The structure and CH-acidity of CF3-substituted β-thiolactones. A theoretical study

Ab initio calculations of the molecules of CH₃- and CF₃-substituted β-propiothiolactones and the productsof their deprotonation were carried out by the restricted Hartree—Fock method with full geometry optimization using the 6–31 G^* basis set. Peculiarities of the geometry and electronic structure of the systems in question were established. Only 2-methyl-β-propiothiolactone forms a mesomeric stabilized carbanion in the case of proton abstraction from the α-position of thiolactone cycle. Carbanions of 3-methyl, 2-, and 3-thrifluoromethyl-β-propiothiolactones are stabilized due to the ring opening to form ketene thiolate ions. The CH-acidity of fluorine-containing β-thiolactones is much higher than that of nonfluorinated analogs (the differences in the deprotonation energies are 13.4 to 25.2 kcal mol⁻¹). Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1719–1725, September, 1998.     

Synthesis of 4-phenyl-1-(2-thienyl)-2,3,4,9-tetrahydro-1H-β-carboline

The Pictet-Spengler reaction involving β-phenyltryptamine was shown to be diastereo-specific with formation primarily of the (1S*,4R*) diastereomer of 4-phenyl-1-(2-thienyl)-2,3,4,9-tetrahydro-1H-β-carboline, a compound with potential GABA-receptor activity. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 468–470, September–October, 2006.     

Two new coumarin biosides from Angelica dahurica

Two new coumarin biosides, tert-O-β-D-apiofuranosyl-(1→6)-O-β-D-glucopyranosyl-byakangelicin (1) and 2′-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyl-peucedanol (2), were isolated from the fresh roots of Angelica dahurica. The structures of the new compounds were elucidated on the basis of spectral analysis. Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 561–563, November–December, 2008.     

Synthesis of a novel 18β-glycyrrhetinic acid derivative

A novel compound, biotinylated 18β-glycyrrhetinic acid (BGA), was synthesized. It is a compound of 18β-glycyrrhetinic acid linked with biotin. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 266–267, May–June, 2006. An erratum to this article is available at .     

Bis(<Emphasis Type="Italic">β</Emphasis>-cyclodextrin)s Linked with an Aromatic Diamine as Fluorescent Sensor for the Molecular Recognition of Bile Salts

The binding behavior of three aromatic diamino-bridged bis(β-cyclodextrin)s (2–4) with four bile salts {cholate (CA), deoxycholate (DCA), glycocholate (GCA) and taurocholate (TCA)} has been investigated at 25 °C in a phosphate buffer (pH=7.20) by fluorescence and 2D NMR spectroscopy. The results indicate that these bis(β-cyclodextrin)s act as fluorescent sensors. From the ROESY spectra, it is deduced that the phenyl moieties of bis(β-cyclodextrin)s 2–4 are partially self included in the cyclodextrin cavity, and are not expelled from the cavity upon complexation with bile guests. Owing to the cooperative host-tether-guest binding mode in which the linker and guest are co-included in the two cyclodextrin cavities, these bis(β-cyclodextrin)s significantly enhance the binding ability and selectivity as compared with the native β-cyclodextrin 1. Possessing suitable tether length, bis(β-cyclodextrin) 3 gives the highest K _S values, ranging up to 39,900 mol⋅L⁻¹, for complexation with CA. The complex stability constants are discussed from the viewpoint of multiple recognitions between host and guest.     

Cardiac glycosides from Strophanthus kombe

Twelve cardiac glycosides and aglycons were isolated from Strophanthus kombe seeds. Of these, eight were identified as cymarin, K-strophanthin-β, K-strophanthoside, periplocymarin, 17α-strophadogenin, erysimin (= helveticoside), erysimoside, and neoglucoerysimoside. Four glycosides, preliminarily designated Sk-x, Sk-y, Sk-z, and Sk-20, were new. Their chemical structures were established as 3β-O-β-D-glucopyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-glucoside), 3β-O-β-D-cymaropyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-cymaroside), 3β-O-β-D-cymaropyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β, 14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-strophanthotrioside), and 3-O-β-D-digitoxopyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β,14β, 19-trihydroxy-card-20(22)enolide (strophanthidol-3-O-gentiobiosyldigitoxoside), respectively. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 156–159, March–April, 2006.     

Two-fragment α-adrenolytics

Dialkyl β-(2-aroxyethylamino)ethylphosphonates,N-[β-(2-methoxyphenoxy)ethyl]-N′-[β-(diethoxyphosphoryl)ethyl]-α,ω-diaminoalkanes, and diethyl β-(N-arylpiperazino)ethyl-phosphonates were synthesized by the reactions of dialkyl vinylphosphonates with β-aroxyethylamines,N-[β-(2-methoxyphenoxy)ethyl]-α,ω-diaminoalkanes, andN-aryl-piperazines, respectively. The compounds synthesized exhibit hypotensive and α-adrenolytic activities. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 987–991, May 1999.     

Synthesis of α-amino-β-keto-esters (β-oxodipeptides)

The synthesis of α-amino-β-keto-esters (β-oxo dipeptides) was studied. Corresponding α-amino-β-ketoesters were prepared from BOC-(L)-Valine and BOC-(L)-isoleucine by coupling with (D,L)-threonine hydrochloride and oxidation with Dess-Martin periodinane (DMP) with a total yield of 48% and 38%, respectively. __________ Translated from Chemistry Online, 2007, 70(10): 793–796 [译自: 化学通报]     

Application Relevant Studies of Fungal β-galactosidases with Potential Application in the Alleviation of Lactose Intolerance

Functional screening studies revealed that Aspergillus carbonarius ATCC6276 produced extracellular β-galactosidase activity potentially suited for use as a lactase digestive supplement in the treatment of lactose intolerance. The crude preparation contained two β-galactosidase activities, β-gal 1 and β-gal 2, which were separated by ion-exchange chromatography. Both enzymes were purified to homogeneity by a combination of gel filtration, ion-exchange, chromatofocusing and hydrophobic interaction chromatographies. β-gal 1 and β-gal 2 displayed differences in molecular mass (110 kDa versus 120 kDa as judged by SDS PAGE) and in a range of additional physicochemical properties. Km values of 83 and 309 mM, respectively, were recorded using lactose as substrate while temperature optima of 55°C versus 65°C were obtained. Unlike current commercialized supplemental lactases, both of the purified enzymes displayed significant stability when exposed to simulated gastric conditions, with β-gal 1in particular retaining 70% residual activity after exposure to pH 2.0 in the presence of pepsin for 2 h. Overall the results indicate that the β-galactosidases of Aspergillus carbonarius ATCC6276, either individually or in combination, may be suitable for use as a digestive supplement for the alleviation of lactose intolerance.