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Lung cancer remains a leading cause of death in cancer patients, and deregulation of apoptosis is a serious concern in clinical practice, even though therapeutic intervention has been greatly improved. Plants are a versatile source of biologically active compounds for anticancer drug discovery, and aspiletrein A (AA) is a steroidal saponin isolated from Aspidistra letreae that has a potent cytotoxic effect on various cancer cell lines. In this study, we investigated and determined the underlying molecular mechanism by which AA induces apoptosis. AA strongly induced apoptosis in NSCLC cells by mediating ROS generation and thereby activating AMP-activated protein kinase (AMPK) signaling. Consequently, downstream signaling and levels of phosphorylated mTOR and Bcl-2 were significantly decreased. Pretreatment with either an antioxidant, N-acetylcysteine, or an AMPK inhibitor, compound C, could reverse the apoptosis-inducing effect and counteract the effect of AA on the AMPK signaling pathway. Decreased levels of Bcl-2 were due to AA-mediating Bcl-2 degradation via a ROS/AMPK/mTOR axis-dependent proteasomal mechanism. Consistently, the apoptotic-inducing effect of AA was also observed in patient-derived malignant lung cancer cells, and it suppressed an in vitro 3D-tumorigenesis. This study identified the underlying mechanism of AA on lung cancer apoptosis, thereby facilitating potential research and development of this compound for further clinical implications. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of complexes between bis(2-pyridyl)-di(4- n -butylphenyl)ethene (KT4) and bis(2-pyridyl)-di(3-methoxyphenyl)ethene (KT18) with transition metals Co(II), Cu(II), Zn(II), and Cd(II) were synthesized and crystallized. The structures of these compounds were confirmed based on IR, NMR, and MS spectra. Moreover, crystals were obtained for ZnKT18, CoKT18, CuKT18, CdKT18, and CdKT4. Single-crystal X-ray diffraction (XRD) demonstrated the ability of these pyridine-based ligands to coordinate to metal ions via two nitrogen atoms in the aromatic heterocycles. Depending on the central metal, they can form different structures. Zn(II) and Co(II) form mononuclear complexes with KT18 , where the metal coordinates to two N atoms and two chloride ions in a tetrahedral geometry (coordination number 4). The complexes CuKT18 , CdKT18 , and CdKT4 are binuclear complexes with one pendant chloride and two bridging chlorides coordinating with the metal ion (coordination number 5). The cytotoxic properties of free ligands and complexes were tested on four cancer lines, including KB, Hep-G2, Lu, and MCF-7. In general, the free ligands have no cytotoxic activity, while all complexes present strong to medium effects on these cancer lines. Several complexes are comparable in activity to cisplatin, a commercial drug used in the treatment of cancer. Specifically, ZnKT4 selectively inhibits the activities of the KB and Hep-G2 cell lines. CdKT4 has a high impact on Hep-G2 and Lu (IC 50 < 5 μM) while CdKT18 exhibits effective anticancer activity against the KB and MCF-7 cell lines. CuKT18 strongly inhibits the growth progress of the KB cancer cell (IC 50 = 9.52 μM). These IC 50 values are lower than those of cisplatin. [ABSTRACT FROM AUTHOR]

A practical strategy for the iodine-promoted synthesis of bis(1-imidazo[1,5-a]pyridyl)arylmethane and its derivatives has been developed. These compounds exhibit high cytotoxicity toward various cancer cell lines and moreover they are promising ligands for the Cu-catalysed synthesis of quinolines. [ABSTRACT FROM AUTHOR]