complex-iv

TMPD dihydrochloride is an active substrate of enzymatically convert redox and an electron donor for the reduction of heme peroxidases.

Talabostat (PT100, Val-boroPro) is a potent, nonselective and orally available dipeptidyl peptidase IV (DPP-IV) inhibitor with a Ki of 0.18 nM. Talabostat is a nonselective DPP-IV inhibitor, inhibiting DPP8 9, FAP, DPP2 and some other DASH family enzymes essentially as potently as it inhibits DPP-IV[1]. Talabostat stimulates the immune system by triggering a proinflammatory form of cell death in monocytes and macrophages known as pyroptosis. The inhibition of two serine proteases, DPP8 and DPP9, activates the proprotein form of caspase-1 independent of the inflammasome adaptor ASC[2]. Talabostat competitively inhibits the dipeptidyl peptidase (DPP) activity of FAP and CD26 DPP-IV, and there is a high-affinity interaction with the catalytic site due to the formation of a complex between Ser630 624 and the boron of talabostat[3]. Talabostat can stimulate immune responses against tumors involving both the innate and adaptive branches of the immune system. In WEHI 164 fibrosarcoma and EL4 and A20 2J lymphoma models, PT-100 causes regression and rejection of tumors. The antitumor effect appears to involve tumor-specific CTL and protective immunological memory. Talabostat treatment of WEHI 164-inoculated mice increases mRNA expression of cytokines and chemokines known to promote T-cell priming and chemoattraction of T cells and innate effector cells[3]. Talabostat treated mice show significant less fibrosis and FAP expression is reduced. Upon PT100 treatment, significant differences in the MMP-12, MIP-1α, and MCP-3 mRNA expression levels in the lungs are also observed. Treatment with PT100 in this murine model of pulmonary fibrosis has an anti-fibro-proliferative effect and increases macrophage activation[4]. [1]. Connolly BA, et al. Dipeptide boronic acid inhibitors of dipeptidyl peptidase IV: determinants of potencyand in vivo efficacy and safety. J Med Chem. 2008 Oct 9;51(19):6005-13. [2]. Okondo MC, et al. DPP8 and DPP9 inhibition induces pro-caspase-1-dependent monocyte and macrophage pyroptosis. Nat Chem Biol. 2017 Jan;13(1):46-53. [3]. Adams S, et al. PT-100, a small molecule dipeptidyl peptidase inhibitor, has potent antitumor effects and augments antibody-mediated cytotoxicity via a novel immune mechanism. Cancer Res. 2004 Aug 1;64(15):5471-80. [4]. Egger C, et al. Effects of the fibroblast activation protein inhibitor, PT100, in a murine model of pulmonary fibrosis. Eur J Pharmacol. 2017 Aug 15;809:64-72.

FMP is a platinum (IV) complex. It significantly upregulates the expression of γ-H2AX and p53, enhances ROS production, and markedly increases the expression of apoptosis (Apoptosis) related proteins (DR5, Fas, caspase-8, Cyt-c, caspase-3, cleaved-PARP1, Bax). FMP exhibits antiproliferative activity against breast cancer.

DPP, a Platinum(IV) complex with a pterostilbene-derived axial ligand, inhibits the JAK2-STAT3 pathway in breast cancer (BC) cells, demonstrating antiproliferative activity. It activates caspase-3 and cleaved poly ADP-ribose polymerase, inducing apoptosis. Furthermore, DPP enhances the maturation and antigen presentation of dendritic cells and exhibits in vivo safety [1].

STAT3-IN-18 (compound SPP), a platinum (IV) complex featuring an axial ligand from sandalwood, suppresses the JAK2-STAT3 pathway in breast cancer (BC) cells and exhibits anti-proliferative properties. It promotes apoptosis by activating caspase-3 and elevating levels of cleaved polyADP-ribose polymerase, in addition to enhancing maturation and antigen presentation in dendritic cells. Moreover, STAT3-IN-18 has demonstrated in vivo safety.

HP661, a selective inhibitor of mitochondrial complex I (NADH dehydrogenase), impedes complex I activity by 77.6% at 1 µM, demonstrating lesser inhibition towards complex III (28.1%) and no inhibitory effects on complexes II and IV. It notably decreases the viability of human lung cancer cells—H460, NCI H441, and trametinib-resistant A549 cells (IC50s = 10.6, 29.7, and 15.1 nM, respectively)—which exhibit high levels of oxidative phosphorylation. In contrast, it shows minimal activity against NCI H358 lung cancer cells and non-cancerous HPNE and MRC-5 cells (IC50s = >10,000 nM for both), which have lower oxidative phosphorylation levels. Furthermore, in an H460 mouse xenograft model, HP661 at a dose of 30 mg/kg twice daily significantly reduces tumor volume and enhances the tumor-growth inhibitory effects of trametinib.