Current Enzyme Inhibition - Volume 18, Issue 3, 2022

Background: In patients with Gastroesophageal Reflux Desease (GERD), the digestive enzyme pepsin can reach the esophagus and extraesophageal sites and cause damage with inflammation and other tedious symptoms. Methods: In this work, a number of biocompatible, non-toxic, and hypoallergenic compounds were tested in vitro as pepsin inhibitors. The residual enzyme activity in the presence of the investigated compounds was measured through a convenient and reliable UV-vis method based on the cleavage of hemoglobin. This method is applicable even if the investigated additives are scarcely soluble in water and the test mixtures are dispersions rather than solutions. Results: A few negatively charged saccharides showed the highest effect among the investigated compounds. The inhibitory activity of pepstatin and lovastatin was also tested with the same method in a wide range of concentrations. These compounds turned out to be effective even if present in extremely low amounts. A docking/molecular dynamic investigation providesuseful insights into the binding site and the mechanism of action of pepstatin as an inactivating agent toward pepsin. Conclusion: In particular, the computational study indicates that the binding with this compound significantly increases the mobility of the active site residues and prevents them from cooperating in the reactive event.

Aim: This study investigates the potential effect of pure curcumin on the inhibition of different enzymes involved in several diseases. Background: Several chronic diseases such as Alzheimer’s, diabetes, and Parkinson’s are related to oxidative stress and enzyme activity. Today, various plant origin products are beneficial against several chronic diseases with secondary metabolites such as phenolic compounds. Curcumin, a polyphenol yellow- orange pigment in turmeric spices, has a wide range of biological activities with quite a safety. Objective: This study aimed to investigate the antioxidant and inhibitory potential against key enzymes involved in human pathology, namely Alzheimer's disease (Acetylcholinesterase (AChE), and Butyrylcholinesterase (BChE)), diabetes (α-glucosidase), hyperpigmentation and Parkinson’s diseases (Tyrosinase) of curcumin. Methods: 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH151;) and hydrogen peroxide radicals (H2O2) assays were used to evaluate the antioxidant capacity of curcumin, and enzyme inhibitory activity was evaluated using in vitro standard procedures. Results: Curcumin exhibited an excellent antioxidant effect with an IC50 value significantly less than Vit C reference. In enzyme inhibitory activity, curcumin demonstrated excellent inhibitory activity against AChE, BChE and α-glucosidase. The finding showed that curcumin was significantly less than the reference galantamine against AChE but more than the references galantamine and acarbose against BChE and α-glucosidase, respectively. Whereas for anti-tyrosinase activity, curcumin displayed weak inhibitory activity compared with the standard inhibitor, Kojic acid. Conclusion: These results indicated that curcumin showed promising antioxidant, anti-Alzheimer, and anti-diabetic properties and might be used as potential natural drugs against these diseases.

Background and Objective: Testosterone under the influence of 5α-reductase enzyme gets converted to dihydrotestosterone and high levels are found to be causative for androgen dependent diseases like benign prostatic hyperplasia. Thus, 5α-reductase has been recognised as an important target for discovering new drugs against Benign Prostatic Hyperplasia and Prostate Cancer. Methods: In the present study, a series of 5α, 6β-Dichloro-17-Oxoandrostan-3β-yl esters (7a-7f) were synthesized and characterized by analytical and spectroscopic methods. The compounds were evaluated for their 5α-reductase inhibitory activity in-vivo by their effect on serum androgen levels. Results: The target compounds (7a-7f) showed increased anti-androgenic activity as compared to finasteride and control, which implies that the target compounds are effective in inhibiting 5α-reductase. Particularly, compound 7b showing highest inhibitory activity and noteworthy D-Score was further sorted by performing solubility and dissolution studies. Results of these studies, when compared with finasteride, showed increased solubility and dissolution of target compound 7b. Conclusion: These results demonstrated that enhancement of activity by the presence of electronegative group at position 3 of the steroidal nucleus makes 7b a lead compound for further exploration and optimal formulation.

Background: The protein tyrosine phosphatases phosphatase 1B (PTP 1B) is a negative regulator of insulin signal transduction, and hence, serves as a therapeutic target in the treatment of diabetes. Objective: The present study investigated the inhibitory effects of p-hydroxybenzaldehyde, vanillin, and syringaldehyde on the activity of protein tyrosine phosphatases phosphatase 1B (PTP 1B) in vitro. Methods: The PTP 1B inhibitory assay and mode of inhibition of the three compounds were determined using p-nitrophenyl phosphate (p-NPP) in a 96-well microplate. Molecular docking was used to predict the binding affinities of the compounds with the PTP 1B. Results: The results showed that syringaldehyde exhibited significantly (p< 0.05) higher PTP 1B inhibitory activity (IC50: 12.75 μM) compared to p-hydroxybenzaldehyde (IC50: 33.79 μM) and vanillin (IC50: 42.82 μM) as well as the standards suramin (IC50: 28.35 μM) and ursolic acid (IC50: 19.45 μM). Syringaldehyde and vanillin showed uncompetitive inhibition, whereas p-hydroxybenzaldehyde showed a mixed inhibition type. The molecular docking simulation predicted negative binding energies of -5.0 kcal/mol, -5.5 kcal/mol, and -5.5 kcal/mol for p-hydroxybenzaldehyde, vanillin, and syringaldehyde, respectively. Conclusion: Syringaldehyde showed higher inhibition of PTP 1B compared to other phenolic aldehydes and could be the mechanism of its antidiabetic activity. Hence, further studies are warranted to confirm the efficacy and toxicity of the compound.

Background: The potential antidiabetic and antioxidant properties of four ruthenium(III) hydroxamate complexes [RuCl(H2O)(L^I-III)2] (1-3) and [RuCl3(H2O)(HL^IV)2] (4) were investigated on α- cell enzymes (α-amylase and α-glucosidase). Methods: In the instance of α-amylase inhibition investigations, the antidiabetic studies of the complexes revealed that they are more active than even the Acarbose as standard, with complex 4 having an IC50 value of 52.31 g/ml. For α-glucosidase inhibition, complex 4 was observed to be the best inhibitor with a remarkable 0.35μg/ml IC50 value, which may be attributed to the size and superior lipophilicity of this complex, enabling it to interact with the biological system more effectively than complexes 1-3. The complexes with the best IC50 values were studied further for enzyme kinetics. Molecular docking studies were performed as well to investigate the interactions between the synthesized complexes and target enzymes viz., α-glucosidase and α-amylase. Results: The obtained in-vitro results have also been supported by the results of the in-silico docking studies. Furthermore, the antiradical activity of Ru(III) complexes was assessed for its effectiveness in reducing oxidative stress. Conclusion: All the complexes (except complex 3) exhibited remarkable antiradical activity.

Background: Glucosidase is a catalytic enzyme that catalyzes, specifically hydrolyses, the carbohydrates to free glucose units in blood in the last step of carbohydrate metabolism. So far, many compounds with α-glucosidase inhibitory activity, for example, acarbose, voglibose etc., have been accounted and commercialized for diabetes therapy. However, xanthones are recognized as efficient glucosidase inhibitors because of their planar structure, and have opened the door for the researchers to utilize the same for designing and developing potent and novel hybrid xanthones for anti-diabetic therapy. Objectives: The current study aimed to determine and evaluate the anti-diabetic potential of different synthetic hydroxylxanthone derivatives using Nicotinamide and Streptozotocin (60mg/kg i.p.) induced diabetic rats. Methods: The partially purified synthetic hydroxyxanthone derivatives, namely A1, A2, A3, A4, and A5, were administered to diabetic rats at a dose of 150mg/kg per oral(p.o.), and the effect of the fraction on blood glucose level was studied for up to 21 days. Further, the synthetic compounds were subjected to spectral analysis for their characterization. Results: The in silico molecular docking results indicated that compound A3 has shown the best binding energy score. Also, the in vivo anti-diabetic potential of the synthetic hydroxyxanthone derivatives has revealed the compounds A3 and A2 to be significantly effective in controlling the blood glucose level when compared to the standard drug miglitol. In addition, compounds A3 and A2 were found to be effective in restoring the enzymes of the liver and lipid profile in Streptozotocin-induced Wistar rat models. Conclusion: With an objective to investigate the compounds for predicting biological activity, it was found that the hydroxyxanthone possesses a safety margin for toxicity and acts as a lead toward the development of potential α-glucosidase inhibitors. These compounds show an excellent correlation between docking results, synthetic data and in vivo anti-diabetic activity. However, further modifications can be done to enhance the potency and binding affinity profile, and minimize toxicity.

Aim: This study aims to identify novel steroidal 5-alpha reductase (5AR) inhibitors using computational approaches. Objectives: The objective of this study is to exploit the steroidal nuclei for possible modifications by creating a library of 17-oximino-5-androsten-3-carboxamide derivatives and identify potent 5AR inhibitors based on docking and pharmacokinetic parameters. Background: Benign prostatic hyperplasia (BPH) is a condition of aged men that is characterized by lower urinary tract symptoms. Excessive production of dihydrotestosterone (DHT) from testosterone has been found to play a major role in its pathophysiology. Studies targeting the 5AR enzyme have so far resulted in the development of two clinically approved 5AR inhibitors. Methods: Atom-based three-dimensional-quantitative structure-activity relationship (3D-QSAR) models have been developed using a selected series of steroidal derivatives as 5AR inhibitors to elucidate the structural properties required for 5AR inhibitory activities. Further in128;’silico studies (molecular docking and pharmacokinetic properties like adsorption, distribution, metabolism, and excretion) of 17- oximino-5-androsten-3-carboxamide derivatives have also been carried out to identify the binding orientation and protein-ligand interactions responsible for the exhibited activity and drug like properties. Results: The best 3D-QSAR model was generated using Partial Least Square method with an excellent correlation coefficient (R², training set) of 0.882, standard deviation (SD) of 0.09, and a predicted coefficient (Q², test set) of 0.814. Docking analysis indicated that the designed series of compounds have comparable binding affinity from -8.961 to -8.017 to the protein and suggested that hydrophobic and electrostatic moieties can have a key role in the inhibition mechanism. Conclusion: 3D-QSAR, molecular docking and pharmacokinetic studies indicated that 17-oximino-5- androsten-3-carboxamide derivatives could be studied further to provide a new strategy for the treatment of BPH.