Synthesis and evaluation of N1-alkylindole-3-ylalkylammonium compounds as nicotinic acetylcholine receptor ligands

Organobase-Catalyzed Umpolung of Amides: The Generation and Transfer of Carbamoyl Anion

A novel organobase-catalyzed umpolung reaction of amides was disclosed. This method provides an efficient method to generate and transfer carbamoyl anions. In this transformation, some of the inherent disadvantages of carbamoyl metal were avoided. The mechanistic analysis revealed that the reaction proceeds through polarity inversion of amide, and various carbamoyl anions were applied in the reaction. Moreover, a wide range of substrates was achieved with moderate to excellent yield.

Spectroscopic characterization, DFT studies, molecular docking and cytotoxic evaluation of 4-nitro-indole-3-carboxaldehyde: A potent lung cancer agent

The 4-nitro-1H-indole-carboxaldehyde (NICA) molecule was characterized experimentally using FT-IR, FT-Raman and UV-Vis spectra, and it was studied theoretically using DFT calculations. The optimized structure of the NICA molecule was determined by DFT calculations using B3LYP functional with cc-pVTZ basis set. The electron localization function (ELF) and local orbital localizer (LOL) studies were performed to visualize the electron delocalization in the molecule. The experimental and theoretical wavenumbers of the title molecule were assigned using VEDA 4.0 program. The charge delocalization and stability of the title molecule were investigated using natural bond orbital (NBO) analysis. Frontier molecular orbitals (FMOs) and related molecular properties were calculated. UV-Vis spectrum was calculated theoretically and validated experimentally. The reactive sites of the molecule were studied from the MEP surface and Fukui function analysis. The molecular docking analysis reveals that the NICA ligand shows better inhibitory activity against RAS, which causes lung cancer. The in vitro cytotoxic activity of the molecule against human lung cancer cell lines (A549) was determined by MTT assay. Thus, the NICA molecule can be used as a potential candidate for the development of the drug against lung cancer.

Synthesis of β-alkoxy-N-protected phenethylamines via one-pot copper-catalyzed aziridination and ring opening

A regioselective, copper-catalyzed, one-pot aminoalkoxylation of styrenes using primary and secondary alcohols and three different iminoiodanes as alkoxy and nitrogen sources respectively, is reported. The β-alkoxy-N-protected phenethylamines obtained were used to synthesise β-alkoxy-N-benzylphenethylamines which are interesting new compounds that could act as possible neuronal ligands.

An efficient, regioselective and rapid copper-catalyzed one-pot aminoalkoxylation of styrenes has been developed using different alcohols and phenyl iminoiodinanes.

Methylpiperidinium Iodides as Novel Antagonists for α7 Nicotinic Acetylcholine Receptors

The α7 nicotinic acetylcholine receptor (nAChR) is expressed in neuronal and non-neuronal cells and is involved in several physiopathological processes, and is thus an important drug target. We have designed and synthesized novel piperidine derivatives as α7 nAChR antagonists. Thus, we describe here a new series of 1-[2-(4-alkoxy-phenoxy-ethyl)]piperidines and 1-[2-(4-alkyloxy-phenoxy-ethyl)]-1-methylpiperidinium iodides (compounds 11a-11c and 12a-12c), and their actions on α7 nAChRs. The pharmacological activity of these compounds was studied in rat CA1 hippocampal interneurons by using the whole-cell voltage-clamp technique. Inhibition of the choline-induced current was less for 11a-11c than for the methylpiperidinium iodides 12a-12c and depended on the length of the aliphatic chain. Those compounds showing strong effects were studied further using molecular docking and molecular dynamics simulations. The strongest and non-voltage dependent antagonism was shown by 12a, which could establish cation–π interactions with the principal (+)-side and van der Waals interactions with the complementary (-)-side in the α7 nAChRs. Furthermore, compound 11a forms hydrogen bonds with residue Q115 of the complementary (-)-side through water molecules without forming cation–π interactions. Our findings have led to the establishment of a new family of antagonists that interact with the agonist binding cavity of the α7 nAChR, which represent a promising new class of compounds for the treatment of pathologies where these receptors need to be negatively modulated, including neuropsychiatric disorders as well as different types of cancer.

The potential of achiral sponge-derived and synthetic bromoindoles as selective cytotoxins against PANC-1 tumor cells

Our quest to isolate and characterize natural products with in vitro solid tumor selectivity is driven by access to repositories of Indo-Pacific sponge extracts. In this project an extract of a species of Haplosclerida sponge obtained from the US NCI Natural Products Repository displayed, by in vitro disk diffusion assay (DDA) and IC50 determinations, selective cytotoxicity with modest potency to a human pancreatic cancer cell line (PANC-1) relative to the human lymphoblast leukemia cell line (CCRF-CEM). Two brominated indoles, the known 6-bromo conicamin (1) and the new derivative, 6-Br-8-keto-conicamin A (2), were identified and 2 (IC50 1.5 μM for the natural product vs 4.1 μM for the synthetic material) was determined to be responsible for the cytotoxic activity of the extract against the PANC-1 tumor cell line. The new natural product and ten additional analogs were prepared for further SAR testing.

Substrate-Controlled Transformation of Azobenzenes to Indazoles and Indoles via Rh(III)-Catalysis

Rh(III)-catalyzed substrate-controlled transformation of azobenzenes to indazoles and 2-acyl (NH) indoles is achieved via C-H functionalization. Generally, good functional groups tolerance, satisfying yields, and excellent regio-selectivity are achieved in this reaction. Mechanistically, the reaction with acrylates undergoes β-hydride elimination, while the reaction with vinyl ketones or acrylamides undergoes nucleophilic addition. Copper acetate was supposed to play different roles in the β-hydride elimination to furnish indazoles and nucleophilic addition of C-Rh bond to deliver 2-acyl (NH) indoles.

Gramicidin conformational changes during riboflavin photosensitized oxidation in solution and the effect of N-methylation of tryptophan residues

During riboflavin mediated photo-oxidation, gramicidin changes from intertwined to monomeric conformation (disaggregation), while the methylated derivative is not photo-oxidized.

Structure-activity relationships of chromone derivatives toward the mechanism of interaction with and inhibition of breast cancer resistance protein ABCG2

We recently identified a chromone derivative, 5-(4-bromobenzyloxy)-2-(2-(5-methoxyindolyl)ethyl-1-carbonyl)-4H-chromen-4-one, named here as chromone 1, as a potent, selective, nontoxic, and nontransported inhibitor of ABCG2-mediated drug efflux (Valdameri et al. J. Med. Chem. 2012, 55, 966). We have now synthesized a series of 14 derivatives to study the structure-activity relationships controlling both drug efflux and ATPase activity of ABCG2 and to elucidate their molecular mechanism of interaction and inhibition. It was found that the 4-bromobenzyloxy substituent at position 5 and the methoxyindole are important for both inhibition of mitoxantrone efflux and inhibition of basal ATPase activity. Quite interestingly, methylation of the central amide nitrogen strongly altered the high affinity for ABCG2 and the complete inhibition of mitoxantrone efflux and coupled ATPase activity. These results allowed the identification of a critical central inhibitory moiety of chromones that has never been investigated previously in any series of inhibitors.