Discovery of potential aldose reductase inhibitors using in silico docking studies

Development of non-acidic 4-methylbenzenesulfonate-based aldose reductase inhibitors; Design, Synthesis, Biological evaluation and in-silicostudies

Design and virtual screening of a set of non-acidic 4-methyl-4-phenyl-benzenesulfonate-based aldose reductase 2 inhibitors had been developed followed by chemical synthesis. Based on the results, the synthesized compounds 2, 4a,b, 7a-c, 9a-c, 10a-c, 11b,c and 14a-c inhibited the ALR2 enzymatic activity in a submicromolar range (99.29-417 nM) and among them, the derivatives 2, 9b, 10a and 14b were able to inhibit ALR2 by IC50 of 160.40, 165.20, 99.29 and 120.6 nM, respectively. Moreover, kinetic analyses using Lineweaver-Burk plot revealed that the most active candidate 10a inhibited ALR2 potently via a non-competitive mechanism. In vivo studies showed that 10 mg/kg of compound 10a significantly lowered blood glucose levels in alloxan-induced diabetic mice by 46.10 %. Moreover, compound 10a showed no toxicity up to a concentration of 50 mg/kg and had no adverse effects on liver and kidney functions. It significantly increased levels of GSH and SOD while decreasing MDA levels, thereby mitigating oxidative stress associated with diabetes and potentially attenuating diabetic complications. Furthermore, the binding mode of compound 10a was confirmed through MD simulation. Noteworthy, compounds 2 and 14b showed moderate antimicrobial activity against the two fungi Aspergillus fumigatus and Aspergillus niger. Finally, we report the thiazole derivative 10a as a new promising non-acidic aldose reductase inhibitor that may be beneficial in treating diabetic complications.

Docking Studies on Biomolecules from Marine Microalga Skeletonema costatum Against Hemolysin Protein of Bioluminescence Disease-Causing Vibrio harveyi

Grow-out and hatchery units of shrimps are being impacted by disease-causing bacterial pathogens and predominantly marine Vibrios. The use of chemicals for governing bacterial pathogens in the aquaculture practices is developing resistance to bacteria. Henceforth, the application of bio-therapeutic agents from marine resources for controlling pathogens is most vital to be considered. Molecular docking is computer-assisted drug design tool to detect and counteract for drug-receptor interaction for known target protein of diseases. Therefore, an effort was made with the extract of the marine micro alga Skeletonema costatum against hemolysin protein of pathogenic bacteria Vibrio harveyi. The extract of S. costatum was tested against growth and virulence produced by V. harveyi during larviculture of Penaeus monodon. The extract was analyzed for phyto-constituents through GC-MS and used them as ligand molecule in docking. S. costatum extract at 200 µg mL-1 was found to decrease 35.20% of cumulative percentage mortality (CPM) in postlarvae of P. monodon against V. harveyi infections. The biomolecule Docasane, an alkane from the extract of S. costatum, exposed highest binding interaction than other compounds during docking analysis. The level of significance (P < 0.05) was found in CPM, growth, and virulence factors of V. harveyi studies. Thus, the present finding predicts that extract of S. costatum containing biomolecules can be recommended for use in the shrimp culture-based grow-out and hatchery units for eliminating bioluminescent V. harveyi.

Flavanones: A potential natural inhibitor of the ATP binding site of PknG of Mycobacterium tuberculosis

Over the years, Mycobacterium tuberculosis has been one of the major causes of death worldwide. As several clinical isolates of the bacteria have developed drug resistance against the target sites of the current therapeutic agents, the development of a novel drug is the pressing priority. According to recent studies on Mycobacterium tuberculosis, ATP binding sites of Mycobacterium tuberculosis serine/threonine protein kinases (MTPKs) have been identified as the new promising drug target. Among the several other protein kinases (PKs), Protein kinase G (PknG) was selected for the study because of its crucial role in modulating bacterium's metabolism to survive in host macrophages. In this work, we have focused on the H37Rv strain of Mycobacterium tuberculosis. A list of 477 flavanones obtained from the PubChem database was docked one by one against the crystallized and refined structure of PknG by in-silico techniques. Initially, potential inhibitors were narrowed down by preliminary docking. Flavanones were then selected using binding energies ranging from -7.9 kcal.mol^-1 to -10.8 kcal.mol^-1. This was followed by drug-likeness prediction, redocking analysis, and molecular dynamics simulations. Here, we have used experimentally confirmed drug AX20017 as a reference to determine candidate compounds that can act as potential inhibitors for PknG. PubChem165506, PubChem242065, PubChem688859, PubChem101367767, PubChem3534982, and PubChem42607933 were identified as possible target site inhibitors for PknG with a desirable negative binding energy of -8.1, -8.3, -8.4, -8.8, -8.6 and -7.9 kcal.mol^-1 respectively. Communicated by Ramaswamy H. Sarma.

In silico molecular docking study of Andrographis paniculata phytochemicals against TNF-α as a potent anti-rheumatoid drug

Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine which plays a crucial role in controlling inflammatory responses. The pathway of Rheumatoid arthritis (RA) leading to TNF-alpha is activated by macrophages and quite often by natural killer cells and lymphocytes. In the inflammatory phase, it is believed to be the main mediator and to be anchored with the progression of different diseases such as ankylosing spondylitis, Crohn's disease, and Rheumatoid arthritis (RA). The major goal of this study is to use in silico docking studies to investigate the anti-inflammatory potential of a bioactive molecule from the medicinal plant Andrographis paniculata. The three-dimensional structures of different phytochemicals of A. paniculata were obtained from PubChem database, and the receptor protein was derived from PDB database. Docking analysis was executed using AutoDock vina, and the binding energies were compared. Bisandrographolide A and Andrographidine C revealed the highest score of -8.6 Kcal/mol, followed by, Neoandrographolide (-8.5 Kcal/mol). ADME and toxicity parameters were evaluated for these high scoring ligands and results showed that Andrographidine C could be a potent drug, whereas Neoandrographolide and Bisandrographolide A can be modified in in vitro and can lead to a promising drug. Further, the top scorer (Andrographidine C) and control drug (Leflunomide) were subjected to 100 ns MD Simulation. The protein complex with Andrographidine C had more stable confirmation with lower RMSD (0.28 nm) and higher binding energy (-133.927 +/- 13.866 kJ/mol). In conclusion, Andrographidine C may be a potent surrogate to the disease-modifying anti-rheumatic drugs (DMARD's) & Non-steroidal anti-inflammatory drugs (NSAID's) that has fewer or minor adverse effects and can aid in RA management.

Molecular docking study of bio-inhibitors extracted from marine macro-alga Ulva fasciata against hemolysin protein of luminescence disease-causing Vibrio harveyi

Shrimp grow-out and hatchery systems are being affected by bacterial disease particularly Vibrios. The use of chemotherapeutic agents in aquaculture practices has to lead to the development of resistance among aquatic bacteria. Thus, health management becomes of major importance in aquaculture. Under this situation, progressing bio-inhibitors from marine resources are most appropriate to be considered against pathogenic bacteria. Molecular docking is an appropriate tool in structural biology and computer-assisted drug design to predict and neutralize a target protein of known diseases. In this study, marine macro-alga Ulva fasciata was aimed at developing inhibitors against luminescence disease-causing pathogenic bacteria Vibrio harveyi. U. fasciata was collected from Thoothukudi, Tamil Nadu, India. Extract of U. fasciata was tested against growth and virulence factors of V. harveyi during Penaeus monodon larviculture. Further U. fasciata extract was subjected to GC-MS analysis to identify the biomolecules. The homology modeling of virulent protein, hemolysin of V. harveyi was designed in this study. Hence, it was aimed for molecular docking against the biomolecules identified from U. fasciata extract. During shrimp larviculture, the extract of U. fasciata (200 μg mL^-1) exhibited reduction on Cumulative Percentage of Mortality (32.40%) in postlarvae against challenge of V. harveyi infection. Biomolecule Methyl dehydroabietate had showed highest binding affinity among the compounds was evaluated in molecular docking study. Statistical analysis had revealed significant differences (p < 0.05) in trials. Therefore, it was proved that the bio-inhibitors from U. fasciata will be a better option for controlling luminescence disease-causing V. harveyi in shrimp grow-out practices.

Addressing selectivity issues of aldose reductase 2 inhibitors for the management of diabetic complications

Aldose Reductase 2 (ALR2), the rate-limiting enzyme of the polyol pathway, plays an important role in detoxification of some toxic aldehydes. Under hyperglycemia, this enzyme overactivates and causes diabetic complications (DC). Therefore, ALR2 inhibition has been established as a potential approach to manage these complications. Several ALR2 inhibitors have been reported, but none of them could reach US FDA approval. One of the main reasons is their poor selectivity over ALR1, which leads to the toxicity. The current review underlines the molecular connectivity of ALR2 with DC and comparative analysis of the catalytic domains of ALR2 and ALR1, to better understand the selectivity issues. This report also discusses the key features required for ALR2 inhibition and to limit toxicity due to off-target activity.