Withametelin inhibits TGF-ß induced Epithelial-to-Mesenchymal Transition and Programmed-Death Ligand-1 expression in vitro.

Withanolides are a group of naturally occurring plant-based small molecules known for their wide range of host cellular functions. The anticancer potential of withanolides has been explored in varying cancer cell lines in vitro. Based on our prior studies, among the tested withanolides, withametelin (WM) has shown significant cytotoxicity with the highest efficacy on HCT-116 colon cancer cells (IC50 0.719 ± 0.12µM). Treatment with WM reduced the TGF-ß driven proliferation, colony-forming ability, migration, and invasiveness of HCT-116 cells in vitro. WM also downregulated the expression of mesenchymal markers such as N-CADHERIN, SNAIL, and SLUG in HCT-116 cells. At the molecular level, WM inhibited TGF-ß induced phosphorylation of SMAD2/3 and reduced the expression of an immune checkpoint inhibitor programmed-death ligand-1 (PD-L1). Our study highlights the possible anticancer mechanisms of WM involving modulation of the TGF-ß pathway and associated target gene expression, suggesting its potential utility in cancer therapy.

A New Lignan (Polonilignan) and Inhibitors of Nitric Oxide Production from Penicillium polonicum, an Endophytic Fungi of Piper nigrum.

Inhibiting nitric oxide (NO) or its production is found to be of therapeutic benefit. To discover natural small molecule inhibitors of NO production, a bioassay- and LC/MS-guided chemical investigation was done on the metabolites of endophytic fungus isolated from fresh Piper nigrum fruits. The isolated pure strain was identified as Penicillium polonicum by 16S rDNA sequence comparison. The culture broth extract of P. polonicum (EEPP) exhibited a significant reduction of NO production (Griess method) in LPS-stimulated RAW 264.7 cells (P<0.0001). To understand the chemical constituents of bioactive EEPP, column chromatography and p-TLC studies were carried out, which yielded eight pure compounds. They were characterised as botryosphaeridione (1), 3-(3,5-di-tert-butyl-4-hydroxy)phenylpropionic acid (2), variabilone (3), 2,4-di-tert-butylphenol (4), indole-3-carboxylic acid (5), tyrosol (6), ethyl ferulate (7) and a new lignan (8) based on the spectral analysis. The structure elucidation of the new lignan, named polonilignan (8), was based on HR-MS, 1 H- & 13 C-NMR, H-H COSY, HSQC and HMBC spectra. Compounds 2, 4, 5 and 6 showed a significant decrease (P<0.0001) in the production of NO in LPS-induced RAW 264.7 cells. Tyrosol (6) and indole-3-carboxylic acid (5) controlled nitrite release with IC50 values of 22.84 and 55.01 µM, respectively. This is the first report of (i) P. polonicum as an endophytic fungus of pepper fruits, (ii) isolation of compounds 1-8 except 6 from P. polonicum culture broth extract and (iii) NO inhibition effect of 2, 4, 5 and 6.