Gene set enrichment analysis of α-amylase and α-glucosidase inhibitors of Cassia glauca

Enhancement of Inhibitory Activity by Combining Allosteric Inhibitors Putatively Binding to Different Allosteric Sites on Cathepsin K

BACKGROUND

Cathepsin K, which is involved in bone resorption, is a good target for treating osteoporosis, but no clinically approved medicine has been developed. Recently, allosteric inhibitors with high specificity and few side effects have been attracting attention for use in new medicines.

METHODS

Cathepsin K inhibitors were isolated from the methanol extract of Chamaecrista nomame (Leguminosae) using cathepsin K inhibition activity-assisted multi-step chromatography. Standard kinetic analysis was employed to examine the mechanism of cathepsin K inhibition when an isolated inhibitor and its derivative were used. The allosteric binding of these cathepsin K inhibitors was supported by a docking study using AutoDock vina. Combinations of allosteric cathepsin K inhibitors expected to bind to different allosteric sites were examined by means of cathepsin K inhibition assay.

RESULTS

Two types of cathepsin K inhibitors were identified in the methanol extract of Chamaecrista nomame. One type consisted of cassiaoccidentalin B and torachrysone 8-β-gentiobioside, and inhibited both cathepsin K and B with similar inhibitory potential, while the other type of inhibitor consisted of pheophytin a, and inhibited cathepsin K but not cathepsin B, suggesting that pheophytin a binds to an allosteric site of cathepsin K. Kinetic analysis of inhibitory activity suggested that pheophytin a and its derivative, pheophorbide b, bind allosterically to cathepsin K. This possibility was supported by a docking study on cathepsin K. The cathepsin K inhibitory activity of pheophytin a and pheophorbide b was enhanced by combining them with the allosteric inhibitors NSC 13345 and NSC94914, which bind to other allosteric sites on cathepsin K.

CONCLUSIONS

Different allosteric inhibitors that bind to different sites in combination, as shown in this study, may be useful for designing new allosteric inhibitory drugs with high specificity and few side effects.

Exploring the therapeutic mechanisms of Cassia glauca in diabetes mellitus through network pharmacology, molecular docking and molecular dynamics

Cassia glauca is reported as anti-diabetic medicinal plant and is also used as an ethnomedicine. However, its mode of action as an anti-diabetic agent has not been clearly elucidated. Hence, the present study investigated the probable mechanism of action of C. glauca to manage diabetes mellitus via network pharmacology and molecular docking and simulations studies. The reported bioactives from C. glauca were retrieved from an open-source database, i.e. ChEBI, and their targets were predicted using SwissTargetPrediction. The proteins involved in the pathogenesis of diabetes were identified from the therapeutic target database. The targets involved in diabetes were enriched in STRING, and the pathways involved in diabetes were identified concerning the KEGG. Cytoscape was used to construct the network among bioactives, proteins, and probably regulated pathways, which were analyzed based on edge count. Similarly, molecular docking was performed using the Glide module of the Schrodinger suite against majorly targeted proteins with their respective ligands. Additionally, the drug-likeness score and ADMET profile of the individual bioactives were predicted using MolSoft and admetSAR2.0 respectively. The stability of these complexes were further studied via molecular dynamics simulations and binding energy calculations. Twenty-three bio-actives were retrieved from the ChEBI database in which cassiarin B was predicted to modulate the highest number of proteins involved in diabetes mellitus. Similarly, GO analysis identified the PI3K-Akt signaling pathway to be primarily regulated by modulating the highest number of gene. Likewise, aldose reductase (AKR1B1) was majorly targeted via the bioactives of C. glauca. Similarly, docking study revealed methyl-3,5-di-O-caffeoylquinate (docking score −9.209) to possess the highest binding affinity with AKR1B1. Additionally, drug-likeness prediction identified cassiaoccidentalin B to possess the highest drug-likeness score, i.e. 0.84. The molecular dynamics simulations and the MMGBSA indicate high stability and greater binding energy for the methyl-3,5-di-O-caffeoylquinate (ΔG_bind = −40.33 ± 6.69 kcal mol⁻¹) with AKR1B1, thus complementing results from other experiments. The study identified cassiarin B, cassiaoccidentalin B, and cinnamtannin A2 as lead hits for the anti-diabetic activity of C. glauca. Further, the PI3K-Akt and AKR1B1 were traced as majorly modulated pathway and target, respectively.

Cassia glauca is reported for anti-diabetic action and is also used as an ethnomedicine.

Gene ontology enrichment analysis of PPAR-γ modulators from Cassia glauca in diabetes mellitus

BACKGROUND

PPAR-γ has an integrative role in the management of insulin resistance; ligands of this receptor have emerged as potent insulin sensitizers and may modulate proteins involved in the pathogenesis of diabetes mellitus. Hence the present study is aimed to identify PPAR-γ modulators from the plant Cassia glauca and predict the ontology enrichment analysis utilizing various in-silico tools.

METHODS

ChEBI database was used to mine the phytoconstituents present in the plant C. glauca, SwissTargetPrediction database was used to identify the targets, and scrutinizing of phytoconstituents modulating PPAR-γ was performed. Autodock4.0 was used to dock phytoconstituent ligands with the target PPAR-γ. Multiple open-source databases and in-silico tools were utilized to predict the drug-likeness characters and predict side effects of the phytoconstituents modulating PPAR-γ and STRING database was used to construct a network between the modulated genes.

RESULTS

Twenty-four phytoconstituents were identified from the plant Cassia glauca from which four were found to modulate PPAR-γ, sennoside was predicted to have the greatest drug-likeness score and a significantly less side effect whereas diphenyl sulfone was predicted to show hepatotoxicity with the greatest pharmacological activity of 0.815. [epicatechin-(4beta- > 8)]5-epicatechin showed the lowest binding affinity with target PPAR-γ i.e. -8.6 kcal/mol and possessing a positive drug-likeness score with no side effect data.

CONCLUSION

Bioctives were found free from probable side effects leaving out diphenyl sulfone having a prediction of hepatotoxicity, the anti-diabetic property of the plant may be due to the presence of [epicatechin-(4beta- > 8)]5-epicatechin which needs further validation by in-vitro and in-vivo protocols.

Identification of α-amylase inhibitors from flavonoid fraction of Feronia elephantum and its integration with in-silico studies

Postprandial hyperglycemia is associated with an increase in blood glucose levels after a meal, which is further associated with various risk factors like cardiovascular diseases. α-amylase is a digestive enzyme and secreted by the salivary glands and pancreas, which helps to catalyze the hydrolysis of the internal α-1,4-glycosidic linkages in starch breaking them into smaller units. Hence, the present study is aimed to identify flavonoids from the fruit pulp of Feronia elephantum as α-amylase inhibitors via in-silico and in-vitro protocols. In-silico tools like ADVERPred, PubChem, MolSoft, Discovery studio 2019, and Autodock 4.0 were used to predict the information related to phytoconstituents, drug-likeness character, and probable side effects. In-vitro α-amylase inhibitory activity was performed with five different concentrations of flavonoid fraction of hydroalcoholic extract of the fruit pulp of Feronia elephantum using 1% starch solution and DNS reagent. Four flavonoids were identified from 25 bio-actives present in the fruit pulp of Feronia elephantum. Three bio-actives were predicted to possess a positive drug-likeness score, from which 5,4-dihydroxy3-3(3-methyl-but2-enyl)3,5,6-trimethoxy-flavone-7-O-β-d-Glucopyranoside was predicted to possess the highest drug-likeness score of 0.70. Vitexin and 5,4-dihydroxy3-3(3-methyl-but2-enyl)3,5,6-trimethoxy-flavone-7-O-β-d-Glucopyranoside were predicted to possess nephrotoxicity as an adverse effect. The percent inhibition of α-amylase by a flavonoid-rich fraction at 100 μg/ml was found to be 45.95% as compared to standard acarbose with 74.79% inhibition at 100 μg/ml. Further, docking studies predicted that vitexin possessed the highest binding affinity (binding energy - 7.98 kcal/mol) as compared to standard acarbose with binding energy - 5.24 kcal/mol. There were no significant side effects predicted, in-vitro α-amylase inhibitory activity of the flavonoid-rich fraction may be due to the presence of vitexin, predicted via in-silico molecular docking; further, which needs to be further validated via in-vivo protocols.