Four new compounds, (+)- and (-)-ecarlottone (1), (±)-fislatifolione (5), (±)-isofislatifolione (6), and (±)-fislatifolic acid (7), and the known desmethoxyyangonin (2), didymocarpin-A (3), and dehydrodidymocarpin-A (4) were isolated from the stem bark of Fissistigma latifolium, by means of bioassay-guided purification using an in vitro affinity displacement assay based on the modulation of Bcl-xL/Bak and Mcl-1/Bid interactions. The structures of the new compounds were elucidated by NMR spectroscopic data analysis, and the absolute configurations of compounds (+)-1 and (-)-1 were assigned by comparison of experimental and computed ECD spectra. (-)-Ecarlottone 1 exhibited a potent antagonistic activity on both protein-protein associations with Ki values of 4.8 μM for Bcl-xL/Bak and 2.4 μM for Mcl-1/Bid.
Cardamonin is a natural chalcone that has been shown to exhibit high anticancer activity. In an attempt to discover analogues of cardamonin with enhanced anticancer activity, 19 analogues were synthesized and tested against A549 and HK1 cell lines. Results of the MTS cell viability assay showed that several derivatives possessed cytotoxic activities that were several-fold more potent than cardamonin. SAR analysis showed the importance of the ketone and alkene groups for bioactivity, while substituting cardamonin's phenolic groups with more polar moieties resulted in activity enhancement. As part of the SAR study and further exploration of chemical space, the effect of metal coordination on cytotoxicity was also investigated, but it was only possible to successfully obtain the Cu (II) complex of cardamonin (19). Compound 19 was the most active analogue possessing IC50 values of 13.2μM and 0.7μM against A549 and HK1 cells, corresponding to a 5- and 32-fold increase in activity, respectively. It was also able to significantly inhibit the migration of A549 and HK1 cells. Further mode of action studies have shown that the most active analogue, 19, induced DNA damage resulting in G2/M-phase cell- cycle arrest in both cell lines. These events further led to the induction of apoptosis by the compound via caspase-3/7 and caspase-9 activation, PARP cleavage and downregulation of Mcl-1 expression. Moreover, 19 inhibited the expression levels of p-mTOR and p-4EBP1, which indicated that it exerted its anticancer activity, at least in part, via inhibition of the mTOR signalling pathway.
In the present study we investigated the effects of panduratin A, isolated from Boesenbergia rotunda, on proliferation and apoptosis in A549 human non-small cell lung cancer cells. Cell proliferation and induction of apoptosis was determined by the real-time cellular analyzer (RTCA), MTT assay and High Content Screening (HCS). The RTCA assay indicated that panduratin A exhibited cytotoxicity, with an IC₅₀ value of 4.4 µg/mL (10.8 µM). Panduratin A arrested cancer cells labeled with bromodeoxyuridine (BrdU) and phospho-Histone H3 in the mitotic phase. The cytotoxic effects of panduratin A were found to be accompanied by a dose-dependent induction of apoptosis, as assessed by DNA condensation, nuclear morphology and intensity, cell permeability, mitochondrial mass/ potential, F-actin and cytochrome c. In addition, treatment with an apoptosis-inducing concentration of panduratin A resulted in significant inhibition of Nuclear Factor-kappa Beta (NF-κB) translocation from cytoplasm to nuclei activated by tumor necrosis factor-alpha (TNF-α), as illustrated by the HCS assay. Our study provides evidence for cell growth inhibition and induction of apoptosis by panduratin A in the A549 cell line, suggesting its therapeutic potential as an NF-κB inhibitor.
Flavokawain C (FKC), a naturally occurring chalcone, has previously been shown to inhibit the growth of colon carcinoma HCT 116 cells through induction of apoptosis and cell cycle arrest. However, the possible underlying mechanisms of cell death as a response to FKC treatment remains unclear. In this study, we performed proteomic analysis of HCT 116 cells treated with FKC to identify proteins that change in abundance. This was followed by bioinformatic analysis to predict possible associated molecular targets or pathways involved in the observed effects of FKC. A total of 35 proteins that changed in abundance (17 increased and 18 decreased) were identified through two-dimensional gel electrophoresis followed by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF/TOF MS). Using the Ingenuity Pathway Analysis (IPA), these proteins were predicted to be involved in cell death and survival, cell cycle, cellular growth and proliferation, protein synthesis, post-translational modification and amino acid metabolism by. Further analysis of the transcript levels of selected proteins using qPCR showed that some of the genes exhibited similar change of profile to that of the proteins'. Our results have provided novel insights into the potential molecular mechanisms underlying FKC-induced apoptosis or cell death in colon cancer cells.