Identification of Potential Aldose Reductase Inhibitors Using Convolutional Neural Network-Based in Silico Screening

Aldose reductase (ALR2) is a notable enzyme of the polyol pathway responsible for aggravating diabetic neuropathy complications. The first step begins when it catalyzes the reduction of glucose to sorbitol with NADPH as a coenzyme. Elevated concentrations of sorbitol damage the tissues, leading to complications like neuropathy. Though considerable effort has been pushed toward the successful discovery of potent inhibitors, its discovery still remains an elusive task. To this end, we present a 3D convolutional neural network (3D-CNN) based ALR2 inhibitor classification technique by dealing with snapshots of images captured from 3D chemical structures with multiple rotations as input data. The CNN-based architecture was trained on the 360 sets of image data along each axis and further prediction on the Maybridge library by each of the models. Subjecting the retrieved hits to molecular docking leads to the identification of the top 10 molecules with high binding affinity. The hits displayed a better blood-brain barrier penetration (BBB) score (90% with more than four scores) as compared to standard inhibitors (38%), reflecting the superior BBB penetrating efficiency of the hits. Followed by molecular docking, the biological evaluation spotlighted five compounds as promising ALR2 inhibitors and can be considered as a likely prospect for further structural optimization with medicinal chemistry efforts to improve their inhibition efficacy and consolidate them as new ALR2 antagonists in the future. In addition, the study also demonstrated the usefulness of scaffold analysis of the molecules as a method for investigating the significance of structurally diverse compounds in data-driven studies. For reproducibility and accessibility purposes, all of the source codes used in our study are publicly available.

Novel indole retinoid derivative induces apoptosis and cell cycle arrest and modulates AKT and ERK signaling in HL-60 cells

Chemotherapy with targeted drugs is the first line therapy option for acute and chronic myeloid leukemia. However, hematopoietic stem cell transplantation may be used in high-risk patients or patients with failed responses to chemo drugs. Discovery and development of more effective new agents with lower side effects is the main aim of leukemia treatment. In this study, a novel retinoid compound with tetrahydronaphthalene ring was synthesized and evaluated for anticancer activity in human chronic and acute myeloid leukemia cell lines K562 and HL-60. Novel N-(1H-indol-1-yl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2-carboxamide was synthesized based on molecular hybridization of the two different bioactive structures retinoid head and indole. The effects of the synthesized carboxamide compound, which was referred to as compound 5, were determined in K562 chronic myeloid leukemia and HL-60 acute myeloid leukemia cell lines and L929 fibroblast cell line, which served as a control. Colorimetric MTT and caspase3 activity tests, flow cytometry, western blot, and microscopic examinations were used to evaluate biological activity. Compound 5 more effectively induced cell death in HL60 cells in comparison to K562 cells and L929 fibroblast cells. Therefore, further mechanism of cell death was investigated in HL60 cell line. It was found that compound 5 induced remarkable cytotoxicity, caspase3 activation, and PARP fragmentation in HL60 cells. Flow cytometric staining showed that the percentage of cells arrested in G0/G1 was also increased with compound 5 treatment. Important modulator proteins of cell proliferation p-ERK, p-AKT, and p-m-TOR were also found to be inhibited with compound 5 treatment. Collectively, our results reveal compound 5, which is a novel indole retinoid compound as a potential active agent for the treatment of acute promyelocytic leukemia.

Synthesis of Some Benzimidazole-derived Molecules and their Effects on PARP-1 Activity and MDA-MB-231, MDA-MB-436, MDA-MB-468 Breast Cancer Cell Viability

Background:

Poly (ADP-ribosyl) polymerase-1 (PARP-1) inhibitors are compounds that are used to treat cancers, which are defective in DNA-repair and DNA Damage-Response (DDR) pathways.

Objective:

In this study, a series of potential PARP-1 inhibitor substituted (piperazine-1-carbonyl)phenyl)-1Hbenzo[ d]imidazole-4-carboxamide compounds were synthesised and tested for their PARP-1 inhibitory and anticancer activities.

Methods:

Compounds were tested by cell-free colorimetric PARP-1 activity and MTT assay in MDA-MB-231, MDA-MB-436, MDA-MB-468 breast cancer, and L929 fibroblast cell lines.

Results:

Our results showed that compound 6a inhibited viability in MDA-MB-231 and MDA-MB-468 cells whereas 8a inhibited viability in MDA-MB-468 cells. Compound 6b significantly inhibited cell viability in tested cancer cells. However, 6b exhibited toxicity in L929 cells, whereas 6a and 8a were found to be non-toxic for L929 cells. Compounds 6a, 6b and 8a exhibited significant inhibition of PARP-1 activity.

Conclusion:

These three compounds exhibited PARP-1 inhibitory activities and anticancer effects on breast cancer cells, and further research will enlighten the underlying mechanisms of their effects.

Three-Dimensional Analysis of Binding Sites for Predicting Binding Affinities in Drug Design

Understanding the interaction between drug molecules and proteins is one of the main challenges in drug design. Several tools have been developed recently to decrease the complexity of the process. Artificial intelligence and machine learning methods offer promising results in predicting the binding affinities. It becomes possible to do accurate predictions by using the known protein-ligand interactions. In this study, the electrostatic potential values extracted from 3-dimensional grid cubes of the drug-protein binding sites are used for predicting binding affinities of related complexes. A new algorithm with a dynamic feature selection method was implemented, which is derived from Compressed Images For Affinity Prediction (CIFAP) study, to predict binding affinities of Checkpoint Kinase 1 and Caspase 3 inhibitors.

Apoptotic Effects of Some Tetrahydronaphthalene Derivatives on K562 Human Chronic Myelogenous Leukemia Cell Line

BACKGROUND

Retinoids which are vitamin A (Retinol) derivatives have been suggested to mediate the inhibition of cancer cell growth and apoptosis. It has been reported that all trans retinoic acid (ATRA) exhibited suppressive effects on different types of leukemia including chronic myelogenous leukemia.

OBJECTIVE

In the present study, we aim to find out the effects of 6 synthetic N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalene-2-yl)-carboxamide derivatives (compound 6-12) on cell viability and apoptotic pathways in K562 human chronic myelogenous leukemia cell line.

METHODS

Cell viability and apoptosis were examined by spectrophotometric thiazolyl blue tetrazolium bromide (MTT) and caspase-3 assay, western blot, RT-PCR and flow cytometry.

RESULTS

Our results indicated that compound 6 (5-(1,2-Dithiolan-3-yl)-N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)pentanamide), 8 (4-(3,4-Dimethoxyphenyl)-N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)butanamide) and 11 (E-3-(4-Hydroxy-3-methoxyphenyl)-N-(3,5,5,8,8-pentamethyl- 5,6,7,8-tetrahydronaphthalen-2-yl)acrylamide) exhibited apoptotic effects in K562 human chronic myelogenous leukemia cell line and induced caspase 3, PARP cleavage, Bax/Bcl-2 ratio, Bad and Bim gene expressions.

CONCLUSION

Some retinoid derivatives tested in this study induced apoptosis of K562 cells which suggest that these compounds may serve as potential agents in the treatment of chronic myelogenous leukemia.

Design, Synthesis and Cytotoxic Activity of Spiro(oxindole-3-3'- pyrrolidine) Derivatives

Background:

Spiro[pyrrolidine-3,3'-oxindole] compounds are reported to be highly bioactive natural and synthetic products. Initially, spirooxindole alkaloids were isolated from plants of the Apocynaceae and Rubiaceae families, which were found to have a common scaffold, spiro[pyrrolidine-3,3'-oxindole], exhibiting anticancer activities., we specifically aimed at the synthesis, characterization and anticancer activity of novel spiro[pyrrolidine-3,3' -oxindole] derivatives, compounds 6a-c and 7.

Methods:

The synthesis was initiated by Knovenegal condensation of indole-2-one with an appropriate benzaldehyde in presence of piperidine to afford compounds 3a-c. Compounds 6a-c were synthesized by an asymmetric 1,3-dipolar cycloaddition between compounds 3a-c and (2S, 3R)-2, 3, 5, 6-tetrahydro-2, 3-diphenyl-1, 4-oxazin-6-one, which is an intermediate compound formed by the Schiff base reaction between 3-methyl-butanal and (2S, 3R)-2, 3, 5, 6-tetrahydro-2, 3-diphenyl- 1,4-oxazin-6-one, in presence of molecular sieves (4Å) under argon atmosphere. Compound 6a was then reacted with ethylamine-HCl in THF at room temperature to yield compound 7.

Results:

Cytotoxic effects of the compounds synthesized were determined on Huh7, MV, HCT116 and MCF7 cancer cell lines by the NCI-60 Sulforhodamine B Assay, using (S)-(+)-Camptothecin as a positive control. In general, target compounds showed better cytotoxic activities against the MCF7 and HCT116 cancer cell lines. It was found that compound 7 exhibited the most potent inhibitory activity with IC50 values of 4.8 µM, 3.9 µM, 14.9 µM and 8.2 µM against the MCF7, HCT116, MV and Huh7 cell lines, respectively.

Conclusion:

It was determined that compounds 6a&6b possess C6'(S)|C8'(R)|C9'(R) stereochemistry and compound 7 adopts C2'(S)|C4'(R)|C5'(R) stereochemistry. Cytotoxicity studies suggest that compound 7 gave rise to the highest anticancer activity against MCF7, HCT116, and Huh7 cancer cell lines.

An application of CIFAP for predicting the binding affinity of Chk1 inhibitors derived from 2-aminothiazole-4-carboxamide

Investigation of protein-ligand interactions obtained from experiments has a crucial part in the design of newly discovered and effective drugs. Analyzing the data extracted from known interactions could help scientists to predict the binding affinities of promising ligands before conducting experiments. The objective of this study is to advance the CIFAP (compressed images for affinity prediction) method, which is relevant to a protein-ligand model, identifying 2D electrostatic potential images by separating the binding site of protein-ligand complexes and using the images for predicting the computational affinity information represented by pIC₅₀ values. The CIFAP method has 2 phases, namely, data modeling and prediction. In data modeling phase, the separated 3D structure of the binding pocket with the ligand inside is fitted into an electrostatic potential grid box, which is then compressed through 3 orthogonal directions into three 2D images for each protein-ligand complex. Sequential floating forward selection technique is performed for acquiring prediction patterns from the images. In the prediction phase, support vector regression (SVR) and partial least squares regression are used for testing the quality of the CIFAP method for predicting the binding affinity of 45 CHK1 inhibitors derived from 2-aminothiazole-4-carboxamide. The results show that the CIFAP method using both support vector regression and partial least squares regression is very effective for predicting the binding affinities of CHK1-ligand complexes with low-error values and high correlation. As a future work, the results could be improved by working on the pose of the ligands inside the grid.

Retinoid N-(1H-benzo[d]imidazol-2-yl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2-carboxamide induces p21-dependent senescence in breast cancer cells

Retinoids have been implicated as pharmacological agents for the prevention and treatment of various types of cancers, including breast cancers. We analyzed 27 newly synthesized retinoids for their bioactivity on breast, liver, and colon cancer cells. Majority of the retinoids demonstrated selective bioactivity on breast cancer cells. Retinoid 17 had a significant inhibitory activity (IC50 3.5 μM) only on breast cancer cells while no growth inhibition observed with liver and colon cancer cells. The breast cancer selective growth inhibitory action by retinoid 17 was defined as p21-dependent cell death, reminiscent of senescence, which is an indicator of targeted receptor mediated bioactivity. A comparative analysis of retinoid receptor gene expression levels in different breast cancer cells and IC50 values of 17 indicated the involvement of Retinoid X receptors in the cytotoxic bioactivity of retinoid 17 in the senescence associated cell death. Furthermore, siRNA knockdown studies with RXRγ induced decrease in cell proliferation. Therefore, we suggest that retinoid derivatives that target RXRγ, can be considered for breast cancer therapies.

Synthesis, anticancer activities and molecular modeling studies of novel indole retinoid derivatives

In this study, novel (E)-3-(5-substituted-1H-indol-3-yl)-1-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)prop-2-en-1-one (5(a-e)) derivatives were synthesized and their anticancer effects were determined in vitro. Novel indole retinoid compounds except 5e have anti-proliferative capacity in liver, breast and colon cancer cell lines. This anti-proliferative effect was further analyzed in breast cancer cell line panel by using the most potent compound 5a. It was determined that 5a can inhibit proliferation at very low IC(50) concentrations in all of the breast cancer cell lines. Here, we present some evidence on apoptotic termination of cancer cell proliferation which may be primarily driven by the inhibition of RXRα and, to a lesser extent, RXRγ.

Synthesis and evaluation ofin vitroantioxidant capacities of some benzimidazole derivatives

New, except 1d, melatonin analogue benzimidazole derivatives were synthesized and characterized in the present study. The potential role of melatonin as an antioxidant by scavenging and detoxifying ROS raised the possibility that compounds that are analogous to melatonin can also be used for their antioxidant properties. Therefore the antioxidant effects of the newly synthesized compounds were investigated in vitro by means of their inhibitory effect on hydrogen peroxide-induced erythrocyte membrane lipid peroxidation (EMLP) and on various erythrocyte antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PD). The synthesized benzimidazole derivatives showed remarkable antioxidant activity in vitro in the H2O2-induced EMLP system. Furthermore their effects on various antioxidant enzymes are discussed and evaluated from the perspective of structure- activity relationships.

Adaptive neuro-fuzzy inference system (ANFIS): A new approach to predictive modeling in QSAR applications: A study of neuro-fuzzy modeling of PCP-based NMDA receptor antagonists

This paper proposes a new method, Adaptive Neuro-Fuzzy Inference System (ANFIS) to evaluate physicochemical descriptors of certain chemical compounds for their appropriate biological activities in terms of QSAR models with the aid of artificial neural network (ANN) approach combined with the principle of fuzzy logic. The ANFIS was utilized to predict NMDA (N-methyl-d-Aspartate) receptor binding activities of phencyclidine (PCP) derivatives. A data set of 38 drug-like compounds was coded with 1244 calculated molecular structure descriptors (clustered in 20 data sets) which were obtained from several sources, mainly from Dragon software. Prior to the progress to the ANFIS system, descriptors from the best subsets were selected using unsupervised forward selection (UFS) to eliminate redundancy and multicollinearity followed by fuzzy linear regression algorithm (FLR) which was used for variable selection. ANFIS was applied to train the final descriptors (Mor22m, E3s, R3v+, and R1e+) using a hybrid algorithm consisting of back-propagation and least-square estimation while the optimum number and shape of related functions were obtained through the subtractive clustering algorithm. Comparison of the proposed method with traditional methods, that is, multiple linear regression (MLR) and partial least-square (PLS) was also studied and the results indicated that the ANFIS model obtained from data sets achieved satisfactory accuracy.

Antimicrobial activities of some tetrahydronaphthalene-benzimidazole derivatives

Novel retinoid derivatives containing a benzimidazole moiety were synthesized and tested for their antimicrobial activity. Their antimicrobial activities against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Candida krusei and Candida albicans were evaluated. While some of the compounds exhibited moderate activity against MRSA, S. aureus, E. faecalis, C. krusei and C. albicans, none of the compounds showed activity against E. coli and P. aeruginosa.

Synthesis and Antioxidant Activity of New Tetrahydro-Naphthalene-Indole Derivatives as Retinoid and Melatonin Analogs

A number of retinoid-related compounds represent classes of antioxidative and proapoptotic agents with promising potential in the treatment of neoplastic diseases. Indeed, the synthetic retinoid amide fenretinide [N-(4-hydroxyphenyl)retinamide] induces apoptosis of cancer cells and acts as a chemotherapeutic drug in cancer therapy. In the present work, and as a continuation of our studies on retinoid-type compounds, the synthesis of melatonin retinamide derivatives was studied as a novel series of melatonin retinoids, using the condensation reaction sequence involving tetrahydrotetramethylnaphthalene carboxylic acid and appropriate melatonin-type moieties. Despite of the weak DPPH inhibition activity pattern of the synthesized compounds, some of them showed a strong inhibition on lipid peroxidation (IVa-b, Va, and VIIa-c, 88, 96, 90, 94, 93, and 86%, respectively at 10(-4) M concentration) when melatonin (85% at 10(-4) M concentration) was used as a reference compound.

Genotoxicity studies on benzimidazole retinoids

Retinoids consist of a family of naturally occuring compounds including all-trans retinoic acid (ATRA), retinal, retinol (vitamin A), 9-cis retinoic acid, 13-cis retinoic acid as well as a large number of synthetic derivatives. Retinoids are known to elicit diverse pharmacological profiles such as controlling cell differentiation/proliferation and modulating specific premalignant lesions and reducing second primary tumors in patients. Clinical use of retinoids is limited due to their toxicity. Three benzimidazole retinoid derivatives (BITN, BITNm, BITNe) were synthesized and were examined in terms of genotoxicity towards human lymphocyte cultures by sister chromatid exchange (SCE) analysis. It has been found that BITN decreased the number of SCEs 20% at 10(-6) M, but had no effect at 10(-5) M. No significant effect on SCEs was observed for BITNm and BITNe at both concentrations. ATRA increased the SCEs (35%) at 10(-5) M but had no effect at 10(-6) M. The results have shown that benzimidazole retinoids did not induce SCE significantly. Besides this, BITN reduced the SCEs and had a protective effect at low concentration. Since the induction of glutathione S-transferase (GST) is associated with anticancer drug resistance, the effects of BITN, BITNm, BITNe and ATRA on human lymphocyte GSTs were also investigated using CDNB as substrate. BITN and BITNm induced GST activities 54% and 49% respectively at 10(-5) M, but had no effect at 10(-6) M. BITNe induced GST activity 62% at 10(-5) M and 35% at 10(-6) M. ATRA had no effect on GST activity at 10(-5) M.

Synthesis and antioxidant properties of some indole ethylamine derivatives as melatonin analogs

The synthesis and lipid peroxidation (LP) inhibition activity of several novel indole melatonin analogues are reported. Compounds have shown variable antioxidant features depending on the substitution pattern. Melatonin and the antioxidant reference compound butyl hydroxy toluen (BHT) were used to compare the antioxidant capability of the compounds synthesized.

Syntheses of Novel Indole Lipoic Acid Derivatives and Their Antioxidant Effects on Lipid Peroxidation

The aim of the study was to examine antioxidant properties of conjugates based on indole and lipoic acid moieties. The design and syntheses of novel indole alpha-lipoic acid derivatives were performed. The antioxidant properties of target compounds were investigated using rat liver microsomal, NADPH-dependent lipid peroxidation inhibition. Some of the target compounds, especially those containing amide linker at position 5 of indole ring, proved to be highly effective in inhibiting lipid peroxidation as compared to alpha-lipoic acid.

Antioxidant Properties of Novel Benzimidazole Retinoids

Our approach was to examine the antioxidant activity of novel retinoid derivatives containing the benzimidazole moiety. Their in vitro effects on rat liver microasomal, NADPH-dependent lipid peroxidation levels and superoxide anion formation were determined. Lipid peroxidation in rat liver microsomes was reduced by some of the compounds in a dose-dependent manner.

Recent studies of aldose reductase enzyme inhibition for diabetic complications

Aldose reductase [ALR2; EC 1.1.1.21], a key enzyme of polyol pathway, catalyzes NADPH-dependent reduction of glucose to sorbitol (Sorbitol pathway), and an excessive accumulation of intracellular sorbitol found in various tissues of diabetic animals and in cells cultured under high glucose conditions has been proposed to be an important factor for the pathogenesis of diabetic complications. The only strategy shown to be consistently beneficial in the treatment of diabetic complications is meticulous control of blood glucose. However, aldose reductase (AR) enzyme inhibition is becoming one of the therapeutic strategies that have been proposed to prevent or ameliorate long-term diabetic complications. Therefore, AR inhibitors (ARIs) hold promise for reducing metabolic nerve injury, but further study is needed. On the other hand, there is strong evidence to show that diabetes is associated with increased oxidative stress. However, the source of this oxidative stress remains unclear. This relationship between diabetic complications and free radical production was also under investigation. The studies suggest that hydroxyl radical is indirectly inhibited by ARIs resulting from decreasing polyol levels and hydroxyl radical formation is related to the early stages of diabetic complications, possibly via the Fenton reaction involving H(2)O(2) produced from the activated polyol pathway. Therefore, it is proposed that hydroxyl radical may accelerate damage to the cell membranes resulting from polyol accumulation. The search for specific inhibitors of AR enzyme has still become a major pharmaceutic challenge, though a number of AR inhibitors have so far been assessed for diabetic complications.

Synthesis and antioxidative properties of novel thiazolidinedione/imidazolidinedione compounds as retinoids

The general term "retinoids" refers to both naturally occurring as well as synthetic compounds which exhibit biological activity similar to vitamin A (retinol). Vitamin A and its two metabolites, retinaldehyde and retinoic acid, are fat-soluble unsaturated isoprenoids necessary for the growth, differentiation and maintenance of epithelial tissues. In this study, we have synthesized thiazolidinedione/imidazolidinedione compounds as retinoids. Their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels and superoxide anion formation were determined.

Anti-cancer activity studies of indolalthiohydantoin (PIT) on certain cancer cell lines

5-(2-Phenyl-3'-indolal)-2-thiohydantoin (PIT) has been evaluated as an anti-cancer compound on several cancer lines organised in to subpanels representing leukemia, melanoma, and cancer of lung, colon, kidney, ovary, breast, prostate and central nervous system by the National Cancer Institute (NCI) anti-cancer drug screen programme. The compound showed inhibitory activity on several cancer cell lines. No information is available on anti-cancer potency of this compound with normal cell lines.

Synthesis and antimicrobial activity of some new flavonyl oxime ether derivatives

The synthesis of a series of 6 compounds related to 2-(4'-formyl-phenyl)-4]H-1-benzopyran-4-one O-substituted oxime and the results of a study of their biological activity are reported. The structural assignments of the compounds is based upon various spectral data. The prepared compounds were screened for their in vitro antibacterial and antifungal activities. Compound F3 exhibited the best antifungal activity compared with ketoconazole and fluconazole.

Evaluation of anti-HIV activity of 5-(2-phenyl-3'-indolal)-2-thiohydantoin

The anti-HIV activity of the previously synthesized 5-(2-phenyl-3'-indolal)-2-thiohydantoin I was evaluated. The compound, containing two structural moieties found in highly active anti-HIV agents, exhibited poor activity and rather high cytotoxicity.

A study on the antioxidant capacities of some benzimidazoles in rat tissues

Seven benzimidazole compounds were synthesized and their in vitro effects on rat liver, lung and kidney microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The significant decrease in male rat liver microsomal LP level was noted only by the compound 4 at 10(-4) M (20%) and 10(-3) M (40%) concentrations whereas the other compounds were ineffective. In lung, only the compound 6 at 10(-4) M concentration exhibited significant alteration, i.e. 56% increase, in LP level. In kidney, however, apart from the compound 4, all the compounds increased LP level (35-52%) significantly. The classical antioxidant, butylated hydroxy toluene (BHT), at 10(-4) M concentration, significantly decreased LP level about 70%, in all the tissues studied. To clarify the effects of compounds 4 and 6 on LP, the responses of some CYPs, which are active in producing reactive oxygen species, to these compounds were also investigated. The compound 4 at 10(-4) and 10(-3) M concentrations inhibited the hepatic microsomal ethoxyresorufin O-deethylase (EROD) (37 and 65%) and pentoxyresorufin O-depenthylase (PROD) (14 and 62%) enzyme activities significantly. However, it did not alter the hepatic microsomal NADPH-cytochrome P450-reductase activity. BHT, at 10(-3) M concentration, significantly inhibited hepatic microsomal EROD (73%), PROD (62%) and NADPH-cytochrome P450 reductase (17%) enzyme activities. Caffeine (10(-3)M) and SKF 525A (10(-3)M), which are specific inhibitors of EROD and PROD enzyme activities, significantly decreased the enzyme activities 33 and 77%, respectively. Caffeine was unable to alter hepatic microsomal NADPH-cytochrome P450 reductase enzyme activity whereas SKF 525A significantly inhibited (80%) it. In lung and kidney, the compound 6 at 10(-4)M concentration significantly increased EROD (44 and 19%) and PROD (103 and 86%) enzyme activities. However, the elevation of PROD enzyme activity in both tissues was observed to be more pronounced than that of EROD enzyme activity. This compound was ineffective on lung and kidney microsomal P450-reductase enzyme activity. These results reveal that the synthesized benzimidazoles have variable tissue dependent in vitro effects on LP due to their distinct effects on CYP activities but not on NADPH-cytochrome P450 reductase activity in rats.

Effects of 2-arylbenzimidazoles on rat hepatic microsomal monooxygenase system

1. The effects of eight newly synthesized 2-aryl substituted benzimidazole derivatives on control and phenobarbital (PB) treated rat liver microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities, and their binding to control and PB-treated rat liver microsomal oxidized cytochrome P-450 are presented. 2. All compounds inhibited ethylmorphine N-demethylase activity with I50 values ranging from 8.50 x 10(-4) M to 27.83 x 10(-4) M in control and ranging from 2.80 x 10(-4) M to 15.79 x 10(-4) M in PB-treated rats. 3. Aniline 4-hydroxylase activity was inhibited by all of the compounds tested having I50 values in the range of 7.04 x 10(-4) M-31.37 x 10(-4) M in PB-treated rats, but only five of the compounds showed inhibitory activity in control rats. 4. Only a few significant regression coefficients could be found between the parameters of the chemicals studied and their inhibitory patterns. 5. No correlation has been observed between the binding of the derivatives and their inhibitory pattern.

An artificial intelligence approach to the study of the structural moieties relevant to drug-receptor interactions in aldose reductase inhibitors

The computer-automated structure evaluation program has been used to study 482 compounds relevant to the inhibition of the aldose reductase enzyme. Major activating/inactivating fragments were generated automatically. The significance of these molecular descriptors with respect to the activity of the compounds is discussed.