Novel Potato Micro-Tuber-Inducing Compound, (3R,6S)-6-Hydroxylasiodiplodin,from a Strain of Lasiodiplodia theobromae

A novel potato micro-tuber-inducing compound was isolated from the culture broth of Lasiodiplodia theobromae Shimokita 2. The structure of the isolated compound was determined as (3R,6S)-6-hydroxylasiodiplodin by means of spectroscopic analyses, the modified Mosher method, and chemical conversion. The compound showed potato micro-tuber-inducing activity at a concentration of 10^?4 M, using the culture of single-node segments of potato stems in vitro.     

Synthesis of enantiopure (S)-6-chlorochroman-4-ol using whole-cell Lactobacillus paracasei biotransformation

Chromane, which has a fused cyclic structure, is a significant molecule that can be found in the structure of many important compounds. Lactobacillus paracasei BD101 was demonstrated as whole-cell biocatalyst for the synthesis of (S)-6-chlorochroman-4-ol with immense enantioselectivity. The conditions of asymmetric reduction were optimized one factor by one factor using L paracasei BD101 to achieve enantiomerically pure product and complete conversion. Using these obtained optimization conditions, asymmetric reduction of 6-chlorochroman-4-one was performed under environmentally friendly conditions; 6-chlorochroman-4-one, having a fused cyclic structure as previously noted to be difficult to asymmetric reduction with biocatalysts, was enantiomerically reduced to (S)-6-chlorochroman-4-ol with an enantiomeric excess >99% on a high gram scale. This study is the first example in the literature for the enantiopure synthesis of (S)-6-chlorochroman-4-ol using a biocatalyst. Also notably, the optical purity of (S)-6-chlorochroman-4-ol obtained in this study through asymmetric bioreduction using whole-cell biocatalyst is the highest value in the literature. In this study, (S)-6-chlorochroman-4-ol was produced on a gram scale by an easy, inexpensive, and environmentally friendly method, which has shown the production of valuable chiral precursors for drug synthesis and other industrial applications. This study provides a convenient method for the production of (S)-6-chlorochroman-4-ol, which can meet the industrial green production demand of this chiral secondary alcohol.     

Characterization of (2S,2'R,3'R)-2-(2',3'-[3H]-Dicarboxycyclopropyl)glycine Binding in Rat Brain

Abstract: [(2S,2′R,3′R)-2-(2′,3′-[³H]Dicarboxycyclopropyl)glycine ([³H]DCG IV) binding was characterized in vitro in rat brain cortex homogenates and rat brain sections. In cortex homogenates, the binding was saturable and the saturation isotherm indicated the presence of a single binding site with a K_D value of 180 ± 33 nM and a B_max of 780 ± 70 fmol/mg of protein. The nonspecific binding, measured using 100 µM LY354740, was <30%. NMDA, AMPA, kainate, l (?)-threo-3-hydroxyaspartic acid, and (S)-3,5-dihydroxyphenylglycine were all inactive in [³H]DCG IV binding up to 1 mM. However, several compounds inhibited [³H]DCG IV binding in a concentration-dependent manner with the following rank order of potency: LY341495 = LY354740 > DCG IV = (2S,1′S,2′S)-2-(2-carboxycyclopropyl)glycine > (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid > (2S,1′S,2′S)-2-methyl-2-(2-carboxycyclopropyl)glycine > l -glutamate = ibotenate > quisqualate > (RS)-α-methyl-4-phosphonophenylglycine = l (+)-2-amino-3-phosphonopropionic acid > (S)-α-methyl-4-carboxyphenylglycine > (2S)-α-ethylglutamic acid > l (+)-2-amino-4-phosphonobutyric acid. N-Acetyl-l -aspartyl-l -glutamic acid inhibited the binding in a biphasic manner with an IC₅₀ of 0.2 µM for the high-affinity component. The binding was also affected by GTPγS, reducing agents, and CdCl₂. In parasagittal sections of rat brain, a high density of specific binding was observed in the accessory olfactory bulb, cortical regions (layers 1, 3, and 4 > 2, 5, and 6), caudate putamen, molecular layers of the hippocampus and dentate gyrus, subiculum, presubiculum, retrosplenial cortex, anteroventral thalamic nuclei, and cerebellar granular layer, reflecting its preferential (perhaps not exclusive) affinity for pre- and postsynaptic metabotropic glutamate mGlu2 receptors. Thus, the pharmacology, tissue distribution, and sensitivity to GTPγS show that [³H]DCG IV binding is probably to group II metabotropic glutamate receptors in rat brain.     

Resolution of N-(2-ethyl-6-methylphenyl) alanine catalyzed by Lipase B from Candida antarctica

A biotransformation process has been developed for the production of (S)-N-(2-ethyl-6-methylphenyl) alanine by enantioselective hydrolysis of racemic methyl ester in the presence of Candida antarctica lipase B (CAL-B). However, the enantioselectivity of CAL-B towards the resolution is not high enough to obtain enantiomerically pure product. In order to improve the enantioselectivity of the enzyme, the effects of surfactants on CAL-B-catalyzed hydrolysis were tested. The results suggest that surfactants can influence the microenvironment of the enzyme, and the addition of Tween-80, in particular, to the reaction medium markedly enhanced the selectivity of CAL-B towards the substrate used, with the enantiomeric ratio (E-value) increasing from 11.3 to 60.1.     

In Vitro Evaluation of 11C-Labeled (S)-Nicotine, (S)-3-Methyl-5-(1-Methyl-2-Pyrrolidinyl)isoxazole, and (R,S)-1-Methyl-2-(3-Pyridyl)azetidine as Nicotinic Receptor Ligands for Positron Emission Tomography Studies

Abstract: The binding characteristics of the novel ¹¹C-labeled nicotinic ligands (R,S)-1-methyl-2-(3-pyridyl) azetidine (MPA) and (S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT-418) were investigated in comparison with those of (S)-[¹¹C]nicotine in vitro in the rat brain to be able to predict the binding properties of the new ligands for positron emission tomography studies in vivo. The data from time-resolved experiments for all ligands indicated fast binding kinetics, with the exception of a slower dissociation of [¹¹C]MPA in comparison with (S)-[¹¹C]nicotine and [¹¹C]ABT-418. Saturation experiments revealed for all ligands two nicotinic receptor binding sites with affinity constants (K_D values) of 2.4 and 560 nM and binding site densities (B_max values) of 65.5 and 223 fmol/mg of protein for (S)-[¹¹C]nicotine, K_D values of 0.011 and 2.2 nM and B_max values of 4.4 and 70.7 fmol/mg of protein for [¹¹C]MPA, and K_D values of 1.3 and 33.4 nM and B_max values of 8.8 and 69.2 fmol/mg of protein for [¹¹C]ABT-418. In competing with the ¹¹C-ligands, epibatidine was most potent, followed by cytisine. A different rank order of potencies was found for (?)-nicotine, (+)-nicotine, MPA, and ABT-418 displacing each of the ¹¹C-ligands. Autoradiograms displayed a similar pattern of receptor binding for all ligands, whereby [¹¹C]MPA showed the most distinct binding pattern and the lowest nonspecific binding. We conclude that the three ¹¹C-labeled nicotinic ligands were suitable for characterizing nicotinic receptors in vitro. The very high affinity of [¹¹C]MPA to nicotinic acetylcholine receptors, its low nonspecific binding, and especially the slower dissociation kinetics of the [¹¹C]MPA from the putative high-affinity nicotinic acetylcholine receptor binding site compared with (S)-[¹¹C]nicotine and [¹¹C]ABT-418 raise the level of interest in [¹¹C]MPA for application in positron emission tomography.     

Determination of the Absolute Configuration of Quercivorol, (1S,4R)-p-Menth-2-en-1-ol,an Aggregation Pheromone of the Ambrosia Beetle Platypus quercivorus (Coleoptera: Platypodidae)

A pair of enantiomers of trans-p-menth-2-en-1-ol, an aggregation pheromone of Platypus quercivorus, was synthesized from (S)- and (R)-limonene. The retention time of the aggregation pheromone from the insect coincided with that of (1S,4R)-p-menth-2-en-1-ol synthesized from (S)-limonene from GC analyses with a chiral column, enabling the absolute configuration of the aggregation pheromone to be determined as (1S,4R).     

Resolution and Synthesis of (S)-1-(2-Naphthyl)ethanol with Immobilized Pea Protein: As a New Biocatalyst

(S)-1-(2-Naphthyl)ethanol was yielded by immobilized pea (Pisum sativum L.) protein (IPP) from (R, S) 2-naphthyl ethanol (>99% ee, yield; about 50%), in which the (R)-enantiomer was selectively oxidized to 2-acetonaphthone. IPP could be reused consecutively at least three times without any decrease of yield and optical purity.     

Production of enantiomerically pure (S)-phenyl(pyridin-2-yl)methanol with Lactobacillus paracasei BD101

Abstract

Asymmetric reduction studies of heteroaryl ketones, including phenyl(pyridin-2-yl)methanone in enantioselective form with biocatalysts are very few, and chiral heteroaryl alcohols have been synthesized generally in the small scale. In this study, seven bacterial strains have been used to produce the (S)-phenyl(pyridin-2-yl)methanol in high enantiomeric excess and yield. Among the tested strains, Lactobacillus paracasei BD101, was found to be the best biocatalyst for the reducing phenyl(pyridin-2-yl)methanone to the (S)-phenyl(pyridin-2-yl)methanol at gram scale. The asymmetric bioreduction conditions were systematically optimized using L. paracasei BD101, which demonstrated excellent enantioselectivity and high level of conversion for the bioreduction reaction. (S)-phenyl(pyridin-2-yl)methanol, which is an analgesic, was produced enantiomerically pure form in the first time on gram scale using a biocatalyst. In total, 5.857?g of (S)-phenyl(pyridin-2-yl)methanol in enantiomerically pure form (>99% enantiomeric excess) was obtained in 52?h with 93% yield using whole cells of L. paracasei BD101. Enantiomerically pure (S)-phenyl (pyridin-2-yl)methanol, which is an analgesic, was first produced in the gram scale using a biocatalyst with excellent ee (>99%) and yield (93%).     

Green synthesis of enantiopure (S)‐1‐(benzofuran‐2‐yl)ethanol by whole‐cell biocatalyst

Optically active aromatic alcohols are valuable chiral building blocks of many natural products and chiral drugs. Lactobacillus paracasei BD87E6, which was isolated from a cereal‐based fermented beverage, was shown as a biocatalyst for the bioreduction of 1‐(benzofuran‐2‐yl) ethanone to (S)‐1‐(benzofuran‐2‐yl) ethanol with highly stereoselectivity. The bioreduction conditions were optimized using L. paracasei BD87E6 to obtain high enantiomeric excess (ee) and conversion. After optimization of the bioreduction conditions, it was shown that the bioreduction of 1‐(benzofuran‐2‐yl)ethanone was performed in mild reaction conditions. The asymmetric bioreduction of the 1‐(benzofuran‐2‐yl)ethanone had reached 92% yield with ee of higher than 99.9% at 6.73 g of substrate. Our study gave the first example for enantiopure production of (S)‐1‐(benzofuran‐2‐yl)ethanol by a biological green method. This process is also scalable and has potential in application. In this study, a basic and novel whole‐cell mediated biocatalytic method was performed for the enantiopure production of (S)‐1‐(benzofuran‐2‐yl)ethanol in the aqueous medium, which empowered the synthesis of a precious chiral intermediary process to be converted into a sophisticated molecule for drug production.     

Conversion of indene to cis-(1S),(2R)-indandiol by mutants of Pseudomonas putida F1

Two mutation and selection methods were used to isolate mutants of Pseudomonas putida F1 which convert indene to cis-(1S),(2R)-indandiol in a toluene-independent fashion. Using soybean or silicone oil as a second phase to deliver indene to the culture, cis-(1S),(2R)-indandiol, cis-(1R),(2S)-indandiol, 1,2-indenediol (or the keto-hydroxy indan tautomer), and the monooxygenation products 1-indenol and 1-indanone were produced from indene as a function of time. Similarly the enantiomeric excess of the cis-(1S),(2R)-indandiol produced also increased with increasing time. In addition, mutants were isolated which produced cis-(1S),(2R)-indandiol of lower optical purity which corresponded to reduced levels of 1,2-indenediol. These data suggest this toluene dioxygenase produces cis-(1S),(2R)-indandiol of low optical purity and that cis-glycol dehydrogenase plays a role in resolving the two cis-1,2-indandiol enantiomers. Received 15 November 1996/ Accepted in revised form 09 March 1997     

Syntheses and Biological Activities of (2S,2′ S)- and (2S,2′R)-Dimethyl 3-Phenyl-2,2′-oxydipropionate,Ether Analogues of a Plant-growth Regulator Isolated from Botrytis squamosa

Ether analogues of a plant growth regulator isolated from Botrytis squamosa, (2S,2′S)- and (2S,3′S)-dimethyl 3-phenyl-2,2′-oxydipro-pionate (1), were prepared by the Williamson synthesis, and the two diastereomers were separated. The absolute configurations of both diastereomers were determined by chemical transformation. The promoting effect of both synthesize analogues on lettuce seedling growth was similar to that of the natural plant growth regulator.     

Experiment and simulation on kinetic resolution of (R,S)-2-chloromandelic acid by enzymatic transesterification

Optically pure 2-chloromandelic acid (ClMA) is a very important chiral drug intermediate for synthesis of (S)-clopidogrel, belonging to the platelet aggregation inhibitor. Enantioselective resolution of (R,S)-2-chloromandelic acid was carried out in organic solvent through irreversible transesterification catalyzed by lipase AK with vinyl acetate acting as the acyl donor. Effects of various conditions on enantioselectivity and activity of lipase were investigated, including organic solvents, temperature, water content, substrate ratio, enzyme loading, and reaction time. Based on homogeneous reaction and Ping-Pong bi-bi mechanism, a quantitative model was constructed to simulate and optimize the reaction process. Under the optimal conditions, excellent results were obtained with high conversion of (R)-2-ClMA (c _R, ≥98.85%) and large enantiomeric excess of substrate (ee _s, ≥98.15%). There is a good agreement between predicted values and experiment data, which indicates that the established method is a powerful tool for optimization of the enantioselective transesterification process for enantiomers separation.     

A facile synthesis of (1S,5R,6S)-5-azido-6-benzyloxycyclohex-2-en-1-ol

A facile and short synthesis of (1S,5R,6S)-5-azido-6-benzyloxycyclohex-2-en-1-ol (1) has been achieved in high yield starting from 4,5-epoxycyclohex-1-ene by using a catalytic asymmetric allylic oxidation reaction.     

Stereoselective Synthesis of erythro-Serricornin, (4R, 6R, 7S)-, and (4S, 6R, 7S)-4,6-Dimethyl-7-hydroxynonan-3-one,Stereoisomers of the Sex Pheromone of Cigarette Beetle

A stereoselective synthesis of erythro-serricornin [(4RS,6R,7S)-4,6-dimethyl-7-hydroxynonan-3-one] was completed starting from l-(+)-tartaric acid. The relative configuration of C(6)-methyl and C(7)-hydroxyl groups in naturally occurring serricornin was threo.     

Synthesis of 3-fluoro-6-S-(2-S-pyridyl) nucleosides as potential lead cytostatic agents

The 3-deoxy-3-fluoro-6-S-(2-S-pyridyl)-6-thio-β-d-glucopyranosyl nucleoside analogs 7 were prepared via two facile synthetic routes. Their precursors, 3-fluoro-6-thio-glucopyranosyl nucleosides 5a-e, were obtained by the sequence of deacetylation of 3-deoxy-3-fluoro-β-d-glucopyranosyl nucleosides 2a-e, selective tosylation of the primary OH of 3 and finally treatment with potassium thioacetate. The desired thiolpyridine protected analogs 7a-c,f,g were obtained by the sequence of deacetylation of 5a-c followed by thiopyridinylation and/or condensation of the corresponding heterocyclic bases with the newly synthesized peracetylated 6-S-(2-S-pyridyl) sugar precursor 13, which was obtained via a novel synthetic route from glycosyl donor 12. None of the compounds 6 and 7 showed antiviral activity, but the 5-fluorouracil derivative 7c and particularly the uracil derivative 7b were endowed with an interesting and selective cytostatic action against a variety of murine and human tumor cell cultures.     

Synthesis and evaluation of (S)-2-ethoxy-3-phenylpropanoic acid derivatives as insulin-sensitizing agents

A series of (S)-2-ethoxy-3-phenylpropanoic acid derivatives were synthesized and their insulin-sensitizing activities were evaluated in 3T3-L1 cells. Compounds 1b and 1d exhibited more potent insulin-sensitizing activity than rosiglitazone.     

Synthesis of Optically Pure (1S, 4S, 5S)-2-Pinen-4-ol (cis-Verbenol) and Its Antipode,the Pheromone of Ips Bark Beetles

The enantiomers of cis-verbenol (4a and 4a′) were first synthesized in optically pure state. (1S, 4S, 5S)-2-Pinen-4-ol (4a′) was dextrorotatory in acetone or in methanol but it was levorotatory in chloroform; cis-verbenols are indistinguishable by a prefix (+) or (?). The designation of the Ips pheromone as (+)-cis-verbenol is therefore ambiguous and it should be called as (1S, 4S, 5S)-2-pinen-4-ol (4a′) or (S)-cis-verbenol.     

Coexpression of a carbonyl reductase and glucose 6-phosphate dehydrogenase in Pichia pastoris improves the production of (S)-1-phenyl-1,2-ethanediol

Abstract

To develop an efficient biocatalyst to produce optically active (S)-phenyl ethanediol (PED), a carbonyl reductase SCRII and glucose 6-phosphate dehydrogenase were coexpressed intracellularly in Pichia pastoris. The recombinant enzyme PpSCRII was purified with a specific activity of 8.32 U mg^?1, over 36% higher than that of Escherichia coli SCRII. The recombinant cells P. pastoris/SCRIIG catalyzed the reduction of 2-hydroxyacetophenone to give (S)-PED with optical purity of >99% in a yield of 96.3%. The yield was improved by 19.9% and 25.7% over E. coli BL21/SCRII and Candida parapsilosis, respectively, when the reaction duration was shorted from 48 h to 24 h. When using glucose 50 g L^?1 as co-substrate, these P. pastoris/SCRIIG cells could be reused ten times and the optical purity and yield of (S)-PED kept at >99% enantiomeric excess and >85%, respectively.     

Lipase-catalyzed Kinetic Resolution of (±)-trans- and cis-2-Azidocycloalkanols

The lipase-catalyzed kinetic resolution of trans- and cis-2-azidocycloalkanols and the preparation of enantiomerically pure trans- and cis-2-aminocycloalkanols are described.

Four kinds of lipases were screened for the acetylation of trans- and cis-2-azidocycloalkanols. Among them, Pseudomonas sp. lipases (lipase PS and lipase AK, Amamo Pharmaceutical Co.) showed the highest enantioselectivity. These products were converted to the corresponding 2-aminocycloalkanols to determine their enantiomeric excess (ee) and absolute configurations by HPLC and CD analyses, using (S)-TBMB carboxylic acid [(S)-2-tert-butyl-2-methyl-1,3-benzodioxole-4-carboxylic acid] as the chiral conversion reagent. The results of the CD analysis proved N,O-bis-(S)-TBMB carboxylated cis-2-aminocycloalkanols to adopt a predominantly N-equatorial conformation.

The partially resolved trans- and cis-2-aminocycloalkanols, except for trans-2-aminocyclopentanol, were recrystallized from ethyl acetate to give enantiomerically pure forms.     

Practical access to the proline analogs (S,S,S)- and (R,R,R)-2-methyloctahydroindole-2-carboxylic acids by HPLC enantioseparation

An efficient methodology for the preparation of the α‐tetrasubstituted proline analog (S,S,S)‐2‐methyloctahydroindole‐2‐carboxylic acid, (S,S,S)‐(αMe)Oic, and its enantiomer, (R,R,R)‐(αMe)Oic, has been developed. Starting from easily available substrates and through simple transformations, a racemic precursor has been synthesized in excellent yield and further subjected to HPLC resolution using a cellulose‐derived chiral stationary phase. Specifically, a semipreparative (250 mm × 20 mm ID) Chiralpak® IC column has allowed the efficient resolution of more than 4 g of racemate using a mixture of n‐hexane/tert‐butyl methyl ether/2‐propanol as the eluent. Multigram quantities of the target amino acids have been isolated in enantiomerically pure form and suitably protected for incorporation into peptides. Chirality, 2011. © 2011 Wiley‐Liss, Inc.