Current Enzyme Inhibition - Volume 16, Issue 2, 2020

The article presents some introductory remarks on viruses and in general how they lead to diseases. With reference to same, it discusses the emergence of a fairly novel coronavirus, 2019- CoV-2 and its possible medication.

Background: Cancer is a disease characterized by the uncontrolled growth and spread of abnormal cells. Around the world, over 10 million cancer cases occur annually. Half of all men and one-third of all women will develop some form of cancer during their lifetime. It is one of the most feared diseases, primarily because half of those diagnosed with cancer die from it. There are several treatments available for cancer. Almost all traditional cytotoxic agents suffer from severe toxicities and other undesirable side effects. Objective: In recent years, the development of targeted medicines has made significant achievements. Unfortunately, though these agents can block key regulators of signaling pathways in cancer, multiple compensatory pathways always attenuate pharmacological effect of single-target drugs. In addition, poor response rates and acquired drug resistance also represent a significant barrier to widespread use of targeted medicines. More recently, a number of combinatorial therapies have expanded treatment options, which can directly block several key signaling pathways and create a synergistic effect. Conclusion: Therefore, in order to overcome these barriers, the present investigation aims to develop a new strategy for designing a single molecule with inhibition of two receptors (PARP1 and STAT3) simultaneously and producing enhanced anti-cancer activity with less and/or null toxicity.

Background: Amylases are the most widely used biocatalysts in starch saccharification and detergent industries. However, commercially available amylases have few limitations viz. limited activity at low or high pH and Ca2+ dependency. Objective: The quest for exploiting amylase for diverse applications to improve the industrial processes in terms of efficiency and feasibility led us to investigate the kinetics of amylase in the presence of metal ions as a function of pH. Methods: The crude extract from soil fungal isolate cultures is subjected to salt precipitation, dialysis and DEAE cellulose chromatography followed by amylase extraction and is incubated with divalent metal ions (i.e., Ca2+, Fe2+, Cu2+, and Hg2+); Michaelis-Menton constant (Km), and maximum reaction velocity (Vmax) are calculated by plotting the activity data obtained in the absence and presence of ions, as a function of substrate concentration in Lineweaver-Burk Plot. Results: Kinetic studies reveal that amylase is inhibited un-competitively at 5mM Cu2+ at pH 4.5 and 7.5, but non-competitively at pH 9.5. Non-competitive inhibition of amylase catalyzed starch hydrolysis is observed with 5mM Hg2+ at pH 9.5, which changes to mixed inhibition at pH 4.5 and 7.5. At pH 4.5, Ca2+ induces K- and V-type activation of amylase catalyzed starch hydrolysis; however, the enzyme has V-type activation at 7mM Ca2+ under alkaline conditions. Also, K- and V-type of activation of amylase is observed in the presence of 7mM Fe2+ at pH 4.5 and 9.5. Conclusion: These findings suggest that divalent ions modulation of amylase is pH dependent. Furthermore, a time-saving and cost-effective solution is proposed to overcome the challenges of the existing methodology of starch hydrolysis in starch and detergent industries.

Background and Objective: Chronic diseases are associated with low-grade inflammation and oxidative damage. Traditional medicines have been used to manage these disorders due to their high polyphenol content and potent antioxidant activity. We evaluated the in-vitro anti-diabetic and antioxidant potential of extracts of several medicinal plants namely, Mangifera indica, Terminalia arjuna, Moringa oleifera, Albizia lebbeck, Terminalia chebula and Hippophae rhamnoides. Methods: Total polyphenol, flavonoid, and saponin contents were estimated by standard methods. Antioxidant activity was measured using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The anti-diabetic potential was evaluated using in-vitro α-glucosidase inhibition assay. Results: Terminalia chebula was found to be the richest in both polyphenols (566.5 ± 21.9 μg Gallic acid equivalents/mg of dry weight) and flavonoids (190.67 ± 10.78 quercetin equivalents/mg of dry weight). Extract of Terminalia arjuna was the richest source of saponins (171.92 ± 12.48 μg saponin equivalents/mg of dry weight). All plant extracts showed potent anti-oxidant activity as reflected by their IC50 values in DPPH assay, with Albizia lebbeck (IC50 = 1.35 μg/ml) being the most potent. All plant extracts also showed potent anti-diabetic activity as inferred from their ability to inhibit α- glucosidase, the principal enzyme involved in the metabolism of dietary carbohydrates in the intestine. It was observed that all tested extracts were more potent (IC50 2.53 to 227 μg/ml) in comparison to the standard α-glucosidase inhibitor Acarbose (IC50=2.7 mg/ml). Conclusion: The plant extracts of Mangifera indica, Terminalia arjuna, Moringa oleifera, Albizia lebbeck, Terminalia chebula, and Hippophae rhamnoides possess potent antioxidant and α- glucosidase inhibitory potential and can aid in the management of postprandial hyperglycemia and oxidative damage.

Background: Diabetes mellitus (DM) is an important global health problem especially in developed countries and insufficient lifestyle induces this phenomenon. Finding efficient treatment for DM is an interesting goal for researchers. Objective: Herein we tried to design and synthesize a series of quinazoline derivatives and investigate their bioactivity as possible α-Glucosidase inhibitor agents. Method: Compounds 1-14 were synthesized using a multicomponent reaction. 1HNMR, 13C NMR, MS, and IR spectroscopy were used for the characterization of synthesized compounds. α- Glucosidase inhibitory activity of compounds 1-14 was evaluated using p-nitrophenyl-α-Dglucopyranoside (pNPG) as a substrate of the α-glucosidase enzyme (EC3.2.1.20, Saccharomyces cerevisiae). The mechanism of inhibition of the α-glucosidase enzyme was investigated using kinetic studies. Molecular docking was also done using autodock software to find the possible mode of interaction of compound 8 and the enzyme active site. Results: Most of the tested compounds showed higher activity in inhibition of the enzyme in comparison to the standard, acarbose. Compound 8 exerted the best activity with the IC50 value of 291.5 μM. A kinetic study indicated a competitive inhibition of the α-glucosidase enzyme by compound 8. Finally, docking studies showed the interactions between compound 8 and enzyme active site residues. Conclusion: 2,4-Diarylquinazoline scaffold has good antidiabetic activity, so it is interesting to synthesize more 2,4-diarylquinazoline derivatives and evaluate their antidiabetic activities.

Background: Struvite/infection stone is one of the major clinical burdens in urinary tract infections that is caused by the ureolytic behavior of pathogenic bacteria. Objective: The current strategy for treating infective stones is mostly antibiotic therapy, which ends in promoting resistance to the organisms. Hence in the present study, we investigated two phytocompounds, eugenol (an allyl-substituted guaiacol) and vanillic acid (a phenolic acid) that are found to be effective in inhibiting the urease enzyme of a nosocomial pathogen Proteus mirabilis. Methods: The enzyme was purified to apparent homogeneity and the kinetic parameters were studied in the presence and in the absence of eugenol and vanillic acid. Molecular docking and simulation were done to understand the level of protein-ligand interactions and the interacting residues. Results: Kinetic parameters obtained from the Michaelis-Menten plot show that both eugenol and vanillic acid exhibit non-competitive inhibition of urease enzyme in a dose-dependent manner. In silico studies showed that eugenol and vanillic acid have almost similar binding affinities to the regulatory pocket of the modeled protein. Dynamics and simulation results indicate that the interaction of ligands with the ARG373 residue of the protein provides a stable bound conformation. Conclusion: Overall, our results suggest that both the phytocompounds eugenol and vanillic acid have a potential application as a new therapy for the inhibition of urease enzyme that could possibly replace the complexions related to struvite stone formation.

Aims: To find out the origin of so-called nitrite - like substance (NLS) that appears in the blood plasma in patients with inflammatory diseases and the mechanism of its occurrence. To justify the possibility of registering its appearance in the blood as a highly sensitive indicator of leukocyte activation. Background: The need for a simple, sensitive and specific method of early diagnosis of inflammation, the key stage of which is the activation of white blood cells. Objective: To find out the origin of so-called nitrite - like substance (NLS) that appears in the blood plasma in patients with inflammatory diseases before the onset of clinical signs. This substance is able to inhibit catalase in the presence of chloride which is typical for nitrite and nitrosoamines. Methods: The catalase activity was determined by the calorimetric method based on the control of the kinetics of heat production accompanying hydrogen peroxide decomposition. Results: Blood plasma contains deposited nitric oxide included in various nitrosyl iron complexes. These complexes effectively interact with the superoxide produced by activated leukocytes. This interaction produces a number of substances that have the ability to inhibit catalase in the presence of chloride. These substances retain the ability to inhibit in the system: hemoglobin-iron chelator, or hemoglobin-mercury salt. Such properties are characteristic of nitrite and nitrosoamines. Normally, these substances are present in plasma in trace amounts. 700 activated cells per microliter (10 times less than normal in human blood) are enough to transform about 30% nitrosyl iron complexes contained in plasma into NLS. Conclusion: The appearance of NLS is a very sensitive indicator of leukocyte activation.