Impairing Powerhouse in Colon Cancer Cells by Hydrazide–Hydrazone-Based Small Molecule

Abstract

Mitochondrion has emerged as one of the unconventional targets in next-generation cancer therapy. Hence, small molecules targeting mitochondria in cancer cells have immense potential in the next-generation anticancer therapeutics. In this report, we have synthesized a library of hydrazide–hydrazone-based small molecules and identified a novel compound that induces mitochondrial outer membrane permeabilization by inhibiting antiapoptotic B-cell CLL/lymphoma 2 (Bcl-2) family proteins followed by sequestration of proapoptotic cytochrome c. The new small molecule triggered programmed cell death (early and late apoptosis) through cell cycle arrest in the G2/M phase and caspase-9/3 cleavage in HCT-116 colon cancer cells, confirmed by an array of fluorescence confocal microscopy, cell sorting, and immunoblotting analysis. Furthermore, cell viability studies have verified that the small molecule rendered toxicity to a panel of colon cancer cells (HCT-116, DLD-1, and SW-620), keeping healthy L929 fibroblast cells unharmed. The novel small molecule has the potential to form a new understudied class of mitochondria targeting anticancer agent.

Apoptosis-inducing activity of a fluorescent barrel-rosette M+/Cl− channel

“…The observed AVD is already an indication of apoptosis. Apoptosis is also evidenced by the disruption of mitochondrial membrane potential (MMP), 67,68 which subsequently results in cytochrome c release. The release of cytochrome c in the cytoplasm switches on the apoptotic signaling cascade.…”

“…This change in ionic homeostasis of cells leads to a disturbance in the electron transport chain in the mitochondrial respiratory cycles, which results in reactive oxygen species (ROS) production. [73][74][75][76] Thus, 2 0 ,7 0 -dichlorodihydrouorescein diacetate (H 2 DCFDA), 68,77 a ROS probe, was used to monitor ROS generation in cells. The probe remains in the non-uorescent state in the diacetate protected form.…”

Hydrazide–Hydrazone Small Molecules as AIEgens: Illuminating Mitochondria in Cancer Cells

“…We further evaluated the change in fluorescence properties in am ethanol/water mixture. [43] These solid-state fluorescence, water titration studies andtheoretical structureo ptimization clearlyconfirmed that 1) ESIPT is not the mechanism involved and 2) dual intramolecular H-bonding is criticalt om aintain the planarity in compounds 4a and 4b to induce aggregation to show AIE property.H owever,a tt his point, the exact mechanism of this photophysical phenomena in these novel hydrazide-hydrazone-based small molecules is elusive and we are currently exploring this area. The frontier molecular orbitals and the energy gap between HOMOsa nd LUMOs of compound 7 were calculated by DFT,w hich showedt hat the energy gap was about4 .21 eV ( % 295 nm;F igure4e), comparable to the energy gapi nc ompound 4a.F inally,w ee xecuted theoretical calculationsb y using the program Gaussian09o nc ompound 7.M ost interestingly,t he optimized molecular geometry of compound 7 showedt hat the dihedral angle of the mono-intramolecular Hbondedm oiety increased to approximately 12.38 (Figure 4f), compared to nearly 08 dihedral angle found in compound 4a.…”

“…Moreover,i no ur previous study,wesynthesized O-phenyl-hydrazide-hydrazone analogue of compound 7,whichshowedn oA IE in the solid state as well as in solution. [43] These solid-state fluorescence, water titration studies andtheoretical structureo ptimization clearlyconfirmed that 1) ESIPT is not the mechanism involved and 2) dual intramolecular H-bonding is criticalt om aintain the planarity in compounds 4a and 4b to induce aggregation to show AIE property.H owever,a tt his point, the exact mechanism of this photophysical phenomena in these novel hydrazide-hydrazone-based small molecules is elusive and we are currently exploring this area.…”

“…This clearly indicated that single intramolecular H‐bonding is not sufficient to maintain coplanarity along the largest molecular axis in compound 7 leading to a lack of aggregated structure with negligible AIE properties. Moreover, in our previous study, we synthesized O‐phenyl‐hydrazide–hydrazone analogue of compound 7 , which showed no AIE in the solid state as well as in solution . These solid‐state fluorescence, water titration studies and theoretical structure optimization clearly confirmed that 1) ESIPT is not the mechanism involved and 2) dual intramolecular H‐bonding is critical to maintain the planarity in compounds 4 a and 4 b to induce aggregation to show AIE property.…”