Structure-Based Virtual Screening and Biological Evaluation of a Calpain Inhibitor for Prevention of Selenite-Induced Cataractogenesis in an in Vitro System

Abstract

Calpains belong to the family of calcium-dependent, structurally related intracellular cysteine proteases that exhibit significant functions in evolution of different types of cataracts in human as well as animal models. Application of calpain inhibitors generated through a virtual screening workflow may provide new avenues for the prevention of cataractogenesis. Hence, in the current study, compounds were first screened for potent calpain inhibitory activity by employing a structure-based approach, and the screening results were then validated through biological experiments in rat lenses. A hit compound, HTS08688, was obtained by structure-based virtual screening. A micromolar concentration of HTS08688 was found to prevent in vitro cataractogenesis in isolated Wistar rat lenses, while maintaining the antioxidant and calcium concentrations at near normal levels. Inhibition of superoxide anion generation, as observed through cytochemical localization studies, and maintenance of structural integrity, as demonstrated by histological analysis of lenticular tissue, also suggested that HTS08688 can ameliorate the cataractous condition induced by selenite in an in vitro rodent model. A cell proliferation assay was performed; the IC 50 value of the screened calpain inhibitor, HTS08688, against human lenticular epithelial cells-b3 was found to be 177 μM/mL. This combined theoretical and experimental approach has demonstrated a potent lead compound, HTS08688, that exhibits putative anticataractogenic activity by virtue of its potential to inhibit calpain.

In Vitro Evaluation of Antileishmanial Activity of Computationally Screened Compounds against Ascorbate Peroxidase To Combat Amphotericin B Drug Resistance

“…In the different earlier studies, the Glide score had been used as a reliable function for sorting of a compound data set against drug target protein. Glide scoring has been found effective for ranking inhibitors (19). Hence, we ranked the hits according to the Glide XP score toward LdAPx.…”

“…The docking and scoring were performed by using default docking parameters. The final scoring of compounds was done based on XP output (19). The interaction (Glide XP score) of known APx inhibitor 4-triazol-5-amino (12) was taken as a positive control in our docking studies.…”

“…2). Similar validation protocols have been implemented by Muralidharan et al (19) and Pavadai et al (25) in virtual screening of libraries, where they got few potential hits through in vitro validation. Furthermore, we clustered these screened compounds with the Tanimoto coefficient, which classifies compounds into groups of similar compounds depending on the calculation of intermolecular distances in chemical spaces.…”

Human Caveolin-1 a Potent Inhibitor for Prostate Cancer Therapy: A Computational Approach

“…A recent study demonstrated that virtual screening is more significant than high-throughput screening because of less time consumption and cost effectiveness 15,16 . Receptor-based virtual screening for various targets including proteases has demonstrated the success rate of in silico studies 17 .…”

“…Initially, the standard precision (SP) and extra-precision (XP) docking were performed to calculate the Glide score and Glide energy. MAP kinase (16). Hence, in the present study, we have ranked the inhibitors based on their glide score.…”