Physalins and neophysalins from the calyx of Physalis alkekengi: Structures and anti-inflammatory efficacy.

To explore potential anti-inflammatory lead compounds, ten new physalin steroids, including three neophysalins (1, 4, and 9) and seven physalins (2, 3, 5-8, and 10), along with eleven known analogs, were isolated from an ethanol extract of the calyx of Physalis alkekengi. The new structures were rigorously determined through comprehensive HRESIMS, 1D/2D-NMR, and X-ray diffraction analysis. Among these compounds, 1 was identified as a new 1,10-seco-neophysalin, and 2 was identified as a new 11,15-cyclo-9,10-seco-physalin characterized by an aromatic A-ring. Evaluation of the anti-inflammatory activities of the isolated compounds revealed that compound 15 displayed remarkable potency, inhibiting NO production in RAW 264.7 macrophages with an IC50 value of 2.26 ± 0.12 μM, while exhibiting low cytotoxicity (IC50 = 90.45 ± 6.10 μM). It suppressed the expression levels of IL-6, IL-1β, iNOS and COX-2, while upregulating the expression levels of HO-1 and Nrf2, indicating the involvement of multiple mechanisms. Further studies indicated that compound 15 significantly attenuated the LPS-induced increase in the phosphorylation of p38, ERK, and JNK in a dose-dependent manner, indicating its potential to exert anti-inflammatory effects through modulation of the MAPK signaling pathway. In vivo studies further demonstrated the efficacy of compound 15, as it showed inhibitory activity against mouse ear edema, achieving an inhibition rate of 37.30 % at a dosage of 25 mg/kg. Importantly, compound 15 (25 mg/kg) significantly ameliorated colitis-related symptoms in a dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) model, highlighting its potential as a therapeutic candidate for inflammatory disorders.