry, and electronic circular dichroism analyses. The compound 1, herein reported for the first time, salvianolic acid P 2, clinopodic acid I 3, and clinopodic acid O 4 were all profiled in vitro on a panel of human (h) expressed carbonic anhydrases (CAs; EC 4.2.1.1) and preferential inhibition for the tumor-associated human carbonic anhydrase (hCA) IX and hCA XII over the constitutively expressed hCA I and hCA II isoforms was observed. X-ray crystallography allowed us to assess the binding mode of salvianolic acid P 2 to hCA II. The compounds exhibited significant cytotoxic effects on the human triple-negative breast cancer cell line MDA-MB-231, suggesting that this class of depsides are promising molecules for future investigation.