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Purification and properties of enantioselective ester hydrolase from a strain of Trichosporon species (DSMZ 11829)
No full textAn isolated strain of Trichosporon species (DSMZ 11829) was capable of producing a novel membrane-bound, enantioselective ester hydrolase. Its application in the kinetic resolution of racemic methyl ester of 6-methoxy-�-methyl-2-naphthaleneacetic acid (naproxen) into
(S)-(+)-naproxen (>99% ee, E∼500) and acyloxy derivatives of 1-chloro-3-(1-naphthyloxy)-2-propanol into (R)-alcohol (>99% ee, E∼550) have already been reported by us. The enzyme designated as TSL was extracted from the cells by toluenization and purified to homogeneity from cell free extract with 8.5% overall yield. The purified enzyme with a specific activity of 831 U/mg protein was achieved by column
chromatography using DEAE-Sepharose, phenyl-Sepharose and Sephadex G-100 resins. The purified enzyme exhibited hydrolytic activity without any noticeable decrease in the rate of hydrolysis or its enantioselectivty in the resolution of racemic naproxen into (S)-(+)-naproxen or
in the resolution of 1-chloro-3-(1-naphthyloxy)-2-propanol and 1-(6-methoxy-2-naphthyl)ethanol. Purified enzyme is a glycosylated monomer with a molecular weight of∼40 kD and isoelectric point (pI)∼4.1. TSLwas maximally active at 30 ◦C and pH 8.0. The enzymewas insensitive to serine reactive agent PMSF, metal chealator EDTA, non-ionic detergent Triton X-100 and reducing agent mercaptoethanol. The N-terminal amino acid sequence of TSL determined as Thr-Val-Thr-Thr-Pro-Thr-Leu-Ser-Ala-Asp-Ala-Lys-Lys-Gly- did not reveal any homology with the N-terminal amino acid sequence of any other known microbial ester hydrolases
Rapid, inexpensive MIC determination of Mycobacterium tuberculosis isolates by using microplate nitrate reductase assay
No full textA rapid colorimetric, microplate-based nitrate reductase assay (NRA) method for antibiotic susceptibility profile of clinical isolates of Mycobacterium tuberculosis was compared with Alamar Blue assay (ABA). The results obtained by both the methods were also compared with conventional agar proportion method. The overall agreement between the results obtained by NRA and ABA was 99% and 98%, respectively, when compared with agar proportion method. Reproducible results for all the isolates were obtained within 8 days by NRA as well as ABA. The specificity of NRA method for M. tuberculosis makes it more suitable method for MIC determination
Isolation of an N-acetyl-d-glucosamine specific lectin from the rhizomes of Arundo donax with antiproliferative activity
No full textA lectin with antiproliferative activity towards human cancer cell lines and mitogenic towards human peripheral blood mononuclear cells was purified from the rhizomes of Arundo donax (Linn.) by affinity chromatography on N-acetyl-D-glucosamine linked to epoxy-activated sepharose-6B. The pure preparation apparently yielded a single band of approximately 15 kDa on SDS–PAGE,pH 8.3, under both reducing and non-reducing conditions. The molecular mass of native lectin was 32 kDa as determined by gel filtration chromatography. This showed the lectin to be a dimer, with subunits not held together by disulphide linkages. The A.
donax lectin (ADL) agglutinated rabbit erythrocytes and the agglutination was inhibited by N-acetyl-D-glucosamine and its diand trimer. The lectin was thermostable upto 55 �C and showed optimum activity in the range of pH 7.0–9.0 and comprised of 2.1% carbohydrate content
Catalytic transfer hydrogenation reactions of PEG-bound succinyl esters
No full textVarious substrates bound to polyethylene glycol (PEG) through succinyl ester linkages were cleaved under catalytic transfer hydrogenation conditions. The substrates with unsaturated functions also underwent hydrogenation. The protocol was found to be suitable for substrates having acid and base labile functional groups
Molecular cloning of enantioselective ester hydrolase fromBacillus pumilusDBRL-191
No full textA gene from Bacillus pumilus expressed under its native promoter was cloned in Escherichia coli. Recombinant B. pumilus esterase(BPE) affects the kinetic resolution of racemic mixtures such as unsubstituted and substituted 1-(phenyl)ethanols (E � 33–103), ethyl 3-hydroxy-3-phenylpropanoate (E � 45–71), trans-4-fluorophenyl-3-hydroxymethyl-N-methylpiperidine (E � 10–13) and ethyl 2-
hydroxy-4-phenylbutyrate (E � 7). The enzyme is composed of a 34-amino acid signal peptide and a 181-amino acid mature protein corresponding to a molecular weight of �19.2 kD and pI � 9.4. 3-D the structural model of the enzyme built by homology modelling using the atomic coordinates from the crystal structure of B. subtilis lipase (LipA) showed a compact minimal a/b hydrolase fold
Synthesis and biological evaluation of chalcones and their derived pyrazoles as potential cytotoxic agents
No full textA series of substituted chalcones and their corresponding pyrazoles were synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 93 compounds screened, 8 compounds, 1s, 3i,j,n, 4i,j,n and 4s, showed marked activity. Compounds 4j,n and 4s were found to be the most promising in this study. SAR is also discussed
Trichosporon beigelli esterase (TBE): a versatile esterase for the resolution of economically important racemates
No full textA hydrolase producing strain Trichosporon beigelli esterase (TBE) isolated from local cottage cheese in its native form has displayed versatility and high efficacy in the kinetic resolution of a wide range of economically important substrates, which include racemic secondary alcohols, such as 1-(6-methoxy-2-naphthyl)ethanol (E � 316), 1-(3,4-methylenedioxyphenyl)ethanol and pentanol(E � 180 and 156 resp.), and alkyl esters of carboxylic acids such as ibuprofen (E � 340), 2-(benzylthio)propanoic acid
(E � 1000). In other substrates such as in the primary alcohol 2-(6-methoxy-2-naphthyl)propan-1-ol and carboxylic acids such as 2-(5-bromo-6-methoxy-2-naphthyl)propanoic acid, 2-(2-naphthyloxy)propanoic acid, and substituted 2-thiopropanoic acids, it displayed moderate to low selectivity. Commercial lipases such as CCL, PPL, and PSL were also used in the resolution of the substrates
for comparative studies
Determination of essential oil quality index by using energy summation indices in an elite strain ofCymbopogon citratus (DC) Stapf [RRL(J)CCA12]
No full textOut of the several accessions of Cymbopogon citratus (DC) Stapf introduced from Central and West India, one accession coded as RRL(J)CCA12, selected through a mass selection technique, was found to have citral (≈80%)as the major constituent in its essential oil. Citral has tremendous application in the flavour and perfume industries. Plant
adaptation was judged by quantifying the regression coefficient (b) value, which was 1.0 using essential oil growth indices.For prediction of essential oil quality index (EOQI), a multiple regression equation was developed for the first time by using essential oil yield/plant and energy summation indices as EOQI (citral %) = 61.6 + 1.09 × essential oil yield/plant(g) − 0.005 × heat use efficiency + 0.675 × phenothermal index. For obtaining a better quality of essential oil (citral ≥78%),the optimal value of independent variable would be: X1 = 2.49; X2 = 0.018 and X3 = 20.47, where X1, X2 and X3 denote essential oil yield/plant, heat use efficiency and phenothermal index, respectively. The validation of the EOQI model is done by correlating the predicted and calculated values of citral (%) which exhibited significant r value = 0.955 at 5%
probability level. The thermal requirement of the selectant was ≈5500 degree days to exhibit plant maturity in terms of
qualitative and quantitative characteristics of its essential oil at 6.0 vegetative leafing stage, with attainment of plant height ≥1.0 m from previous date of harvest (December 2001). Prediction of essential oil quality by using the mathematical model is helpful for integrating the growth processes and evaluating crop management strategies. Copyright © 2004 John Wiley
& Sons, Ltd
Epivernadol diacetate
No full textIn the crystal structure of the title compound, (4aR,5R,6S,7S,8aS)-methyl 8a-ethenyloctahydro-5-acetoxy-7-{[2-(acetoxymethyl)-1-oxo-2-propenyl]oxy}-[alpha],4-bis(methylene)-3-oxo-1H-2-benzopyran-6-acetate, C24H28O10, the molecule has a cis configuration at the junction of the two six-membered rings and not a trans configuration as was assigned on the basis of NMR data in solution [Asaka et al. (1977). Phytochemistry, 16, 1838-1839]
Immunosuppressive properties of an ethyl acetate fraction from Euphorbia royleana
No full textThe objective of the study was to investigate the activity of the ethyl acetate (EA) fraction of Euphorbia royleana latex on cellular and humoral-mediated immune responses and phagocytic function of the cells of the reticuloendothelial system in mice. Oral administration of EA at doses of 50, 100 and 200 mg/kg p.o. in mice with sheep red blood cells (SRBC) as an antigen-inhibited both the delayed-type hypersensitivity reaction and the production of circulating antibody titre. Reduction of CD4+ T cell counts in the peripheral whole blood and the neutrophil counts in pleural exudates of the animals treated with EA was observed by flowcytometric analysis. Process of phagocytosis was also inhibited in in vivo and in vitro experimental test models. The oral LD50 in both rats and mice was more than 2.5 g/kg body weight