Three new dibenzoxanthenes were synthesized and their antitumor activity were investigated. Compounds 3a-3c showed significant cytotoxicity to HeLa cells. The 1,3-diphenylisobenzofuran (DBPF) assay demonstrated that compounds could produce singlet oxygen. Cell cloning and wound healing assays demonstrated that compounds 3a-3c effectively inhibited HeLa cell cloning and migration. After entering the mitochondria, the compounds caused a decrease in mitochondrial membrane potential, an increase in intracellular ROS and Ca2+ levels, and blocked the cell cycle in the G2/M phase. Through protein immunoblotting, the apoptotic mechanism was studied, the results show that 3a-3c regulated Bcl-2 family protein, caused abnormal mitochondrial function, which led to mitochondrial apoptotic pathway. ROS, GPX4, GSH and MDA assay indicated that compounds 3a-3c caused intracellular lipid peroxidation in HeLa cells leading to ferroptosis. GSDME cleavage and elevation of LDH release induced the occurrence of pyroptosis. Therefore, we conclude that the compounds cause cell death through three pathways: apoptosis, ferroptosis and pyroptosis.

Cyclometalated iridium(iii) compounds have been widely explored due to their outstanding photo-physical properties and multiple anticancer activities. In this paper, three cyclometalated iridium(iii) compounds [Ir(ppy)(2)(DBDIP)]PF6 (5a), [Ir(bzq)(2)(DBDIP)]PF6 (5b), and [Ir(piq)(2)(DBDIP)]PF6 (5c) (ppy: 2-phenylpyridine; bzq: benzo[h]quinoline; piq: 1-phenylisoquinoline, and DBDIP: 2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and the mechanism of antitumor activity was investigated. Compounds photoactivated by visible light show strong cytotoxicity against tumor cells, especially toward A549 cells. Biological experiments such as migration, cellular localization, mitochondrial membrane potential and permeability, reactive oxygen species (ROS) and calcium ion level detection were performed, and they demonstrated that the compounds induced the apoptosis of A549 cells through a mitochondrial pathway. At the same time, oxidative stress caused by ROS production increases the release of damage-related molecules and the expression of porogen gasdermin D (GSDMD), and the content of LDH released from damaged cell membranes also increased. Besides, the content of the lipid peroxidation product, malondialdehyde (MDA), increased and the expression of GPX4 decreased. These indicate that the compounds promote cell death by combining ferroptosis and pyroptosis. The results reveal that cyclometalated iridium(iii) compounds 5a-5c may be a potential chemotherapeutic agent for photodynamic therapy of cancers.

In this paper, a series of glycyrrhetic acid derivatives 3a–3f were synthesized via the esterification reaction. The cytotoxicity of these compounds against five tumor cells (SGC-7901, BEL-7402, A549, HeLa and B16) and normal LO2 cells was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The results showed that compound 3a exhibited high antiproliferative activity against HeLa cells (IC50 = 11.4 ± 0.2 μM). The anticancer activity was studied through apoptosis, cloning, and scratching; the levels of the intracellular ROS, GSH, and Ca2+; and the change in the mitochondrial membrane potential, cell cycle arrest and RNA sequencing. Furthermore, the effects of compound 3a on gene expression levels and metabolic pathways in HeLa cells were investigated via transcriptomics. The experimental results showed that this compound can block the cell cycle in the S phase and inhibit cell migration by downregulating Focal adhesion kinase (FAK) expression. Moreover, the compound can reduce the intracellular glutathione (GSH) content, increase the Ca2+ level and the intracellular ROS content, and induce a decrease in the mitochondrial membrane potential, further leading to cell death. In addition, it was also found that the mechanism of compounds inducing apoptosis was related to the regulation of the expression of mitochondria-related proteins B-cell lymphoma-2 (Bcl-2), Bcl-2-Associated X (Bax), and the activation of the caspase proteins. Taken together, this work provides a help for the development of glycyrrhetinic acid compounds as potential anticancer molecules.

Three benzoxanthone derivatives were synthesized through a new photochemical strategy. The in vitro cytotoxic activity of these compounds was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and their partition coefficients (logP) were measured by shake flask method. The pKa values of the compounds were detected by potentionmetric titration. The interaction of the compounds with calf thymus DNA (CT-DNA) was investigated by electronic absorption, luminescence spectra and viscosity. A molecular docking analysis was performed. The antitumor efficacy of the compounds was evaluated by cell apoptosis, cell cycle arrest, intracellular Ca2+ concentrations and reactive oxygen species (ROS) levels. The mitochondrial membrane potential was assayed using JC-1 (5,5′,6,6′-tetrachloro-1,1,3′,3′-tetraethyl-imidacarbocyanine iodide) as the fluorescence probe. The expression of Bcl-2 family protein, caspase 3 and poly ADP-ribose polymerase (PARP) was explored by western blot. The results showed that the compounds induced apoptosis through a ROS-mediated mitochondrial dysfunction pathway. This work provides an efficient approach to synthesize benzoxanthone derivatives, and is helpful for understanding the apoptotic mechanism.

Ligand HMSPIP (2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its iridium(III) complexes [Ir(ppy)2(HMSPIP)]PF6 (ppy = 2-phenylpyridine, Ir1) and [Ir(bzq)2(HMSPIP)]PF6 (bzq = benzo[h]quinoline, Ir2) were synthesized. The complexes were characterized by 1H NMR, 13C NMR, and UV/Vis spectra. The cytotoxicity of the complexes toward cancer cells were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, the scratch wound healing and colony-forming were also investigated. MTT assay certificated that the complexes show high toxic effect on the HeLa cells. The cell cycle assay illustrated that the complexes blocked cell growth at G0/G1 phase in HeLa cells. A series of subsequent experiments showed that the complexes first enter the endoplasmic reticulum (ER) and then enter the mitochondria, leading to an increase in intracellular Ca2+ and reactive oxygen species (ROS) content, depolarizing mitochondrial membrane potential (MMP), and ultimately resulting in apoptosis. In addition, the experimental results revealed that the complexes not only increase the level of ROS but also inhibit the production of GSH and eventually produce large amounts of MDA and further leading to cell death. Taken together, we consider that the complexes can be used as potential candidate drugs for HeLa cancer treatment.