E-pharmacophore filtering and molecular dynamics simulation studies in the discovery of potent drug-like molecules for chronic kidney disease.

Chronic kidney disease (CKD) is a prominent health issue reported globally. The level of the vitamin D receptor (VDR) and cytochrome P450 enzyme 24-hydroxylase (CYP24A1) are crucial in the pathogenesis of secondary hyperparathyroidism (sHPT) in CKD. An elevated expression of the CYP24A1 leads to the deficiency of vitamin D and resistance to vitamin D therapy. Hence, VDR agonists and CYP24A1 antagonists are suggested to CKD patients for the management of biochemical complications. CTA-018 is a recently reported analog and acts as a potent CYP24A1 inhibitor. It inhibits CYP24A1 with an IC50 27 ± 6 nM, about 10 times more potentially than the non-selective inhibitor ketoconazole (253 ± 20 nM), and it is also been reported to induce the VDR expression. Thus, CTA-018 is under clinical trial among CKD patients. In this study, combined molecular docking and pharmacophore filtering were employed to identify compounds better than CTA-018. A huge set of 9127 compounds from Sweet Lead database were docked into the active site of VDR using Glide XP program. E-pharmacophore was developed from both the targets along with CTA-018. The compounds retrieved from the two different pharmacophore-based screening were re-docked into the active site of CYP24A1. The hits that bind well at both the active sites and matched with the pharmacophore models were considered as possible dual functional molecules against VDR and CYP24A1. Further, molecular dynamics simulation and subsequent energy decomposition analyses were also performed to study the role of specific amino acids in the active site of both VDR and CYP24A1.

Differences in intestinal mucin dynamics between germ-free and conventionally reared chickens after mannan-oligosaccharide supplementation.

A germ-free (GF) chicken model was used to test 2 hypotheses: 1. microbial colonization of the gastrointestinal tract (GIT) influences mucin gene expression and mucin types; and 2. mannan oligosaccharide (MOS) supplementation affects GIT cells directly, without bacteria mediation, compared with bacterial-mediated effect (i.e., indirectly). Gnotobiotic isolators were used: 1) GF, 2) with a single bacteria population, and 3) conventionalized by exposure to cecal bacterial contents. Each was divided to 2 diet groups: with or without MOS (2 kg/t) for 1 wk. Results show that the absence of bacteria in the GIT caused a reduction in neutral and acidic goblet cell (GC) number and density, an increase in sulfated mucin, absence of sialylated GC, and reduced mucin 2 mRNA expression in the small intestine of GF compared with conventional birds. These results indicate a reduced development of mucin production and secretion in the absence of GIT bacteria implying a less mature small intestine mucosa, supporting our first hypothesis. Results from the single bacteria population group were not conclusive and did not support any of the hypotheses. Supplementation of MOS, regardless of microbial presence, caused a reduction in neutral GC number and density but increased neutral GC area. The MOS caused different effects on acidic mucins in conventional and GF birds, causing a reduction in sialylated GC number (conventional) and a reduction in sulfated GC density (GF), all supporting a direct effect of MOS in GF animals, in addition to an indirect effect via gut microflora.