16-Morpholino quaternary ammonium steroidal derivatives as neuromuscular blocking agents: Synthesis, biological evaluation and in silico probe of ligand–receptor interaction

Ensemble-Based Virtual Screening Led to the Discovery of Novel Lead Molecules as Potential NMBAs

Neuromuscular blocking agents (NMBAs) are routinely used during anesthesia to relax skeletal muscle. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels; NMBAs can induce muscle paralysis by preventing the neurotransmitter acetylcholine (ACh) from binding to nAChRs situated on the postsynaptic membranes. Despite widespread efforts, it is still a great challenge to find new NMBAs since the introduction of cisatracurium in 1995. In this work, an effective ensemble-based virtual screening method, including molecular property filters, 3D pharmacophore model, and molecular docking, was applied to discover potential NMBAs from the ZINC15 database. The results showed that screened hit compounds had better docking scores than the reference compound d-tubocurarine. In order to further investigate the binding modes between the hit compounds and nAChRs at simulated physiological conditions, the molecular dynamics simulation was performed. Deep analysis of the simulation results revealed that ZINC257459695 can stably bind to nAChRs' active sites and interact with the key residue Asp165. The binding free energies were also calculated for the obtained hits using the MM/GBSA method. In silico ADMET calculations were performed to assess the pharmacokinetic properties of hit compounds in the human body. Overall, the identified ZINC257459695 may be a promising lead compound for developing new NMBAs as an adjunct to general anesthesia, necessitating further investigations.

Synthesis and Antitumor Activity of Diosgenin Hydroxamic Acid and Quaternary Phosphonium Salt Derivatives

Diosgenin, a component separated from Dioscorea plants, is an important starting material for steroid hormone drugs and semisynthetic steroids. In the work, two series of diosgenin derivatives were designed, synthesized, and evaluated for their cellular anticancer activities. Most of the target compounds exhibited good inhibitory activities against four cell lines, Aspc-1 (human colon adenocarcinoma cells), H358 (human nonsmall cell lung cancer cells), HCT116 (human colorectal adenocarcinoma cells), and SW620 (human metastatic pancreatic cancer cells). Among them, the representative compound 2.2f exhibited 7.9-341.7-fold antiproliferative activities against the above-mentioned four cell lines compared with the lead compound diosgenin.

Synthesis of diosgenyl quaternary ammonium derivatives and their antitumor activity

Giosgenin is a naturally steroidal saponin exhibiting a variety of biological activities including antitumor ones. A series of novel diosgenyl quaternary ammonium derivatives were designed and synthesized to develop potential anti-tumor agents in our research. All novel derivatives were characterized by 1H NMR, 13C NMR and HR-MS, and evaluated for their in vitro anti-proliferative activities using MTT assay. The human cancer cell lines were A549 (Human lung cancer cell), H1975 (Human lung adenocarcinoma cell), A431 (Human skin squamous cell carcinoma), HCT-116 (Human colorectal adenocarcinoma cell), Aspc-1 (Human metastatic pancreatic cancer cell), Ramos (Human B lymphoma cell), HBE (Human bronchial epithelioid cell) and LO2 (Human normal hepatocyte).

New selenosteroids as antiproliferative agents

Starting from natural steroids (diosgenin, hecogenin, smilagenin, estrone), we have prepared a wide panel of selenoderivatives, including benzoselenazolones, selenosemicarbazones, isoselenocyanates, selenoureas, selenocyanates and diselenides, with the aim of developing new families of potential chemotherapeutic agents. The modification of the organoselenium moieties, and their position on the steroid provided valuable information concerning the antiproliferative activities. Among all the families accessed herein, the best profile was achieved for selenoureas on the A ring of estrone, which exhibited GI₅₀ values in the range 2.0-4.1 μM for all the tested tumor cell lines, with increased potency compared with commonly used chemotherapeutic agents, like 5-fluorouracil and cisplatin. Cell cycle analysis revealed that selenoureas induced accumulation of cells in the G₁ phase of the cell cycle in the breast cancer cell lines HBL-100 and T-47D; therefore, a different mechanism than cisplatin, that induces cell cycle accumulation in the S phase as a result of DNA damage, must be involved. In the rest of the tumor cells, a slight increase of the S compartment was observed. Moreover, selenosteoids turned out to be excellent glutathione peroxidase (GPx) mimics for the catalytic removal of deleterious H₂O₂ (t_1/2 8.0-22.5 min) and alkyl peroxides (t_1/2 23.0-38.9 min) when used in substoichiometric amounts (1% molar ratio), thus providing a valuable tool for reducing the intrinsic oxidative stress in tumor progression.

Explorative study on the anticancer activity, selectivity and metabolic stability of related analogs of aminosteroid RM-133

RM-133 is a key representative of a new family of aminosteroids reported as potent anticancer agents. Although RM-133 produced interesting results in 4 mouse xenograft cancer models when injected subcutaneously, it needs to be improved to increase its in vivo potency. Thus, to obtain an analog of RM-133 with a better drug potential, a structure-activity relationship study was conducted by synthesizing eleven RM-133-related compounds and addressing their antiproliferative activity on 3 human cancer cells (HL-60, OVCAR-3 and PANC-1) and 3 human normal cell lines (primary ovary, pancreas and renal proximal tubule) as well as their metabolic stability in human liver microsomes. When the 2β-tertiary amine of RM-133 was transformed into a salt or moved to position 3β, the anticancer activity was lost. Modifying the orientation of the side chain of RM-133 increased anticancer activity and selectivity, but led to a drastic loss of stability. The protection of the 3α-hydroxyl of RM-133 by the formation of an ester or a carbamate stabilized the molecule against the phase I metabolic enzymes without affecting its anticancer activity. In comparison to RM-133, the 3-dimethylcarbamate derivative 3 is more selective for cancer cells over normal cells and is much more stable in liver microsomes. Those results support the use of a pro-drug strategy targeting the 3α-hydroxyl of RM-133 as an approach to improve its drug properties. The work presented will enable the development of an optimized anticancer drug of the aminosteroid family that is suitable for a future phase I clinical trial.

3,16-Bisquaternary ammonium steroid derivatives as neuromuscular blocking agents: synthesis and biological evaluation

Neuromuscular blocking agents (NMBAs) are widely used in surgery to achieve skeleton muscles relaxation under light anesthesia status. In this work, we synthesized a series of 3,16-bisquaternary ammonium steroidal NMBAs. Among them, three compounds exhibited higher in vitro activities than the commenced drug rocuronium. In addition, structure-activity relationship was unveiled. We found that the intact acetylcholine-like moiety in D-ring was not necessary for maintaining activity but both the acetyl group and the quaternary nitrogen were very essential.

Cucurbit[n]uril type hosts for the reversal of steroidal neuromuscular blocking agents

The ideal neuromuscular blocking agent (NMBA) is regarded as being a non-depolarizing equivalent of succinylcholine, having a rapid onset and short duration of action, with minimal side effects. In the absence of a single drug, the administration of an aminosteroid NMBA, such as rocuronium, followed by reversal using an acetylcholinesterase inhibitor, such as neostigmine, is commonly employed. A different and safer approach to rapidly reversing the action of the NMBA, by encapsulating it with a macrocyclic or acyclic host molecule, such as the cyclodextrin sugammadex or more recently, cucurbituril-type hosts such as cyclic cucurbit[7]uril and the acyclic glycoluril tetramer calabadion 1, is described.