Syntheses of Enantiopure Aliphatic Secondary Alcohols and Acetates by Bioresolution with Lipase B from <em>Candida antarctica</em>

The lipase B from Candida antarctica (Novozym 435^?, CALB) efficiently catalyzed the kinetic resolution of some aliphatic secondary alcohols: (±)-4-methylpentan-2-ol (1), (±)-5-methylhexan-2-ol (3), (±)-octan-2-ol (4), (±)-heptan-3-ol (5) and (±)-oct-1-en-3-ol (6). The lipase showed excellent enantioselectivities in the transesterifications of racemic aliphatic secondary alcohols producing the enantiopure alcohols (>99% ee) and acetates (>99% ee) with good yields. Kinetic resolution of rac-alcohols was successfully achieved with CALB lipase using simple conditions, vinyl acetate as acylating agent, and hexane as non-polar solvent.     

Chemoenzymatic synthesis of piperoxan,prosympal, dibozane,and doxazosin

The synthesis of both enantiomers of 1,4-benzodioxan-2-carboxylic acid 1, a key synthetic intermediate for the therapeutic agents piperoxan, prosympal, dibozane, and doxazosin was achieved with good yields and high enantioselectivities via the Arthrobacter sp. lipase catalyzed kinetic resolution of ester (±)-17a. The influence of the co-solvents and the immobilization of the lipase upon kinetic resolution demonstrated that immobilized whole cells, in the presence of n-butanol as a co-solvent, resulted in the optimal resolution of the substrate (ee ～99%, E = 535) at 258 mmol (50 g/L) substrate concentration.     

Extraction of acephate pesticide in environmental and agricultural samples by spectrophotometric method

In the present study, we have synthesis the azo dye for the reaction of p-amino antipyrine with HCl in NaNO₂ solution a 1:1 ​M ratio that was kept -5°C for 1–2 ​h, as result the absorption spectra observed at λ_max ​= ​460 ​nm. Beer’s law is obeyed over the awareness variety of 1 ​μg–100 ​μg ​mL^-1. The standard deviation and relative well-known deviation are 0.007 and 1.38%. The molar absorptivity and Sandell's sensitivity had been located to be 0.98 ​× ​10⁵ ​L ​mol^-1 ​cm^-1 and 0.99 ​× ​10^-3 ​μg ​cm^-2, respectively. Spectroscopy method used for the detection of Acephate pesticides on vegetable, fruit, soil, and water samples. FTIR method was used to consider and achieve structural information about the presented intermolecular interactions for vegetable samples. The eco-friendliness of the developed methods was assessed using the spectroscopy analytical tool on vegetables, fruit, soil, and water samples.     

The influence of microwave irradiation on lipase-catalyzed kinetic resolution of racemic secondary alcohols

The influence of microwave irradiation on the Novozyme 435^® (Candida antarctica lipase) catalyzed kinetic resolution of secondary alcohols with different functional groups was studied in comparison to the use of conventional heating at 60 °C. p-Chlorophenyl acetate was used as an acyl donor and toluene as the solvent. (±)-1-Phenyl-1-propanol 1, (±)-1-(4-bromophenyl)-propan-1-ol 3, (±)-1-phenylbut-3-en-1-ol 5 and (±)-3-bromo-2-(2-hydroxypropyl)-1,4-dimethoxynaphthalene 7 were successfully resolved into their (S)-alcohols and (R)-esters, respectively, in good enantiomeric excess. Resolution of (±)-ethyl-5-(4-methoxybenyloxy)-3-hydroxypentanoate 9 afforded its (R)-alcohol and (S)-ester using this method. In addition, microwave-assisted lipase transesterification of meso-symmetric diol 11 effected desymmetrization to ester 12 with high enantiomeric excess. In all cases studied, the conversion value for the microwave-assisted lipase kinetic resolution of secondary alcohols was higher than that obtained using conventional heating.     

Exploring the potential of biodiesel derived crude glycerol into high value malic acid: Biosynthesis,process optimization and kinetic assessment

In this study, Zygosaccharomyces rouxii, a sugar tolerant yeast culture was explored for the production of high value malic acid using crude glycerol from biodiesel plant. In addition, the effect of addition of glutamic acid (precursor) (0.25 to 1%), temperature (15 to 30 ​°C) and time (0 to 24 days) of the fermentation process was also investigated by both conventional as well as Response Surface Methodology (RSM). The highest malic acid of 72.1 ​± ​0.05 ​g/L was obtained and RSM predicts the accurate optimized conditions such as 30% crude glycerol concentration in the fermentative media with 0.75% addition of precursor with initial pH 5 ​at 20 ​°C for 20 days. This study reveals that the crude glycerol can be efficiently used and the production of malic acid was raised with 3 folds correspond to no precursor under optimal conditions. The growth and product kinetics were studied by Monod, Logistic, Leudeking Piret as well as Logistic incorporated Leudeking-Piret models with and without precursor and Logistic incorporated Leudeking-Piret model allowed the best fit for the malic acid production.     

Highly enantioselective enzymatic resolution of aromatic β-amino acid amides with Pd-catalyzed racemization

The kinetic resolution of an aromatic β-amino acid amide 3a–d via N-acylation was explored with two lipases, Candida antarctica lipase A (CALA) and Pseudomonas stutzeri lipase (PSL). The PSL-catalyzed resolution proceeded with excellent enantioselectivity (E = >400) to give both acylated products and unreacted substrates in enantiopure forms. Three additional aromatic β-amino acid amides 3b–d were also resolved by PSL with a high level of enantioselectivity (E = >200). The PSL-catalyzed resolution of 3a was coupled with a Pd-catalyzed racemization to obtain enantiopure N-acylated product (R)-4a (>99% ee) in high yield (90%).     

Enantiomeric resolution by lipase-catalysed esterification of a trans-5,6-dihydro-1,10-phenanthroline possessing helical and central chirality

Lipase-catalysed enantioselective esterification was carried out to obtain the kinetic resolution of (±)-trans-5-hydroxy-6-methoxy-1,10-phenanthroline (±)-1b. Different lipases from Candida cylindracea, Candida antarctica, Rhizomucor miehei, Pseudomonas fluorescens and Pseudomonas cepacia were tested in an unusual methanol/vinyl acetate (8:92 v/v) reaction mixture P. fluorescens lipase showed good enantiodifferentiation (E = 48) and allowed us to prepare both enantiomers (+)-(5S,6S,M)-1b and (−)-(5R,6R,P)-1b with an enantiomeric excess of >97%.     

Phytochemical analysis and antidiabetic efficacy of Morus rubra

Morus rubra (red mulberry) is a folk medicine used in management of diabetes. The aim of this article to investigate the antidiabetic activity of hydro alcoholic leaf extracts of Morus rubra in the sprague dawley male rats (SD) model. Authentication of plant material, total Phenolic contents, total flavonoid contents, HPLC analysis, in-vitro antioxidant activity, acute toxicity, in-vivo oral glucose tolerance test, in-vivo STZ induced antidiabetic activity along with biochemical parameters (triglycerides, low-density lipoprotein, high-density lipoprotein, total cholesterol, serum glutamate phosphotransferase, serum glutamate oxaloacetic acid transferase, urea and creatinine). The total phenolic contents 60.32 ​± ​0.80 ​mg/g GAE (gallic acid equivalent) were found higher in ethanolic extract. The total flavonoids 16 ​± ​0.42 ​mg/g QE (quercetin equivalent) were found in petroleum ether extract. M. rubra leaf extracts were tested by HPLC for qualitative and quantitative analysis. 100 ​mg of the dried powder of Morus leaves was dissolve in methanol: water (80:20, v/v) for analysis. Chromatograms of HPLC show the presence of chlorogenic acid 0.55 mg/gm, quercetin 1.90 ​mg/g, isoquercetin 0.68 mg/gm and rutin 0.10 mg/gm. IC₅₀ (Inhibitory concentration) value has been found higher in chloroform extract (92.89 ​μg/ml). Metformin drug is used for positive control, which causes 14.6% improvement in glucose tolerance while M. rubra has been found 11.4. % at the dose of 300 ​mg/kg body wt in normal rats. In STZ treated diabetic rats, it reduces 13.0% blood glucose level while metformin reduces 21.9% up to dosing level of 300 ​mg/kg body wt. It produces reduction in biochemical parameters like, total cholesterol (TC), triglycerides (TG), SGPT, LDL, urea, creatinine and SGOT while HDL has been increased. Results show the hydro-alcoholic leaves extract of Morus rubra exhibited antidiabetic, antioxidant and hypolipidemic properties. This suggests that M. rubra has great potential to develop novel antidiabetic drug to manage this disastrous disease.     

Chemoenzymatic synthesis of chiral 4-(N,N-dimethylamino)pyridine derivatives

Chiral 4-(N,N-dimethylamino)pyridine derivatives have been prepared through a chemoenzymatic synthesis where the enzymatic kinetic resolution of a family of 4-chloro-2-(1-hydroxyalkyl)pyridines is the key step for the formation of potentially important chiral catalysts. Pseudomonas cepacia lipase (PSL) showed excellent enantioselectivity in the acylation of the (R)-enantiomers (E > 200) using vinyl acetate as acylating agent and THF as solvent, obtaining products and substrates enantiomerically pure and with excellent yields.     

Kinetic resolution of fluorinated propargyl alcohols by lipase-catalyzed enantioselective transesterification

In order to obtain optically active fluorinated propargyl alcohols, a lipase-catalyzed kinetic resolution has been carried out. The effect of lipase types, organic solvents, reaction temperature, and acyl donors was examined in the lipase-catalyzed transesterification of 1,1,1-trifluoro-4-phenyl-3-butyn-2-ol. Various enantiomerically pure fluorinated propargyl alcohols have been successfully prepared in good enantiomeric excess (>84%) by Novozym 435-catalyzed transesterification with vinyl butanoate at 60 °C in n-hexane. In some cases, the enantiomeric purities were excellent (>99% ee).     

Chemoenzymatic synthesis of enantiomerically pure 1,2-diols employing immobilized lipase in the ionic liquid [bmim]PF6

Significantly enhanced enantioselectivity in the enzymatic kinetic resolution of 1,2-diols employing immobilized lipase from Pseudomonas cepacia (PS-C, ‘Amano’) results from the use of the ionic liquid [bmim]PF₆ as reaction medium.     

Highly enantioselective acylation of chlorohydrins using Amano AK lipase from P. fluorescens immobilized on silk fibroin–alginate spheres

Aromatic, allylic, and aliphatic compounds containing a chlorohydrin group were selected as substrates for the enzymatic kinetic resolution mediated by Amano AK lipase from Pseudomonas fluorescens immobilized in silk friboin-alginate spheres. Thus, the enantioselectivity of the process was sufficient for the production of the desired alcohols and acetates in good yields and high enantiomeric purities. This Letter provides a simple, cheap, and practical protocol for enantioselective synthesis of chlorohydrins and reinforces the versatility of silk fibroin as supports for heterogeneous catalysts.     

High-yielding metalloenzymatic dynamic kinetic resolution of fluorinated aryl alcohols

Dynamic kinetic resolution (DKR) of various fluorinated aryl alcohols by a combination of lipase-catalyzed enzymatic resolution with in situ ruthenium-catalyzed alcohol racemization is described. (R)-Selective Candida antarctica lipase B (CALB) was employed for transesterification of different fluoroaryl alcohols in DKR reactions delivering the corresponding acetates in high yield (?97%) with excellent enantiomeric excess (?98%).     

Kinetics of ethanol production from carob pods extract by immobilizedSaccharomyces cerevisiae cells

Kinetics of ethanol production from carob pods extract by immobilizedS. cerevisiae cells in static and shake flask fermentation have been investigated. Shake flask fermentation proved to be a better fermentation system for the production of ethanol than static fermentation. The optimum values of ethanol concentration, ethanol productivity, ethanol yield, and fermentation efficiency were obtained at pH range 3.5–6.5 and temperature between 30–35°C. A maximum ethanol concentration (65 g/L), ethanol productivity (8.3 g/Lh), ethanol yield (0.44 g/g), and fermentation efficiency (95%) was achieved at an initial sugar concentration of 200, 150, 100, and 200 g/L, respectively. The highest values of specific ethanol production rate and specific sugar uptake rate were obtained at pH 6.5, temperature 40°C, and initial sugar concentration of 100 g/L. Other kinetic parameters, biomass concentration, biomass yield, and specific biomass production rate were maximum at pH 5.5, temperature 30°C, and initial sugar concentration 150 g/L. Under the same fermentation conditions non-sterilized carob pod extract gave higher ethanol concentration than sterilized medium. In repeated batch fermentations, the immobilizedS. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 5 d.     

Development and validation of analytical method for estimation of bilastine in bulk and pharmaceutical (tablet) dosage form

BackgroundThe present work describe a simple, linear, precise, robust, accurate and selective HPLC method for estimation of Bilastine in bulk and tablet dosage form. Bilastine is a second generation antihistamine medication. Generally it is used for treatment of allergic rhinoconjunctivitis and urticaria (hives). Methanol: Acetonitrile: Phosphoric Acid Buffer pH 2.1 in proportion of (21:33:46) was used as mobile phase with flow rate 1.0 ​ml/min. The column used for the method development is 250 ​× ​4.6 mm ​× ​5 ​μm dimension.ResultIn the range of 5–25 ​μg/ml the linearity of Bilastine shows a correlation coefficient of 0.9981.ConclusionThe method was validated as per ICH guidelines for linearity, precision, accuracy, robustness.     

Novel high throughput green UPLC-MS/MS methods for determination of desmopressin with special sample handling

Objectives of present investigation were to develop novel high throughput green UPLC-MS/MS methods for quality control of desmopressin formulations. Two liquid chromatographic methods: Method-I based on isocratic elution and method-II based on gradient elution were developed and validated. Methods were green, since less amount of organic solvent (≤75 ​μL, per sample run time) was utilized in mobile phase. Mobile phase (0.1% formic acid in ACN, and in water), flow rate was 300 ​μL/min. Desmopressin retention time and sample run time for Method-I were 0.59 and 1.0 ​min, respectively. Retention time and sample run time for method-II were 2.03 and 2.5 ​min, respectively. Double charged ions [M ​+ ​2H]²⁺ of desmopressin (m/z 535.33 ​> ​120) were monitored in multi-reaction monitoring mode. Desmopressin was directly analyzed in water samples. Calibration curves were prepared between 50 and 600 ​ng/mL. The values of r² were 0.999. Assay and dissolution study of desmopressin formulation was successfully performed using these methods. Desmopressin was found to adsorb or react with different type of materials while handling. The specific filters (Chromafil® Xtra PTFE-45/25 0.45 ​μm, syringe filter) and tubes (glass tubes or Neutral graduated micro test tubes) were used for handling desmopressin samples.     

Trichosporon beigelli esterase (TBE): a versatile esterase for the resolution of economically important racemates

A 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.     

Kinetic resolution of allylic alcohols via stereoselective acylation catalyzed by lipase PS-30

By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic allylic alcohols has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 968. Substituent effect is briefly discussed.     

Nano engineered biodegradable capsules for the encapsulation and kinetic release studies of ciprofloxacin hydrochloride

Polyelectrolyte based nano and micro capsules have been extensively studied as promising drug carrier in recent years. Natural degradable capsules have received great deal of attention due to their fascinating structural and morphological characteristics, biocompatibility, sustained and targeted-release capabilities. In this work, chitosan - dextran sulphate nano capsules were prepared via Layer-by-Layer (L-b-L) technique using sacrificial template for drug delivery applications. The loading and in vitro release studies were performed using ciprofloxacin hydrochloride as a model drug. The release media used in the study are plain water and Phosphate Buffered Saline (PBS). The optimum drug load was 389 ​μg, at a loading pH of 2.1 and a temperature of 25 ​°C for 50 ​min encapsulation time. The drug loaded capsules exhibited a slow and sustained release up to 24 ​h and the maximum release rate was obtained at pH 1.2 in water and pH 7.4 in PBS. Least amount of drug release occurred at pH 5.0 in both the release media. The amounts of drug release in water at pH 1.2, pH 5.0 and pH 7.4 are 309 ​μg, 163 ​μg and 251 ​μg respectively where as the corresponding values in the case of PBS (at pH 1.2, pH 5.0 and pH 7.4) are 236 ​μg, 198 ​μg and 251 ​μg respectively. Two different models namely, Ritger - Peppas and Higuchi models were chosen to study the release kinetics behaviour of ciprofloxacin hydrochloride. The prepared bio-degradable capsules had potential as drug carrier for targeting antibacterial drugs with diverse functionality.