Isolation and characterization of bioactive principles of the leaves and stems of Physalis philadelphica

An ethyl acetate-soluble extract of the leaves and stems of Physalis philadelphica has been investigated, leading to the isolation of three new withanolides, philadelphicalactones A () and B (), and ixocarpalactone B (), four known withanolides, ixocarpalactone A (), withaphysacarpin (), 18-hydroxywithanolide D (), and withanone (), one new ceramide, (2S,3S,4R,9E)-1,3,4-trihydroxy-2-[(2′R)-2′-hydroxytetracosanoylamino]-9-octadecene (), two known ceramides, (2S,3S,4R)-2-[(2′R)-2′-hydroxytetracosanoylamino]-1,3,4-octadecanetriol (), and (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (), as well as the known chlorophyllide a (). The structures of the new compounds were elucidated based on spectroscopic and chemical methods. Single-crystal X-ray diffraction analysis was used to confirm the relative stereochemistry of compounds and . The absolute stereochemistry of compounds and was established by Mosher ester methodology and chemical transformation. All isolates were evaluated for their potential cancer chemopreventive properties utilizing in vitro assays to determine quinone reductase induction and inhibition of murine epidermal JB6 cell transformation.