An integrated molecular modeling approach for the tryptase monomer-curcuminoid recognition analysis: conformational and bioenergetic features

Cyclocurcumin as Promising Bioactive Natural Compound: An Overview

Although identical in molecular formula and weight, curcumin and cyclocurcumin show remarkable differences in their reactivity. Both are natural compounds isolated from the rhizome of turmeric, the former is involved in the diketo/keto-enol tautomerism through the bis-α,β-unsaturated diketone unit according to the polarity of the solvent, while the latter could react by trans-cis isomerization due to the presence of the α,β-unsaturated dihydropyranone moiety. Even if curcumin is generally considered responsible of the therapeutical properties of Curcuma longa L. due to its high content, cyclocurcumin has attracted great interest over the last several decades for its individual behavior and specific features as a bioactive compound. Cyclocurcumin has a hydrophobic nature characterized by fluorescence emission, solvatochromism, and the tendency to form spherical fluorescent aggregates in aqueous solution. Molecular docking analysis reveals the potentiality of cyclocurcumin as antioxidant, enzyme inhibitor, and antiviral agent. Promising biological activities are observed especially in the treatment of degenerative and cardiovascular diseases. Despite the versatility emerging from the data reported herein, the use of cyclocurcumin seems to remain limited in clinical applications mainly because of its low solubility and bioavailability.

Insight parameter drug design for human β-tryptase inhibition integrated molecular docking, QSAR, molecular dynamics simulation, and pharmacophore modelling studies of α-keto-[1,2,4]-oxadiazoles

Dengue hemorrhagic fever (DHF) is severe dengue with a hallmark of vascular leakage. β-tryptase has been found to promote vascular leakage in DHF patients, which could be a potential target for DHF treatment. This study aims to develop a theoretical background for designing and selecting human β-tryptase inhibitors through computational studies. Thirty-four α-keto-[1,2,3]-oxadiazoles scaffold-based compounds were used to generate 2D-QSAR models and for molecular docking studies with β-tryptase (PDB Code 4A6L). In addition, molecular dynamics (MD) simulation and molecular mechanics generalised born surface area (MM-GBSA) analysis on the binding of the reported most active compound, compound 11e, towards β-tryptase were performed. Finally, a structure-based pharmacophore model was generated. The selected 2D-QSAR models have statistically proven good models by internal and external validation as well as the y-randomization test. The docking results of compound 11e showed lower CDOCKER energy than the 4A6L co-crystallised ligand and a similar binding pattern as the 4A6L co-crystallised ligand. From molecular dynamics simulation, 4A6L in compound 11e bound state has RMSD below 2 Å throughout the 500 ns simulation, indicating the docked complex is stable. Besides, MM-GBSA analysis suggested the 4A6L-compound 11e docked complex (-66.04 Kcal/mol) is structurally as stable as the 4A6L-native ligand co-crystallized structure (-66.84 Kcal/mol). The best pharmacophore model identified features included hydrogen bond acceptor, ionic interaction, hydrophobic interaction, and aromatic ring, which contribute to the inhibitory potency of a compound. This study supplied insight and knowledge for developing novel chemical compounds with improved inhibition of β-tryptase.Communicated by Ramaswamy H. Sarma.

Hybrid Synthetic and Computational Study of an Optimized, Solvent-Free Approach to Curcuminoids

A green and optimized protocol has been developed for the preparation of symmetric 1,7-bis(aryl)-1,6-heptadiene-3,5-diones and asymmetric 2-aryl-6-arylidenecyclohexanones with modified substrate scope and good functional group tolerance. Syntheses proceed smoothly under solvent-free conditions, providing moderate to excellent product yields with a minimal workup procedure. Control experiments, spectroscopic, and computational studies support a mechanism involving the boron-assisted in situ generation of imine intermediates. Crystal structures of three curcuminoids and isolated mechanistic intermediates are reported. The data provide insight for the further development of solvent-free protocols toward diverse curcumin derivatives in the fields of pharmaceutical and synthetic chemistries.