Capturing of neurotoxins causing diabetes stress and nervous breakdown in the aqueous medium by naphthazarin esters.

The fear of an increase in blood sugar can be very traumatic. Being diabetic either type I or type II leads to a disorder called diabetes distress having traits of stress, depression, and anxiety. Among risk factors of diabetes mellitus heavy and trace metal toxicity emerges as new risk factors reported in many studies. In this study we target toxic metals, viz., Ni2+, Zn2+, and Cu2+, involved in the pathogenesis of diabetes and diabetic stress with naphthazarin esters. The compounds C1-C3 isolated from the leaves and roots of Arnebia guttata were tested for their metal-binding ability in an aqueous medium in UV-Visible and nuclear magnetic resonance (NMR) studies. These probes are well-known naphthoquinones present in the Arnebia species. In the UV-Visible titrations of compounds C1-C3 with Na2+, K2+, Zn2+, Ca2+, Cu2+, Mg2+, Co2+, and Ni2+ ions, significant binding was observed with Ni2+, Cu2+, and Zn2+ ions in MeOH/H2O. There occurs a beautiful formation of red-shifted bands between the 520 to 620 nm range with a synergistic increase in absorbance. Also, the disappearance of proton peaks in the 1H NMR spectrum on addition of metal ions confirmed binding. Compounds C1-C3 isolated from A. guttata came out as potent Ni2+, Zn2+, and Cu2+ sensors that are reportedly involved in islet function and induction of diabetes.

Amino Appended Coumarin Composites for Pb2+ Capturing in Aqueous Medium.

The C1-C3 receptors were synthesized by using coumarin and amines viz., 1-butylpiperazine (1), cis-myrtanylamine (2), and 3-methyldiphenyl amine (3) at room temperature without using harsh conditions. All the probes show beautiful and strong binding with Pb2+ ions among all the tested essential elements of human body. The binding is clearly seen and confirmed in UV-visible, NMR and HPLC studies. Also, all the substituted amines (1-3) are well known bioactives viz., piperazine as anthelmintic, cis-myrtanyl use for cannabinoid receptor (CB2) antagonists, 3-methyldiphenyl is used in probes for selective detection of explosive nitroaromatic compounds further increases their sensitivity for use as Pb2+ sensor. As they are already well in use for research on human body metabolomics their future introduction as sensors in the human body for lead toxicity is highly favourable.

Mechanistic studies on polyphenol rich fractions of Kangra tea by HPTLC and NMR for their antioxidant activities.

Abstract: The antioxidant activity in tea is largely driven by its polyphenolic content, however, the antioxidant reaction mechanism and the compounds involved are not well characterized. Therefore, in this study, we performed in-depth profiling of the antioxidant reaction mechanism of Green Tea (GT), Black Tea (BT), and their polyphenolic fractions with free radical using state-of-the-art analytical techniques. The polyphenol enriched fractions from GT and BT were isolated using column chromatography. Catechins were isolated and characterized by diverse spectroscopic techniques. Samples were screened for their antioxidant activity by HPTLC and further evaluated using a spectrophotometer. The free radical reactions with GT, BT, enriched fractions viz, GT Polyphenols (GTP), BT Polyphenols (BTP), and isolated catechins were studied using the 13C NMR technique. The highest polyphenol content was found in GTP (795.4 ± 0.012 mg/g) whereas GT (321.0 ± 0.028 mg/g) showed maximum flavonoids content. Individual catechins isolated from GTP were EGCG, ECG, EGC, EC and C. Antioxidant activity followed the order EGCG > ECG > EGC > EC > GTP > C > BTP > GT > BT. In GT, the antioxidant reaction mechanism showed single electron and H-transfer in all catechins, which involved the transformation of the hydroxyl group to the carbonyl group. Whereas in BT theaflavins, conversion of the benzotropolone ring to the six-membered ring was observed. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05297-w.

Pb2+ sensing by coumarin sulphonamide hybrids in aqueous medium.

Metals play an important role in various metabolic activities in the human body, but above desired concentrations, a role reversal occurs that causes deadly outcomes viz., cancer. Metals cannot be cracked down and are non-biodegradable. It is the bioaccumulation of toxic metals inside the biomatrices, that further intensifies the research on different means of metal detoxification from different matrices. Among heavy toxic metals lead is a brutal carcinogen that requires pitiless sensors for its capturing. The use of heterocycles for metal sensing in supramolecular chemistry is preferred due to the strong chelation they offer to toxic metals. The C1-C3 probes were synthesized and studied for their Pb2+ binding ability. All the probes were prepared by treating bromoacetyl coumarin with camphor sulphonamide, 5-dimethylamino-1-naphthalene sulphonamide, and methyl-2-amino-sulphonyl benzoate at room temperature. The probes show selective binding with Pb2+ ions in aqueous acetonitrile among different tested metal ions viz., Cu2+ , Zn2+ , Ni2+ , Mn2+, and Pb2+ ions as shown in ultraviolet (UV)-visible, nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC) studies. These sulphur-containing probes bind very well with Pb2+ ions by offering selectivity in binding positions that capture lead ions at their minimum possible concentration.

Epigallocatechin gallate suppresses premature senescence of preadipocytes by inhibition of PI3K/Akt/mTOR pathway and induces senescent cell death by regulation of Bax/Bcl-2 pathway.

The phytochemical epigallocatechin gallate (EGCG) has been reported to alleviate age-associated immune disorders and organ dysfunction. However, information regarding the mechanistic role of EGCG in the suppression of cellular senescence is limited. The present study thus assessed the effects and underlying mechanisms of EGCG in the inhibition of senescence as well as its potential to selectively eliminate senescent cells (senolytics) using 3T3-L1 preadipocytes. Premature senescence was established in cells by repeated exposure of H2O2 at a sub-lethal concentration (150 µM). H2O2 treated cells showed characteristic senescence-associated features including increased cell size, senescence-associated ß-galactosidase activity (SA-ß-gal), development of senescence-associated secretory phenotype (SASP), activation of reactive oxygen species (ROS) and pathways, DNA damage as well as induction of cell cycle inhibitors (p53/p21WAF1/p16INK4a). In addition, a robust activation of PI3K/Akt/mTOR and AMPK pathways was also observed in H2O2 treated cells. Presence of EGCG (50 and 100 µM) showed significant downregulation of PI3K/Akt/mTOR and AMPK signaling along with the suppression of ROS, iNOS, Cox-2, NF-κB, SASP and p53 mediated cell cycle inhibition in preadipocytes. In addition, EGCG treatment also suppressed the accumulation of anti-apoptotic protein Bcl-2 in senescent cells thereby promoting apoptosis mediated cell death. Our results collectively show that EGCG acts as an mTOR inhibitor, SASP modulator as well as a potential senolytic agent thereby indicating its multi-faceted attributes that could be useful for developing anti-aging or age-delaying therapies.

Diet supplemented with phytochemical epigallocatechin gallate and probiotic Lactobacillus fermentum confers second generation synbiotic effects by modulating cellular immune responses and antioxidant capacity in aging mice.

PURPOSE: In the present study, we systematically identified and evaluated a synbiotic combination of phytochemical epigallocatechin gallate (EGCG) and probiotic bacteria in amelioration of immunosenescence and oxidative stress in aged mice. METHODS: Inhibitory effects of EGCG against different bacterial species were evaluated in vitro, followed by analysis to identify potential combination of EGCG and probiotic bacteria against alleviation of oxidative and inflammatory stress ex vivo. The best synbiotic combination, vis-à-vis prebiotic and probiotic supplementation alone, was then evaluated in aged Swiss albino mice for modulation of various immunological and antioxidative parameters. RESULTS: EGCG strongly inhibited the growth of pathogenic microbes as compared to probiotic bacteria. A combination of EGCG with probiotic Lactobacillus fermentum (LF) provided evidence of additive effects in the amelioration of oxidative and inflammatory stress-induced cell death. In vivo study revealed that combined supplementation of LF and EGCG significantly enhanced neutrophil oxidative index, CD3+ cell numbers and activation status, Th1/Th2 cytokines in splenic supernatants as well as liver Nrf-2 expression in comparison with treatments with LF or EGCG alone. The combined application of EGCG and LF did not simply result in additive or synergistic effects in relation with individual treatments. CONCLUSION: These observations suggest that EGCG could be considered as a potential prebiotic that can offer second generation synbiotic health beneficial effects for the alleviation of some of the deleterious aspects of immunosenescence and aging.

Correction to: Diet supplemented with phytochemical epigallocatechin gallate and probiotic Lactobacillus fermentum confers second generation synbiotic effects by modulating cellular immune responses and antioxidant capacity in aging mice.

Authors of the original article have observed an inadvertent error in their manuscript post-publication.

Chrysin isolated from Pyrus pashia fruit ameliorates convulsions in experimental animals.

Objective: The traditional use of the ethanolic extract of the fruit of Pyrus pashia (EPP) as a potential anticonvulsant was validated using experimental animal models. Furthermore, the anticonvulsant activity of isolated chrysin was investigated against experimental animal models to draw a possible therapeutic mechanism of EPP. Additionally, the safety profile of chrysin was evaluated to explore the possible therapeutic alternative in the management of epilepsy. Method: The anticonvulsant activity in terms of duration of onset of hind limb tonic extension and convulsion of standardized EPP was evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ) model of experimental epilepsy respectively. Furthermore, the anticonvulsant activity and electrophysiological properties of chrysin was investigated in addition to antioxidant activity against PTZ-induced convulsion in experimental animals. Moreover, the neurotoxic profile of the chrysin was assessed in terms of duration of movement and running in photoactometer and rotarod apparatus, respectively. Results: EPP (100, 200, and 400 mg/kg) exhibited significant anticonvulsant activity against an acute model of MES and PTZ-induced convulsions in experimental animals. Furthermore, chrysin (2.5, 5, and 10 mg/kg) also exhibited significant anticonvulsant activity against PTZ-induced convulsions in rats. In addition, chrysin did not exhibit sedative-like behavior in experimental rodents. Discussion: EPP could be considered as a potential and alternative therapeutic option in the management of epilepsy.

Consumption of green tea epigallocatechin-3-gallate enhances systemic immune response, antioxidative capacity and HPA axis functions in aged male swiss albino mice.

The present investigation assessed the potential of green tea phytochemical epigallocatechin-3-gallate (EGCG) in alleviating age-associated aberrations in immunity, hypothalamus-pituitary-adrenal (HPA) axis and redox homeostasis using 16 months old male Swiss albino mice. Four groups of animals (n = 6 per group) were supplemented with either aqueous EGCG at 25, 50 and 100 mg/kg/animal or vehicle control for 6 weeks. A concurrent analysis of CD4+ and CD8+ lymphocytes in splenocytes, differential leucocyte population, T cell differentiation markers in peripheral blood mononuclear cells (PBMCs), neutrophil functions, immunoglobulins profile in intestine, circulatory HPA axis hormonal levels as well as inflammatory and oxidative stress in the liver was performed. We observed a remarkable increase in plasma dehydroepiandrosterone (DHEA) levels of 100 mg EGCG fed animals while eosinophils and monocytes counts in blood increased. EGCG consumption increased the fraction of CD3+CD8+ cells in splenocytes and CD28 expression on PBMCs. The immunoglobulins profile revealed decreased production of secretory IgA, IgE and IgG1/IgG2a ratio. Liver extracts showed increase in superoxide dismutase activity and total antioxidant capacity while lipid peroxidation along with inflammatory markers (IL-6 and TNF-α) decreased. Our results collectively show that EGCG consumption during aging strengthens systemic immunity by enhancing cellular immune response and simultaneously attenuating antibody response aided by an increase in adrenal DHEA production. Thus, consumption of green tea may be beneficial in alleviating some of the deleterious aspects of aging and immunosenescence in elderly.

Stress-Tolerant Viridibacillus arenosi Strain IHB B 7171 from Tea Rhizosphere as a Potential Broad-Spectrum Microbial Inoculant.

Viridibacillus arenosi strain IHB B 7171 identified based on 16S rRNA gene sequence produced colony forming units (cfu/ml) ranging from 3.3 × 104 to 1.2 × 1010 under pH 5-11, 2.2 × 102 to 1.4 × 1010 for temperature 5-40 °C, 2.4 × 102 to 1.1 × 1010 for PEG 6000 10-30%, 2.2 × 102 to 1.4 × 1010 for 2.5-10% NaCl, 3.1 × 103 to 1.7 × 109 for 2.5-7.5 mM CaCl2, 2.2 × 102 to 1.4 × 107 for 2.5-7.5 mM AlCl3, and 3.2 × 102 to 1.2 × 107 for 2.5-7.5 mM FeCl3. The activities of plant growth-promoting attributes with the increasing acidity, desiccation and salinity ranged from 408 to 101, 20 to 8, 14 to 5 µg/ml P-liberated from tri-calcium phosphate, aluminium phosphate and iron phosphate, 20-9% siderophore units, 14-4 µg/ml IAA and 190-16 α-ketobutyrate h/mg protein ACC-deaminase activity. Plant height, leaf number, and leaf weight on treatment with bacterial inoculum showed an increment of 9.5, 17.6, 54.5 and 31.0% in tea seedlings, respectively. The bacterium also enhanced plant height and yield by 10 and 13% in pea and 2.8 and 13.9% in wheat. The results exhibited stress-tolerance and plant growth-promoting activities by the strain under stressed growth-conditions with potential as a broad-spectrum plant growth-promoting rhizobacterium.

Anthocyanins enriched purple tea exhibits antioxidant, immunostimulatory and anticancer activities.

Purple coloured tea shoot clones have gained interest due to high content of anthocyanins in addition to catechins. Transcript expression of genes encoding anthocyanidin reductase (ANR), dihydroflavonol-4-reductase (DFR), anthocyanidin synthase (ANS), flavonol synthase (FLS) and leucoantho cyanidin reductase (LAR) enzymes in three new purple shoot tea clones compared with normal tea clone showed higher expression of CsDFR, CsANR, CsANS and lower expression of CsFLS and CsLAR in purple shoot clones compared to normal clone. Expression pattern supported high content of anthocyanins in purple tea. Four anthocyanins (AN1-4) were isolated and characterized by UPLC-ESI-QToF-MS/MS from IHBT 269 clone which recorded highest total anthocyanins content. Cyanidin-3-O-ß-d-(6-(E)-coumaroyl) glucopyranoside (AN2) showed highest in vitro antioxidant activity (IC50 DPPH = 25.27 ± 0.02 µg/mL and IC50 ABTS = 10.71 ± 0.01 µg/mL). Anticancer and immunostimulatory activities of cyanidin-3-glucoside (AN1), cyanidin-3-O-ß-d-(6-(E)-coumaroyl) glucopyranoside (AN2), delphinidin-3-O-ß-d-(6-(E)-coumaroyl) glucopyranoside (AN3), cyanidin-3-O-(2-O-ß-xylopyranosyl-6-O-acetyl)-ß-glucopyranoside (AN4) and crude anthocyanin extract (AN5) showed high therapeutic perspective. Anthocyanins AN1-4 and crude extract AN5 showed cytotoxicity on C-6 cancer cells and high relative fluorescence units (RFU) at 200 µg/mL suggesting promising apoptosis induction activity as well as influential immunostimulatory potential. Observations demonstrate potential of purple anthocyanins enriched tea clone for exploitation as a nutraceutical product.

Screening and purification of catechins from underutilized tea plant parts and their bioactivity studies.

Comparative investigation of major phytoconstituents was performed from various parts of tea plant viz. apical bud, subtending 1st-5th leaf, stem, coarse leaves, flowers, fruits and roots. From the results of comparative RP-HPLC-DAD analysis it was found that underutilized tea parts especially coarse leaves, flowers and fruits contains abundant amount of phenolics (17.5%) and catechins (4-5%). From these underutilized tea plant parts the catechins were extracted and purified and then screened for their anticancer, immunomodulatory effect and antimicrobial activity against food borne pathogens. The results showed that tea fruit extract exhibited higher toxicity against oral cancer cells and also promotes proliferation of mice splenocytes. The results of antimicrobial studies revealed the inhibitory effect of these extracts against both gram positive and gram negative bacteria. These investigations clearly demonstrated that the underutilized tea plant parts could act as economical and sustainable bioresource of functionally active constituents which further lead to the development of new cost-effective nutraceuticals and other formulations.

Osmotin-expressing transgenic tea plants have improved stress tolerance and are of higher quality.

Drought is a major stress that affects the yield and quality of tea, a widely consumed beverage crop grown in more than 20 countries of the world. Therefore, osmotin gene-expressing transgenic tea plants produced using earlier optimized conditions were evaluated for their tolerance of drought stress and their quality. Improved tolerance of polyethylene glycol-induced water stress and faster recovery from stress were evident in transgenic lines compared with the normal phenotype. Significant improvements in growth under in-vitro conditions were also observed. Besides enhanced reactive oxygen species-scavenging enzyme activity, the transgenic lines contained significantly higher levels of flavan-3-ols and caffeine, key compounds that govern quality and commercial yield of the beverage. The selected transgenic lines have the potential to meet the demands of the tea industry for stress-tolerant plants with higher yield and quality. These traits of the transgenic lines can be effectively maintained for generations because tea is commercially cultivated through vegetative propagation only.

Interpretation of Indian orthodox tea using multi-sensing impedometric technique.

Twelve different orthodox Indian tea samples were collected from tea growing and processing sites of Kangra (Valley), India. The percentage of major chemical constituents responsible for the tea quality has been determined by HPLC and UV-vis spectrophotometer. Impedance response using Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC), Polyaniline (PANI) (emraldine salt) and Poly Pyrrole (PPY) working electrodes in tea infusions in the frequency range of 1 Hz to 100 kHz has been measured for 30 days on each tea sample. The impedance response of these working electrodes along with the determined chemical concentrations was subjected to Principal Component Analysis (PCA). It was possible to map the antioxidant levels in these tea samples with few exceptions from the score plot of PCA.

Analysis of the essential oil of large cardamom (Amomum subulatum Roxb.) growing in different agro-climatic zones of Himachal Pradesh, India.

BACKGROUND: The aim of the present study was to investigate variations in the chemical composition of the essential oil from seeds of large cardamom grown at different altitudes in Himachal Pradesh, India. The composition of the essential oil was determined by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). RESULTS: The oil components showed qualitative and quantitative variations in the composition. GC and GC-MS analysis led to the identification of 55 compounds representing 98% of total oil. Major components in the oil were 1,8-cineole, α-terpineol, DL-limonene, nerolidol, 4-terpineol, δ-terpineol, δ-3-carene, ß-myrcene, germacrene D, α-terpinene and longifolenaldehyde. The oil yields obtained were 9.8-19.5 g kg(-1). Cardamom oil from Himachal Pradesh was found to contain new compounds, viz. 4-terpineol, δ-3-carene, trans-sabinene hydrate, 1-phellandrene, α-terpinene, bicyclo-germacrene, isopinocarveol and ledenoxid-II. α-Terpenyl acetate, the major constituent of small cardamom, was also detected in the oil of large cardamom grown in Himachal Pradesh. Application of aroma extract dilution analysis revealed 35 compounds having aroma impact with the flavour dilution factor ranging from 2 to 1024, and 34 of these compounds were identified. The five most intense aromatic components are dl-limonene, 1,8-cineole, ß-myrcene, α-pinene, α-basabolol. This is the first time that the characterisation of odour-active compounds has been carried out on large cardamom. CONCLUSION: The presence of 4-terpineol, δ-3-carene, trans-sabinene hydrate, 1-phellandrene, α-terpinene, 1-terpineol, bicyclogermacrene, isopinocarveol, ledenoxid-II, longifolenaldehyde and α-terpenyl acetate make the aroma of the oil different from large cardamom oil of Sikkim and could offer potential as a new food flavour.

Nutritional and neutraceutical composition of five wild culinary-medicinal species of genus Pleurotus (higher Basidiomycetes) from northwest India.

Five wild culinary-medicinal species of genus Pleurotus (Fr.) P. Kumm. (P. floridanus Singer, P. pulmonarius (Fr.) Quél., P. sapidus Quél., P. cystidiosus O.K. Miller, and P. sajor-caju (Fr.) Singer), collected from different localities of Northwest India, were studied for their nutritional and nutraceutical composition. Composition analysis of nutrients involved determining proteins, fats, ash, fiber, and carbohydrates using standard biochemical techniques. Minerals were estimated by an atomic absorption spectrophotometer and toxic metals were determined by the Reinsch test method. The analysis of nutraceuticals included determination of sugars by high-performance liquid chromatography, fatty acids by gas chromatography, and antioxidants such as ß-carotene, lycopene, and total phenolic compounds with methanolic extract using a colorimetric assay. In the samples analyzed, carbohydrates dominated over protein and other macronutrients. Carbohydrates ranged from 85.86 to 88.38%, protein 0.98 to 2.17%, crude fat 0.62 to 0.84%, crude fibers 2.76 to 3.12%, and ash content 1.03 to 2.20%. Macro- and microminerals (calcium, magnesium, sodium, potassium, copper, zinc, and iron) also were found in substantial amount, whereas toxic metals (lead, silver, arsenic, mercury, and antimony) were not detected. Three main sugars-sucrose (0.338-2.011%), glucose (0.553-0.791%), and xylose (0.01%)-were detected. Among fatty acids, monounsaturated fatty (37.17-68.29%) acids were documented in a higher proportion than saturated fatty acids (26.07-47.77%). In terms of antioxidant composition, all species contained ascorbic acid, phenols, carotene, and lycopene. Ascorbic acid content ranged from 0.46 to 0.49 mg/100 g, total phenolic compounds ranged from 6.76 to 16.92 mg/100 g of gallic acid, ß-carotene ranged from 0.134 to 0.221 µg/100 g, and lycopene from 0.055 to 0 .075 µg/100 g.

Targeted UHPLC-QTOF-IMS based metabolite profiling for bioactive compounds in Rosa webbiana wallich ex royle: An unexploited native from western himalayas.

The current study focused on the tissues of wild Rosa webbiana from different altitudes of Indian Western Himalayas for vitamin C content, total phenolics, flavonoids, total sugars, and antioxidant potential. To date, there are very few studies on underutilized tissues viz. fruits, leaves and stem of Rosa webbiana growing in the higher altitudes. The targeted UHPLC-QTOF-IMS illustrated the phenolics fingerprinting of tissue extracts. Twelve bioactive compounds were detected with quercetin, kaempferol, and their derivatives dominantly in stem and leaves. The results have revealed that fruits possessed the highest vitamin C, and sugar contents (960, and 191.6 mg/100 g, respectively). Compared to other tissues, leaves showed the highest total phenolics as well as best results in vitro assays employed to assess antioxidant potential. The antioxidant activity showed a positive correlation with total phenolics. A significant variation in total phenolics, total flavonoids, and antioxidant potential was mainly attributed to oxidative stress on plants due to altitude difference, and secondary metabolite production. Taken together, the underutilized tissues of Rosa webbiana could be exploited as a promising, low-cost resource of phenolic compounds in food, cosmetic, and pharmaceutical industries. Our study will pave the way to developing food products from Rosa webbiana, a natural source for health-conscious people.

Biochemical Characterization of γ-Glutamyl Transpeptidase from Bacillus altitudinis IHB B1644 and Its Application in the Synthesis of l-Theanine.

An extracellular γ-glutamyl transpeptidase (GGT) produced from Bacillus altitudinis IHB B1644 was purified to homogeneity employing ion-exchange chromatography. GGT comprised two subunits of 40 and 22 kDa determined by SDS-PAGE. The maximum enzyme activity was optimal at pH 9 and 37 °C. The purified enzyme was stable from pH 5-10 and <50 °C. Steady-state kinetic studies revealed a Km value of 0.538 mM against γ-GpNA. For substrate specificity, GGT showed highest affinity for l-methionine. The inhibitors' effect demonstrated that serine or threonine and tryptophan residues are essential for enzyme activity. l-Theanine production was optimized by employing a one-variable-at-a-time approach with 60-65% conversion rate. The final reaction consisted of 20 mM l-glutamine, 200 mM ethylamine hydrochloride, and 10 U mL-1 enzyme concentration at 37 °C in Tris-Cl (50 mM, pH 9) for 5 h. l-Theanine was purified using a Dowex 50W X 8 hydrogen form resin and confirmed by HPLC and 1H NMR spectroscopies.

Selective binding of Ni2+ and Cu2+ metal ions with naphthazarin esters isolated from Arnebia euchroma.

Naphthazarin esters (C1-C4) isolated from the roots of Arnebia euchroma are found as skilled dual chemosensors for Ni2+ and Cu2+ among Pb2+ , Na2+ , K2+ , Hg2+ , Mg2+ , and Ca2+ metal ions. C1-C4 esters exhibited a red shift of 54 nm with Ni2+ and 30 nm with Cu2+ metal ions in absorption. There is a formation of red-shifted bands between 517 and 613 nm in the absorption spectrum of C1-C4 sensors on binding with Ni2+ and Cu2+ ions. The addition of Ni2+ and Cu2+ ions to sensors C1-C4 stimulates a remarkable color change from reddish pink to purple and light blue, respectively. These color changes can be identified with the naked eye. The significant downfield shifts of CO and OH peaks in nuclear magnetic resonance (NMR) spectrum confirm the chelation as binding mechanism. With ultraviolet-visble and NMR studies, it is found that C1-C4 esters possessed notable selectivity and sensitivity toward Ni2+ and Cu2+ over other metal ions.

Statistical optimization of culture conditions of mesophillic gamma-glutamyl transpeptidase from Bacillus altitudinis IHB B1644.

Microbial gamma-glutamyl transpeptidase (GGT) is a key enzyme in production of several γ-glutamyl compounds with food and pharmaceutical applications. Bacterial GGTs are not commercially available in the market owing to their low production from various sources. Thus, the study was focused on achieving the higher GGT production from B. altitudinis IHB B1644 by optimizing the culture conditions using one-variable-at-a-time (OVAT) strategy. A mesophillic temperature of 28 °C, agitation 200 rpm and neutral pH 7 were found to be optimal for higher GGT titre. Among the medium components, the monosaccharide glucose served as the best carbon source over disaccharides, and yeast extract was the preferred organic nitrogen source over inorganic nitrogen sources. The statistical approaches (Plakett-Burman and response surface methodology) were further employed for the optimization of medium components. Medium composition: 0.1% w/v glucose, 0.3% w/v yeast extract, 0.03% w/v magnesium sulphate, 0.20% w/v potassium dihydrogen phosphate and 2.5% w/v sodium chloride with inoculum size (1% v/v) was suitable for higher GGT titres (449 U ml-1). Time kinetics showed the stability of enzyme up to 96 h of incubation suggesting its application in the industrial use. The proposed strategy resulted in 2.6-fold increase in the GGT production compared to that obtained in the unoptimized medium. The results demonstrated that RSM was fitting to identify the optimum production conditions and this finding should be of great importance for commercial GGT production.