Synthesis and evaluation of novel xanthene-based thiazoles as potential antidiabetic agents.

A series of xanthene-based thiazoles was synthesized and characterized by different scpectroscopic methods, i.e. Proton nuclear magnetic resonance (1 H NMR), carbon nuclear magnetic resonance (13 C NMR), infrared spectroscopy, carbon hydrogen nitrogen analysis, and X-ray crystallography. The inhibition potencies of 18 newly synthesized thiazole derivatives were investigated on the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase (α-Amy), and α-glycosidase (α-Gly) enzymes in accordance with their antidiabetic and anticholinesterase ability. The synthesized compounds have the highest inhibition potential against the enzymes at low nanomolar concentrations. Among the 18 newly synthesized molecules, 3b and 3p were superior to the known commercial inhibitors of the enzymes and have a much more effective inhibitory potential, with IC50 : 2.37 and 1.07 nM for AChE, 0.98 and 0.59 nM for BChE, 56.47 and 61.34 nM for α-Gly, and 152.48 and 124.84 nM for α-Amy, respectively. Finally, the optimized 18 compounds were subjected to molecular docking to describe the interaction between thiazole derivatives and AChE, BChE, α-Amy, and α-Gly enzymes in which important interactions were monitored with amino acid residues of each target enzyme.

A new virus of the family Tombusviridae infecting sugarcane.

Many viral diseases of sugarcane negatively affect yield. A sugarcane accession originating from South Africa exhibiting mosaic symptoms was processed for high-throughput sequencing. Bioinformatic analysis revealed two known sugarcane viruses and a contig of around 2,800 nucleotides resembling umbra-like viruses of the family Tombusviridae. The sequence of the viral contig was confirmed by cloning and Sanger sequencing, and the ends of the virus sequence were determined. Open reading frame analysis revealed the presence of four ORFs. Phylogenetic analysis of the complete virus sequence showed that this virus clusters with other umbra-like viruses of the family Tombusviridae.

COVID-19: A Global Challenge with Old History, Epidemiology and Progress So Far.

Humans have witnessed three deadly pandemics so far in the twenty-first century which are associated with novel coronaviruses: SARS, Middle East respiratory syndrome (MERS), and COVID-19. All of these viruses, which are responsible for causing acute respiratory tract infections (ARTIs), are highly contagious in nature and/or have caused high mortalities. The recently emerged COVID-19 disease is a highly transmittable viral infection caused by another zoonotic novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Similar to the other two coronaviruses such as SARS-CoV-1 and MERS-CoV, SARS-CoV-2 is also likely to have originated from bats, which have been serving as established reservoirs for various pathogenic coronaviruses. Although, it is still unknown how SARS-CoV-2 is transmitted from bats to humans, the rapid human-to-human transmission has been confirmed widely. The disease first appeared in Wuhan, China, in December 2019 and quickly spread across the globe, infected 48,539,872 people, and caused 1,232,791 deaths in 215 countries, and the infection is still spreading at the time of manuscript preparation. So far, there is no definite line of treatment which has been approved or vaccine which is available. However, different types of potential vaccines and therapeutics have been evaluated and/or are under clinical trials against COVID-19. In this review, we summarize different types of acute respiratory diseases and briefly discuss earlier outbreaks of coronaviruses and compare their occurrence and pathogenicity with the current COVID-19 pandemic. Various epidemiological aspects of COVID-19 such as mode of spread, death rate, doubling time, etc., have been discussed in detail. Apart from this, different technical issues related to the COVID-19 pandemic including use of masks and other socio-economic problems associated with the pandemic have also been summarized. Additionally, we have reviewed various aspects of patient management strategies including mechanism of action, available diagnostic tools, etc., and also discussed different strategies for the development of effective vaccines and therapeutic combinations to deal with this viral outbreak. Overall, by the inclusion of various references, this review covers, in detail, the most important aspects of the COVID-19 pandemic.

Characterization and complete genome sequence of a panicovirus from Bermuda grass by high-throughput sequencing.

Bermuda grass samples were examined by transmission electron microscopy and 28-30 nm spherical virus particles were observed. Total RNA from these plants was subjected to high-throughput sequencing (HTS). The nearly full genome sequence of a panicovirus was identified from one HTS scaffold. Sanger sequencing was used to confirm the HTS results and complete the genome sequence of 4404 nt. This virus was provisionally named Bermuda grass latent virus (BGLV). Its predicted open reading frames follow the typical arrangement of the genus Panicovirus. Based on sequence comparisons and phylogenetic analyses BGLV differs from other viruses and therefore taxonomically it is a new member of the genus Panicovirus, family Tombusviridae.

Pulicaria glutinosa extract: a toolbox to synthesize highly reduced graphene oxide-silver nanocomposites.

A green, one-step approach for the preparation of graphene/Ag nanocomposites (PE-HRG-Ag) via simultaneous reduction of both graphene oxide (GRO) and silver ions using Pulicaria glutinosa plant extract (PE) as reducing agent is reported. The plant extract functionalizes the surfaces of highly reduced graphene oxide (HRG) which helps in conjugating the Ag NPs to HRG. Increasing amounts of Ag precursor enhanced the density of Ag nanoparticles (NPs) on HRG. The preparation of PE-HRG-Ag nanocomposite is monitored by using ultraviolet-visible (UV-Vis) spectroscopy, powder X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The as-prepared PE-HRG-Ag nanocomposities display excellent surface-enhanced Raman scattering (SERS) activity, and significantly increased the intensities of the Raman signal of graphene.

Ambient surface analysis of organic monolayers using direct analysis in real time Orbitrap mass spectrometry.

A better characterization of nanometer-thick organic layers (monolayers) as used for engineering surface properties, biosensing, nanomedicine, and smart materials will widen their application. The aim of this study was to develop direct analysis in real time high-resolution mass spectrometry (DART-HRMS) into a new and complementary analytical tool for characterizing organic monolayers. To assess the scope and formulate general interpretation rules, DART-HRMS was used to analyze a diverse set of monolayers having different chemistries (amides, esters, amines, acids, alcohols, alkanes, ethers, thioethers, polymers, sugars) on five different substrates (Si, Si3N4, glass, Al2O3, Au). The substrate did not play a major role except in the case of gold, for which breaking of the weak Au-S bond that tethers the monolayer to the surface, was observed. For monolayers with stronger covalent interfacial bonds, fragmentation around terminal groups was found. For ester and amide-terminated monolayers, in situ hydrolysis during DART resulted in the detection of ions characteristic of the terminal groups (alcohol, amine, carboxylic acid). For ether and thioether-terminated layers, scission of C-O or C-S bonds also led to the release of the terminal part of the monolayer in a predictable manner. Only the spectra of alkane monolayers could not be interpreted. DART-HRMS allowed for the analysis of and distinction between monolayers containing biologically relevant mono or disaccharides. Overall, DART-HRMS is a promising surface analysis technique that combines detailed structural information on nanomaterials and ultrathin films with fast analyses under ambient conditions.

2,2'-[(E,E)-cis-(Cyclo-hexane-1,4-di-yl)bis-(nitrilo-methanylyl-idene)]diphenol.

In the title compound, C(20)H(22)N(2)O(2), the asymmetric unit contains two independent half-mol-ecules, which are both completed by crystallographic inversion symmetry. The cyclo-hexane rings of both mol-ecules adopt chair conformations; the N atoms are in equatorial orientations in one mol-ecule and in axial orientations in the other. Both mol-ecules feature two intra-molecular O-H⋯N hydrogen bonds, which generate S(6) rings.

Dibenzo[b,g]indeno-[1',2':3,4]fluoreno[1,2-d]oxonine-5,11,16,21-tetra-one.

The asymmetric unit of the title compound, C34H16O5, contains two independent mol-ecules (A and B) with similar conformations. The two benzene rings attached to the nine-membered ring are inclined to one another at 63.62 (14)° in mol-ecule A and 68.23 (12)° in mol-ecule B. One intra-moleculer C-H⋯O hydrogen bond occurs in mol-ecule A and two are observed in mol-ecule B. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional network structure with R(2)2(10) and R(2)2(24) ring motifs. Aromatic π-π stacking interactions [centroid-centroid distances = 3.7572 (19), 3.6996 (19) and 3.7043 (19) Å] are also observed. The unit cell contains a pair of voids of 37 (2) Å(3) about an inversion centre but the residual electron density (highest peak = 0.19 e Å(-3) and deepest hole = -0.20 e Å(-3)) in the difference Fourier map suggests that no solvent mol-ecule occupies this void.

2-Anilino-3-(2-hy-droxy-prop-yl)-4-methyl-1,3-thia-zol-3-ium chloride.

In the title compound, C(13)H(17)N(2)OS(+)·Cl(-), the thia-zolium ring mean plane makes a dihedral angle of 55.46 (9)° with the benzene ring. In the propanol group, the N-C-C-C and N-C-C-O torsion angles are 172.58 (15) and 52.9 (2)°, respectively, and the S-C-C-C torsion angle is 178.99 (18)°. In the crystal, mol-ecules are linked by O-H⋯Cl and N-H⋯Cl hydrogen bonds, forming zigzag chains along [001]. There is also a C-H⋯Cl inter-action present.

2-Amino-4-(4-chloro-phen-yl)-7,7-dimethyl-5-oxo-5,6,7,8-tetra-hydro-4H-chromene-3-carbonitrile propan-2-one monosolvate.

In the title compound, C(18)H(17)ClN(2)O(2)·C(3)H(6)O, the 4H-pyran ring is nearly planar [maximum deviation = -0.108 (1) Å] and the cyclo-hexene ring is puckered [puckering parameters Q(T) = 0.4596 (17) Å, θ = 55.9 (2)° and ϕ = 226.5 (3)°]. The 4H-pyran ring is approximately perpendicular to the benzene ring [dihedral angle = 84.35 (7)°] and is almost coplanar with the mean plane of the cyclo-hexene ring [dihedral angle = 8.64 (7)°]. In the crystal, inversion-related main mol-ecules are linked into dimers by pairs of N-H⋯N hydrogen bonds, generating an R(2) (2)(12) graph-set motif. These dimers are further connected by N-H⋯O and C-H⋯N hydrogen bonds, forming a layer structure extending parallel to the (011) plane. In addition, the mol-ecules within the layers inter-act with each other via C-H⋯π inter-actions.

2-Amino-4-(4-methyl-phen-yl)-5-oxo-5,6,7,8-tetra-hydro-4H-chromene-3-carbonitrile.

The 4H-pyran ring of the title compound, C(17)H(16)N(2)O(2), is nearly planar [maximum deviation = 0.077 (2) Å] and the cyclo-hexene ring adopts a flattened chair conformation [puckering parameters: Q(T) = 0.435 (2) Å, θ = 122.0 (3)° and ϕ = 53.5 (3)°]. The 4H-pyran ring is almost perpendicular to the benzene ring [dihedral angle = 87.23 (8)°] and is almost coplanar with the mean plane of the cyclo-hexene ring [dihedral angle = 8.01 (8)°]. In the crystal, inversion-related mol-ecules are linked by pairs of inter-molecular N-H⋯N hydrogen bonds, forming inversion dimers with R(2) (2)(12) ring motifs. These dimers are further connected by N-H⋯O and C-H⋯N hydrogen bonds, forming a layer structure extending parallel to (0-12). Mol-ecules within the layers inter-act with each other via C-H⋯π inter-actions.

2-Amino-4-(4-meth-oxy-phen-yl)-5-oxo-5,6,7,8-tetra-hydro-4H-chromene-3-carbonitrile 1,4-dioxane hemisolvate.

In the crystal structure of the title compound, C(17)H(16)N(2)O(3)·0.5C(4)H(8)O(2), pairs of N-H⋯N hydrogen bonds link mol-ecules into dimers with R(2) (2)(12) motifs, which are connected by N-H⋯O hydrogen bonds, forming a supra-molecular array in the ab plane. The 1,4-dioxane ring, which lies about an inversion center, adopts a chair conformation.

2-Amino-4-(4-meth-oxy-phen-yl)-7,7-di-methyl-5-oxo-5,6,7,8-tetra-hydro-4H-chromene-3-carbonitrile propan-2-one monosolvate.

In the crystal structure of the title compound, C(19)H(20)N(2)O(3)·C(3)H(6)O, mol-ecules are linked into inversion dimers with an R(2) (2)(12) motif by pairs of N-H⋯N hydrogen bonds. These dimers are further connected into chains running along the a axis by N-H⋯O hydrogen bonds. C-H⋯N and C-H⋯π inter-actions also feature in the packing. The cyclohexene ring adopts nearly an envelope conformation [puckering parameters are Q(T) = 0.456 (2) Å, θ = 54.6 (3)° and ϕ = 225.2 (3)°].

Localized Resolution of Identity Approach to the Analytical Gradients of Random-Phase Approximation Ground-State Energy: Algorithm and Benchmarks.

We develop and implement a formalism which enables calculating the analytical gradients of particle-hole random-phase approximation (RPA) ground-state energy with respect to the atomic positions within the atomic orbital basis set framework. Our approach is based on a localized resolution of identity (LRI) approximation for evaluating the two-electron Coulomb integrals and their derivatives, and the density functional perturbation theory for computing the first-order derivatives of the Kohn-Sham (KS) orbitals and orbital energies. Our implementation allows one to relax molecular structures at the RPA level using both Gaussian-type orbitals (GTOs) and numerical atomic orbitals (NAOs). Benchmark calculations against previous implementations show that our approach delivers adequate numerical precision, highlighting the usefulness of LRI in the context of RPA gradient evaluations. A careful assessment of the quality of RPA geometries for small molecules reveals that post-KS RPA systematically overestimates the bond lengths. We furthermore optimized the geometries of the four low-lying water hexamers-cage, prism, cyclic, and book isomers, and determined the energy hierarchy of these four isomers using RPA. The obtained RPA energy ordering is in good agreement with that yielded by the coupled cluster method with single, double and perturbative triple excitations, despite that the dissociation energies themselves are appreciably underestimated. The underestimation of the dissociation energies by RPA is well corrected by the renormalized single excitation correction.

ßC1 of chili leaf curl betasatellite is a pathogenicity determinant.

BACKGROUND: Cotton leaf curl disease in the Indian subcontinent is associated with several distinct begomoviruses that interact with a disease-specific DNA satellite named Cotton leaf curl Multan betasatellite (CLCuMB). However, we have recently reported that Chili leaf curl betasatellite (ChLCB) is also occasionally found associated with the disease in Pakistan. The question as to whether ChLCB contributes to the development of disease symptoms such as leaf curling and enations remain to be answered. We have previously shown that the expression of ßC1 of CLCuMB develops all symptoms of cotton leaf curl disease in Nicotiana benthamiana when expressed from PVX vector. FINDINGS: The role of ChLCB in the induction of typical disease symptoms was studied by its expression from PVX vector in N. benthamiana. The expression of ßC1 from PVX vector developed severe leaf curl symptoms and leaf-like enations that resemble the phenotype induced by ßC1 of CLCuMB. CONCLUSIONS: The results presented here show that the expression of ßC1 of ChLCB from PVX vector exhibit phenotype typical of cotton leaf curl and therefore ChLCB may contribute to the disease symptoms.

Carbonic Anhydrase Inhibitory Potential of 1,2,4-triazole-3-thione Derivatives of Flurbiprofen, Ibuprofen and 4-tert-butylbenzoic Hydrazide: Design, Synthesis, Characterization, Biochemical Evaluation, Molecular Docking and Dynamic Simulation Studies.

BACKGROUND: The over-expression of the carbonic anhydrases results in some specific carcinomas including pancreatic, gastric and brain tumor. Tumors are distinguished under hypoxic conditions and various investigations are being carried out to target the known hypoxic areas of the tumors to increase the sensitivity towards standard therapeutic treatment. OBJECTIVE: Herein, we have designed and synthesized some biologically important esters, hydrazides, thiocarbamates, 1,2,4-triazole-3-thiones and Schiff bases. The purpose of the research was to evaluate the derivative against carbonic anhydrase and to assess the toxicity of the same compounds. METHOD: The structures of all the compounds were characterized by FT-IR, mass spectrometry, elemental analysis, 1H and 13C NMR spectroscopy. The synthetic derivatives were screened for their inhibitory potential against carbonic anhydrase II by in vitro assay. Double reciprocal plots for inhibition kinetics of the potent compounds were constructed and mode of inhibition was determined. Furthermore, to check the cytotoxicity, these derivatives were tested against human breast adenocarcinoma by MTT method. RESULTS: X-ray diffraction analysis of the compounds 10, 14 and 15 showed that they did not have any π-π or C-H…π interactions. The experimental results were validated by molecular docking and dynamic simulations of the potent compounds in the active pocket of enzyme. Important binding interactions of potent compounds with the key residues in the active site of the carbonic anhydrase enzyme were revealed. Drug likeness profile of the derivatives was evaluated to determine the physicochemical properties. CONCLUSION: The proposed synthetic approach provides a suitable platform for the generation of a new library of compounds which could potentially be employed in the future testing and optimization of inhibitor potencies.

Plant extracts as green reductants for the synthesis of silver nanoparticles: lessons from chemical synthesis.

The increasing use of silver (Ag) nanoparticles (NPs) in daily-life applications, electronics, or catalysis calls for green and cost-efficient synthetic methods. Ag NPs are used especially in biomedicine because of their antibacterial, antifungal, or anticancer properties. Chemical synthesis allows tuning the particle morphology, size, and crystallinity, but requires toxic and hazardous chemicals. Bioinspired synthetic protocols have shown promise to minimize environmental impact, but biological protocols for the synthesis of Ag NPs lack control on the morphology and crystallinity. This review briefly compiles the chemical synthesis of Ag NPs and contrasts it with "green" protocols based on lessons learnt from chemical synthesis. The synthesis of Ag NPs with different plant extracts and the associated phytomolecules, their chemical and biological effects, and their effect on particle synthesis are described and put into perspective to improve green protocols. The surface functionalization of Ag NPs by phytomolecules and the mechanisms of their biomedical applications are summarized.

The Prediction of a New CLCuD Epidemic in the Old World.

Cotton leaf curl disease (CLCuD), the most complex disease of cotton, is a major limiting biotic factor to worldwide cotton productivity. Several whitefly-transmitted monopartite begomoviruses causing CLCuD have been characterized and designated as CLCuD-associated begomoviruses. Despite of being reported over 100 years ago in Africa, CLCuD became economically pandemic causing massive losses to cotton production in Pakistan and India during past couple of decades. In Asia, cotton has faced two major epidemics during this period viz. "Multan epidemic" and "Burewala epidemic." The "Multan epidemic" era was 1988-1999 after which the virus remained calm until 2002 when "Burewala epidemic" broke into the cotton fields in Indo-Pak subcontinent, till 2013-2014. However, both the epidemics were caused by monopartite begomovirus complex. Similarly in Africa, Cotton leaf curl Gezira virus with associated DNA-satellites causes CLCuD. Quite recently, in the Old World (both Asia and Africa), bipartite begomoviruses have started appearing in the areas under cotton cultivation. Under such aggravated circumstances, it seems we are heading toward another epidemic of CLCuD in the Old World. Here we articulate the causes and potential emergence of the third epidemic of CLCuD in Asia. The current situation of CLCuD in Asia and Africa is also discussed.

Calixarene: A Versatile Material for Drug Design and Applications.

The therapy of various diseases by the drugs entrapped in calixarene derivatives is gaining attraction of researchers nowadays. Calixarenes are macrocyclic nano-baskets which belong to cavitands class of host-guest chemistry. They are the marvelous hosts with distinct hydrophobic three dimensional cavities to entrap and encapsulate biologically active guest drugs. Calixarene and its derivatives develop inclusion complexes with various types of drugs and vitamins for their sustained/targeted release. Calixarene and its derivatives are used as carriers for anti-cancer, anti-convulsant, anti-hypertensive, anthelmentic, anti-inflammatory, antimicrobial and antipsychotic drugs. They are the important biocompatible receptors to improve solubility, chemical reactivity and decrease cytotoxicity of poorly soluble drugs in supramolecular chemistry. This review focuses on the calixarene and its derivatives as the state-of-the-art in host-guest interactions for important drugs. We have also critically evaluated calixarenes for the development of prodrugs.

Synthesis, Structural Characterization and Antinociceptive Activities of New Arylated Quinolines via Suzuki-Miyaura Cross Coupling Reaction.

BACKGROUND: The quinoline ring system is one of the most commonly encountered heterocycles in medicinal chemistry, due to the pharmaceutical and medicinal uses of derivatives containing this ring. These quinoline-based compounds have remarkable biological activity, as they are employed as antimalarial, antibacterial, antifungal, and antitumor agents. The quinoline nucleus can be synthesized by various traditional methods such as the Skraup reaction, Friedlaender synthesis, Combes quinoline synthesis, Larock quinoline synthesis, among others. METHODS: The aim of the present work is to synthesize a number of new arylated quninolines having significant antinoceciptive effect through the Suzuki-Miyaura cross coupling reaction using 3- bromoquinoline as a starting material. RESULTS: A number of new quinoline derivatives have been synthesized. Structures of the newly synthesized compounds were confirmed by means of IR, NMR, and mass spectrometry, and by elemental analysis. In addition, the molecular structures of two representative derivatives were determined with the aid of X-ray crystallography. Additionally, the antinociceptive activity of the prepared compounds was evaluated in vivo; results revealed that most of the tested compounds exhibited a dosedependent antinociceptive effect. CONCLUSION: Prepared compounds were found to exhibit significant antinociceptive activities and could be used as potential analgesic agents. Further work, however, may be required to establish the safety and efficacy of these compounds.