Cytotoxic withanolides from the stems and leaves of Physalis ixocarpa

The stems and leaves of the tomatillo (Physalis ixocarpa or Physalis philadelphica) were considered agricultural waste during the processing of tomatillo fruits. However, their potential value for utilization has not yet been explored. The investigation resulted in the isolation of a total of 29 withanolides, out of which 15 never reported. These newly discovered withanolides were then tested for their cytotoxicity against eight different human tumor cell lines. Compounds 2-3, 6-7, 17, 19, and 25-27 displayed encouraging cytotoxic effects. Given the potent inhibitory activity of physagulin C (25) on the proliferation of HepG2 cells in vitro, further investigation was conducted to determine its molecular mechanism. Physagulin C inhibited epithelial-mesenchymal transition (EMT) process through the down-regulation of the JAK2/STAT3 and PI3K/AKT/mTOR pathways. Withanolides presenting in the stems and leaves of tomatillo make the plant possess potential commercial importance. Therefore, tomatillos could be commercialized worldwide in the food and pharmaceutical industries.

Anti-inflammatory effects of three withanolides isolated from Physalis angulata L. in LPS-activated RAW 264.7 cells through blocking NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis angulata L. is commonly used in many countries as popular medicine for the treatment of a variety of diseases such as malaria, hepatitis, dermatitis and rheumatism. But the anti-inflammatory active constituents of this medicinal plant and their molecular mechanism are still not elucidated clearly.

AIM OF THE STUDY

The aim of the study is to isolate and identify a series of compounds from the ethanolic extract of Physalis angulata L., and to investigate the anti-inflammatory activities in vitro and the molecular mechanism of physagulin A, physagulin C, and physagulin H.

MATERIALS AND METHODS

In order to further understand the anti-inflammatory mechanism of the three compounds, their potential anti-inflammatory activities were investigated in vitro in LPS-activated RAW 264.7 macrophage cells by Griess assay, ELISA, Western blot and immunofluorescence methods in the present study.

RESULTS

Physagulin A, physagulin C, and physagulin H could not only inhibit the release of NO, PGE₂, IL-6 and TNF-α, but also could down-regulate the expression of iNOS and COX-2 proteins. Furthermore, physagulin A, physagulin C, and physagulin H could remarkably block the degradation of IκB-α and the nuclear translocation of NF-κB/p65 in LPS-activated RAW 264.7 cells. However, none of them could inhibit the phosphorylation of MAPKs family proteins ERK, JNK and p38. Thus, the anti-inflammatory actions of physagulin A, physagulin C, and physagulin H were mainly due to the significant inhibition of NF-κB signaling pathway rather than MAPKs signaling pathway.

CONCLUSIONS

All the results clearly showed that physagulin A, physagulin C, and physagulin H demonstrated potent anti-inflammatory activity and can be used as novel NF-κB inhibitors. They are potential to be developed as an alternative or complementary agents for inflammatory diseases.