Mamata Joshi

1H NMR Based Targeted Metabolite Profiling for Understanding the Complex Relationship Connecting Oxidative Stress with Endometriosis

Accumulating evidence indicates the active role of oxidative stress in the development of endometriosis; however, the mechanism of reactive oxygen species generation is poorly understood. Metabonomics/metabolomics is a scientific discipline that can be used to study changes in metabolite ensembles associated with disease pathophysiology. The present study focuses on the use of proton nuclear magnetic resonance spectroscopy based targeted metabolite profiling approach to explore dysregulation in metabolites expression in women with endometriosis. Further, association of oxidative stress with the metabolite ensembles, if any, is investigated. Using multivariate statistics, partial least square discriminant analysis model was generated which could classify endometriosis patients with sensitivity and specificity of 92.83% and 100%, respectively, and with a classification rate of 96.4%. In conjunction with increased glucose metabolism, citrate and succinate were found to be elevated in endometriosis patients. Higher levels of reactive oxygen species, lipid peroxidation, and advanced oxidation protein products and lower levels of total antioxidant capacity, superoxide dismutase, catalase, and glutathione were also observed. Increased glucose metabolism and defects in the mitochondrial respiratory system are suggested to be the possible sources of excessive reactive oxygen species generation in endometriosis.

Probing molecular level interaction of oseltamivir with H5N1-NA and model membranes by molecular docking, multinuclear NMR and DSC methods.

Structure-based drug design has led to the introduction of three drugs--oseltamivir (GS-4104), zanamivir (GG-167) and peramivir (RWJ-270201) which target the enzyme neuraminidase, for treatment of influenza infections. Using comparative docking studies we propose that more potent molecules against neuraminidase can be obtained by appending extra positively charged substituents at the C5 position of the oseltamivir skeleton. This provides an additional interaction with the enzyme and may overcome the problem of resistance encountered with these drugs. To get an insight into the transport and absorption of oseltamivir--the ethyl ester prodrug (GS-4104) as well as its mechanism of action, we have carried out 1H, 13C, 31P NMR, DSC and TEM studies on GS-4104 with model membranes prepared from DMPC/DPPC/POPC. These studies reveal that interactions between GS-4104 and the membrane are both electrostatic (involving H-bonding) and hydrophobic (involving the hydrophobic chain and cyclohexene ring of GS-4104) in nature. The prodrug is seen to increase the fluidity as well as stabilize the bilayer phase of the membrane. This property may be responsible for preventing viral entry into the cells by preventing fusion of the virus outer coat with the cell membrane.

Search for novel neuraminidase inhibitors: Design, synthesis and interaction of oseltamivir derivatives with model membrane using docking, NMR and DSC methods

As a part of our ongoing program of developing novel influenza virus inhibitors, some new derivatives of oseltamivir were prepared by modifying the amino group with glycyl, acetyl, benzyl and prolyl moieties. The interactions of these derivatives with neuraminidase have been probed by molecular modeling techniques. Further, the interaction of these derivatives with model membranes prepared from DPPC and the effect on the thermotropic behavior and polymorphism of the bilayers have been investigated by multinuclear NMR and DSC methods. Results indicate that the glycyl derivative of oseltamivir has the most profound effects on the membrane, compared to other derivatives and seems to be the most promising derivative for further pharmacological evaluation as a neuraminidase inhibitor.

1)H NMR serum metabonomics for understanding metabolic dysregulation in women with idiopathic recurrent spontaneous miscarriage during implantation window.

In an attempt to find out the association of metabolic dysregulation with poor endometrial receptivity and pregnancy loss, serum metabonomic profiling of women with idiopathic recurrent spontaneous miscarriage (IRSM) is carried out and compared with fertile controls. (1)H nuclear magnetic resonance (NMR)-based metabonomics was used to obtain serum metabolic profiles of 36 women with IRSM and 28 proven fertile women during the window of implantation. The acquired data were analyzed using multivariate principal component analysis, partial least-squares-discriminant analysis, and orthogonal projection to latent structure with discriminant analysis. A clear metabolic differentiation was evident between IRSM and control samples. The distinguishing metabolites, l-lysine, l-arginine, l-glutamine, l-histidine, l-threonine, l-phenylalanine, and l-tyrosine are significantly up-regulated in IRSM as compared to controls. These altered metabolites may be involved in the molecular mechanism of exaggerated inflammatory response and vascular dysfunction associated with poor endometrial receptivity in women with IRSM. The present work proposes a vital association of metabolic dysfunction with the disease pathogenesis.

In search of a novel antifungal agent: probing molecular interactions of fluconazole and its analogues with model membranes by NMR and DSC techniques.

Objectives  In search of a novel antifungal agent with high susceptibility and increased antifungal potency it is necessary to increase the overall lipophilicity of these agents. In view of that, we have synthesized different carboxylic acid ester analogues of fluconazole, such as fluconazole‐benzoate, fluconazole‐p‐nitrobenzoate, fluconazole‐p‐methoxybenzoate and fluconazole‐toluate, with varying degrees of lipophilicity. In order to probe molecular level interactions of these molecules with biomembrane, lipid bilayers prepared from l‐α‐dipalmitoyl phosphatidyl choline (DPPC) as the model membrane were used.

Repeated implantation failure versus repeated implantation success: discrimination at a metabolomic level

STUDY QUESTION Is there any difference at the serum metabolic level between women with recurrent implantation failure (RIF) and women with recurrent implantation success (RIS) when undergoing in vitro fertilization (IVF)? SUMMARY ANSWER Eight metabolites, including valine, adipic acid, l-lysine, creatine, ornithine, glycerol, d-glucose and urea, were found to be significantly up-regulated in women with RIF when compared with women with RIS. WHAT IS KNOWN ALREADY Despite transfer of three high-grade embryos per cycle, RIF following three or more consecutive IVF attempts occurs in a group of infertile women. Conversely, there is a group of women who undergo successful implantation each cycle, yet have a poor obstetric history. STUDY DESIGN, SIZE, DURATION This study was conducted over a period of 10 years (January 2004-October 2014). Groups of 28 women with RIF (age ≤40 years and BMI ≤28) and 24 women with RIS (age and BMI matched) were selected from couples with primary infertility reporting at the Institute of Reproductive Medicine, Kolkata, India. Women recruited in the RIF group had history of implantation failure in at least three consecutive IVF attempts, in which three embryos of high-grade quality were transferred in each cycle. PARTICIPANTS/MATERIALS, SETTING, METHODS Blood samples were collected from both the groups during the implantation window following overnight fasting for at least 10 h (7-10 days post ovulation). Samples were analyzed using a 700 MHz NMR spectrometer and acquired spectra were subjected to chemometric and statistical analysis. Serum levels of endothelial nitric oxide synthase (eNOS) were measured using an enzyme immunoassay technique. MAIN RESULTS AND THE ROLE OF CHANCE Valine, adipic acid, l-lysine, creatine, ornithine, glycerol, d-glucose and urea were found to be significantly down-regulated in women with RIS when compared with those with RIF, with fold change values of 0.81, 0.82, 0.79, 0.80, 0.78, 0.68, 0.76 and 0.74, respectively. Further, serum eNOS was found to be significantly lower in women with RIF when compared with RIS (P < 0.05), indicating possible impairment in nitric oxide production. Metabolites, mostly related to energy metabolism, lipid metabolism and the arginine metabolic pathway were found to be considerably altered and are likely to be associated with the RIF phenomenon. However, the interplay between these molecules in RIF is complex and holds merit for further exploration. LIMITATIONS, REASONS FOR CAUTION In-depth studies of the arginine metabolic pathway in endometrial tissues seem necessary to validate our findings. A limitation of the present study is that the metabolic level changes, eNOS and nitric oxide levels have not been investigated in the endometrial tissues of the two groups of women. It would be interesting to investigate whether there exists a direct link between metabolic dysregulation and genetic factors that affects implantation in RIF women. WIDER IMPLICATIONS OF THE FINDINGS We speculate that tissue metabolomics can provide an improved understanding of the metabolic dysfunction associated with RIF. The identification of serum metabolic marker(s) in women with RIS may help with strategies of early therapeutic intervention, which may improve the chances of implantation significantly in women otherwise susceptible to IVF failure. STUDY FUNDING/COMPETING INTERESTS One of the authors, S.R.C. acknowledges the Council of Scientific and Industrial Research (CSIR), Government of India [No: 9/81(1228)/14, EMR-I] for financial support.

In-vitro metabolic inhibition and antifertility effect facilitated by membrane alteration: search for novel antifertility agent using nifedipine analogues.

In search of non-hormonal male contraceptives, analogues of nifedipine, which causes reversible infertility, have been synthesized and their interaction at molecular level with model membrane has been probed. Analogues act differently with respect to their antifertility action. This is achieved by altering the cell metabolism thereby directly affecting the motility which is responsible for fertility. Secondly, these drugs bind differently to the interior of the cell-membrane affecting the membrane fluidity, architecture and dynamics. Sulfasalazine and D(4) interact to a larger extent and alter the lipid bilayer phase to a hexagonal. D(1), D(2) and D(3) do not have considerable effect. D(4) is the most promising candidate as a lead compound for the development of novel non-hormonal male antifertility agents.

Serum metabolomics of Indian women with polycystic ovary syndrome using 1H NMR coupled with a pattern recognition approach

Polycystic ovary syndrome (PCOS) is one of the most commonly occurring metabolic and endocrinological disorders affecting women of reproductive age. Metabolomics is an emerging field that holds promise in understanding disease pathophysiology. Recently, a few metabolomics based studies have been attempted in PCOS patients; however, none of them have included patients from the Indian population. The main objective of this study was to investigate the serum metabolomic profile of Indian women with PCOS and compare them with controls. Proton nuclear magnetic resonance (1H NMR) was used to first identify the differentially expressed metabolites among women with PCOS from the Eastern region of India during the discovery phase and further validated in a separate cohort of PCOS and control subjects. Multivariate analysis of the binned spectra indicated 16 dysregulated bins in the sera of these women with PCOS. Out of these 16 bins, 13 identified bins corresponded to 12 metabolites including 8 amino acids and 4 energy metabolites. Amongst the amino acids, alanine, valine, leucine and threonine and amongst the energy metabolites, lactate and acetate were observed to be significantly up-regulated in women with PCOS when compared with controls. The remaining 4 amino acids, l-glutamine, proline, glutamate and histidine were down-regulated along with 2 energy metabolites: glucose and 3-hydroxybutyric acid. Our findings showed dysregulations in the expression of different metabolites in the serum of women with PCOS suggesting the involvement of multiple pathways including amino acid metabolism, carbohydrate/lipid metabolism, purine and pyrimidine metabolism and protein synthesis.

Hierarchy in guanidine unfolding of DLC8 dimer: regulatory functional implications.

Folding-unfolding caused by environmental changes play crucial regulatory roles in protein functions. To gain an insight into these for DLC8, a cargo adaptor in dynein motor complex, we investigated here the unfolding of homodimeric DLC8 by GdnHCl, a standard unfolding agent. Fluorescence spectroscopy revealed a three-state unfolding transition with midpoints at 1.5 and 4.0 M GdnHCl. The HSQC spectrum at 1.5 M GdnHCl displayed peaks belonging to a folded monomer. NMR chemical shift perturbations, line broadening effects and (15)N relaxation measurements at low GdnHCl concentrations identified a hierarchy in the unfolding process, with the dimer interface--the cargo binding site--being the most susceptible followed by the helices in the interior. Similar observations were made earlier for small pH perturbations and thus the early unfolding events appear to be intrinsic to the protein. These, by virtue of their location, influence target binding efficacies and thus have important regulatory implications.

NMR-based metabonomics for understanding the influence of dormant female genital tuberculosis on metabolism of the human endometrium

STUDY QUESTION Does investigation of metabolic perturbations in endometrial tissue of women with dormant genital tuberculosis (GTB) during the window of implantation (WOI) assist in improving the understanding of endometrial receptivity? SUMMARY ANSWER In dormant GTB cases significant alterations in endometrial tissue metabolites occur, largely related to energy metabolism and amino acid biosynthesis in dormant GTB cases. WHAT IS KNOWN ALREADY As an intracellular pathogen, Mycobacterium tuberculosis strongly influences the metabolism of host cells causing metabolic dysregulation. It is also accepted that dormant GTB impairs the receptive status of the endometrium. Global metabolic profiling is useful for an understanding of disease progression and distinguishing between diseased and non-diseased groups. STUDY DESIGN, SIZE, DURATION Endometrial tissue samples were collected from patients reporting at the tertiary infertility care center during the period September 2011-March 2013. Women having tested positive for GTB were considered as the study group (n = 24). Normal healthy women undergoing sterilization (n = 26) and unexplained infertile women with repeated IVF failure (n = 21) volunteered to participate as controls. PARTICIPANTS/MATERIALS, SETTING, METHODS Endometrial tissue samples were collected 6-10 days after confirmation of ovulation. PCR and BACTEC-460 culture were used for diagnosing GTB. Proton nuclear magnetic resonance (1H NMR) spectra of tissue were recorded using a 700 MHz Bruker Avance AV III spectrometer. Following phase and baseline correction of all NMR spectra by Bruker Topspin 2.1 software, spectral peak alignment of the data was performed. Multivariate analysis was applied to all spectra and individual metabolites identified and multiple correlation analysis was performed. MAIN RESULTS AND THE ROLE OF CHANCE Leucine, isoleucine, acetate, lactate, glutamate, glutamine, methionine, lysine, creatine, glycogen, glycine, proline and choline were found to be significantly increased (P < 0.05) in endometrial tissue of women with dormant GTB compared with unexplained infertile women with repeated implantation failure. Valine, citrate, succinate and aspartate were also observed to be significantly up-regulated (P < 0.01). Furthermore, a significant decrease in glucose (P < 0.05), threonine (P < 0.05), tyrosine (P < 0.01) and phenylalanine (P < 0.0001) was observed in women with dormant GTB. Pearsons correlation analysis between the expression of various endometrial receptivity markers and metabolites showed a significant negative correlation (-0.236 to -0.545, P < 0.05). Also, the metabolites were positively correlated with endometrial receptivity markers (0.207 to 0.618, P < 0.05). LIMITATIONS, REASONS FOR CAUTION It is often difficult to diagnose dormant GTB because it tends to exist without any clinical signs or symptoms. In addition, the diagnosis of GTB by culture remains a challenge due to low detection rates and its paucibacillary nature. Testing for prostate-specific antigen or the Y chromosome in order to account for the possible influences of recent exposure to semen on endometrial metabolism would be important. WIDER IMPLICATIONS OF THE FINDINGS The metabolic changes associated with the dormant tubercle infection are of potential relevance to clinicians for the treatment of dormant GTB-related infertility. STUDY FUNDING/COMPETING INTERESTS Government of India, Indian Council of Medical Research. There are no conflicts of interest.