“Thioureidopeptide”: Novel Synthon for the Synthesis of <Emphasis Type="Italic">N,N′, N″</Emphasis>-Trisubstituted Guanidinopeptide Mimics

The synthesis of N ^α-protected N,N′,N″-trisubstituted guanidinopeptide mimic molecules suitably decorated in peptide backbone has been delineated in one pot employing HgCl₂ as a desulphurizing agent. Chiral N ^α -protected thioureidopeptide esters were employed as synthons for the synthesis of title molecules. The protocol is simple and the reaction conditions employed were mild, amenable to the amino acid chemistry.     

Molecular modeling of cornulin (CRNN) for docking with phytocompounds from Justicia adhatoda L.

Cornulin (CRNN) is linked with tumour progression. Therefore, it is of interest to document data on the molecular modeling of cornulin (CRNN) for docking with phytocompounds (Pyrazinamide, Anisotine, Vasicinone, Vasicoline) from Justicia adhatoda L. Thus, we document the optimal binding features of these compounds with the cornulin model for further consideration.     

Molecular docking analysis of SARS-CoV-2 linked RNA dependent RNA polymerase (RdRp) with compounds from Plectranthus amboinicus

It is of interest to document the moelcular docking analysis of SARS-CoV-2 linked RNA dependent RNA polymerase (RdRp) with compounds from Plectranthus amboinicus. Hence, we report the binding features of rutin, Luteolin, Salvianolic acid A, Rosmarinic acid and p-Coumaric acid with the target protein SARS-CoV-2 linked RNA dependent RNA polymerase (RdRp) for further consideration.     

Molecular docking analysis of vascular endothelial growth factor receptor with bioactive molecules from Piper longum as potential anti-cancer agents

It is known that vascular endothelial growth factor receptor (VGFR) is linked with cancer. Therefore, it is of interest to document the molecular binding features of bioactive molecules from Piper longum as potential anti-cancer agents with VGFR2 for further consideration. Thus, we document the binding features of four compounds (sesamin, fargesin, longamide and piperlonguminine) with VGFR2 for further consideration in drug discovery.     

Reduced Expression of CD45 Protein-tyrosine Phosphatase Provides Protection against Anthrax Pathogenesis

The modulation of cellular processes by small molecule inhibitors, gene inactivation, or targeted knockdown strategies combined with phenotypic screens are powerful approaches to delineate complex cellular pathways and to identify key players involved in disease pathogenesis. Using chemical genetic screening, we tested a library of known phosphatase inhibitors and identified several compounds that protected Bacillus anthracis infected macrophages from cell death. The most potent compound was assayed against a panel of sixteen different phosphatases of which CD45 was found to be most sensitive to inhibition. Testing of a known CD45 inhibitor and antisense phosphorodiamidate morpholino oligomers targeting CD45 also protected B. anthracis-infected macrophages from cell death. However, reduced CD45 expression did not protect anthrax lethal toxin (LT) treated macrophages, suggesting that the pathogen and independently added LT may signal through distinct pathways. Subsequent, in vivo studies with both gene-targeted knockdown of CD45 and genetically engineered mice expressing reduced levels of CD45 resulted in protection of mice after infection with the virulent Ames B. anthracis. Intermediate levels of CD45 expression were critical for the protection, as mice expressing normal levels of CD45 or disrupted CD45 phosphatase activity or no CD45 all succumbed to this pathogen. Mechanism-based studies suggest that the protection provided by reduced CD45 levels results from regulated immune cell homeostasis that may diminish the impact of apoptosis during the infection. To date, this is the first report demonstrating that reduced levels of host phosphatase CD45 modulate anthrax pathogenesis.Interactions between microbes and immune cells play a critical role in microbial pathogenesis. Many pathogenic organisms exploit the host immune machinery and subsequently modulate cell function, signaling, migration, and cytoskeleton rearrangement. Hence, identifying host cellular components with which microbes interact will allow for a more comprehensive understanding of microbial pathogenesis, define common strategies used by multiple pathogens, and elucidate unique tactics evolved by individual species to help establish infections or evade host innate responses. Another interesting aspect of infection is that diverse pathogens seem to target common cellular pathways (1, 2). Thus, identifying host targets exploited by multiple pathogens will be useful in the development of broad-spectrum host-oriented therapeutics and vaccines.Protein kinases and phosphatases regulate a range of cellular responses to external and internal stimuli, including cell proliferation, metabolism, and apoptosis. Aberrant kinase and/or phosphatase activities underlie many different types of pathological conditions from cancer to infectious diseases. Protein kinases have been extensively investigated as targets for drug discovery. In addition, phosphatases are now being recognized as important regulators of many biological processes. In particular, there is an increasing interest in protein-tyrosine phosphatases (PTPs)³ as drug targets (3–8) because immune cells express a remarkably high proportion of the 107 PTP genes in the human genome (9) and also due to the growing number of human diseases discovered to be associated with PTP abnormalities (9–11). The involvement of cellular and bacterial PTPs during intracellular microbial pathogenesis has been a topic of significant interest (2, 12, 13). The bacterial PTP YopH, secreted by Yersinia pestis, interferes with the host adhesion-regulated signaling pathway via dephosphorylation of selective tyrosine-phosphorylated proteins (14). Activation of host PTPs after infection with bacteria or their virulence factors has been demonstrated for a diverse group of microorganisms such as Mycobacterium tuberculosis and Leishmania donovani (13). Specific mechanistic models of how PTPs contribute to the development of infection and disease progression by highly lethal organisms still remain unclear.Bacillus anthracis, a Gram-positive spore-forming bacterium, is the etiologic agent of anthrax. The lethal toxin (LT) produced by B. anthracis can cleave host cell mitogen-activated protein kinase kinases (MAPKK), thereby affecting the immune response and the host ability to fight the infection (15, 16). Macrophages are the primary targets of anthrax LT. However, macrophages from only certain strains of mice are susceptible to LT-mediated cell death (17, 18). To date, there is no known direct relation between MAPKK cleavage and LT-induced macrophage cell death, as LT-resistant macrophages exhibit MAPKK cleavage (19–21). This suggests that another cellular target(s) may play a role in anthrax pathogenesis.Previously, using a chemical genetic approach, we identified a class of Cdc25 inhibitors that protected macrophages from cell death induced by anthrax LT (22). Although Cdc25 was not the cellular target, induction of anti-apoptotic responses by the compounds via either the MAPK-dependent or -independent pathways was responsible for the protective phenotype.In the present study we investigated if the previously identified phosphatase inhibitors (22) and their analogs produced any phenotypic changes in the B. anthracis infection model. Two compounds that previously protected LT-treated macrophages (22) also protect B. anthracis-infected macrophages. Subsequent in vitro phosphatase profiling studies identified CD45, a previously unknown target of one of the small molecules, as the most sensitive enzyme to the inhibitor. We then investigated the effect of CD45 reduction in anthrax pathogenesis both in cells and in vivo by using antisense phosphorodiamidate morpholino oligomers and mice engineered to express reduced levels of CD45.     

In silico studies on the substrate specificity of an l-arabinose isomerase from Bacillus licheniformis

l-Arabinose isomerase (BLAI) from Bacillus licheniformis was found to be active only with l-arabinose, unlike other l-arabinose isomerases (l-AIs) active with a variety of aldoses. Therefore, the differences in molecular interactions and substrate orientation in the active site of l-AIs have been examined and the residue at position 346 is proposed to be responsible for the unique substrate specificity of BLAI.     

Mechanism of anti-diabetic action, efficacy and safety profile of GII purified from fenugreek (Trigonella foenum-graceum Linn.) seeds in diabetic animals

Mechanism of action of GII (100 mg/kg body weight, po for 15 days) purified from fenugreek (T. foenum-graecum) seeds was studied in the sub-diabetic and moderately diabetic rabbits. In the sub-diabetic rabbits it did not change much the content of total lipids, glycogen and proteins in the liver, muscle and heart (glycogen was not studied in the heart). However, in the moderately diabetic rabbits same treatment decreased total lipids more in the liver (21%) than those in the heart and muscle. Total protein content increased (14%) in the liver but negligible change (5-7%) was observed in heart and muscle. Glycogen increased (17%) in the liver but not in the muscle of the moderately diabetic rabbits (glycogen was not estimated in the heart). Among the enzymes of glycolysis, activity of glucokinase was not affected in the liver of both the sub-diabetic and moderately diabetic rabbits. Phosphofructokinase and pyruvate kinase activity in both sub-diabetic and moderately diabetic rabbits increased (13-50%) indicating stimulation of glycolysis. The activity of gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-diphosphatase of the sub-diabetic rabbits decreased in the liver (15-20%) but not in the kidneys. In the moderately diabetic rabbits after treatment with GII, glucokinase in the liver was not affected much (-9%) but increased well in the muscle (40%). Phosphofructokinase and pyruvate kinase were moderately increased both in the liver and the muscle (18-23%). The gluconeogenic enzyme glucose-6-phosphatase decreased reasonably well in the liver and kidneys (22, 32%). Fructose-1,6-diphosphatase decreased only slightly (10, 9%) in the moderately diabetic rabbits. Thus GII seems to decrease lipid content of liver and stimulate the enzymes of glycolysis (except glucokinase) and inhibit enzymes of gluconeogenesis in the liver of the diabetic especially moderately diabetic rabbits.     

Molecular docking and structure-based virtual screening studies of potential drug target,CAAX prenyl proteases,of Leishmania donovani

Targeting CAAX prenyl proteases of Leishmania donovani can be a good approach towards developing a drug molecule against Leishmaniasis. We have modeled the structure of CAAX prenyl protease I and II of L. donovani, using homology modeling approach. The structures were further validated using Ramachandran plot and ProSA. Active site prediction has shown difference in the amino acid residues present at the active site of CAAX prenyl protease I and CAAX prenyl protease II. The electrostatic potential surface of the CAAX prenyl protease I and II has revealed that CAAX prenyl protease I has more electropositive and electronegative potentials as compared CAAX prenyl protease II suggesting significant difference in their activity. Molecular docking with known bisubstrate analog inhibitors of protein farnesyl transferase and peptidyl (acyloxy) methyl ketones reveals significant binding of these molecules with CAAX prenyl protease I, but comparatively less binding with CAAX prenyl protease II. New and potent inhibitors were also found using structure-based virtual screening. The best docked compounds obtained from virtual screening were subjected to induced fit docking to get best docked configurations. Prediction of drug-like characteristics has revealed that the best docked compounds are in line with Lipinski’s rule. Moreover, best docked protein–ligand complexes of CAAX prenyl protease I and II are found to be stable throughout 20 ns simulation. Overall, the study has identified potent drug molecules targeting CAAX prenyl protease I and II of L. donovani whose drug candidature can be verified further using biochemical and cellular studies.