Exploration of multifaceted molecular mechanism of angiotensin-converting enzyme 2 (ACE2) in pathogenesis of various diseases.

Angiotensin converting enzyme 2 (ACE2) is a homolog of ACE (a transmembrane bound dipeptidyl peptidase enzyme). ACE2 converts angiotensinogen to the heptapeptide angiotensin-(1-7). ACE2 and its product, angiotensin-(1-7), have counteracting effects against the adverse actions of other members of renin-angiotensin system (RAS). ACE2 and its principal product, angiotensin-(1-7), were considered an under recognized arm of the RAS. The COVID-19 pandemic brought to light this arm of RAS with special focus on ACE2. Membrane bound ACE2 serves as a receptor for SARS-CoV-2 viral entry through spike proteins. Apart from that, ACE2 is also involved in the pathogenesis of various other diseases like cardiovascular disease, cancer, respiratory diseases, neurodegenerative diseases and infertility. The present review focuses on the molecular mechanism of ACE2 in neurodegenerative diseases, cancer, cardiovascular disease, infertility and respiratory diseases, including SARS-CoV-2. This review summarizes unveiled roles of ACE2 in the pathogenesis of various diseases which further provides intriguing possibilities for the use of ACE2 activators and RAS modulating agents for various diseases.

Improved 3D-QSAR Prediction by Multiple Conformational Alignments and Molecular Docking Studies to Design and Discover HIV-I Protease Inhibitors.

BACKGROUND: Inhibition of HIV-I protease enzyme is a strategic step for providing better treatment in retrovirus infections, which avoids resistance and possesses less toxicity. OBJECTIVES: In the course of our research to discover new and potent protease inhibitors, 3D-QSAR (CoMFA and CoMSIA) models were generated using 3 different alignment techniques, including multifit alignment, docking based and Distill based alignment for 63 compounds. Novel molecules were designed from the output of this study. METHODS: A total of 3 alignment methods were used to generate CoMFA and CoMSIA models. A Distill based alignment method was considered a better method according to different validation parameters. A 3D-QSAR model was generated and contour maps were discussed. The biological activity of designed molecules was predicted using the generated QSAR model to validate QSAR. The newly designed molecules were docked to predict binding affinity. RESULTS: In CoMFA, leave one out cross-validated coefficient (q2), conventional coefficient (r2) and predicted correlation coefficient (r2Predicted) values were found to be 0.721, 0.991 and 0.780, respectively. The best obtained CoMSIA model also showed significant cross-validated coefficient (q2), conventional coefficient (r2) and predicted correlation coefficient (r2Predicted) values of 0.714, 0.987 and 0.721, respectively. Steric and electrostatic contour maps generated from CoMFA and hydrophobic and hydrogen bond donor and hydrogen bond acceptor contour maps from CoMSIA models were used to design new and bioactive protease inhibitors by incorporating bioisosterism and knowledge-based structure-activity relationship. CONCLUSION: The results from both these approaches, ligand-based drug design and structure-based drug design, are adequate and promising to discover protease inhibitors.

Pharmacophore modeling, virtual screening and 3D-QSAR studies of 5-tetrahydroquinolinylidine aminoguanidine derivatives as sodium hydrogen exchanger inhibitors.

Sodium hydrogen exchanger (SHE) inhibitor is one of the most important targets in treatment of myocardial ischemia. In the course of our research into new types of non-acylguanidine, SHE inhibitory activities of 5-tetrahydroquinolinylidine aminoguanidine derivatives were used to build pharmacophore and 3D-QSAR models. Genetic Algorithm Similarity Program (GASP) was used to derive a 3D pharmacophore model which was used in effective alignment of data set. Eight molecules were selected on the basis of structure diversity to build 10 different pharmacophore models. Model 1 was considered as the best model as it has highest fitness score compared to other nine models. The obtained model contained two acceptor sites, two donor atoms and one hydrophobic region. Pharmacophore modeling was followed by substructure searching and virtual screening. The best CoMFA model, representing steric and electrostatic fields, obtained for 30 training set molecules was statistically significant with cross-validated coefficient (q(2)) of 0.673 and conventional coefficient (r(2)) of 0.988. In addition to steric and electrostatic fields observed in CoMFA, CoMSIA also represents hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields. CoMSIA model was also significant with cross-validated coefficient (q(2)) and conventional coefficient (r(2)) of 0.636 and 0.986, respectively. Both models were validated by an external test set of eight compounds and gave satisfactory prediction (r(pred)(2)) of 0.772 and 0.701 for CoMFA and CoMSIA models, respectively. This pharmacophore based 3D-QSAR approach provides significant insights that can be used to design novel, potent and selective SHE inhibitors.

Synthesis of benzimidazolyl-1,3,4-oxadiazol-2ylthio-N-phenyl (benzothiazolyl) acetamides as antibacterial, antifungal and antituberculosis agents.

To affiliate multiple bioactivities in a compact heteronuclei, two series of benzimidazole based 1,3,4-oxadiazoles were synthesized and assessed in vitro for their efficacy as antimicrobial agents against eight bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Proteus vulgaris, Shigella flexneri), four fungi (Aspergillus niger, Aspergillus fumigatus, Aspergillus clavatus, Candida albicans) and Mycobacterium tuberculosis H37Rv and best results were observed amongst the N-benzothiazolyl aetamide series. The lipophilicity (LogP) influence on the biological profile (MICs) of the prepared products was also discussed. Upon biological screening, it was observed that the majority of the compounds were found to possess a significant broad spectrum antimicrobial (3.12-25 µg/mL of MIC) and antitubercular (6.25-25 µg/mL of MIC) potential. The structural assignments of the new products were done on the basis of IR, (1)H NMR, (13)C NMR spectroscopy and elemental analysis.

8,9-Epoxyeicosatrienoic acid protects the glomerular filtration barrier.

Glomerular dysfunction and proteinuria characterize focal segmental glomerulosclerosis (FSGS) associated with chronic kidney disease. FSGS is resistant to treatment and a circulating permeability factor (FSPF) frequently causes post-renal transplantation recurrence. In order to explore the role of 5,6-, 8,9-, 11,12- and 14,15-epoxyeicosatrienoic acids (EETs), we determined their effect on FSPF-induced increase in glomerular albumin permeability (P alb) using an in vitro assay. Exogenous 8,9-EET (1-1000 nM) dose-dependently prevented the FSPF-induced increase in P alb. The other three EET regioisomers, 8,9-EET metabolite, 8,9-dihydroxyeicosatrienoic acid and unrelated 11,14-eicosadienoic acid (100 nM each) were not effective suggesting specificity of the observed glomerular protection by 8,9-EET. Synthetic analogs of 8,9-EET containing one double bond antagonized the effect of 8,9-EET on the FSPF-induced increase in P alb. Analogs containing two double bonds did not antagonize the effect of 8,9-EET and significantly blocked the FSPF-induced increase in P alb. These novel findings suggest a unique protective role for 8,9-EET in the glomerulus. Stable analogs of 8,9-EET may be valuable in developing effective management/treatment of glomerular dysfunction.

Multiple antiapoptotic targets of the PI3K/Akt survival pathway are activated by epoxyeicosatrienoic acids to protect cardiomyocytes from hypoxia/anoxia.

Epoxyeicosatrienoic acids (EETs) reduce infarction of the myocardium after ischemia-reperfusion injury to rodent and dog hearts mainly by opening sarcolemmal and mitochondrial potassium channels. Other mediators for the action of EET have been proposed, although no definitive pathway or mechanism has yet been reported. Using cultured cells from two rodent species, immortalized myocytes from a mouse atrial lineage (HL-1) and primary myocytes derived from neonatal rat hearts, we observed that pretreatment with EETs (1 microM of 14,15-, 11,12-, or 8,9-EET) attenuated apoptosis after exposure to hypoxia and reoxygenation (H/R). EETs also preserved the functional beating of neonatal myocytes in culture after exposure to H/R. We demonstrated that EETs increased the activity of the prosurvival enzyme phosphatidylinositol 3-kinase (PI3K). In fact, cardiomyocytes pretreated with EET and exposed to H/R exhibited antiapoptotic changes in at least five downstream effectors of PI3K, protein kinase B (Akt), Bcl-x(L)/Bcl-2-associated death promoter, caspases-9 and -3 activities, and the expression of the X-linked inhibitor of apoptosis, compared with vehicle-treated controls. The PI3K/Akt pathway is one of the strongest intracellular prosurvival signaling systems. Our studies show that EETs regulate multiple molecular effectors of this pathway. Understanding the targets of action of EET-mediated protection will promote the development of these fatty acids as therapeutic agents against cardiac ischemia-reperfusion.

Stereospecific cross-coupling of alpha-(thiocarbamoyl)organostannanes with alkenyl, aryl, and heteroaryl iodides.

Racemic and scalemic PTC-protected alpha-hydroxystannanes cross-couple with alkenyl/aryl/heteroaryl iodides in moderate to good yields using copper(I) thiophene-2-carboxylate (CuTC) in THF at or below room temperature. Simple aryl iodides and 1-iodocyclohexene, two classes of electrophiles that typically react sluggishly, are also good substrates. Cross-couplings proceed with retention of configuration at the alkenyl- and stannyl-substituted stereocenters.

Cyclomaltooligosaccharide-assisted spectroscopic discrimination of phthalimido-derived amino acids through the formation of molecular aggregates.

Spectroscopic evidence was used to demonstrate the formation of molecular associates in an aqueous solution of phthalimido tryptophan. These molecular associates are loosely formed through pi-pi aromatic stacking, properties that are not sufficient to cause NMR spectroscopic enantiomeric discrimination. A cyclomaltooligosaccharide with a larger cavity, such as cyclomaltooctaose (gamma-cyclodextrin), is capable of forming a ternary complex with these molecular associates and enhances pi-pi aromatic stacking interactions, resulting in NMR enantiomeric discrimination. Electrospray-ionization mass spectroscopy (ESIMS) and NOESY two-dimensional NMR spectroscopic methods were used to study these complexes. Association constants and thermodynamic data for these cyclomaltooligosaccharide complexes were also estimated.

Cyclomaltooligosaccharide (cyclodextrin)-assisted enantiomeric recognition of benzo[lmn][3,8]phenanthroline-derived amino acids.

Formation of self-assembly molecular aggregates and cyclomaltooligosaccharide (cyclodextrin) molecular aggregates with benzo[lmn][3,8]phenanthroline-derived amino acids is presented. The nature of the molecular aggregates was studied by negative-ion electrospray-ionization mass spectrometry (ESIMS). The enantiomeric recognition was demonstrated by NMR enantiomeric discrimination of the amino acid derivatives in aqueous solutions of cyclodextrins.