Zeaxanthin Production by Novel Marine Isolates from Coastal sand of India and its Antioxidant Properties

Zeaxanthin carotenoids are class of commercially important natural products and diverse biomolecules produced by plants and many microorganisms. Bacteria often produce a cocktail of polar and nonpolar carotenoids limiting their industrial applications. Marine members of the family Flavobacteriaceae are known to produce potential carotenoids such as astaxanthin and zeaxanthin. A few bacterial species have been reported for the predominant production zeaxanthin. Here, we report the molecular identification of the zeaxanthin as a major carotenoid produced by two novel bacteria (YUAB-SO-11 and YUAB-SO-45) isolated from sandy beaches of South West Coast of India and the effect of carbon sources on the production of zeaxanthin. The strains were identified based on the 16S rRNA gene sequencing as a member of genus Muricauda. The closest relatives of YUAB-SO-11 and YUAB-SO-45 were Muricauda aquimarina (JCM 11811^T) (98.9 %) and Muricauda olearia (JCM 15563^T) (99.2 %), respectively, indicating that both of these strains might represent a novel species. The highest level of zeaxanthin production was achieved (YUAB-SO-11, 1.20?±?0.11 mg g^?1) and (YUAB-SO-45, 1.02?±?0.13 mg g^?1) when cultivated in marine broth supplemented with 2 % NaCl (pH 7) and incubated at 30 °C. Addition of 0.1 M glutamic acid, an intermediate of citric acid cycle, enhanced the zeaxanthin production as 18 and 14 % by the strains YUAB-SO-11 and YUAB-SO-45 respectively. The zeaxanthin showed in vitro nitric oxide scavenging, inhibition of lipid peroxidation, and 2,2-diphenyl-1-picryl hydrazyl scavenging activities higher than the commercial zeaxanthin. The results of this study suggest that two novel strains YUAB-SO-11 and YUAB-SO-45 belonging to genus Muricauda produce zeaxanthin as a predominant carotenoid, and higher production of zeaxanthin was achieved on glutamic acid supplementation. The pigment showed good in vitro antioxidant activity, which can be exploited further for commercial applications.     

Synthesis of new chiral 1,3,4-thiadiazole-based di- and tri-arylsulfonamide residues and evaluation of in vitro anti-HIV activity and cytotoxicity

A series of new chiral 1,3,4-thiadiazole-based bis-sulfonamides 4a–4w and tri-sulfonamide analogue 5 was synthesized and evaluated as anti-HIV agents. The reaction of chiral amino acids 1 with sulfonyl chlorides 2, followed by subsequent reaction of resultant N-protected amino acids 2a–2f with thiosemicarbazide in the presence of excess phosphorous oxychloride afforded N-(1-(5-amino-1,3,4-thiadiazol-2-yl)alkyl)-4-arylsulfonamides 3a–3f. Treatment of 2a–2f with substituted sulfonyl chlorides in portions furnished the target bis-sulfonamide analogues 4a–4w in good yields, together with the unexpected 5. The new compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. Compounds 4s were the most active in inhibiting HIV-1 with IC₅₀?=?9.5 μM (SI?=?6.6), suggesting to be a new lead in the development of an antiviral agent. Interestingly, compound 5 exhibited significant cytotoxicity of >?4.09 μM and could be a promising antiproliferative agent.     

The differential modulation of USP activity by internal regulatory domains, interactors and eight ubiquitin chain types

Ubiquitin-specific proteases (USPs) are papain-like isopeptidases with variable inter- and intramolecular regulatory domains. To understand the effect of these domains on USP activity, we have analyzed the enzyme kinetics of 12 USPs in the presence and absence of modulators using synthetic reagents. This revealed variations of several orders of magnitude in both the catalytic turnover (k_cat) and ubiquitin (Ub) binding (K_M) between USPs. Further activity modulation by intramolecular domains affects both the k_cat and K_M, whereas the intermolecular activators UAF1 and GMPS mainly increase the k_cat. Also, we provide the first comprehensive analysis comparing Ub chain preference. USPs can hydrolyze all linkages and show modest Ub-chain preferences, although some show a lack of activity toward linear di-Ub. This comprehensive kinetic analysis highlights the variability within the USP family.     

The preparation of novel nanofilled polymer composites using poly(l-lactic acid) and protein fibers

In this communication, we present novel nanofilled polymer composites prepared using a poly(l-lactic acid) (PLLA) matrix and amyloid fibers. Amyloid fibers are made from protein sources’ and share many of the same material properties as spider silk, but exist at significantly smaller length scales with diameters of 5–10 nm. This work highlights the potential use of amyloid fibers as nanofillers in the development of renewable polymeric materials with tuneable properties. Improvements in the glass transition temperature (T_g), elongation at break and Young’s modulus was measured, while the yield strength of the new materials was not seriously hampered.     

Characterization studies on the additives mixed l-arginine phosphate monohydrate (LAP) crystals

l-arginine phosphate monohydrate (LAP), potassium thiocyanate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na₂SO₃) mixed LAP (LAP:Na₂SO₃) single crystals were grown by slow cooling technique. The effect of microbial contamination and coloration on the growth solutions was studied. The crystalline powders of the grown crystals were examined by X-ray diffraction and the lattice parameters of the crystals were estimated. From the FTIR spectroscopic analysis, various functional group frequencies associated with the crystals were assigned. Vickers microhardness studies were done on {1 0 0} faces for pure and additives mixed LAP crystals. From the preliminary surface second harmonic generation (SHG) results, it was found that the SHG intensity at (1 0 0) face of LAP:KSCN crystal was much stronger than that of pure LAP.     

Detection of energetic light charged particles by solid state nuclear track detectors

Experiments have been carried out to detect ₂ ³He particles and : rotons having energies up to 10 MeV/nucleon by using Kodak CA80-15, cellulose nitrate plastic track detector. Various etching conditions were tried in order to develop tracks for whole of the energy range considered. Detailed analysis seems to indicate that at high energies, the tracks are mainly produced by “secondaries” (elastically scattered nuclei of C, N, O and H, and other reaction products) while in the low energy region, the slowed down “primaries” play the dominant role. The prolonged etching factors of these detectors for different types of tracks have also been obtained and used to derive their average etchable ranges in the materials concerned.     

Chemically modified screen-printed electrodes as efficient potentiometric sensors for cyclobenzaprine hydrochloride determination in pure and pharmaceutical preparations

Chemically modified screen-printed electrodes (SPEs) with 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt [Alizarin Red (ALZ.R)] and tricresylphosphate (TCP) were fabricated and examined for potentiometric determination of cyclobenzaprine hydrochloride (CZP.HCl) in pure and pharmaceutical samples. The content of ALZ.R in the prepared SPEs varied, which significantly affected their potentiometric response during CZP.HCl estimation. The measured potential value was dependent on the pH of the studied solution. A stable modified SPE sensor was prepared with reproducible readings within 22 days. A wide linear concentration range could be measured with Nernestian slope value of 60.12 ± 0.18 mV decade⁻¹. Based on the recorded analytical parameters of these modified SPEs, a sensitive and reliable detection of CZP.HCl in pharmaceutical samples could be attained.     

Novel sepiolite reinforced emerging composite polymer electrolyte membranes for high-performance direct methanol fuel cells

Methanol permeation is the main issue of Nafion membranes when they are used as a polymer electrolyte membrane (PEM) in direct methanol fuel cells (DMFCs). In the current study, novel nanocomposite polymer membranes are prepared by the integration of surface-modified sepiolite (MS) in polyvinylidene fluoride grafted polystyrene (PVDF-g-PS) copolymer as PEM in DMFCs. Sepiolite (SP) surface is chemically modified using vinyltriethoxysilane and analyzed by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocomposite PVDF-g-PS/MS membranes are prepared by phase inversion technique and subsequently treated with chlorosulfonic acid to induce sulfonic acid (SO₃H) active sites at the membrane surface. The prepared nanocomposite membranes (S-PPMS) are analyzed for their physicochemical characteristics in terms of water uptake percentage, cation exchange capacity, proton conductivity (σ), and methanol permeability. MS dispersion in the copolymer matrix is proved through morphological SEM examination. The S-PPMS membranes exhibit increased proton conductivity due to the presence of well-dispersed MS and surface functional –SO₃H groups. A peak power density of 210 mWcm^?2 is recorded for S-PPMS10 at 110 °C, which is higher than the output obtained from Nafion-117. These promising results indicate the potential utilization of prepared nanocomposite PEMs for DMFC application.     

Synthesis,characterisation and mesomorphic behaviours of non-symmetrically substituted 1,2,4- and 1,3,4-oxadiazole derivatives

Two series of non-symmetrically substituted bent-core mesogens derived from the central 3,5 and 2,5 cores of the 1,2,4- and 1,3,4-oxadiazole derivatives, respectively, containing ether and ester linkage have been synthesised by several straightforward synthetic procedures, and their mesomorphic behaviour was studied by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The last five homologues of the 1,2,4-oxadiazole series exhibit a monotropic nematic phase on cooling, while the 1,3,4-oxadiazole derivatives do not show any liquid crystalline properties but rather a crystal to isotropic transition is observed by OPM. We show that the bent angles of the 1,2,4- and 1,3,4-oxadiazole rings are crucial in observing the liquid crystal (LC) phases formed, and also that the length of the alkyl substituent is observed to have a significant effect on the nature of the LC phases.