Indolo[2,3-e]benzazocines and indolo[2,3-f]benzazonines and their copper(II) complexes as microtubule destabilizing agents.

A series of four indolo[2,3-e]benzazocines HL1-HL4 and two indolo[2,3-f]benzazonines HL5 and HL6, as well as their respective copper(II) complexes 1-6, were synthesized and characterized by 1H and 13C NMR spectroscopy, ESI mass spectrometry, single crystal X-ray diffraction (SC-XRD) and combustion analysis (C, H, N). SC-XRD studies of precursors Vd, VIa·0.5MeOH, of ligands HL4 and HL6·DCM, and complexes 2·2DMF, 5·2DMF, 5'·iPrOH·MeOH provided insights into the energetically favored conformations of eight- and nine-membered heterocycles in the four-ring systems. In addition, proton dissociation constants (pKa) of HL1, HL2 and HL5, complexes 1, 2 and 5, overall stability constants (log ß) of 1, 2 and 5 in 30% (v/v) DMSO/H2O at 298 K, as well as thermodynamic solubility of HL1-HL6 and 1-6 in aqueous solution at pH 7.4 were determined by UV-vis spectroscopy. All compounds were tested for antiproliferative activity against Colo320, Colo205 and MCF-7 cell lines and showed IC50 values in the low micromolar to sub-micromolar concentration range, while some of them (HL1, HL5 and HL6, 1, 2 and 6) showed remarkable selectivity towards malignant cell lines. Ethidium bromide displacement studies provided evidence that DNA is not the primary target for these drugs. Rather, inhibition of tubulin assembly is likely the underlying mechanism responsible for their antiproliferative activity. Tubulin disassembly experiments showed that HL1 and 1 are effective microtubule destabilizing agents binding to the colchicine site. This was also confirmed by molecular modelling investigations. To the best of our knowledge, complex 1 is the first reported transition metal complex to effectively bind to the tubulin-colchicine pocket.

Enriching Chemical Space of Bioactive Scaffolds by New Ring Systems: Benzazocines and Their Metal Complexes as Potential Anticancer Drugs.

The search for new scaffolds of medicinal significance combined with molecular shape enhances their innovative potential and continues to attract the attention of researchers. Herein, we report the synthesis, spectroscopic characterization (1H and 13C NMR, UV-vis, IR), ESI-mass spectrometry, and single-crystal X-ray diffraction analysis of a new ring system of medicinal significance, 5,6,7,9-tetrahydro-8H-indolo[3,2-e]benzazocin-8-one, and a series of derived potential ligands (HL1-HL5), as well as ruthenium(II), osmium(II), and copper(II) complexes (1a, 1b, and 2-5). The stability of compounds in 1% DMSO aqueous solutions has been confirmed by 1H NMR and UV-vis spectroscopy measurements. The antiproliferative activity of HL1-HL5 and 1a, 1b, and 2-5 was evaluated by in vitro cytotoxicity tests against four cancer cell lines (LS-174, HCT116, MDA-MB-361, and A549) and one non-cancer cell line (MRC-5). The lead compounds HL5 and its copper(II) complex 5 were 15× and 17×, respectively, more cytotoxic than cisplatin against human colon cancer cell line HCT116. Annexin V-FITC apoptosis assay showed dominant apoptosis inducing potential of both compounds after prolonged treatment (48 h) in HCT116 cells. HL5 and 5 were found to induce a concentration- and time-dependent arrest of cell cycle in colon cancer cell lines. Antiproliferative activity of 5 in 3D multicellular tumor spheroid model of cancer cells (HCT116, LS-174) superior to that of cisplatin was found. Moreover, HL5 and 5 showed notable inhibition potency against glycogen synthase kinases (GSK-3α and GSK-3ß), tyrosine-protein kinase (Src), lymphocyte-specific protein-tyrosine kinase (Lck), and cyclin-dependent kinases (Cdk2 and Cdk5) (IC50 = 1.4-6.1 µM), suggesting their multitargeted mode of action as potential anticancer drugs.

Elucidation of Structure-Activity Relationships in Indolobenzazepine-Derived Ligands and Their Copper(II) Complexes: the Role of Key Structural Components and Insight into the Mechanism of Action.

Indolo[3,2-d][1]benzazepines (paullones), indolo[3,2-d][2]benzazepines, and indolo[2,3-d][2]benzazepines (latonduines) are isomeric scaffolds of current medicinal interest. Herein, we prepared a small library of novel indolo[3,2-d][2]benzazepine-derived ligands HL1-HL4 and copper(II) complexes 1-4. All compounds were characterized by spectroscopic methods (1H and 13C NMR, UV-vis, IR) and electrospray ionization (ESI) mass spectrometry, while complexes 2 and 3, in addition, by X-ray crystallography. Their purity was confirmed by HPLC coupled with high-resolution ESI mass spectrometry and/or elemental analysis. The stability of compounds in aqueous solutions in the presence of DMSO was confirmed by 1H NMR and UV-vis spectroscopy measurements. The compounds revealed high antiproliferative activity in vitro in the breast cancer cell line MDA-MB-231 and hepatocellular carcinoma cell line LM3 in the low micromolar to nanomolar concentration range. Important structure-activity relationships were deduced from the comparison of anticancer activities of HL1-HL4 and 1-4 with those of structurally similar paullone-derived (HL5-HL7 and 5-7) and latonduine-derived scaffolds (HL8-HL11 and 8-11). The high anticancer activity of the lead drug candidate 4 was linked to reactive oxygen species and endoplasmic reticulum stress induction, which were confirmed by fluorescent microscopy and Western blot analysis.

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction.

Paullone isomers are known as inhibitors of tubulin polymerase and cyclin dependent kinases (Cdks), which are potential targets for cancer chemotherapy. Herein we report an efficient and clean pathway to the fourth isomer, which remained elusive so far, namely 7,8-dihydroindolo[2,3-d][1]benzazepin-6(5H)-one. Moreover, we demonstrate the generality of our pathway by synthesizing two closely related analogues, one containing a bromo substituent and the other one incorporating an 8-membered instead of a 7-membered ring. The key transformation in this four-step synthesis, with an overall yield of 29%, is the Fischer indole reaction of 2-nitrophenylacetyl acetoacetate with 1-benzyl-1-phenylhydrazine in acetic acid that delivers methyl 2-(1-benzyl-3-(2-nitrophenyl)-1H-indol-2-yl)acetate in 55% yield.

BH4-deficient hyperphenylalaninemia in Russia.

A timely detection of patients with tetrahydrobiopterin (BH4) -deficient types of hyperphenylalaninemia (HPABH4) is important for assignment of correct therapy, allowing to avoid complications. Often HPABH4 patients receive the same therapy as phenylalanine hydroxylase (PAH) -deficiency (phenylketonuria) patients-dietary treatment-and do not receive substitutive BH4 therapy until the diagnosis is confirmed by molecular genetic means. In this study, we present a cohort of 30 Russian patients with HPABH4 with detected variants in genes causing different types of HPA. Family diagnostics and biochemical urinary pterin spectrum analyses were carried out. HPABH4A is shown to be the prevalent type, 83.3% of all HPABH4 cases. The mutation spectrum for the PTS gene was defined, the most common variants in Russia were p.Thr106Met-32%, p.Asn72Lys-20%, p.Arg9His-8%, p.Ser32Gly-6%. We also detected 7 novel PTS variants and 3 novel QDPR variants. HPABH4 prevalence was estimated to be 0.5-0.9% of all HPA cases in Russia, which is significantly lower than in European countries on average, China, and Saudi Arabia. The results of this research show the necessity of introducing differential diagnostics for HPABH4 into neonatal screening practice.