A novel withanolide with an unprecedented carbon skeleton from Physalis angulata

A novel withanolide, aromaphysalin A (1), possessing an exceptional C(11)–C(15) bond and an unprecedented 4,9-cyclized aromatic ring (ring A), is isolated from stems and leaves of Physalis angulata L. Its structure was determined by a combination of HRESIMS, 2D NMR spectra, and theoretical calculations. Compound 1 exhibited inhibitory activity on NO production with an IC50 value of 51.64 μM. A plausible biosynthetic pathway for 1 is also discussed.