Current Enzyme Inhibition - Volume 15, Issue 3, 2019

Background: Cancer is a very serious public health problem ranking as the second leading cause of death worldwide. Angiogenesis plays a vital role as a prerequisite for tumor growth and metastasis, and is indispensable in the further stage advancement of cancer. Objective: Targeting several enzymes and receptors in angiogenesis’ signal transduction pathway will likely offer many more prospects for successful and superior therapeutic intervention. Methods: Thus, druggable targets in the angiogenesis pathway such as pro-MMP9, MMP-9, EGFR, VEGF-A, VEGFR-1, VEGFR-2, c-MET kinase, KIT kinase, CSF1R, TIE-2, and RET tyrosine kinase were the subject of this molecular docking study involving Alpinumisoflavone (AIF), a multi-targeted natural product with known anticancer activities. Results: The results showed that AIF exhibited good binding affinity with all the selected key angiogenesis promoting proteins with greatest in silico activity in MMP-9 and VEGFR-2. Moreover, in silico ADMET studies showed that AIF has good intestinal absorption property and solubility, and very low probability of being carcinogenic, mutagenic, and toxic to embryo or fetus. Conclusion: Molecular docking study revealed that Alpinumisoflavone (AIF) could serve as a promising lead in the development of angiogenesis (multikinase) inhibitor based on its predicted binding affinity with vital angiogenesis targets.

Background: Benign prostatic hyperplasia and prostate cancer are androgen-dependent diseases, and dihydrotestosterone (DHT), a 5α-reduced metabolite of testosterone (T), has been implicated as a causative factor in the progression of these diseases. The 5α-reductase enzyme (5α-R) converts T to DHT, which is responsible for increasing cell proliferation, and hence inhibition of this enzyme could lead to potential treatments for these afflictions. Objective: This study focused on evaluating the biological activity of three series of pregnenolone derivatives as inhibitors of 5α-R and as antiandrogens on androgen-dependent glands. Methods: To determine the biological activity of these compounds, we evaluated the effect of each one on suppressing the activity of both types of isozymes of 5α-R (1 and 2) by 50% (IC50). Using animal studies, we assessed the effect of these derivatives on the weight of the prostate, seminal vesicles, and diameter of the flank organs of castrated hamsters previously dosed with 1 mg/Kg T. Results: In vitro experiments showed that derivatives 1f, 2b, and 3d were very effective inhibitors of the activity of 5α-R2, showing IC50 values of 21.8, 20, and 15 nM, respectively. Derivatives 2b and 3b showed a lower inhibition effect on 5α-R1. The data also indicated that derivatives 2b, 1f, 3b, and 3d were very active in reducing prostate weight in the hamster model of benign prostatic hyperplasia. Discussion: Pharmacological experiments showed that pregnenolone derivatives possess an antiandrogenic effect because of the inhibition of DHT production in androgen-dependent glands. Conclusion: The pregnenolone derivatives studied suppressed type 2 5α-reductase activity and because of this, the weight and dimension of androgen-dependent organs were decreased.

Background: Natural plant active compounds were found to inhibit the activity of several enzymes that may be related to several diseases. Objective: This study aimed at testing the antidiabetic activity related to the phenol content by in vitro α-Amylase inhibitory action effect of aqueous, organic and essential oil extracts of Haplophyllum tuberculatum, collected in the town of Laghouat in the steppe region of Algeria. Methods: Two types of aqueous extracts were prepared: Decoction and Diffusion extracts. The organic extracts were prepared with successful maceration in hexane, dichloromethane, ethyl acetate, ethanol and methanol. Also, essential oils were obtained by hydrodistillation. The analysis of the total Phenol content of our extracts was done with Folin-Ciocalteu reagent, as the flavonoid content was obtained in mixture with aluminum trichloride. The effects of the plant extracts on the catalytic efficiency of α-amylase enzyme were represented by the enzymatic inhibitory percentage of each extract in which the inhibitory activity was expressed as IC50. Results: The total phenol content showed values ranging between 0.27 and 11.97 mg gallic acid equivalent / g dry matter. The flavonoid contents vary from 0.05 to 1.50 mg equivalent of rutin /g of dry matter. All the extracts showed good inhibitory activity against α- amylase of IC50, values ranged from 0.05 to 50.03 mg/ml. Conclusion: This study reports for the first time the inhibitory capacity of Algerian Haplophyllum tuberculatum species against α-amylase which could provide natural biologically active agents to be used in the management of diabetes.

Background: Chemotherapy has shown varying success rates in the treatment of metastatic cancer in the last 50 years. One of the problems in the use of many chemotherapeutic agents is to increase the expression of glutathione transferase enzyme (GST; EC 2.5.1.18). Therefore, the development of GST inhibitors is important to improve the effectiveness of antitumor drugs and to overcome multi-drug resistance. Introduction: Glutathione S-transferases (GSTs) are a major member of enzymes serving in the detoxification of exogenous and endogenous substances. But, it has been reported that GSTs are overexpressed in many tumour cells, and it has been found to be related to developing resistance to anticancer drugs by these cells. The development of GST inhibitors is important to increase the efficacy of antitumor drugs and overcome multi-drug resistance. The aim of our study was to investigate the effect of natural compounds including curcumin, resveratrol, and quercetin on GST enzyme activity. We also aimed to specify inhibition mechanism of the compounds on human erythrocytes GST (hGST) with in silico study. Methods: GST was purified from human erythrocytes using affinity chromatography (glutathione agarose). The enzyme purity was checked with SDS-PAGE. After the inhibitory effect of the curcumin, quercetin, resveratrol was investigated. Lastly, inhibition mechanisms of these natural compound were identified with induced-fit docking method. Results: GST was purified with 19.31% yield from human erythrocytes. In inhibition studies, Ki values of curcumin, quercetin, resveratrol were determined as 0.0021 ± 0.0008, 0.0257 ± 0.0011, 663.3301 ± 0.0936 μM respectively. According to our results, all natural products showed the inhibition effect and the order of inhibition is as follows: curcumin > quercetin > resveratrol. Conclusion: According to the results of the in vitro and in silico studies, it can be said that curcumin, quercetin, resveratrol are the inhibitors of human erythrocyte GST. In conclusion, these observations may be of great importance for the potential use of these natural compounds as chemopreventive agents.

Aims and Objectives: This study aimed to characterize a coniferyl alcohol dehydrogenase from sugarcane stalks. Also, the purification of CAD from sugarcane stalks was also carried out to study kinetic properties and substrate specificity. Background: Sugarcane plants contain an alcohol dehydrogenase able to reduce both coniferyl and sinapyl aldehydes to their correspondent alcohols, although there are reasonable grounds for suspecting that these are two distinct enzymes. Methods: The enzyme, coniferyl alcohol dehydrogenase was 125-fold purified from sugarcane stalks. Its activity was estimated by HPLC by calculating the amount of product formed. Results: The enzyme showed an optimum pH value of 7.9, at an optimum temperature of 20-22°C and a molecular mass of 48 kDa. The Km value for coniferyl alcohol was 3.03 μM and the enzyme was shown to be inhibited by an excess of the substrate from 17 μM. This dehydrogenase showed a similar affinity to sinapyl alcohol (Km 1.78 μM). Conclusion: This paper provides circumstantial evidence about the existence of two different alcohol dehydrogenases, specific to each of the substrates.