Potential Disruption of Systemic Hormone Transport by Tobacco Alkaloids Using Computational Approaches.

Tobacco/nicotine is one of the most toxic and addictive substances and continues to pose a significant threat to global public health. The harmful effects of smoking/nicotine affect every system in the human body. Nicotine has been associated with effects on endocrine homeostasis in humans such as the imbalance of gonadal steroid hormones, adrenal corticosteroid hormones, and thyroid hormones. The present study was conducted to characterize the structural binding interactions of nicotine and its three important metabolites, cotinine, trans-3'-hydroxycotinine, and 5'-hydroxycotinine, against circulatory hormone carrier proteins, i.e., sex-hormone-binding globulin (SHBG), corticosteroid-binding globulin (CBG), and thyroxine-binding globulin (TBG). Nicotine and its metabolites formed nonbonded contacts and/or hydrogen bonds with amino acid residues of the carrier proteins. For SHBG, Phe-67 and Met-139 were the most important amino acid residues for nicotine ligand binding showing the maximum number of interactions and maximum loss in ASA. For CBG, Trp-371 and Asn-264 were the most important amino acid residues, and for TBG, Ser-23, Leu-269, Lys-270, Asn-273, and Arg-381 were the most important amino acid residues. Most of the amino acid residues of carrier proteins interacting with nicotine ligands showed a commonality with the interacting residues for the native ligands of the proteins. Taken together, the results suggested that nicotine and its three metabolites competed with native ligands for binding to their carrier proteins. Thus, nicotine and its three metabolites may potentially interfere with the binding of testosterone, estradiol, cortisol, progesterone, thyroxine, and triiodothyronine to their carrier proteins and result in the disbalance of their transport and homeostasis in the blood circulation.

Organotin Antifouling Compounds and Sex-Steroid Nuclear Receptor Perturbation: Some Structural Insights.

Organotin compounds (OTCs) are a commercially important group of organometallic compounds of tin used globally as polyvinyl chloride stabilizers and marine antifouling biocides. Worldwide use of OTCs has resulted in their ubiquitous presence in ecosystems across all the continents. OTCs have metabolic and endocrine disrupting effects in marine and terrestrial organisms. Thus, harmful OTCs (tributyltin) have been banned by the International Convention on the Control of Harmful Antifouling Systems since 2008. However, continued manufacturing by non-member countries poses a substantial risk for animal and human health. In this study, structural binding of common commercial OTCs, tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPT), diphenyltin (DPT), monophenyltin (MPT), and azocyclotin (ACT) against sex-steroid nuclear receptors, androgen receptor (AR), and estrogen receptors (ERα, ERß) was performed using molecular docking and MD simulation. TBT, DBT, DPT, and MPT bound deep within the binding sites of AR, ERα, and Erß, showing good dock score, binding energy and dissociation constants that were comparable to bound native ligands, testosterone and estradiol. The stability of docking complex was shown by MD simulation of organotin/receptor complex with RMSD, RMSF, Rg, and SASA plots showing stable interaction, low deviation, and compactness of the complex. A high commonality (50-100%) of interacting residues of ERα and ERß for the docked ligands and bound native ligand (estradiol) indicated that the organotin compounds bound in the same binding site of the receptor as the native ligand. The results suggested that organotins may interfere with the natural steroid/receptor binding and perturb steroid signaling.

Endocrine disruption: Molecular interactions of environmental bisphenol contaminants with thyroid hormone receptor and thyroxine-binding globulin.

Many bisphenol A (BPA) analogs have been commercially used recently, such as 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4'-ethylidenebisphenol, 4,4'-methylenediphenol (BPF), 4,4'-(1,4-phenylenediisopropylidene)bisphenol (BPP), 4,4'-dihydroxydiphenyl sulfone (BPS), 4,4'-cyclohexylidenebisphenol (BPZ), 4,4'-(hexafluoroisopropylidene)diphenol (BPAF), 4,4'-(1-phenylethylidene)bisphenol (BPAP), and 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane (TMBPA), to circumvent adverse effects of BPA. However, their increasing use is also contaminating the environment, which is a potential cause of concern for human health. Thyroid hormone transport and signaling are potential targets for endocrine-disrupting activity of BPA analogs. Thyroxine-binding globulin (TBG) is the major carrier protein for thyroxine (T4) and triiodothyronine (T3) in blood. Thyroid hormones exert their action through thyroid hormone receptors (TRα and TRß). This report presents the thyroid-disrupting potential of indicated nine BPA analogs from structure-based studies with TBG and TRα. Each BPA analog formed important polar and hydrophobic interactions with a number of residues of TBG and TRα. Majority of TBG residues (77-100%) and TRα residues (70-91%) interacting with BPA analogs were common with those of native ligands T4 and T3, respectively. Majority of BPA analogs interacted with TBG forming a salt bridge interaction at Lys-270. The hydrogen-bonding interaction of T3 with TRα at His-381 was also shared by majority of analogs. The binding energy for BPP, BPB, BPZ, BPAP, and TMBPA with both proteins was closer to binding energy of respective native ligands. The similarity in structural binding characteristics suggested potential disrupting activity of thyroid hormone signaling and transport.

Molecular interactions of thyroxine binding globulin and thyroid hormone receptor with estrogenic compounds 4-nonylphenol, 4-tert-octylphenol and bisphenol A metabolite (MBP).

AIM: Endocrine disruption due to environmental chemical contaminants is a global human health issue. The aim of present study was to investigate the structural binding aspects of possible interference of commonly detected environmental contaminants on thyroid function. MATERIAL AND METHODS: Three compounds, 4-tert-octylphenol (4-tert-OP), 4-nonylphenol (4-NP), and 4-methyl-2,4-bis(4-hydroxypentyl)pent-1-ene (MBP) were subjected to induced fit docking (IFD) against thyroxine binding globulin (TBG) and thyroid hormone receptor (THR). Structural analysis included molecular interactions of the amino acid residues and binding energy estimation between the ligands and the target proteins. KEY RESULTS: All the ligands were successfully placed in the ligand binding pocket of TBG and THR using induced fit docking (IFD). The IFD results revealed high percentage of commonality in interacting amino acid residues between the aforementioned compounds and the native ligand for both TBG and THR. The results of our study further revealed that all the compounds have the potential to interfere with thyroid transport and signaling. However, MBP showed higher binding affinity for both TBG and THR, suggesting higher thyroid disruptive potential as compared to 4-t-OP and 4-NP. Furthermore, our results also suggest that the reported disruptive effects of BPA could actually be exerted through its metabolite; MBP. SIGNIFICANCE: This work implies that all the three compounds 4-NP, 4-t-OP and especially MBP have the potential to interfere with thyroid hormone transport and signaling. This potentially leads to disruption of thyroid hormone function.

A novel terpenoid class for prevention and treatment of KRAS-driven cancers: Comprehensive analysis using in situ, in vitro, and in vivo model systems.

Inhibiting the disease progression in KRAS-driven cancers after diagnosis has been a difficult task for clinicians to manage due to the lack of effective intervention/preventive therapies. KRAS-driven cancers depend on sustained KRAS signaling. Although developing inhibitors of KRAS signaling has proven difficult in the past, the quest for identifying newer agents has not stopped. Based on studies showing terpenoids as modulators of KRAS-regulated downstream molecular pathways, we asked if this chemical family has an affinity of inhibiting KRAS protein activity. Using crystal structure as a bait in silico, we identified 20 terpenoids for their KRAS protein-binding affinity. We next carried out biological validation of in silico data by employing in situ, in vitro, patient-derived explant ex vivo, and KPC transgenic mouse models. In this report, we provide a comprehensive analysis of a lup-20(29)-en-3b-ol (lupeol) as a KRAS inhibitor. Using nucleotide exchange, isothermal titration calorimetry, differential scanning fluorimetry, and immunoprecipitation assays, we show that lupeol has the potential to reduce the guanosine diphosphate/guanosine triphosphate exchange of KRAS protein including mutant KRASG12V . Lupeol treatment inhibited the KRAS activation in KRAS-activated cell models (NIH-panel, colorectal, lung, and pancreatic intraepithelial neoplasia) and patient tumor explants ex vivo. Lupeol reduced the three-dimensional growth of KRAS-activated cells. The pharmacokinetic analysis showed the bioavailability of lupeol after consumption via oral and intraperitoneal routes in animals. Tested under prevention settings, the lupeol consumption inhibited the development of pancreatic intraepithelial neoplasia in LSL-KRASG12D/Pdx-cre mice (pancreatic ductal adenocarcinoma progression model). These data suggest that the selected members of the triterpene family (such as lupeol) could be exploited as clinical agents for preventing the disease progression in KRAS-driven cancers which however warrants further investigation.

Structural binding interactions of tetrabromobisphenol A with sex steroid nuclear receptors and sex hormone-binding globulin.

Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant owing to its efficient fire-breaking property. However, leaching of TBBPA into the environment has been a global health concern due to the endocrine-disrupting activity (EDA) associated with TBBPA exposure. Limited studies are available on the hazardous effects of TBBPA on reproductive function. The aim of the present study was the structural characterization of potential EDA of TBBPA in reproductive hormone signaling and transport including steroid nuclear receptors, such as estrogen receptor alpha (ERα), estrogen receptor beta (ERß), androgen receptor (AR), progesterone receptor (PR), and the steroid transport protein, sex hormone-binding globulin (SHBG). The structural binding characterization of TBBPA with the sex steroid nuclear receptors and transport protein was performed by induced-fit docking using the Schrödinger 2017 suite. The results revealed that the TBBPA binding pattern and molecular interactions with the indicated receptors and transport protein displayed overall similarity with their respective native ligands. The estimated binding energy value of TBBPA for ERα was similar to the native ligand, estradiol, indicating tight binding and greater potential for TBBPA to disrupt ERα signaling. For ERß, AR, PR and SHBG, the estimated binding energy values were also close to their respective native ligands, indicating potential for interference in native hormone signaling and transport. In conclusion, TBBPA exposure in humans may potentially cause disruption of sex steroid signaling and transport, and thus lead to reproductive dysfunction.

Protective role of Roflumilast against cadmium-induced cardiotoxicity through inhibition of oxidative stress and NF-κB signaling in rats.

Cadmium (Cd), a potent cardiotoxic environmental heavy metal, induces oxidative stress and membrane disturbances in cardiac myocytes. Phosphodiesterase (PDEs) retards the positive inotropic effects of ß-adrenoceptor activation by decreasing levels of cAMP via degradation. Hence, PDE inhibitors sensitize the heart to catecholamine and are therefore, used as positive inotropic agents. The present study was designed to probe the potential attenuating effects of the selective PDE4 inhibitor (Roflumilast, ROF), on cardiac biomarkers, lipid profile, lipid peroxidation products, antioxidant status and histology of cardiac tissues against Cd-induced cardiotoxicity in rats. Rats were randomly distributed into four different groups: group 1, served as the normal control group. Group 2, served as the toxic control group and were administered Cd (3 mg/kg, i.p.) for next 7 days. Groups 3 and 4, served as treatment groups that received Cd with concomitant oral administration of ROF doses (0.5 and 1.5 mg/kg), respectively for 7 days. Serum samples of toxic control group rats resulted in significant (P < 0.001) increase in lactate dehydrogenase (LDH), creatine phosphokinase (CPK), total cholesterol (TC), triglycerides (TG) and low density lipoproteins (LDL) levels with concomitant decrease in high density lipoproteins (HDL) levels in serum which were found reversed with both of ROF treatment groups. Cd also causes significant increased (P < 0.001) in myocardial malondialdehyde (MDA) contents while cardiac glutathione (GSH) level, superoxide dismutase (SOD) and catalase (CAT) enzyme activities were found decreased whereas both doses of ROF, significantly reversed these oxidative stress markers and antioxidant enzymes. Cardiotoxicity induced by Cd also resulted in enhanced expression of non-phosphorylated and phosphorylated form of NF-κB p65 and decreased expression of glutathione-S-transferase (GST) and NQO1 which were found reversed with ROF treatments, comparable to normal control group. Histopathological changes were also improved by ROF administration as compared to Cd treated rats alone. In conclusion, Roflumilast exhibited attenuating effect against Cd-induced cardiac toxicity.

The Protective Effect of Naringenin on Oxaliplatin-Induced Genotoxicity in Mice.

Oxaliplatin is a third generation platinum based anti-cancer drug used against various human malignancies but displays genotoxic properties against normal cells. Naringenin is a naturally occurring bioflavonoid that possesses anti-oxidant properties and has protective effects against DNA damage. The aim of this study is to examine the protective effects of naringenin on oxaliplatin-induced DNA damage in mice. A total of 50, male BALB/c mice were randomly divided equally into five groups. Oxaliplatin toxicity was induced by a single dose (7 mg/kg body weight (b.w.)) injection (intraperitoneally (i.p.)) of oxaliplatin. Naringenin was given orally for ten consecutive days at two doses, 20 mg/kg b.w. (dose I) and 40 mg/kg b.w. (dose II), to group I and group II, respectively. On the tenth day of the experiment, animals in groups III, IV, and V were given a single i.p. injection of oxaliplatin (7 mg/kg b.w.). All the animals were sacrificed 24 h after oxaliplatin treatment. The extent of genotoxicity was assessed by multiple genotoxicity assays (8-hydroxydeoxy-guanosine marker, comet, micronucleus and chromosomal aberration assays, oxidative stress-marker Glutathione evaluation) in order to determine diverse kinds of DNA damage. The results indicated that naringenin administration significantly reduced the DNA damage induced by oxaliplatin possibly due to its strong anti-oxidant properties. The results suggest that naringenin is a potential candidate for future development as a chemoprotective agent against chemotherapy associated complications.

Structural characterization of potential endocrine disrupting activity of alternate plasticizers di-(2-ethylhexyl) adipate (DEHA), acetyl tributyl citrate (ATBC) and 2,2,4-trimethyl 1,3-pentanediol diisobutyrate (TPIB) with human sex hormone-binding globulin.

Plasticizers are chemical compounds used to increase the softness and fluidity of polymer materials. Phthalate compounds constitute the most common class of compounds used as plasticizers. However, phthalate plasticizers, especially the predominant di(2-ethylhexyl)phthalate, have been shown to have adverse effects on environment and human health. Hence, efforts have been made to use safer and environmentally friendly alternate non-phthalate plasticizers in industrial applications. The present study involves structural binding studies on endocrine disrupting potential of three high volume alternate plasticizer compounds, i.e., di-(2-ethylhexyl) adipate (DEHA), acetyl tributyl citrate (ATBC) and 2,2,4-trimethyl 1,3-pentanediol diisobutyrate (TPIB) with sex hormone binding globulin (SHBG). This study showed that DEHA, ATBC and TPIB bind in the ligand binding pocket of SHBG and the structural binding results suggested that the three alternate plasticizers may interfere in the steroid binding of SHBG and thus may cause dysfunction in sex steroid homeostasis.

Structural insights into the camel milk lactoperoxidase: Homology modeling and molecular dynamics simulation studies.

Lactoperoxodase (LPO) is a heme peroxidase enzyme present in mammalian milk. It is an antimicrobial protein with wide range of industrial applications. Although the three dimensional structure of LPO from various mammalian species has been reported, but its structure from camel source is still unknown. So far, the crystallization attempts have not been successful in determining camel LPO (cLPO) structure. Herein, we developed the three dimensional structure of cLPO by homology modeling approach using prime module available in Schrodinger suite. The developed model in complex with ligand hypothiocyanate (OSCN-) was further validated by Ramachandran plot followed by molecular dynamics (MD) simulation studies using Desmond module of Schrodinger. cLPO model exhibited overall structural similarity with template crystal structure, however, it displayed different interaction pattern of amino acid residues with ligand OSCN- in comparison to template crystal structure. Moreover, the ligand binding site environment in cLPO is more polar, less hydrophobic, and harbours more number of charged residues than template crystal structure. The substrate binding pocket environment of cLPO shows a considerable difference from template crystal structure. This subsequently resulted in dissimilar behaviour of ligand during the course of MD simulation studies.

Structural studies on inhibitory mechanisms of antibiotic, corticosteroid and catecholamine molecules on lactoperoxidase.

AIM: Lactoperoxidase (LPO) is an essential protein with broad spectrum antimicrobial activity present in mammalian milk. It imparts immunity to infants against wide range of pathogenic infections. Several in vitro studies have shown inhibition of LPO activity by pharmaceutical compounds including commonly used antibiotics such as ampicillin and gentamicin, and molecules like prednisolone, norepinephrine, etc. Prescription of such drugs to lactating mothers might have adverse health effects on infants. The aim of our study was the elucidation of the structural aspects of the inhibitory mechanism of ampicillin, gentamicin, amoxicillin, prednisolone and norepinephrine on LPO. MATERIAL AND METHODS: Three dimensional structure of camel LPO (cLPO) was developed using homology modeling and used for in silico experimental studies. The Schrödinger induced fit docking along with binding affinity estimation experiments were performed. The cLPO and Ligands were prepared using Protein Preparation Wizard and Ligprep modules available in Schrodinger suite. For estimating Binding affinity Prime Molecular Mechanics with Generalized Born and Surface Area (MMGB-SA) module was used. KEY RESULTS: The five drug ligands formed three to five hydrogen bonding interactions with cLPO. Amino acids Arg-231, Asp-232, Ser-370, Arg-371 and Glu-374 of cLPO were crucial for these interactions. The binding affinity values for gentamicin were highest and for norepinephrine were the lowest. SIGNIFICANCE: This study concludes that the five drug molecules show potential ability to inhibit the LPO activity. Further, a very high sequence similarity of cLPO with human LPO imparts high significance to these conclusions in relation to human health especially in new born infants.

In silico identification of genes involved in chronic metabolic acidosis.

AIMS: Chronic metabolic acidosis (CMA) refers to increased plasma acidity due to disturbed acid-base equilibrium in human body. CMA leads to many dysfunctions including disorders of intestinal metabolism and barrier functions. The human body responds to these intestinal dysfunctions by creating a compensatory mechanism at genomic level in intestinal epithelial cells. This study was to identify the molecular pathways involved in metabolic dysfunction and compensatory adaptations in intestinal epithelium during CMA. MAIN METHODS: In silico approaches were utilized to characterize a set of 88 differentially expressed genes (DEGs) from intestinal cells of rat CMA model. Interaction networks were constructed for DEGs by GeneMANIA and hub genes as well as enriched clusters in the network were screened using GLay. Gene Ontology (GO) was used for enriching functions in each cluster. KEY FINDINGS: Four gene hubs, i.e., trefoil factor 1, 5-hydroxytryptamine (serotonin) receptor 5a, solute carrier family 6 (neurotransmitter transporter), member 11, and glutamate receptor, ionotropic, n-methyl d-aspartate 2b, exhibiting the highest node degree were predicted. Six biologically related gene clusters were also predicted. Functional enrichment of GO terms predicted neurological processes such as neurological system process regulation and nerve impulse transmission which are related to negative and positive regulation of digestive system processes., intestinal motility and absorption and maintenance of gastrointestinal epithelium. SIGNIFICANCE: The study predicted several important genomic pathways that potentially play significant roles in metabolic disruptions or compensatory adaptations of intestinal epithelium induced by CMA. The results provide a further insight into underlying molecular mechanisms associated with CMA.

Endocrine disruption: In silico interactions between phthalate plasticizers and corticosteroid binding globulin.

Endocrine disruption is a phenomenon when a man-made or natural compound interferes with normal hormone function in human or animal body systems. Endocrine-disrupting compounds (EDCs) have assumed considerable importance as a result of industrial activity, mass production of synthetic chemicals and environmental pollution. Phthalate plasticizers are a group of chemicals used widely and diversely in industry especially in the plastic industry, and many of the phthalate compounds have endocrine-disrupting properties. Increasing evidence indicates that steroid nuclear receptors and steroid binding proteins are the main targets of endocrine disruption. Corticosteroid-binding globulin (CBG) is a steroid binding protein that binds and transports cortisol in the blood circulation and is a potential target for endocrine disruption. An imbalance of cortisol in the body leads to many health problems. Induced fit docking of nine important and environmentally relevant phthalate plasticizers (DMP, BBP, DBP, DIBP, DnHP, DEHP, DINP, DnOP, DIDP) showed interactions with 10-19 amino acid residues of CBG. Comparison of the interacting residues of CBG with phthalate ligands and cortisol showed an overlapping of the majority (53-82%) of residues for each phthalate. Five of nine phthalate compounds and cortisol shared a hydrogen bonding interaction with the Arg-252 residue of CBG. Long-chain phthalates, such as DEHP, DINP, DnOP and DIDP displayed a higher binding affinity and formed a number of interactions with CBG in comparison to short-chain phthalates. The similarity in structural binding characteristics of phthalate compounds and native ligand cortisol suggested potential competitive conflicts in CBG-cortisol binding function and possible disruption of cortisol and progesterone homeostasis.

Amelioration of hyperglycaemia and modulation of antioxidant status by Alcea rosea seeds in alloxan-induced diabetic rats.

CONTEXT: Alcea rosea L. (Malvaceae) has various medicinal uses including anticancer, anti-inflammatory and analgesic properties. However, there is no report on its antidiabetic activity. OBJECTIVE: Alcea rosea seed extracts were evaluated for antihyperglycaemic and antioxidative potential in diabetic rats. MATERIALS AND METHODS: Single intra-peritoneal injection of alloxan (130 mg/kg b.w.) was used for induction of diabetes in Albino Wistar rats. Antihyperglycaemic and antioxidant activities of methanol and aqueous extracts of Alcea rosea seed (100 and 300 mg/kg b.w.), administered orally on daily basis for 15 days, were assessed in vivo for fasting blood glucose level and antioxidant status of liver and pancreas. Metformin was used as a positive control. RESULTS: Aqueous and methanol extracts (300 mg/kg b.w.) decreased blood glucose level in diabetic rats by 24% and 46%, respectively. Administration of aqueous and methanol extracts at 300 mg/kg b.w. significantly (p < 0.01) modulated the antioxidant status of liver in diabetic rats by increasing levels of GR (22.5 ± 1.0, 24.4 ± 1.02 µg GSSG utilized/min/mg of protein), GPx (20.7 ± 1.2, 23.6 ± 2.04 µg GSH utilized/min/mg of protein), SOD (36.1 ± 1.7, 39.05 ± 1.5 units/mg of protein) and CAT (1744.5 ± 132.5, 1956.6 ± 125.2 nmol H2O2 decomposed/min/mg of protein), respectively. Similar results were observed for pancreas. DISCUSSION AND CONCLUSIONS: Antihyperglycaemic and antioxidative potentials of Alcea rosea seeds suggest its usefulness in management of diabetes and its complications. This is the first report on antidiabetic activity of this plant.

Computational insights into the molecular interactions of environmental xenoestrogens 4-tert-octylphenol, 4-nonylphenol, bisphenol A (BPA), and BPA metabolite, 4-methyl-2, 4-bis (4-hydroxyphenyl) pent-1-ene (MBP) with human sex hormone-binding globulin.

Environmental contamination has been one of the major drawbacks of the industrial revolution. Several man-made chemicals are constantly released into the environment during the manufacturing process and by leaching from the industrial products. As a result, human and animal populations are exposed to these synthetic chemicals on a regular basis. Many of these chemicals have adverse effects on the physiological functions, particularly on the hormone systems in human and animals and are called endocrine disrupting chemicals (EDCs). Bisphenol A (BPA), 4-tert-octylphenol (OP), and 4-nonylphenol (NP) are three high volume production EDCs that are widely used for industrial purposes and are present ubiquitously in the environment. Bisphenol A is metabolized in the human body to a more potent compound (MBP: 4-Methyl-2, 4-bis (4-hydroxyphenyl) pent-1-ene). Epidemiological and experimental studies have shown the three EDCs to be associated with adverse effects on reproductive system in human and animals. Sex hormone-binding globulin (SHBG) is a circulatory protein that binds sex steroids and is a potential target for endocrine disruptors in the human body. The current study was done in order to understand the binding mechanism of OP, BPA, NP, and MBP with human SHBG using in silico approaches. All four compounds showed high binding affinity with SHBG, however, the binding affinity values were higher (more negative) for MBP and NP than for OP and BPA. The four ligands interacted with 19-23 residues of SHBG and a consistent overlapping of the interacting residues for the four ligands with the residues for the natural ligand, dihydrotestosterone (DHT; 82-91% commonality) was shown. The overlapping SHBG interacting residues among DHT and the four endocrine disruptors suggested that these compounds have potential for interference and disruption in the steroid binding function.

Spontaneous preterm birth and single nucleotide gene polymorphisms: a recent update.

BACKGROUND: Preterm birth (PTB), birth at <37 weeks of gestation, is a significant global public health problem. World-wide, about 15 million babies are born preterm each year resulting in more than a million deaths of children. Preterm neonates are more prone to problems and need intensive care hospitalization. Health issues may persist through early adulthood and even be carried on to the next generation. Majority (70 %) of PTBs are spontaneous with about a half without any apparent cause and the other half associated with a number of risk factors. Genetic factors are one of the significant risks for PTB. The focus of this review is on single nucleotide gene polymorphisms (SNPs) that are reported to be associated with PTB. RESULTS: A comprehensive evaluation of studies on SNPs known to confer potential risk of PTB was done by performing a targeted PubMed search for the years 2007-2015 and systematically reviewing all relevant studies. Evaluation of 92 studies identified 119 candidate genes with SNPs that had potential association with PTB. The genes were associated with functions of a wide spectrum of tissue and cell types such as endocrine, tissue remodeling, vascular, metabolic, and immune and inflammatory systems. CONCLUSIONS: A number of potential functional candidate gene variants have been reported that predispose women for PTB. Understanding the complex genomic landscape of PTB needs high-throughput genome sequencing methods such as whole-exome sequencing and whole-genome sequencing approaches that will significantly enhance the understanding of PTB. Identification of high risk women, avoidance of possible risk factors, and provision of personalized health care are important to manage PTB.

Endocrine disruption: In silico perspectives of interactions of di-(2-ethylhexyl)phthalate and its five major metabolites with progesterone receptor.

BACKGROUND: Di-(2-ethylhexyl)phthalate (DEHP) is a common endocrine disrupting compound (EDC) present in the environment as a result of industrial activity and leaching from polyvinyl products. DEHP is used as a plasticizer in medical devices and many commercial and household items. Exposure occurs through inhalation, ingestion, and skin contact. DEHP is metabolized to a primary metabolite mono-(2-ethylhexyl)phthalate (MEHP) in the body, which is further metabolized to four major secondary metabolites, mono(2-ethyl-5-hydroxyhexyl)phthalate (5-OH-MEHP), mono(2-ethyl-5-oxyhexyl)phthalate (5-oxo-MEHP), mono(2-ethyl-5-carboxypentyl)phthalate (5-cx-MEPP) and mono[2-(carboxymethyl)hexyl]phthalate (2-cx-MMHP). DEHP and its metabolites are associated with developmental abnormalities and reproductive dysfunction within the human population. Progesterone receptor (PR) signaling is involved in important reproductive functions and is a potential target for endocrine disrupting activities of DEHP and its metabolites. This study used in silico approaches for structural binding analyses of DEHP and its five indicated major metabolites with PR. METHODS: Protein Data bank was searched to retrieve the crystal structure of human PR (Id: 1SQN). PubChem database was used to obtain the structures of DEHP and its five metabolites. Docking was performed using Glide (Schrodinger) Induced Fit Docking module. RESULTS: DEHP and its metabolites interacted with 19-25 residues of PR with the majority of the interacting residues overlapping (82-95 % commonality) with the native bound ligand norethindrone (NET). DEHP and each of its five metabolites formed a hydrogen bonding interaction with residue Gln-725 of PR. The binding affinity was highest for NET followed by DEHP, 5-OH-MEHP, 5-oxo-MEHP, MEHP, 5-cx-MEPP, and 2-cx-MMHP. CONCLUSION: The high binding affinity of DEHP and its five major metabolites with PR as well as a high rate of overlap between PR interacting residues among DEHP and its metabolites and the native ligand, NET, suggested their disrupting potential in normal PR signaling, resulting in adverse reproductive effects.

Human sex hormone-binding globulin as a potential target of alternate plasticizers: an in silico study.

BACKGROUND: Currently, alternate plasticizers are used to replace phthalate plasticizers in children's toys, medical equipments and food packaging, due to the adverse effects of phthalate compounds on human health and laws prohibiting their use. Current information regarding the safety and potential adverse effects of alternate plasticizers is limited and recent studies have found alternate plasticizers to display similar characteristics to those observed in phthalate plasticizers. This study was undertaken to evaluate and predict the potential endocrine disrupting activity of the three most commonly used alternate plasticizers: di(2-ethylhexyl)terephthalate (DEHT), tris(2-ethylhexyl)trimellitate (TOTM), and diisononyl hexahydrophthalate (DINCH) against human sex hormone-binding globulin (SHBG) using in silico approaches. MATERIALS AND METHODS: The crystal structure of human SHBG (Id: 1D2S) was retrieved from Protein Data Bank. PubChem database was searched for the structures of alternate plasticizers, DEHT, TOTM, and DINCH. Docking was performed using Glide (Schrodinger) Induced Fit Docking module. RESULTS: Induced Fit Docking of three alternate plasticizer compounds indicated that each of the three compounds fitted well into the steroid binding pocket of SHBG. Docking displays showed interactions of alternate plasticizers with 25-30 amino-acid residues of SHBG; 18-20 amino residues overlapped between the natural ligand, DHT, and the three compounds (commonality of 82-91 %). The hydrogen-bonding interaction of the amino-acid residue, Asn-82, of SHBG was also present in displays of DHT and all the three alternate phthalates. The binding affinity of all the three alternate phthalates was higher than DHT; maximum in DINCH followed by TOTM and DEHT. CONCLUSION: Our results suggested that the three alternate plasticizers have potential to engage the important interacting residues of SHBG and thus interfere in its steroid homeostatic function.

In Silico Identification of Novel Erlotinib Analogues Against Epidermal Growth Factor Receptor.

Cancer is one of the major health challenges in modern times. Considering its high mortality rate, many proteins that are linked to cancer have been targeted for therapy, with one of them being the epidermal growth factor receptor (EGFR). A drug that is currently in the market for the treatment of non-small cell lung cancer and targets EGFR is erlotinib. In a quest for improved efficacy of erlotinib, herein we report molecular docking studies of thirteen erlotinib analogues by modification of the alkyne and anilino groups, all of which displayed better binding affinity than erlotinib. We identified aziridinyl analogue (S)- 13B: with the best binding energy of all the analogues studied.

Endocrine Disruption: Computational Perspectives on Human Sex Hormone-Binding Globulin and Phthalate Plasticizers.

Phthalates are a class of high volume production chemicals used as plasticizers for household and industrial use. Several members of this chemical family have endocrine disrupting activity. Owing to ubiquitous environmental distribution and exposure of human population at all stages of life, phthalate contamination is a continuous global public health problem. Clinical and experimental studies have indicated that several phthalates are associated with adverse effects on development and function of human and animal systems especially the reproductive system and exposures during pregnancy and early childhood are by far of utmost concern. Sex hormone-binding globulin (SHBG) is a plasma carrier protein that binds androgens and estrogens and represents a potential target for phthalate endocrine disruptor function in the body. In the present study, the binding mechanism of the nine phthalates i.e. DMP, DBP, DIBP, BBP, DNHP, DEHP, DNOP, DINP, DIDP with human SHBG was delineated by molecular docking simulation. Docking complexes of the nine phthalates displayed interactions with 15-31 amino acid residues of SHBG and a commonality of 55-95% interacting residues between natural ligand of SHBG, dihydrotestosterone, and the nine phthalate compounds was observed. The binding affinity values were more negative for long chain phthalates DEHP, DNOP, DINP, and DIDP compared to short chain phthalates such as DMP and DBP. The Dock score and Glide score values were also higher for long chain phthalates compared to short chain phthalates. Hence, overlapping of interacting amino acid residues between phthalate compounds and natural ligand, dihydrotestosterone, suggested potential disrupting activity of phthalates in the endocrine homeostasis function of SHBG, with long chain phthalates expected to be more potent than the short chain phthalates.