Anju Chadha - Academia.edu (original) (raw)

Papers by Anju Chadha

ChemInform, Jun 17, 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform, Aug 7, 2007

Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure ... more Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure (3E,5E)-Alkyl-2-hydroxy-6-arylhexa-3,5-dienoates by Candida parapsilosis ATCC 7330 Mediated Deracemization of the Racemates.-(THANGAVEL, V.; CHADHA*, A.; Tetrahedron 63 (2007) 19, 4126-4133; Dep.

Tetrahedron-asymmetry, 2008

A highly enantioselective one pot, novel biocatalytic method for the asymmetric reduction of aryl... more A highly enantioselective one pot, novel biocatalytic method for the asymmetric reduction of aryl imines is reported. Treatment of aryl imines with Candida parapsilosis ATCC 7330 in aqueous medium produces the enantiomerically pure (R)-secondary amines in moderate ...

ChemInform, Oct 23, 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Tetrahedron-asymmetry, Apr 1, 2008

Plant Cell Tissue and Organ Culture, Apr 26, 2017

Phytochemistry, Dec 1, 2018

Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which... more Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which are a class of cyclic peptides derived from plants, possessing several applications. Somatic embryo culture of V. odorata was developed, via indirect somatic embryogenesis, to serve as an alternative to natural plant biomass for sustainable and continuous production of its bioactive ingredients, such as cyclotides. Among the various combinations of phytohormones tested, Murashige and Skoog medium supplemented with 1 mg/l thidiazuron gave rise to the maximum frequency of induction (86.7%) and a high number of somatic embryos (3) from an embryogenic callus. Identification and characterization of cyclotides in the somatic embryos were carried out using a Fourier transform mass spectrometer coupled with liquid chromatography (LC-FTMS). Among the cyclotides identified in the study, few were found to be exclusively present in the somatic embryo culture. Furthermore, the relative abundance of the cyclotides was higher in somatic embryo extract than in the natural plant extract. The biological activities (cytotoxic, haemolytic and antimicrobial) of the somatic embryos and the parent plant were compared. Unlike the natural plants, the somatic embryo extracts demonstrated specificity i.e. they were found to be potent against cancerous cells but not against non-cancerous cell line or red blood cells. In contrast to the plant extract, the somatic embryos extracts were found to be potent against Escherichia coli and Staphylococcus aureus. These results suggest that somatic embryos of V. odorata (rich in cyclotides) can be used as an alternative to plant biomass for its therapeutic applications and germplasm conservation.

Tetrahedron, May 1, 2007

Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure ... more Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure (3E,5E)-Alkyl-2-hydroxy-6-arylhexa-3,5-dienoates by Candida parapsilosis ATCC 7330 Mediated Deracemization of the Racemates.-(THANGAVEL, V.; CHADHA*, A.; Tetrahedron 63 (2007) 19, 4126-4133; Dep.

Tetrahedron-asymmetry, May 1, 2007

Deracemisation of racemic (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates using Candida parapsi... more Deracemisation of racemic (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates using Candida parapsilosis ATCC 7330 resulted in the formation of one enantiomer in high enantiomeric excess [up to> 99% ee] and isolated yields [up to 79%]. The absolute configuration of the ...

Applied Biochemistry and Biotechnology, Jul 28, 2013

Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted... more Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted in optically pure alkyl-3-hydroxybutanoates in good yields (up to 72%) and excellent enantiomeric excess (up to >99 %). A detailed and systematic optimisation study was necessary and was carried out to avoid the undesired transesterification reaction during the course of asymmetric reduction. Under optimised conditions, the (S)-alkyl hydroxyesters were produced predominantly except for the methyl ester which formed the (R)-enantiomer. To the best of our knowledge, the biocatalytic asymmetric reduction of isoamyl-3-oxobutanoate to (S)-isoamyl-3-hydroxybutanoate is reported here for the first time.

Scientific Reports, Oct 14, 2016

Confocal microscopic studies with the resting cells of yeast, Candida parapsilosis ATCC 7330, a r... more Confocal microscopic studies with the resting cells of yeast, Candida parapsilosis ATCC 7330, a reportedly versatile biocatalyst for redox enzyme mediated preparation of optically pure secondary alcohols in high optical purities [enantiomeric excess (ee) up to >99%] and yields, revealed that the yeast cells had large vacuoles under the experimental conditions studied where the redox reaction takes place. A novel fluorescence method was developed using 1-(6-methoxynaphthalen-2-yl)ethanol to track the site of biotransformation within the cells. This alcohol, itself non-fluorescent, gets oxidized to produce a fluorescent ketone, 1-(6-methoxynaphthalen-2-yl)ethanone. Kinetic studies showed that the reaction occurs spontaneously and the products get released out of the cells in less time [5 mins]. The biotransformation was validated using HPLC. Candida parapsilosis ATCC 7330 is an established biocatalyst for the preparation of numerous optically pure aryl/ aliphatic secondary alcohols and aryl amines using different strategies namely, asymmetric reduction 1-3 , deracemisation 4-6 and oxidative kinetic resolution 7. These optically pure secondary alcohols are produced from either prochiral ketones or racemic alcohols in reaction times as short as 5 min or even up to 24 h. These small organic molecules which are biotransformed as reported in this study, possibly enter the cells by passive diffusion i.e. transport of molecules across the membranes from higher to lower concentration without any additional energy requirement 8. Once inside the cell, the molecule gets transformed and is excreted from the cell due to which it is possible to extract the material from the reaction mixture and determine its optical purity, spectral analysis and yield. The present study addresses the question about the site of biotransformation inside the cell. A fluorogenic assay for confocal microscopic studies was developed for this purpose. The experimental results were validated using HPLC. The most widely used methods for localisation studies are subcellular fractionation, immunohistochemical studies and fluoro-probe techniques. It is known that cells consist of different dehydrogenases and other metabolic enzymes even under extremely unfavourable conditions 9. In the case of the three reported bacterial dehydrogenases, class I ADHs, are localised in the periplasm; class II ADHs are present as soluble monomers in the periplasm and class III ADHs are present in acetic acid bacteria and are also localised in the periplasmic side of the cytoplasmic membrane 10. Localisation of alcohol dehydrogenases (ADHs) in various mammalian tissues mainly use immunohistochemical studies 11,12 , immuno-gold labeling 13 , Western blotting 14 and fluorimetric assays 15. Only a few reports are available till date on the localisation of alcohol dehydrogenases in yeast cells. ADH-I and ADH-II were localised in the cytosol while ADH-III was localised in the mitochondrial matrix based on subcellular fractionation 16,17. Using a green fluorescent protein, a commonly used fluorescent tag, obtained from the jelly fish Aequorea victoria, ADH-IV and ADH-V were localised in the mitochondria and cytoplasm respectively 18 ; and the localisation of ADH VI and VII which were obtained from over-expression studies remains ambiguous 18-20. However, tracking the site of biotransformation of small organic molecules (alcohols/ketones) by resting yeast cells is not yet reported.

Journal of Photochemistry and Photobiology A-chemistry, 2011

Photophysical studies of four generations of polyglycerol dendrons with isopropylidene end groups... more Photophysical studies of four generations of polyglycerol dendrons with isopropylidene end groups and dansyl moiety as a fluorophore attached at the focal point were carried out. All the four generations showed similar behaviour in their absorption transitions but the emission maximum for all generations of dendrons showed strong dependence on the solvent polarity. The solvatochromic shift of emission maximum showed linearity in the Lippert-Mataga plot, indicating the dominant importance of general solvent effect in all generations of dendrons. Photophysical parameters such as fluorescence quantum yield, fluorescence lifetime and radiative decay rate constant showed solvent polarity dependence. The detailed photophysical study reveals that due to the increased influence of the repeating dendron units of the higher order dendrons on the dansyl microenvironment, it becomes less and less influenced by the solvent.

Acta crystallographica, Feb 27, 2013

Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoat... more Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoate to ethyl (R)-4-phenyl-2-hydroxybutanoate, a precursor of angiotensin-converting enzyme inhibitors such as Cilazapril and Benazepril. The carbonyl reductase was expressed in Escherichia coli and purified by GST-affinity and size-exclusion chromatography. Crystals were obtained by the hanging-drop vapour-diffusion method and diffracted to 1.86 Å resolution. The asymmetric unit contained two molecules of carbonyl reductase, with a solvent content of 48%. The structure was solved by molecular replacement using cinnamyl alcohol dehydrogenase from Saccharomyces cerevisiae as a search model.

Whittall/Practical Methods for Biocatalysis and Biotransformations 2, 2012

ABSTRACT This chapter contains sections titled: ω-Transaminases – Useful Biocatalysts for Chiral ... more ABSTRACT This chapter contains sections titled: ω-Transaminases – Useful Biocatalysts for Chiral Amine SynthesisPreparative Scale Production of a Bulky–Bulky Chiral Amine Using an Engineered TransaminaseSynthesis of Optically Pure Amines Employing ω-TransaminasesA Fast, Sensitive Assay and Scale-Up of ω-Transaminase Catalysed ReactionsAsymmetric Synthesis of L-3-Hydroxyadamantylglycine Using Branched Chain AminotransferaseAsymmetric Reduction of Aryl Imines Using Candida parapsilosis ATCC 7330

RSC Advances, 2015

Enantio-& chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using... more Enantio-& chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using Candida parapsilosis ATCC 7330 Sowmyalakshmi Venkataraman a and Anju Chadha a,b* Enantiomerically pure βand γ-nitro alcohols were prepared from their respective nitro ketones by asymmetric reduction mediated by the biocatalyst, Candida parapsilosis ATCC 7330 under optimized reaction conditions (ee up to >99%; yields up to 76%). This biocatalyst exhibits high chemoselectivity and reduces the keto group in preference to nitro group along with good enantioselectivity to produce enantiomerically enriched nitro alkanols. The asymmetric reduction of aliphatic nitro ketones was carried out in water with ethanol as cosolvent and glucose as cosubstrate using the whole cells of Candida parapsilosis ATCC 7330 in much lesser time (4 h). For the first time, the biocatalytic asymmetric reduction of the following ketones is reported here: 1-nitro-butan-2-one, 1-nitro-pentan-2-one, 3-methyl-1-nitro-butan-2-one and 1-cyclohexyl-2nitroethanone to produce (R)-alcohols [ee up to 79%, yield up to 74%] and 1-nitro-hexan-2-one and 1-nitro-heptan-2-one to produce (S)-alcohols [ee up to 81%, yield up to 76%].

Organic chemistry, Oct 8, 2015

ChemInform, Jun 17, 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform, Aug 7, 2007

Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure ... more Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure (3E,5E)-Alkyl-2-hydroxy-6-arylhexa-3,5-dienoates by Candida parapsilosis ATCC 7330 Mediated Deracemization of the Racemates.-(THANGAVEL, V.; CHADHA*, A.; Tetrahedron 63 (2007) 19, 4126-4133; Dep.

Tetrahedron-asymmetry, 2008

A highly enantioselective one pot, novel biocatalytic method for the asymmetric reduction of aryl... more A highly enantioselective one pot, novel biocatalytic method for the asymmetric reduction of aryl imines is reported. Treatment of aryl imines with Candida parapsilosis ATCC 7330 in aqueous medium produces the enantiomerically pure (R)-secondary amines in moderate ...

ChemInform, Oct 23, 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Tetrahedron-asymmetry, Apr 1, 2008

Plant Cell Tissue and Organ Culture, Apr 26, 2017

Phytochemistry, Dec 1, 2018

Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which... more Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which are a class of cyclic peptides derived from plants, possessing several applications. Somatic embryo culture of V. odorata was developed, via indirect somatic embryogenesis, to serve as an alternative to natural plant biomass for sustainable and continuous production of its bioactive ingredients, such as cyclotides. Among the various combinations of phytohormones tested, Murashige and Skoog medium supplemented with 1 mg/l thidiazuron gave rise to the maximum frequency of induction (86.7%) and a high number of somatic embryos (3) from an embryogenic callus. Identification and characterization of cyclotides in the somatic embryos were carried out using a Fourier transform mass spectrometer coupled with liquid chromatography (LC-FTMS). Among the cyclotides identified in the study, few were found to be exclusively present in the somatic embryo culture. Furthermore, the relative abundance of the cyclotides was higher in somatic embryo extract than in the natural plant extract. The biological activities (cytotoxic, haemolytic and antimicrobial) of the somatic embryos and the parent plant were compared. Unlike the natural plants, the somatic embryo extracts demonstrated specificity i.e. they were found to be potent against cancerous cells but not against non-cancerous cell line or red blood cells. In contrast to the plant extract, the somatic embryos extracts were found to be potent against Escherichia coli and Staphylococcus aureus. These results suggest that somatic embryos of V. odorata (rich in cyclotides) can be used as an alternative to plant biomass for its therapeutic applications and germplasm conservation.

Tetrahedron, May 1, 2007

Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure ... more Hydroxycarboxylic acids (ether carboxylic acids) and esters Q 0450 Preparation of Optically Pure (3E,5E)-Alkyl-2-hydroxy-6-arylhexa-3,5-dienoates by Candida parapsilosis ATCC 7330 Mediated Deracemization of the Racemates.-(THANGAVEL, V.; CHADHA*, A.; Tetrahedron 63 (2007) 19, 4126-4133; Dep.

Tetrahedron-asymmetry, May 1, 2007

Deracemisation of racemic (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates using Candida parapsi... more Deracemisation of racemic (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates using Candida parapsilosis ATCC 7330 resulted in the formation of one enantiomer in high enantiomeric excess [up to> 99% ee] and isolated yields [up to 79%]. The absolute configuration of the ...

Applied Biochemistry and Biotechnology, Jul 28, 2013

Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted... more Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted in optically pure alkyl-3-hydroxybutanoates in good yields (up to 72%) and excellent enantiomeric excess (up to >99 %). A detailed and systematic optimisation study was necessary and was carried out to avoid the undesired transesterification reaction during the course of asymmetric reduction. Under optimised conditions, the (S)-alkyl hydroxyesters were produced predominantly except for the methyl ester which formed the (R)-enantiomer. To the best of our knowledge, the biocatalytic asymmetric reduction of isoamyl-3-oxobutanoate to (S)-isoamyl-3-hydroxybutanoate is reported here for the first time.

Scientific Reports, Oct 14, 2016

Confocal microscopic studies with the resting cells of yeast, Candida parapsilosis ATCC 7330, a r... more Confocal microscopic studies with the resting cells of yeast, Candida parapsilosis ATCC 7330, a reportedly versatile biocatalyst for redox enzyme mediated preparation of optically pure secondary alcohols in high optical purities [enantiomeric excess (ee) up to >99%] and yields, revealed that the yeast cells had large vacuoles under the experimental conditions studied where the redox reaction takes place. A novel fluorescence method was developed using 1-(6-methoxynaphthalen-2-yl)ethanol to track the site of biotransformation within the cells. This alcohol, itself non-fluorescent, gets oxidized to produce a fluorescent ketone, 1-(6-methoxynaphthalen-2-yl)ethanone. Kinetic studies showed that the reaction occurs spontaneously and the products get released out of the cells in less time [5 mins]. The biotransformation was validated using HPLC. Candida parapsilosis ATCC 7330 is an established biocatalyst for the preparation of numerous optically pure aryl/ aliphatic secondary alcohols and aryl amines using different strategies namely, asymmetric reduction 1-3 , deracemisation 4-6 and oxidative kinetic resolution 7. These optically pure secondary alcohols are produced from either prochiral ketones or racemic alcohols in reaction times as short as 5 min or even up to 24 h. These small organic molecules which are biotransformed as reported in this study, possibly enter the cells by passive diffusion i.e. transport of molecules across the membranes from higher to lower concentration without any additional energy requirement 8. Once inside the cell, the molecule gets transformed and is excreted from the cell due to which it is possible to extract the material from the reaction mixture and determine its optical purity, spectral analysis and yield. The present study addresses the question about the site of biotransformation inside the cell. A fluorogenic assay for confocal microscopic studies was developed for this purpose. The experimental results were validated using HPLC. The most widely used methods for localisation studies are subcellular fractionation, immunohistochemical studies and fluoro-probe techniques. It is known that cells consist of different dehydrogenases and other metabolic enzymes even under extremely unfavourable conditions 9. In the case of the three reported bacterial dehydrogenases, class I ADHs, are localised in the periplasm; class II ADHs are present as soluble monomers in the periplasm and class III ADHs are present in acetic acid bacteria and are also localised in the periplasmic side of the cytoplasmic membrane 10. Localisation of alcohol dehydrogenases (ADHs) in various mammalian tissues mainly use immunohistochemical studies 11,12 , immuno-gold labeling 13 , Western blotting 14 and fluorimetric assays 15. Only a few reports are available till date on the localisation of alcohol dehydrogenases in yeast cells. ADH-I and ADH-II were localised in the cytosol while ADH-III was localised in the mitochondrial matrix based on subcellular fractionation 16,17. Using a green fluorescent protein, a commonly used fluorescent tag, obtained from the jelly fish Aequorea victoria, ADH-IV and ADH-V were localised in the mitochondria and cytoplasm respectively 18 ; and the localisation of ADH VI and VII which were obtained from over-expression studies remains ambiguous 18-20. However, tracking the site of biotransformation of small organic molecules (alcohols/ketones) by resting yeast cells is not yet reported.

Journal of Photochemistry and Photobiology A-chemistry, 2011

Photophysical studies of four generations of polyglycerol dendrons with isopropylidene end groups... more Photophysical studies of four generations of polyglycerol dendrons with isopropylidene end groups and dansyl moiety as a fluorophore attached at the focal point were carried out. All the four generations showed similar behaviour in their absorption transitions but the emission maximum for all generations of dendrons showed strong dependence on the solvent polarity. The solvatochromic shift of emission maximum showed linearity in the Lippert-Mataga plot, indicating the dominant importance of general solvent effect in all generations of dendrons. Photophysical parameters such as fluorescence quantum yield, fluorescence lifetime and radiative decay rate constant showed solvent polarity dependence. The detailed photophysical study reveals that due to the increased influence of the repeating dendron units of the higher order dendrons on the dansyl microenvironment, it becomes less and less influenced by the solvent.

Acta crystallographica, Feb 27, 2013

Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoat... more Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoate to ethyl (R)-4-phenyl-2-hydroxybutanoate, a precursor of angiotensin-converting enzyme inhibitors such as Cilazapril and Benazepril. The carbonyl reductase was expressed in Escherichia coli and purified by GST-affinity and size-exclusion chromatography. Crystals were obtained by the hanging-drop vapour-diffusion method and diffracted to 1.86 Å resolution. The asymmetric unit contained two molecules of carbonyl reductase, with a solvent content of 48%. The structure was solved by molecular replacement using cinnamyl alcohol dehydrogenase from Saccharomyces cerevisiae as a search model.

Whittall/Practical Methods for Biocatalysis and Biotransformations 2, 2012

ABSTRACT This chapter contains sections titled: ω-Transaminases – Useful Biocatalysts for Chiral ... more ABSTRACT This chapter contains sections titled: ω-Transaminases – Useful Biocatalysts for Chiral Amine SynthesisPreparative Scale Production of a Bulky–Bulky Chiral Amine Using an Engineered TransaminaseSynthesis of Optically Pure Amines Employing ω-TransaminasesA Fast, Sensitive Assay and Scale-Up of ω-Transaminase Catalysed ReactionsAsymmetric Synthesis of L-3-Hydroxyadamantylglycine Using Branched Chain AminotransferaseAsymmetric Reduction of Aryl Imines Using Candida parapsilosis ATCC 7330

RSC Advances, 2015

Enantio-& chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using... more Enantio-& chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using Candida parapsilosis ATCC 7330 Sowmyalakshmi Venkataraman a and Anju Chadha a,b* Enantiomerically pure βand γ-nitro alcohols were prepared from their respective nitro ketones by asymmetric reduction mediated by the biocatalyst, Candida parapsilosis ATCC 7330 under optimized reaction conditions (ee up to >99%; yields up to 76%). This biocatalyst exhibits high chemoselectivity and reduces the keto group in preference to nitro group along with good enantioselectivity to produce enantiomerically enriched nitro alkanols. The asymmetric reduction of aliphatic nitro ketones was carried out in water with ethanol as cosolvent and glucose as cosubstrate using the whole cells of Candida parapsilosis ATCC 7330 in much lesser time (4 h). For the first time, the biocatalytic asymmetric reduction of the following ketones is reported here: 1-nitro-butan-2-one, 1-nitro-pentan-2-one, 3-methyl-1-nitro-butan-2-one and 1-cyclohexyl-2nitroethanone to produce (R)-alcohols [ee up to 79%, yield up to 74%] and 1-nitro-hexan-2-one and 1-nitro-heptan-2-one to produce (S)-alcohols [ee up to 81%, yield up to 76%].

Organic chemistry, Oct 8, 2015