K. V. Dileep

Anti-Inflammatory Property of n-Hexadecanoic Acid: Structural Evidence and Kinetic Assessment

Ester bond hydrolysis of membrane phospholipids by Phospholipase A2 and consequent release of fatty acids are the initiating steps of inflammation. It is proposed in this study that the inhibition of phospholipase A2 is one of the ways to control inflammation. Investigations are carried out to identify the mode of inhibition of phospholipase A2 by the n‐hexadecanoic acid. It may help in designing of specific inhibitors of phospholipase A2 as anti‐inflammatory agents. The enzyme kinetics study proved that n‐hexadecanoic acid inhibits phospholipase A2 in a competitive manner. It was identified from the crystal structure at 2.5 Å resolution that the position of n‐hexadecanoic acid is in the active site of the phospholipase A2. The binding constant and binding energy have also been calculated using Isothermal Titration Calorimetry. Also, the binding energy of n‐hexadecanoic acid to phospholipase A2 was calculated by in silico method and compared with known inhibitors. It may be concluded from the structural and kinetics studies that the fatty acid, n‐hexadecanoic acid, is an inhibitor of phospholipase A2, hence, an anti‐inflammatory compound. The inferences from the present study validate the rigorous use of medicated oils rich in n‐hexadecanoic acid for the treatment of rheumatic symptoms in the traditional medical system of India, Ayurveda.

Design of potent inhibitors of acetylcholinesterase using morin as the starting compound

Inhibition of acetylcholinesterase (AChE) is a promising treatment strategy for Alzheimers disease (AD). Oxidative stress, inflammation and accumulation of metal ions at sites of neurodegeneration have been observed in association with AD. Flavonoids are well known for their action against inflammation and oxidative stress. Hence, they can be used for treating diseases such as AD, cancer, atherosclerosis and Parkinsons disease. Flavonols such as quercetin, myricetin, galangin, fisetin and kaempferol have been reported as inhibitors of AChE. In the present work, the enzyme inhibitory properties of morin, a flavonol, has been tested against AChE. The binding pattern of morin and 12 other flavonols at the active site of human AChE has been analyzed using molecular modeling and docking methods. In order to enhance the binding affinity of AChE for morin, in silico structural modification of the compound was carried out. The structural elements responsible for its biological functions were retained during the modification. Some of the derivatives possessed better binding energies than morin and hence they could be used as drug lead compound for the treatment of AD.

Binding to PLA2 May Contribute to the Anti-Inflammatory Activity of Catechol

Inhibiting PLA2 activity should, in theory, be an effective approach to control the inflammation. Several naturally occurring polyphenolic compounds have been reported as inhibitors of PLA2. Among the naturally occurring polyphenols, catechol (1,2‐dihydroxybenzene) possesses anti‐inflammatory activity. Catechol can inhibit cyclooxygenase and lipo‐oxygenase. By means of enzyme kinetic study, it was revealed that catechol can inhibit PLA2 also. Crystal structure showed that catechol binds to PLA2 at the opening of the active site cleft. This might stop the entry of substrate into the active site. Hence, catechol can be used as a lead compound for the development of novel anti‐inflammatory drugs with PLA2 as the target.

Molecular docking studies of curcumin analogs with phospholipase A2

The enzyme phospholipase A2 is responsible for the hydrolysis of membrane phospholipids that release arachidonic acid, which serves as a substrate for pro-inflammatory mediators, such as prostaglandins and leucotriens. The binding of the substrate to PLA2 occurs through a well-formed hydrophobic channel. So blocking the hydrophobic channel is an effective way to inhibit PLA2. Compounds inhibiting PLA2 have been implicated as potential therapeutic agents in the treatment of inflammation related diseases. Curcumin is a well studied compound isolated from the plant Curcuma longa. The PLA2 inhibiting activity of curcumin has been studied in our laboratory. The present study focuses whether any of the curcumin analogs can bind PLA2 more strongly than curcumin. To check this, binding of twenty eight different curcumin analogs to PLA2 have been studied by molecular modeling and docking. The mode of interactions of compounds with strong binding are discussed and reported here. It has been observed that four analogs namely rosmarinic acid, tetrahydrocurcumin, dihydrocurucmin and hexahydrocurcumin possess better binding energy than curcumin. The present study may lead to the better understanding of PLA2 inhibition by curcumin analogs. This may help to develop better anti-inflammatory drugs.

Flavanone glycosides as acetylcholinesterase inhibitors: computational and experimental evidence.

Acetylcholinesterase hydrolyzes the neurotransmitter called acetylcholine and is crucially involved in the regulation of neurotransmission. One of the observable facts in the neurodegenerative disorders like Alzheimers disease is the decrease in the level of acetylcholine. Available drugs that are used for the treatment of Alzheimers disease are primarily acetylcholinesterase inhibitors with multiple activities. They maintain the level of acetylcholine in the brain by inhibiting the acetylcholinesterase function. Hence acetylcholinesterase inhibitors can be used as lead compounds for the development of drugs against AD. In the present study, the binding potential of four flavanone glycosides such as naringin, hesperidin, poncirin and sakuranin against acetylcholinesterase was analysed by using the method of molecular modeling and docking. The activity of the top scored compound, naringin was further investigated by enzyme inhibition studies and its inhibitory concentration (IC50) towards acetylcholinesterase was also determined.

Interactions of selected indole derivatives with phospholipase A2: in silico and in vitro analysis

AbstractPhospholipase A2 (PLA2) is one of the key enzymes involved in the formation of inflammatory mediators. Inhibition of PLA2 is considered to be one of the efficient methods to control inflammation. In silico docking studies of 160 selected indole derivatives performed against porcine pancreatic PLA2 (ppsPLA2) suggested that, CID2324681, CID8617 (indolebutyric acid or IBA), CID22097771 and CID802 (indoleacetic acid or IAA) exhibited highest binding energies. In silico analysis was carried out to predict some of the ADME properties. The binding potential of these compounds with human non pancreatic secretory PLA2 (hnpsPLA2) was determined using molecular docking studies. In order to corroborate the in silico results, enzyme kinetics and isothermal titration calorimetric analysis of the two selected compounds, IAA and IBA were performed against ppsPLA2. From the analysis, it was concluded that IAA and IBA can act as competitive inhibitors to the enzyme and may be used as anti inflammatory agents. FigureInhibitory activity of IAA and IBA against PLA2

An isoquinoline alkaloid, berberine, can inhibit fungal alpha amylase: enzyme kinetic and molecular modeling studies.

Aspergillus flavus is a commonly found fungal pathogen, which produces aflatoxins, highly toxic and hepatocarcinogenic natural compounds. Inhibition of fungal alpha amylase activity has been found to limit the ability of the fungus to produce aflatoxins. Berberine, an isoquinoline alkaloid commonly found in many medicinal plants, was identified to inhibit the growth of A. flavus. The amount of berberine required to inhibit the fungal mycelial growth was determined. The compound was also found to inhibit the alpha amylase from the A. flavus. The binding affinity of the compound toward alpha amylase and the enzyme inhibitory activity have been determined by enzyme kinetic studies and Isothermal Titration Calorimetric analysis. Molecular modeling and docking studies were carried out to understand the enzyme–ligand interactions.

An in silico approach for the identification of inhibitors against Acetylcholinesterase

Acetylcholinesterase (AChE) is one of the crucial enzymes involved in nerve response and function. The loss of cholinergic activity is mainly characterized by the rapid hydrolysis of acetylcholine by AChE, which leads to a neurodegenerative disorder called Alzheimer’s disease (AD). Donepezil, an efficient inhibitor of AChE, is widely used in the therapy of AD. The compounds which show above 50% similarity to donepezil were collected from ZINC database. Virtual screening and Induced Fit Docking analysis of these compounds against AChE were carried out to explore the compounds with better binding affinity than donepezil. ADME profile was carried out to identify the compounds having potential to be a drug. The biological activity spectrum of compounds was determined using a program called PASS. Binding potential of the selected compounds toward BChE was also analyzed. In silico analysis proved that compounds such as ZINC13802320, ZINC11709541, ZINC08750211, ZINC02040474, and ZINC49718337 can be used as a lead compounds for the development drugs against AD.

Derivatives Form Better Lipoxygenase Inhibitors than Piperine: In Vitro and In Silico Study

Piperine is a secondary metabolite of black pepper. Its uses in medicine were already studied. However, its derivatives have not gained considerable attention. In the presented study, the Lipoxygenase (LOX) inhibitory activity of piperine and its derivatives, piperonylic acid, piperic acid, and piperonal have been assessed and compared by enzyme kinetics, ITC and molecular modeling experiments. The presented investigations expressed that all the studied compounds inhibited LOX by binding at its active site. The IC50 values of these compounds were deduced from the kinetics data and found to be 85.79, 43.065, 45.17, and 50.78 μm for piperine, piperonylic acid, piperic acid, and piperonal, respectively. The binding free energies obtained from ITC experiments were −7.47, −8.33, −8.09, and −7.86 kcal/mol for piperine, piperonylic acid, piperic acid, and piperonal, respectively. Similarly, the glide scores obtained for piperine, piperonylic acid, piperic acid, and piperonal were −7.28, −10.32, −10.72, and −9.57 kcal/mol, respectively. The results of ITC and molecular modeling experiments suggested that piperonylic acid and piperonal exhibit stronger binding at the active site than piperine does. From the presented studies, it could be concluded that derivatives of piperine may be of higher significance than piperine for certain medicinal applications, implicating (Ayurvedic) fermented herbal drugs with piperine in them.

Inhibitory activity of IAA and IBA against lipoxygenase: in silico and in vitro validation

Inhibition of leukotriene biosynthesis is considered to be one of the potential treatment strategies for controlling inflammation, respiratory diseases and many neurodegenerative disorders. Designing of specific functional inhibitors against Lipoxygenases (LOX) has got considerable attention due to its ability to block leukotriene biosynthesis. Molecular docking analysis of two indole derivatives such as indoleacetic acid (IAA) and indolebutyric acid (IBA) are reported here. Both compounds give glide scores better than that of protocatechuic acid and nitro catechol, the two known LOX inhibitors. From the enzyme kinetic analysis, it was revealed that IAA and IBA inhibit competitively. The IC50 values determined for both IAA and IBA were 42.98 μM and 17.82 μM, respectively. The binding free energy of these compounds was determined using isothermal titration calorimetric assay and was found to be − 6.12 kcal/mol for IAA and − 7.84 kcal/mol for IBA. From the analysis, it can be concluded that both IAA and IBA might be useful as anti-inflammatory agents.