Rational Design, Synthesis, and Evaluation of Fluorescent CB2 Receptor Ligands for Live-Cell Imaging: A Comprehensive Review.

The cannabinoid receptors CB1 and CB2 are class A G protein-coupled receptors (GPCRs) that are activated via endogenous lipids called endocannabinoids. The endocannabinoid system (ECS) plays a critical role in the regulation of several physiological states and a wide range of diseases. In recent years, drug discovery approaches targeting the cannabinoid type 2 receptor (CB2R) have gained prominence. Particular attention has been given to selective agonists targeting the CB2 receptors to circumvent the neuropsychotropic side effects associated with CB1 receptors. The pharmacological modulation of CB2R holds therapeutic promise for various diseases, such as inflammatory disorders and immunological conditions, as well as pain management and cancer treatment. Recently, the utilization of fluorescent probes has emerged as a valuable technique for investigating the interactions between ligands and proteins at an exceptional level of spatial and temporal precision. In this review, we aim to examine the progress made in the development of fluorescent probes targeting CB2 receptors and highlight their significance in facilitating the successful clinical translation of CB2R-based therapies.

Cannabinoformins: Designing Biguanide-Embedded, Orally Available, Peripherally Selective Cannabinoid-1 Receptor Antagonists for Metabolic Syndrome Disorders.

We have designed orally bioavailable, non-brain-penetrant antagonists of the cannabinoid-1 receptor (CB1R) with a built-in biguanide sensor to mimic 5'-adenosine monophosphate kinase (AMPK) activation for treating obesity-associated co-morbidities. A series of 3,4-diarylpyrazolines bearing rational pharmacophoric pendants designed to limit brain penetration were synthesized and evaluated in CB1R ligand binding assays and recombinant AMPK assays. The compounds displayed high CB1R binding affinity and potent CB1R antagonist activities and acted as AMPK activators. Select compounds showed good oral exposure, with compounds 36, 38-S, and 39-S showing <5% brain penetrance, attesting to peripheral restriction. In vivo studies of 38-S revealed decreased food intake and body weight reduction in diet-induced obese mice as well as oral in vivo efficacy of 38-S in ameliorating glucose tolerance and insulin resistance. The designed "cannabinoformin" four-arm CB1R antagonists could serve as potential leads for treatment of metabolic syndrome disorders with negligible neuropsychiatric side effects.

Virtual screening of natural products inspired in-house library to discover potential lead molecules against the SARS-CoV-2 main protease.

SARS-CoV-2, a new coronavirus emerged in 2019, causing a global healthcare epidemic. Although a variety of drug targets have been identified as potential antiviral therapies, and effective candidate against SARS-CoV-2 remains elusive. One of the most promising targets for combating COVID-19 is SARS-CoV-2 Main protease (Mpro, a protein responsible for viral replication. In this work, an in-house curated library was thoroughly evaluated for druggability against Mpro. We identified four ligands (FG, Q5, P5, and PJ4) as potential inhibitors based on docking scores, predicted binding energies (MMGBSA), in silico ADME, and RMSD trajectory analysis. Among the selected ligands, FG, a natural product from Andrographis nallamalayana, exhibited the highest binding energy of -10.31 kcal/mol close to the docking score of clinical candidates Boceprevir and GC376. Other ligands (P5, natural product from cardiospermum halicacabum and two synthetic molecules Q5 and PJ4) have shown comparable docking scores ranging -7.65 kcal/mol to -7.18 kcal/mol. Interestingly, we found all four top ligands had Pi bond interaction with the main amino acid residues HIS41 and CYS145 (catalytic dyad), H-bonding interactions with GLU166, ARG188, and GLN189, and hydrophobic interactions with MET49 and MET165 in the binding site of Mpro. According to the ADME analysis, Q5 and P5 are within the acceptable range of drug likeliness, compared to FG and PJ4. The interaction stability of the lead molecules with viral protease was verified using replicated MD simulations. Thus, the present study opens up the opportunity of developing drug candidates targeting SARS-CoV-2 main protease (Mpro) to mitigate the disease.Communicated by Ramaswamy H. Sarma.

Targeting Sterol O-Acyltransferase/Acyl-CoA:Cholesterol Acyltransferase (ACAT): A Perspective on Small-Molecule Inhibitors and Their Therapeutic Potential.

Sterol O-acyltransferase (SOAT) is a membrane-bound enzyme that aids the esterification of cholesterol and fatty acids to cholesterol esters. SOAT has been studied extensively as a potential drug target, since its inhibition can serve as an alternative to statin therapy. Two SOAT isozymes that have discrete functions in the human body, namely, SOAT1 and SOAT2, have been characterized. Over three decades of research has focused on candidate SOAT1 inhibitors with unsatisfactory results in clinical trials. Recent research has focused on targeting SOAT2 selectively. In this perspective, we summarize the literature covering various SOAT inhibitory agents and discuss the design, structural requirements, and mode of action of SOAT inhibitors.

One-Pot Synthesis of Thio-Augmented Sulfonylureas via a Modified Bunte's Reaction.

We report the development of a one-pot Bunte's reaction-enabled expeditious platform under aqueous conditions for the scalable conversion of sulfonylureas to synthetically versatile thio-sulfonylureas. The reaction was further propagated in the same pot to yield diverse chiral and achiral isothiosulfonyl analogs. The protocol enabled the synthesis of various drug-like molecules and was applied to an enantiomeric synthesis of a cannabinoid receptor antagonist SLV326.

Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity.

A new quaternary telluride, Ba4Ge2Sb2Te10, was synthesized at high temperature via the reaction of elements. A single-crystal X-ray diffraction study shows that the title compound crystallizes in its own structure type in the monoclinic P21/c space group having cell dimensions of a = 13.984(3) Å, b = 13.472(3) Å, c = 13.569(3) Å, and ß = 90.16(3)° with four formula units per unit cell (Z = 4). The pseudo-one-dimensional crystal structure of Ba4Ge2Sb2Te10 consists of infinite 1∞[Ge2Sb2Te10]8- stripes, which are separated by Ba2+ cations. Each of the Ge(1) atoms is covalently bonded to four Te atoms, whereas the Ge(2) atom is covalently bonded with one Sb(2) and three Te atoms in a distorted tetrahedral geometry. The title compound is the first example of a chalcogenide that shows Ge-Sb bonding. The Sb(1) atom is present at the center of the seesaw geometry of four Te atoms. In contrast, the Sb(2) atom forms a seesaw geometry by coordinating with one Ge(2) and three Te atoms. Condensation of these Ge and Sb centered polyhedral units lead to the formation of 1∞[Ge2Sb2Te10]8- stripes. The temperature-dependent resistivity study suggests the semimetallic/degenerate semiconducting nature of polycrystalline Ba4Ge2Sb2Te10. The positive sign of Seebeck coefficient values indicates that the predominant charge carriers are holes in Ba4Ge2Sb2Te10. An extremely low lattice thermal conductivity of ∼0.34 W/mK at 773 K was observed for polycrystalline Ba4Ge2Sb2Te10, which is presumably due to the lattice anharmonicity induced by the stereochemically active 5s2 lone pair of Sb. The electronic structure of Ba4Ge2Sb2Te10 and the bonding of atom pairs in the structure have been analyzed by means of ELF analysis and crystal orbital Hamilton population (COHP) analysis.

Ba2Ln1-xMn2Te5 (Ln = Pr, Gd, and Yb; x = Ln vacancy): syntheses, crystal structures, optical, resistivity, and electronic structure.

Three new isostructural quaternary tellurides, Ba2Ln1-xMn2Te5 (Ln = Pr, Gd, and Yb), have been synthesized by the molten-flux method at 1273 K. The single-crystal X-ray diffraction studies at 298(2) K showed that Ba2Ln1-xMn2Te5 crystallize in the space group -C2/m of the monoclinic crystal system. There are six unique crystallographic sites in this structure's asymmetric unit: one Ba site, one Ln site, one Mn site, and three Te sites. The Ln site in the Ba2Ln1-xMn2Te5 structure is partially filled, which leaves about one-third of the Ln sites vacant (□) for Pr and Gd compounds. These structures do not contain any homoatomic or metallic bonding and can be charge-balanced as (Ba2+)2(Gd/Pr3+)2/3(Mn2+)2(Te2-)5. The refined composition for the Yb compound is Ba2Yb0.74(1)Mn2Te5 and can be charge-balanced with a mixed valence state of Yb2+/Yb3+. The crystal structures of Ba2Ln1-xMn2Te5 consist of complex layers of [Ln1-xMn2Te5]4- stacked along the [100] direction, with Ba2+ cations separating these layers. The Ln atoms are bound to six Te atoms that form a distorted octahedral geometry around the central Ln atom. Each Mn atom in this structure is coordinated to four Te atoms in a distorted tetrahedral fashion. These LnTe6 and MnTe4 units are the main building blocks of the Ba2Ln1-xMn2Te5 structure. The optical absorption study performed on a polycrystalline Ba2Gd2/3Mn2Te5 sample reveals a direct bandgap of 1.06(2) eV consistent with the DFT study. A semiconducting behavior was also observed for polycrystalline Ba2Gd2/3Mn2Te5 from the resistivity study. The temperature-dependent magnetic studies on a polycrystalline sample of Ba2Gd2/3Mn2Te5 did not reveal any long-range magnetic order down to 5 K. The effective magnetic moment (µeff) of 10.37µB calculated using the Curie-Weiss law is in good agreement with the theoretical value (µcal) of 10.58µB.

Furan derivatives impair proliferation and affect ultrastructural organization of Trypanosoma cruzi and Leishmania amazonensis.

Chagas disease and leishmaniasis are neglected diseases caused by parasites of the Trypanosomatidae family and together they affect millions of people in the five continents. The treatment of Chagas disease is based on benznidazole, whereas for leishmaniasis few drugs are available, such as amphotericin B and miltefosine. In both cases, the current treatment is not entirely efficient due to toxicity or side effects. Encouraged by the need to discover valid targets and new treatment options, we evaluated 8 furan compounds against Trypanosoma cruzi and Leishmania amazonensis, considering their effects against proliferation, infection, and ultrastructure. Many of them were able to impair T. cruzi and L. amazonensis proliferation, as well as cause ultrastructural alterations, such as Golgi apparatus disorganization, autophagosome formation, and mitochondrial swelling. Taken together, the results obtained so far make these compounds eligible for further steps of chemotherapy study.

InCl3: A Versatile Catalyst for Synthesizing a Broad Spectrum of Heterocycles.

This review deals with the recent applications of the indium trichloride (InCl3) catalyst in the synthesis of a broad spectrum of heterocyclic compounds. Over the years, a number of reviews on the applications of InCl3-catalyzed organic synthesis have appeared in the literature. It is evident that InCl3 has emerged as a valuable catalyst for a wide range of organic transformations due to its stability when exposed to moisture and also in an aqueous medium. The most attractive feature of this review is the application of the InCl3 catalyst for synthesizing bioactive heterocyclic compounds. The study of InCl3-catalyzed organic reactions has high potential and better intriguing aspects, which are anticipated to originate from this field of research.

A bis-indole/carbazole based C5-curcuminoid fluorescent probe with large Stokes shift for selective detection of biothiols and application to live cell imaging.

A series of heterocyclic C5-curcuminoids (bis(arylmethylidene)acetones) (PJ1-PJ6) having a large Stokes shift (Δλ = 104-173 nm) have been synthesized for the selective detection of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in living cells. The compounds were synthesized using a new methodology via deacetylation under microwave conditions. The photophysical properties of these compounds have been studied. Prominent colour changes from bright yellow to colourless in the presence of thiols were observed for PJ1. Live cell imaging has been employed with PJ1 for the utilization of the probe to detect homocysteine in A375 cells and apoptosis in AGS cells.

Establishment of atropisomerism in 3-indolyl furanoids: a synthetic, experimental and theoretical perspective.

Introduction of axial chirality in bioactive 3-indolyl furanoids has been achieved by systematic alteration of functional groups around the stereogenic axis, keeping in mind that atropisomerically pure analogues may possess different binding affinities and selectivities towards a target protein. The kinetics of racemization of axially chiral 3-indolyl furanoids have been studied through chiral HPLC analysis, electronic circular dichroism (ECD) spectroscopy, and computational modeling. The results identify the configurational parameters for optically pure 3-indolyl furanoids to exist as stable and isolable atropisomeric form.