Kinetic resolution of 1-chloro-3-(1-naphthyloxy)-2-propanol,an intermediate in the synthesis of beta-adrenergic receptor blockers

(R)- and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol are intermediates in the synthesis of β-adrenergic blocking agents and antihypertensive drugs such as propranolol and nadoxolol. Herein, improvement in the preparation of racemic 1-chloro-3-(1-naphthyloxy)-2-propanol generated from 1-naphthol and epichlorohydrin are reported. In addition, kinetic resolution studies have been conducted to obtain both (R) and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol. These compounds were obtained in highly optically pure form by the stereoselective hydrolysis of its acyl derivatives using whole cell preparations containing enzymes from native sources. The results were compared with those obtained using commercial lipases.     

Purification of a moderate thermotolerant Bacillus coagulans BTS1 lipase and its properties in a hydro-gel system

An alkaline thermotolerant lipase of Bacillus coagulans BTS1 was successively purified by ammonium sulfate precipitation and DEAE anion exchange chromatography. The purified lipase immobilized in alginate beads showed an optimal activity at pH 7.5 and 55 degrees C. A pH of 5.0 or 10.0 completely quenched the activity of immobilized lipase. The alginate-bound lipase retained its activity following exposure to most of the organic solvents including amines, alkanes and alcohols. Chloride salt of Al3+, Co2+, Mg2+ and NH4+ modulated the lipase activity of alginate-immobilized enzyme. The alginate entrapped lipase showed a preferentially high activity towards p-nitrophenyl palmitate (C: 16) and activity of matrix increased following exposure to SDS. Moreover, the immobilized lipase retained more than 50% of its activity after 3rd cycle of reuse.     

Enhancement of ethyl propionate synthesis by poly (AAc-co-HPMA-cl-MBAm)-immobilized Pseudomonas aeruginosa MTCC-4713, exposed to Hg2+ and NH4+ ions

A purified alkaline thermo-tolerant bacterial lipase from Pseudomonas aeruginosa MTCC-4713 was immobilized on a poly (AAc-co-HPMA-cl-MBAm) hydrogel. The hydrogel-bound lipase achieved 93.6% esterification of ethanol and propionic acid (300 mM: 100 mM) into ethyl propionate at temperature 65 degrees C in 3 h in the presence of a molecular sieve (3 angstroms). In contrast, hydrogel-immobilized lipase pre-exposed to 5 mM of HgCl2 orNH4Cl resulted in approximately 97% conversion of reactants in 3 h into ethyl propionate under identical conditions. The salt-exposed hydrogel was relatively more efficient in repetitive esterification than the hydrogel-bound lipase not exposed to any of the cations. Moreover, bound lipase exposed Hg2+ or NH4+ ions showed altered specificity towards p-nitrophenyl esters and was more hydrolytic towards higher C-chain p-nitrophenyl esters (p-nitrophenyl laurate and p-nitrophenyl palmitate with C 12 and C 16 chain) than the immobilized lipase not exposed to any of the salts. The later showed greater specificity towards p-nitrophenyl caprylate (C 8).     

Bioreduction of a carbon–nitrogen double bond using immobilized baker''s yeast’a first report

Immobilized baker's yeast entrapped in calcium alginate beads efficiently reduces N-benzylidinemethylamine to N-methylbenzylamine in hexane at 37°C and tetrahydrofuran (THF) at 30°C in the presence of 18-crown-6, while in the presence of water as cosolvent and glucose as an additive N-benzylidinemethylamine undergoes decomposition. Benzaldoxime in a hexane–water (1:9) solvent system containing glucose as an additive is reduced to N-benzylhydroxylamine. On using an ethanol–water (1:1) solvent system, benzaldoxime is converted to benzyl alcohol and in hexane, benzene, THF, hexane–water (1:1) or acetonitrile–water (1:1) solvent systems, or using dried baker's yeast in different solvent systems, transformation of benzaldoxime does not occur.     

Biological treatment of textile dye acid violet-17 by bacterial consortium in an up-flow immobilized cell bioreactor

AIMS: To develop a cost effective and efficient biological treatment process for small scale textile processing industries (TPI) releasing untreated effluents containing intense coloured Acid violet-17 (AV-17), a triphenyl methane (TPM) group textile dye. METHODS AND RESULTS: The samples collected from effluent disposal sites of TPI were used for selective enrichment of microbial populations capable of degrading/decolourizing AV-17. A consortium of five bacterial isolates was used to develop an up-flow immobilized cell bioreactor for treatment of feed containing AV-17. The bioreactor, operating at a flow rate of 6 ml x h(-1), resulted in 91% decolourization of 30 mg AV-17/l with 94.3 and 95.7% removal of biochemical oxygen demand and chemical oxygen demand of the feed. Comparison of the input and output of the bioreactor by UV-visible, thin layer chromatography and (1)H-nuclear magnetic resonance spectroscopy indicates conversion of the parent dye into unrelated metabolic intermediates. SIGNIFICANCE: These results will form a basis for developing 'on-site' treatment system for TPI effluents to achieve decolourization and degradation of residual dyes.     

Enantioselective resolution of 3-phenylthio-2-propanol with Humicola lanuginosa lipase

The acetylation of 3-phenylthio-2-propanol (168 mg) was performed with vinyl acetate (1 ml) using different lipases from 15°C to 51°C. As a result, the (R)-enantiomer was selectively acetylated and the (S)-enantiomer was non-reactive in all the cases. An appropriate choice of conditions can be made to isolate both (R)-alcohol (ee 99%, 36 h, conversion 46%, sub/enz: 1/2) and (S)-alcohol (ee 93%, 38 h, conversion 46%, THF, sub/enz: 1 l^–1) using Humicola lanuginosalipase (Lipolase). Increasing the amount of enzyme increased the ee.     

Biodegradation of acid blue-15, a textile dye,by an up-flow immobilized cell bioreactor

Acid blue-15, a complex and resonance-stabilized triphenylmethane (TPM) textile dye, resistant to transformation, was decolorized/degraded in an up-flow immobilized cell bioreactor. A consortium comprised of isolates belonging to Bacillus sp., Alcaligenes sp. and Aeromonas sp. formed a multispecies biofilm on refractory brick pieces used as support material. The TPM dye was degraded to simple metabolic intermediates in the bioreactor with 94% decolorization at a flow rate of 4 ml h^–1.     

Candida antarctica lipase-B-catalyzed kinetic resolution of 1,3-dialkyl-3-hydroxymethyl oxindoles

Candida antarctica (CAL-B) lipase-catalyzed resolution of 1,3-dialkyl-3-hydroxymethyl oxindoles has been performed to obtain (R)-1,3-dialkyl-3-acetoxymethyl oxindoles with up to 99% ee and (S)-1,3-dialkyl-3-hydroxymethyl oxindoles with up to 78% ee using vinyl acetate as acylating agent and acetonitrile as solvent transforming (S)-3-allyl-3-hydroxymethyl oxindole to (3S)-1′-benzyl-5-(iodomethyl)-4,5-dihydro-2H-spiro[furan-3,3′-indolin]-2′-one. The optically active 3-substituted-3-hydroxymethyl oxindoles and spiro-oxindoles are among the key synthons in the synthesis of potentially biologically active molecules.     

Bioresolution of racemic phenyl glycidyl ether by a putative recombinant epoxide hydrolase from <Emphasis Type="Italic">Streptomyces griseus</Emphasis> NBRC 13350

In order to produce enantiomerically pure epoxides for the synthesis of value-added chemicals, a novel putative epoxide hydrolase (EH) sgeh was cloned and overexpressed in pET28a/Escherichia coli BL21(DE3). The 1047 bp sgeh gene was mined from Streptomyces griseus NBRC 13350 genome sequence. The recombinant hexahistidyl-tagged SGEH was purified (16.6-fold) by immobilized metal-affinity chromatography, with 90% yield as a homodimer of 100 kDa. The recombinant E. coli whole cells overexpressing SGEH could kinetically resolve racemic phenyl glycidyl ether (PGE) into (R)-PGE with 98% ee, 40% yield, and enantiomeric ratio (E) of 20. This was achieved under the optimized reaction conditions i.e. cell/substrate ratio of 20:1 (w/w) at pH 7.5 and 20?°C in 10% (v/v) dimethylformamide (DMF) in a 10 h reaction. 99% enantiopure (R)-PGE was obtained when the reaction time was prolonged to 12 h with a yield of 34%. In conclusion, an economically viable and environment friendly green process for the production of enantiopure (R)-PGE was developed by using wet cells of E. coli expressing recombinant SGEH.     

Effect of Solvents and Kinetic Parameters on Synthesis of Ethyl Propionate Catalysed by Poly (AAc-co-HPMA-cl-MBAm)-Matrix-Immobilized Lipase of Pseudomonas aeruginosa BTS-2.

Summary A purified alkaline thermo-tolerant bacterial lipase from Pseudomonas aeruginosa BTS-2 was immobilized on a poly (AAc-co-HPMA-cl-MBAm) hydrogel network. The hydrogel showed approximately 95% binding efficiency for lipase (specific activity 1.96 U mg⁻¹). The immobilized enzyme achieved 65.1% conversion of ethanol and propionic acid (100 mM each) into ethyl propionate in n-nonane at 65 °C in 9 h. When alkane of C-chain length lower than n-nonane was used as the organic solvent, the conversion of ethanol and propionic acid into ethyl propionate decreased with a decrease in the log P value of alkanes. The immobilized lipase retained approximately 30% of its original catalytic activity after five cycles of reuse for esterification of ethanol and propionic acid into ethyl propionate at temperature 65 °C in 3 h. Addition of a molecular sieve (3 ?) to the reaction mixture enhanced the formation of ethyl propionate to 89.3%. Moreover, ethanol and propionic acid when taken a molar ratio of 3:1 further promoted the conversion rate to 94%. However, an increase in the molar ratio of propionic acid with respect to ethanol resulted in a decline of ethyl propionate synthesis.