Gotowa bibliografia na temat „N-methylhydantoin”

A nematicidal actinomycete strain WH06 was isolated from soil samples and was identified using 16S rRNA as Micromonospora sp. Through medium screening and fermentation, 10 metabolites were isolated from the ethyl acetate extract of its fermentation broth using Sephadex LH-20 and silica gel column chromatography. These compounds were identified as N-acetyltyramine (1), N-acetyltryptamine (2), 1-methylhydantoin (3), benzenepropanoic acid (4), cyclo-(L-Pro-L-Tyr) (5), cyclo(L-Phe-Gly) (6), catechol (7), methyl (4-hydroxyphenyl)acetate (8), 3-hydroxybenzoic acid (9), and 4-hydroxybenzoic acid (10). In an in vitro assay against Meloidogyne incognita, a root-knot nematode, compounds 1, 4, 9, and 10 show nematicidal activity. Among them, benzenepropanoic acid (4) causes 99.02% mortality of nematode at 200 μg mL−1 after 72 h. Moreover, compound 4 also displays activity in inhibiting egg hatching of M. incognita. This suggests that Micromonospora sp. WH06 is a promising candidate for biocontrol of M. incognita.

Prostate cancer (PCa), bladder cancer (BCa), and renal cell carcinoma (RCC) are the most prevalent cancer among urological cancers. However, there are no cancer-specific symptoms that can differentiate them as well as early clinical signs of urological malignancy. Furthermore, many metabolic studies have been conducted to discover their biomarkers, but the metabolic profiling study to discriminate between these cancers have not yet been described. Therefore, in this study, we aimed to investigate the urinary metabolic differences in male patients with PCa (n = 24), BCa (n = 29), and RCC (n = 12) to find the prominent combination of metabolites between cancers. Based on 1H NMR analysis, orthogonal partial least-squares discriminant analysis was applied to find distinct metabolites among cancers. Moreover, the ranked analysis of covariance by adjusting a potential confounding as age revealed that 4-hydroxybenzoate, N-methylhydantoin, creatinine, glutamine, and acetate had significantly different metabolite levels among groups. The receiver operating characteristic analysis created by prominent five metabolites showed the great discriminatory accuracy with AUC > 0.7 for BCa vs. RCC, PCa vs. BCa, and RCC vs. PCa. This preliminary study compares the metabolic profiles of BCa, PCa, and RCC, and reinforces the exploratory role of metabolomics in the investigation of human urine.

Abstract We describe an improved enzymatic ultraviolet absorbance method for assaying creatinine in serum, plasma, and urine. Creatinine is hydrolyzed by creatinine iminohydrolase (EC 3.5.4.21) to ammonia and N-methylhydantoin. The ammonia produced combines with 2-oxoglutarate and NADPH in the presence of glutamate dehydrogenase to yield glutamate and NADP+. The consumption of NADPH, measured by a two-point fixed-time assay, is proportional to the amount of creatinine in the sample. The assay is carried out in two steps: The first step eliminates background absorbance in hyperlipemic samples and endogenous ammonia through a "clearing system" and an isocitrate dehydrogenase-based "ammonia scavenger system"; the second step starts creatinine measurement. The method affords a simple, rapid, and sensitive assay with good precision and extended linearity; it employs working solutions stable at least 4 months. Test results compare closely with those of the isotope dilution-mass spectrometry Definitive Method, the HPLC procedure, and the fuller's earth method. The proposed method is not subject to interference from several metabolites or from the 72 drugs tested. Because it is easily automated, the method is suitable for routine work in clinical laboratories.

Creatinine is an important biomarker for evaluating the renal function and its concentration in serum can be utilized for early detection of kidney disease, thyroid disorders, and muscular dystrophy. Accurate, reliable, and decentralized testing of creatinine has become vital owing to the rising trajectory of Chronic Kidney Disease and its associated risk factors – diabetes and hypertension. The conventional analytical techniques to estimate serum creatinine are limited by its non-specificity, prevalent in the optical Jaffe assay, and the high costs, involved in the enzymatic assays. This has led to intensive research efforts in developing an accurate, robust, and sensitive sensor for estimating the concentration of creatinine in serum with cost-effective solutions. This underlies the focus of the thesis as it primarily discusses various approaches and challenges faced in developing the intended sensor. The primary challenge in estimation of serum creatinine is posed by its reduced concentration in the complex matrix of blood, which is constituted by varied proteins, whole cells, immunoglobulins, ions, and other metabolites. The electro-inactivity of creatinine further complicates the measurement by an electrochemical route. This necessitates selection of a redox probe that has an inherently high selectivity for creatinine to address both issues. In this thesis, we have explored non-enzymatic and enzymatic approaches for its detection. One of the non-enzymatic approaches, involves utilization of a transition metal – iron that has an affinity for creatinine. The other non-enzymatic approach involves electrochemical estimation of creatinine by picric acid that is already utilized in the optical Jaffe reaction. Both the approaches provide reliable estimation of creatinine in saline and prove the feasibility of estimation of the reduced concentrations of serum creatinine by non-enzymatic techniques. The enzymatic approach involves one-step hydrolysis of creatinine by creatinine deiminase. The resulting N-methylhydantoin is quantified by a highly selective transition metal-based redox probe – cobalt. This is a novel route for creatinine estimation that has provided reliable quantification in serum and even, whole blood. The enzymatic approach assures a higher sensitivity and specificity of detection in real samples. Another major issue that limits the clinical use of electrochemical biosensors for the analytes present in lower concentrations, is electrode fouling caused by the non-electroactive components of the blood. We have investigated different strategies to minimize this fouling by serum proteins – albumin. The strategies differ based on the interaction of the redox probe with albumin and are classified into albumin-reactive and albumin-non-reactive systems. Dilution with appropriate electrode surface modification has proven effective for albuminreactive systems. A unique size and charge filter composite has been devised for albumin-non-reactive systems. This filter composite can be tuned and further optimized with any disposable electrode platform, based on the required extent and nature of filtration. It also serves as a viable pre-treatment or activation layer for the lower cost ultramicroelectrodes. Decentralized testing necessitates minimal user involvement and no technical pre-requisites for the measurement. Hence, we have proposed a sequential drop technique of the sensing chemistry constituting cobalt ions on disposable screenprinted electrodes as a decentralized testing solution with minimal user involvement. We have also explored electrodeposition of cobalt ions as an alternate platform that further minimizes the user involvement by confinement of the sensing chemistry on the electrode surface. Thus, this thesis provides a comprehensive exploration of non-enzymatic and enzymatic techniques for quantification of serum creatinine. The device based on enzymatic technique has demonstrated success in estimation of creatinine from whole blood samples of patients with no sample pre-processing, a reduced turnaround time and high accuracy over a wide dynamic range and has laid the foundation for the intended point-of-care device.