Current Computer - Aided Drug Design - Volume 15, Issue 5, 2019

Tuberculosis, malaria, dengue, chikungunya, leishmaniasis etc. are a large group of neglected tropical diseases that prevail in tropical and subtropical countries, affecting one billion people every year. Minimal funding and grants for research on these scientific problems challenge many researchers to find a different way to reduce the extensive time and cost involved in the drug discovery cycle of these problems. Computer-aided drug design techniques have already been proved successful in the discovery of new molecules rationally by reducing the time and cost involved in the development of drugs. In the current minireview, we are highlighting on the molecular modeling studies published during 2010-2018 for target specific antitubercular agents. This review includes the studies of Structure-Based (SB) and Ligand-Based (LB) modeling and those involving Machine Learning (ML) techniques against different antitubercular targets such as dihydrofolate reductase (DHFR), enoyl Acyl Carrier Protein (ACP) reductase (InhA), catalase-peroxidase (KatG), enzyme antigen 85C, protein tyrosine phosphatases (PtpA and PtpB), dUTPase, thioredoxin reductase (MtTrxR), etc. The information presented in this review will help the researchers to get acquainted with the recent progress in the modeling studies of antitubercular agents.

Background: Computational or in silico studies are undertaken to assess the drug like properties of lead compounds. These studies help in fast prediction of relevant properties. Objective: Through this review, an effort is made to encapsulate some of the important parameters which should be met by a compound for it to be considered as a potential drug candidate along with an overview of automated softwares which can be used for making various predictions. Methods: Drug uptake, its absorption, evacuation and associated hazardous effects are important factors for consideration in drug designing and should be known in early stages of drug development. Several important physicochemical properties like molecular weight, polar surface area (PSA), molecular flexibility etc. have to be taken into consideration in drug designing. Toxicological assessment is another important aspect of drug discovery which predicts the safety and adverse effects of a drug. Results: Additionally, bioactivity scores of probable drug leads against various human receptors can also be predicted to evaluate the probability of them to act as a potential drug candidate. The in vivo biological targets of a molecule can also be efficiently predicted by molecular docking studies. Conclusion: Some important software like iGEMDOCK, AutoDock, OSIRIS property explorer, Molinspiration, MetaPrint2D, admetSAR and their working methodology and principle of working have been summarized in this review.

Background: Identifying immunogenic proteins is the first stage in vaccine design and development. VaxiJen is the most widely used and highly cited server for immunogenicity prediction. As the developers of VaxiJen, we are obliged to update and improve it regularly. Here, we present an updated dataset of bacterial immunogens containing 317 experimentally proven immunogenic proteins of bacterial origin, of which 60% have been reported during the last 10 years. Methods: PubMed was searched for papers containing data for novel immunogenic proteins tested on humans till March 2017. Corresponding protein sequences were collected from NCBI and UniProtKB. The set was curated manually for multiple protein fragments, isoforms, and duplicates. Results: The final curated dataset consists of 306 immunogenic proteins tested on humans derived from 47 bacterial microorganisms. Certain proteins have several isoforms. All were considered, and the total protein sequences in the set are 317. The updated set contains 206 new immunogens, compared to the previous VaxiJen bacterial dataset. The average number of immunogens per species is 6.7. The set also contains 12 fusion proteins and 41 peptide fragments and epitopes. The dataset includes the names of bacterial microorganisms, protein names, and protein sequences in FASTA format. Conclusion: Currently, the updated VaxiJen bacterial dataset is the best known manually-curated compilation of bacterial immunogens. It is freely available at http://www.ddg-pharmfac.net/vaxi jen/dataset. It can easily be downloaded, searched, and processed. When combined with an appropriate negative dataset, this update could also serve as a training set, allowing enhanced prediction of the potential immunogenicity of unknown protein sequences.

Background: In the past few years, several developments have been made to understand and control the complications and harmful side-effects associated with the disorder diabetes mellitus (DM). Many new steps have been taken in a better understanding of the pathophysiology of the disease. With the advancement in the field of medical sciences, various novel therapies have been developed to efficiently control the pathological effects of diabetes mellitus. Recently, phytochemicals possessing various medicinal properties have opened up a new vast range of opportunities to design novel therapeutic drugs against diabetes mellitus. Objective: The present study aims to identify and screen phytochemicals as potent and novel inhibitors against diabetes mellitus. Methods: Three major biological targets of diabetes mellitus named Cytochrome P450, glycogen synthase kinase and PPARγ are targeted using phytochemicals by performing pharmacological properties prediction, molecular docking and density functional theory studies. Results: Out of 108 phytochemicals, 20, 12 and 3 phytochemicals showed higher binding affinity values as compared to chemically synthesized drugs against cytochrome P450, glycogen synthase kinase and PPARγ, respectively. Conclusion: The screened phytochemicals have strong inhibitory potential against diabetes mellitus and in future, these compounds, holding immense potential, can be considered as candidate drugs for treating diabetes mellitus.

Background: Imidazoles are considered as potent antimicrobial agents. In view of this 2-mercaptoimidazoles were synthesized and evaluated for antimicrobial study. Methods: Some new 2-mercaptoimidazoles 4a-r were synthesized using substituted aniline and substituted phenacyl bromides in the presence of anhydrous sodium carbonate or potassium carbonate and potassium thiocyanate under solvent-free conditions catalyzed by eco-friendly ptoluene sulfonic acid. Results: The structure of compounds was evaluated on the basis of Infrared spectroscopy (IR), 1HNMR (proton nuclear magnetic resonance) and mass spectral studies. These novel compounds were screened for in-vitro antibacterial and antifungal potency against Staphyllococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Further, the study was rationalized by molecular modeling studies. All the compounds were subjected to molecular modeling studies for inhibition of enzyme 14α-demethylase. Conclusions: The compounds were found to be effective in inhibiting the growth of pathogens. The in-silico results depicted that, all the synthesized compounds have minimum binding energy and good affinity towards the active site and thus can be considered as good inhibitors of 14α- demethylase enzyme.

Background: Rho-kinase is an essential downstream target of GTP-binding protein RhoA, and plays a crucial role in the calcium-sensitization pathway. Rho-kinase pathway is critically involved in phosphorylation state of myosin light chain, leading to increased contraction of smooth muscles. Inhibition of this pathway has turned out to be a promising target for several indications such as cardiovascular diseases, glaucoma and inflammatory diseases. Methods: The present work focuses on a division-based 2D quantitative structure-activity relationship (QSAR) analysis along with a docking study to predict structural features that may be essential for the enhancement of selectivity and potency of the target compounds. Furthermore, a set of indoles and azaindoles were also projected based on the regression equation as novel developments. Molecular docking was applied for exploring the binding sites of the newly predicted set of compounds with the receptor. Results: Results of the docked conformations suggested that introduction of non-bulky and substituted groups in the hinge region of ROCK-II ATP binding pocket would improve the activity by decreasing the bulkiness or length of the compounds. Conclusion: ADME studies were performed to ascertain the novelty and drug-like properties of the designed molecules, respectively.

Background: Management of Co-existence of Acquired immunodeficiency syndrome and Tuberculosis has become a global challenge due to the emergence of resistant strains and pill burden. Objective: Hence the aim of the present work was to design and evaluate compounds for their dual activity on HIV-1 and Tuberculosis (TB). Methods: A series of seven, novel Thiazolidin-4-one derivatives were synthesized and evaluated for their anti-HIV and anti-tubercular activity along with Molecular docking studies. All the seven compounds displayed promising activity against the replication of HIV-1 in cell-based assays. The four most active compounds were further evaluated against X4 tropic HIV-1UG070 and R5 tropic HIV-1VB59 primary isolates. The binding affinity of all the designed compounds for HIV-RT and Mycobacterium tuberculosis Enol Reductase (MTB InhA) was gauged by molecular docking studies which revealed crucial thermodynamic interactions governing their binding. Results: The CC50 values for the test compounds were in the range of, 15.08-34.9 μg/ml, while the IC50 values were in the range of 16.1-27.13(UG070; X4) and 12.03-23.64 (VB59; R5) μg/ml. The control drug Nevirapine (NVP) exhibited CC50 value of 77.13 μg/ml and IC50 value of 0.03 μg/ml. Amongst all these compounds, compound number 3 showed significant activity with a TI value of 2.167 and 2.678 against the HIV-1 X4 and the R5 tropic virus respectively. In anti-mycobacterial screening, the compounds proved effective in inhibiting the growth of both log phase and starved MTB cultures. Conclusion: Compound 3 has been found to be active against HIV-1 as well as MTB.

Background: Thiadiazole not only acts as “hydrogen binding domain” and “two-electron donor system” but also as constrained pharmacophore. Methods: The maleate salt of 2-((2-hydroxy-3-((4-morpholino-1, 2,5-thiadiazol-3-yl) oxy) propyl) amino)- 2-methylpropan-1-ol (TML-Hydroxy)(4) has been synthesized. This methodology involves preparation of 4-morpholino-1, 2,5-thiadiazol-3-ol by hydroxylation of 4-(4-chloro-1, 2,5-thiadiazol-3-yl) morpholine followed by condensation with 2-(chloromethyl) oxirane to afford 4-(4-(oxiran-2-ylmethoxy)-1,2,5-thiadiazol- 3-yl) morpholine. Oxirane ring of this compound was opened by treating with 2-amino-2-methyl propan-1- ol to afford the target compound TML-Hydroxy. Structures of the synthesized compounds have been elucidated by NMR, MASS, FTIR spectroscopy. Results: The DSC study clearly showed that the compound 4-maleate salt is crystalline in nature. In vitro antibacterial inhibition and little potential for DNA cleavage of the compound 4 were explored. We extended our study to explore the inhibition mechanism by conducting molecular docking, ADMET and molecular dynamics analysis by using Schrödinger. The molecular docking for compound 4 showed better interactions with target 3IVX with docking score of -8.508 kcal/mol with respect to standard ciprofloxacin (docking score= -3.879 kcal/mol). TML-Hydroxy was obtained in silico as non-carcinogenic and non-AMES toxic with good percent human oral absorption profile (69.639%). TML-Hydroxy showed the moderate inhibition against Mycobacteria tuberculosis with MIC 25.00 μg/mL as well as moderate inhibition against S. aureus, Bacillus sps, K. Pneumoniae and E. coli species. Conclusion: In view of the importance of the 1,2,5-thiadiazole moiety involved, this study would pave the way for future development of more effective analogs for applications in medicinal field.