Pyridine and pyrimidine ring syntheses from 4-(4-morpholino)-3-pentenone and from ethyl 3-(4-morpholino)-2-butenoate

3-Substituted 2(1H)-pyridones are produced from reaction of 4-(4-morpholino)-3-pentenone 1 with each of the following carbon acids: cyanoacetamide, malononitrile, cyanothioacetamide, acetylacetamide, benzoyl-acetonitrile. Reaction of ethyl 3-(4-morpholino)-2-butenoate 2 with cyanoacetamide gives the corresponding hydroxypyridone. Pyrimidines are formed by reaction of 1 and of 2 with benzamidine and with S-benzylthio-urea; in the last case, the eliminated morpholine displaces the benzylthio group to give the final product.     

Autofluorescence characterization of advanced glycation end products of hemoglobin

This article describes the analysis of autofluorescence of advanced glycation end products of hemoglobin (Hb-AGE). Formed as a result of slow, spontaneous and non-enzymatic glycation reactions, Hb-AGE possesses a characteristic autofluorescence at 308/345 nm (lambda(ex)/lambda(em)). Even in the presence of heme as a quenching molecule, the surface presence of the glycated adduct gave rise to autofluorescence with the quantum yield of 0.19. The specificity of monoclonal antibody developed against common AGE structure with Hb-AGE was demonstrated using reduction in fluorescence polarization value due to increased molecular volume while binding. The formation of fluorescent adduct in hemoglobin in the advanced stage of glycation and the non-fluorescent HbA(1c) will be of major use in distinguishing and to know the past status of diabetes mellitus. While autofluorescence correlated highly with HbA(1c) value under in vivo condition (r = 0.85), it was moderate in the clinical samples (r = 0.55). The results suggest a non-linear relation between glycemia and glycation, indicating the application of Hb-AGE as a measure of susceptibility to glycation rather than glycation itself.     

Noise induced transition in Josephson junction with second harmonic

We show a noise induced transition in Josephson junction with fundamental as well as second harmonic. A periodically modulated multiplicative colored noise can stabilize an unstable configuration in such a system. The stabilization of the unstable configuration has been captured in the effective potential of the system obtained by integrating out the high frequency components of the noise. This is a classical approach to understand the stability of an unstable configuration due to the presence of such stochasticity in the system and our numerical analysis confirms the prediction from the analytical calculation.     

Stimuli‐Responsive Supramolecular Hydrogels and Their Applications in Regenerative Medicine

Supramolecular hydrogels are a class of self‐assembled network structures formed via non‐covalent interactions of the hydrogelators. These hydrogels capable of responding to external stimuli are considered to be smart materials due to their ability to undergo sol–gel and/or gel–sol transition upon subtle changes in their surroundings. Such stimuli‐responsive hydrogels are intriguing biomaterials with applications in tissue engineering, delivery of cells and drugs, modulating tissue environment to promote innate tissue repair, and imaging for medical diagnostics among others. This review summarizes the recent developments in stimuli‐responsive supramolecular hydrogels and their potential applications in regenerative medicine. Specifically, various structural aspects of supramolecular hydrogelators involved in self‐assembly, the role of external stimuli in tuning/controlling their phase transitions, and how these functions could be harnessed to advance applications in regenerative medicine are focused on. Finally, the key challenges and future prospects for these versatile materials are briefly described.     

Inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid for copper corrosion in nitric acid medium: a combined experimental and theoretical investigation

Structural Chemistry - A combined experimental and theoretical study is presented to predict and analyze the inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid molecule for...     

Grease immobilized on polyethyleneimine cotton cloth

Jack bean urease was immobilized on polyethylenimine-coated cotton cloth by adsorption following by crosslinking with dimethyl suberimidate. Of the various methods used, crosslinking with dimethyl suberimidate was found to stabilize the enzyme with minimal inactivation. Cloth-bound urease showed a shift in pH optimum towards the acidic side without appreciable change in temperature optimum and thermostability. Cloth-bound urease could be used repeatedly for urea hydrolysis without appreciable loss in activity. Alternatively, urease cloth could be stitched in the form of a bag containing ammonia adsorbent and used for urea hydrolysis with simultaneous removal of ammonia.     

Fluorescence and biochemical characterization of glycated hemoglobin

Isoelectric focusing (IEF) of glycated hemoglobin (GHb) was carried out in ultra-thin polyacrylamide gels to separate the hemoglobin-advanced glycation endproducts (Hb-AGEs) from the hemoglobin-A_1C (HbA_1C) fraction. Precast polyacrylamide gels (Ampholine^® PAGplate) were used in Pharmacia LKB Multiphor II for this purpose. The separated bands for Hb-AGE and HbA_1C based on their isoelectric point (pI), were confirmed with the purifed fractions obtained from the cation exchange chromatographic technique. From the calibration curve, the pI values were found to be 6.748 and 6.495 for HbA_1C and Hb-AGE, respectively. The lowering of pI values for glycated hemoglobin, when compared to unglycated hemoglobin (pI = 6.852), can be attributed to the glycation at the amino terminals of the peptide chains. Increased reduction in pI value for Hb-AGE can be attributed to the effect of glycation of amino groups at various sites on the peptide chains, apart from the terminal amino groups. Fluorescence analysis was carried out for the purified fraction of Hb-AGE which showed the formation of a new fluorophor adduct having the excitation and emission maxima at 308 nm and 345 nm, respectively. Time-dependent formation of Hb-AGE under in vitro conditions was monitored by fluorescence (308/345 nm) over a period of 120 days, which showed its formation only after 3 weeks of incubation.     

Assessment of Dentifrices Against Candida Biofilm

The invasion of opportunistic pleiomorphic Candida albicans into oral cavity environment leads to development and progression of its resistance to both naturally occurring antifungal peptides in human saliva as well as commercially available antifungal therapies. As a result of this, the usage and popularity of natural medicine and dentifrices had increased significantly in the last decade. In the present investigation, we have assessed the action of locally available dentifrices against C. albicans biofilm. Disk diffusion test showed maximum zone of inhibition (20?mm) by herbal dentifrice (D-5) as compared to other dentifrices when incubated at 37?°C and 48?h. Assessment of dentifrice D-5 for its effectiveness against C. albicans was further shown in MIC₉₀ (3.12?mg?mL^?1) and SMIC₉₀ (6.2?mg?mL^?1) values for planktonic and sessile cells (biofilm forming), respectively. Our data depicted 80% reduction in the cell surface hydrophobicity when 6.2?mg?mL^?1 of herbal dentifrice D-5 was used against 48-h grown Candida biofilm at 37?°C. Visualization of herbal dentifrice D-5-treated C. albicans biofilm under SEM revealed drastic reduction in the dense network of yeast, hyphae, and pseudohyphae enclosed in its ECM as compared to its control biofilm. The data were further supported by CLSM analysis which depicted C. albicans architecture disruption by herbal dentifrices. From the above data, it is inferred that these studies would provide researchers and medical practitioners with better insight into the antifungal effect of natural herbal dentifrices.