Liposomal heme as oxygen carrier under semi-physiological conditions orientation study of heme embedded in a phospholipid bilayer by an electrooptical method

The meso-tetra(α,α,α,α(o-pivalamidophenyl))porphinato iron-mono(1-lauryl-2-methylimidazole) complex embedded in the bilayer of dimyristoylphosphatidylcholine (liposomal heme) binds molecular oxygen reversibly at pH 7 and 37°C. Orientation of the iron porphyrin complex in the phospholipid bilayer was studied by electric birefringence and dichroism. It was observed that both the phospholipid bibilayer of liposome and the porphyrin plane are oriented nearly in parallel to the electric field. Therefore the angle between the porphyrin plane and the bilayer is considered to be practically small.     

Association of sugar-based carboranes with cationic liposomes: an electron spin resonance and light scattering study

The possibility of cationic (di-oleoyltrimethylammonium propane, DOTAP)/(l-α-dioleoylphosphatidyl-ethanolamine, DOPE) liposomes to act as carriers of boronated compounds such as 1,2-dicarba-closo-dodecaboran(12)-1-ylmethyl](β-d-galactopyranosyl)-(1→4)-β-d-glucopyranoside and 1,2-di-(β-d-gluco-pyranosyl-ox)methyl-1,2-dicarba-closo-dodeca-borane(12) has been investigated by Electron Spin Resonance (ESR) of n-doxyl stearic acids (n-DSA) and Quasi-Elastic Light Scattering (QELS). Both these carboranes have potential use in Boron Neutron Capture Therapy (BNCT), which is a targeted therapy for the treatment of radiation resistant tumors. They were shown to give aggregation both in plain water and in saline solution. Carborane aggregates were, however, disrupted when DOTAP/DOPE liposome solutions were used as dispersing agents. The computer analysis of the ESR spectra from carborane-loaded liposomes allowed to establish an increase of the order degree in the liposome bilayer with increasing carborane concentration, together with a decreased mobility. The same discontinuities of both correlation time and order parameter with respect to temperature variations were observed in carborane-containing and carborane-free liposomes. This suggested that a homogeneous dispersion of nitroxides and carboranes occurred in the liposome bilayer. The ESR line shape analysis proved that no dramatic changes were induced in the liposome environment by carborane insertion. QELS data showed that the overall liposome structure was preserved, with a slight decrease in the mean hydrodynamic radius and increase in polydispersity caused by the guest molecules.     

Flavonoids from Millettia pulchra

Chemical examination of Millettia pulchra yielded (?)-maackiain, (?)-pterocarpin, (?)-sophoranone and the new compounds (6S, 6aS, 11aR)-6α-methoxypterocarpin, (6S, 6aS,11aR)-6α-methoxyhomopterocarpin, (2S)5,7,4′-trihydroxy-8,3′,5′-triprenylflavanone, (2R,3R)7,4′-dihydroxy-8,3′,5′-triprenyldihydroflavanol, 5,7,2′,4′-tetrahydroxy-6,3′-diprenylisoflavone and 5,7,4′-trihydroxy-2′-methoxy-6,3′-diprenylisoflavone.     

Two new guaiane sesquiterpenes from Datura metel L. with anti-inflammatory activity

Chemical investigation of an acidic methanol extract of the whole plants of Datura metel resulted in the isolation of two new guainane sesquiterpenes, 1β,5α,7β-guaiane-4β,10α,11-triol (1) and 1α,5α,7α-11-guaiene-2α,3β,4α,10α,13-pentaol (2), along with eight known compounds: pterodontriol B (3), disciferitriol (4), scopolamine (5), kaempferol 3-O-β-d-glucosyl(1 → 2)-β-d-galactoside 7-O-β-d-glucoside (6), kaempferol 3-O-β-glucopyranosyl(1 → 2)-β-glucopyranoside-7-O-α-rhamnopyranoside (7), pinoresinol 4′′-O-β-d-glucopyranoside (8), (7R,8S,7′S,8′R)-4,9,4′,7′-tetrahydroxy-3,3′-dimethoxy-7,9′-epoxy-lignan-4-O-β-d-glucopyranoside (9), and (7S,8R,7′S,8′S)-4,9,4′,7′-tetrahydroxy-3,3′-dimethoxy-7,9′-epoxylignan-4-O-β-d-glucopyranoside (10). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D NMR and MS spectra. Compounds 2-4 and 6-10 were shown to have modest anti-inflammatory effects through inhibition of NO production in LPS-stimulated BV cells.     

Nonallergenic urushiol derivatives inhibit the oxidation of unilamellar vesicles and of rat plasma induced by various radical generators

Urushiols consist of an o-dihydroxybenzene (catechol) structure and an alkyl chain of 15 or 17 carbons in the 3-position of a benzene ring and are allergens found in the family Anacardiaceae. We synthesized various veratrole (1,2-dimethoxybenzene)-type and catechol-type urushiol derivatives that contained alkyl chains of various carbon atom lengths, including –H, –C₁H₃, –C₅H₁₁, –C₁₀H₂₁, –C₁₅H₃₁, and –C₂₀H₄₁, and investigated their contact hypersensitivities and antioxidative activities. 3-Decylcatechol and 3-pentadecylcatechol displayed contact hypersensitivity, but the other compounds did not induce an allergic reaction, when the ears of rats were sensitized by treatment with the compounds every day for 20 days. Catechol-type urushiol derivatives (CTUDs) exerted very high radical-scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl radical and inhibited lipid peroxidation in a methyl linoleate solution induced by 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN). However, veratrole-type urushiol derivatives did not scavenge or inhibit lipid peroxidation. CTUDs also acted as effective inhibitors of lipid peroxidation of the egg yolk phosphatidylcholine large unilamellar vesicle (PC LUV) liposome system induced by various radical generators such as AMVN, 2,2′-azobis(2-amidino-propane) dihydrochloride, and copper ions, although their efficiencies differed slightly. In addition, CTUDs suppressed formation of cholesteryl ester hydroperoxides in rat blood plasma induced with copper ions. CTUDs containing more than five carbon atoms in the alkyl chain showed excellent lipophilicity in a n-octanol/water partition experiment. These compounds also exhibited high affinities to the liposome membrane using the ultrafiltration method of the PC LUV liposome system. Therefore, CTUDs seem to act as efficient antioxidative compounds against membranous lipid peroxidation owing to their localization in the phospholipid bilayer. These results suggest that nonallergenic CTUDs act as antioxidants to protect against oxidative damage of cellular and subcellular membranes.     

Two new flavonols,including one flavan dimer,from the roots of Indigofera stachyodes

A new flavan dimer, 2α,3α-epoxyflavan-5,7,3′,4′-tetraol-(4β→8)-flavan-5′′,7′′,4′′′-triol (1), and a new flavonol, 3-O-(3-nitropropanoyl)-2,3-cis-5,7,3′,4′-tetrahydroxyflavan (2), together with a known compound, 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β→8)-epicatechin (3), were isolated from the roots of Indigofera stachyodes. Their structures were elucidated by spectroscopic techniques including MS, 1D NMR, and 2D NMR. Compounds 2 and 3 were evaluated to determine their protective effects against carbon tetrachloride (CCl₄)-induced hepatotoxicity in the human liver cell line HL-7702. The results showed that 2 and 3 could protect HL-7702 cells from injury induced by CCl₄, with cell survival rates of 122.0% and 72.5%, respectively.     

Dilignol glycosides from needles of Picea abies

(2R,3R)-2 3-Dihydro-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-5-benzofuranpropanol 4′-O-β-d-glucopyranoside [dihydrodehydrodiconiferyl alcohol glucoside], (2R,3R)-2 3-dihydro-7-hydroxy-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-5-benzofuranpropanol 4′-O-β-d-glucopyranoside and 4′-O-α-l-rhamnopyranoside, 1-(4′-hydroxy-3′-methoxyphenyl)-2- [2″-hydroxy-4″-(3-hydroxypropyl)phenoxy]-1, 3-propanediol 1-O-β-d-glucopyranoside and 4′-O-β-d-xylopyranoside, 2,3-bis[(4′-hydroxy-3′-methoxyphenyl)-methyl]-1,4-butanediol 1-O-β-d-glucopyranoside [(?)-seco-isolariciresinol glucoside] and (1R,2S,3S)-1,2,3,4-tetrahydro-7-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-6-methoxy-2 3-naphthalenedimethanol α²-O-β-d-xylopyranoside [(?)-isolariciresinol xyloside] have been isolated from needles of Picea abies and identified.     

Synthesis of purine and pyrimidine 2′-deoxynucleosides from a 1,2-dithio sugar precursor

9-(2-S-Ethyl-2-thio- and α-D-mannofuranosyl)adenine (8α and 8β) were synthesized from ethyl 3,5,6-tri-O-acetyl-2-S-ethyl-1,2-dithio-α-D-mannofuranoside (1) by bromination followed by coupling of the resultant bromide (2) with 6-benzamido-(chloromercuri)purine. The 2-chloro analogues (10α and 10β) of 8α and 8β were obtained by way of a fusion reaction between 1,3,5,6-tetra-O-acetyl-2-S- ethyl-2-thio-α-D-mannofuranose (5) and 2,6-dichloropurine. Fusion of the bromide 2 with 2,4-bis(trimethylsilyloxy)pyrimidine and its 5-methyl derivative led to 1-(2-S- ethyl-2-thio-β-D-mannofuranosyl)uracil (16) and its thymine analogue (15). The action of Raney nickel led to rapid dechlorination of 10α and 10β, and all of the 2′-thio-nucleosides underwent desulfurization to give the corresponding 2′-deoxynucleosides. Sequential periodate oxidation-borohydride reduction converted the hexofuranosyl nucleosides into their pentofuranosyl analogues. Thus prepared were 9-(2-deoxy-α-and β-D-arabino-hexofuranosyl)adenine (11α and 11β) and their 2-deoxy-D-threo-pentofuranosyl counterparts (6α and 2′-deoxy-3′-epiadenosine, 6β), and 1-(2-deoxy- β-D-arabino-hexofuranosyl)-thymine (17) and -uracil (18) and their 2-deoxy-D-threo-pentofuranosyl counterparts (3′-epithymidine, 21, and 2′-deoxy-3′-epiuridine, 20). Detailed n.m.r.-spectral correlations are described for the series, and various derivatives of the nucleosides are reported.     

Ionylideneacetic Acids and Abscisic Acid Biosynthesis by Cercospora rosicola

Several compounds having the basic α-ionylideneacetic acid structure were tested in Cercospora rosicola resuspensions. At 100 μm, all the compounds inhibited abscisic acid (ABA) biosynthesis. Time studies with unlabelled and deuterated (2Z,4E)- and (2E,4E)-α-ionylideneacetic acids showed rapid conversions into both (2Z,4E)- and (2E,4E)-4′-keto-α-ionylideneacetic acids as major products. Incorporation of the label into ABA was specific for the 2Z,4E-isomer. Minor products, identified by GC-MS, were (2Z,4E)- and (2E,4E)-4′-hydroxy-α-ionylideneacetic acids and (2Z,4E)-1′-hydroxy-α-ionylideneacetic acid. The conversion to (2Z,4E)-l′-hydroxy-α-ionylideneacetic acid has not been previously reported and was specific for the 2Z,4E-isomer. A time study for the conversion of methyl esters of [²H₃]-(2Z,4E)- and [²H₃]-(2E,4E)-4′-keto-α-ionylideneacetates showed a slow introduction of the l′-hydroxyl group and specificity for 2Z,4E-isomer. Conversion of the ethyl esters of (2Z,4E)- and (2E,4E)-l′-hydroxy-α-ionylideneacetates into the ethyl esters of both ABA and (2E,4E)-ABA demonstrated that ABA can be formed by oxidation of the 4′-position after the insertion of the 1′-hydroxy group. The ethyl 1′-hydroxy acids were also isomerized to the corresponding ethyl (2Z,4E)- and ethyl (2E,4E)-3′-hydroxy-β-ionylideneacetates. Ethyl (2Z,4E)-1′-hydroxy acid also gave small amounts of ethyl l′,4′-trans-diol of ABA. These results suggest that ABA may be formed through a (2Z,4E)-1′-hydroxy-α-ionylidene-type intermediate in addition to the previously proposed route through (2Z,4E)-4′-keto-α-ionylideneacetic acid.     

Conformational dynamics in mixed α/β-oligonucleotides containing polarity reversals: A molecular dynamics study using time-averaged restraints*

Nucleic acid duplexes featuring a single alpha-anomeric thymidine inserted into each DNA strand via 3′-3′ and 5′-5′ phosphodiester linkages exhibit local conformational dynamics that are not adequately depicted by conventional restrained molecular dynamics (rMD) methods. We have used molecular dynamics with time-averaged NMR restraints (MDtar) to explore its applicability to describing the conformational dynamics of two α-containing duplexes – d(GCGAAT-3′-3′-αT-5′-5′-CGC)₂ and d(ATGG-3′-3′-αT-5′-5′-GCTC)?r(gagcaccau). In contrast to rMD, enforcing NOE-based distance restraints over a period of time in MDtar rather than instantaneously results in better agreement with the experimental NOE and J-data. This conclusion is based on the dramatic decreases in average distance and coupling constant violations (Δd _av, J _rms, and ΔJ _av) and improvements in sixth-root R-factors (R ^x). In both duplexes, the deoxyribose ring puckering behavior predicted independently by pseudorotation analysis is portrayed remarkably well using this approach compared to rMD. This indicates that the local dynamic behavior is encoded within the NOE data, although this is not obvious from the local R ^x values. In both systems, the backbone torsion angles comprising the 3′-3′ linkage as well as the (high S-) sugars of the α-nucleotide and preceding residue (α?1) are relatively static, while the conformations of the 5′-5′ linkage and the sugar in the neighboring β-nucleotide (α+1) show enhanced flexibility. To reduce the large ensembles generated by MDtar to more manageable clusters we utilized the PDQPRO program. The resulting PDQPRO clusters (in both cases, 13 structures and associated probabilities extracted from a pool of 300 structures) adequately represent the structural and dynamic characteristics predicted by the experimental data.     

Synthesis of glycos-3-yl-α,γ-diamino acids. Synthesis of four diastereomeric spiro-3,4′-(R and S)-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-ribo-hexofuranose)-3′-(R and S)-acetamido-2′-pyrrolidinones

Treatment of (Z)-3-deoxy-1,2:5,6-di-O-isopropylidine-3-C-(methoxycarbonyl)-methylene-α-d-ribo-hexofuranose (1) with diazomethane in ether afforded the unstable Δ¹- and Δ²-pyrazolines 2 and 2a. High-pressure hydrogenation of the latter compounds over Raney nickel afforded a mixture of amines 3, 5, 7, and 9 (in 80% yield), which were separated by chromatography. Acetylation of these compounds yielded the N-acetyl derivatives 4, 6, 8, and 10. X-Ray analysis of compounds 8 and 10 showed them to be spiro-3,4′-(R)-(3-deoxy-1,2:5,6-di-O-isopropylidine-α-d-ribo-hexofuranose)-3′-(R)-[and 3′-(S)]-acetamido-2′-pyrrolidinone, respectively. The structures of compounds 4 and 6 (determined by chemical means) were the corresponding spiro-3,4′-(S)-3′-(R)-acetamido-2′-pyrrolidinone and 3′-(S)-acetamido-2′-pyrrolidinone, respectively.     

Sesquiterpenoids and lignans from the fruits of Illicium simonsii Maxim

Twenty-two known compounds were isolated from the 95% alcohol extract of the fruits of Illicium simonsii Maxim, including seven sesquiterpenoids (16–22) and fifteen lignans (1–15). In the present research, compounds 3 ((7S,8R,8′S)-3,3′-dimethoxy-4,4′,9-trihydroxy-7,9′-epoxylignan-7′-one), 4 ((−)-(7′S,8S,8′R)-4,4′-dihydroxy-3,3′,5,5′-tetramethoxy-7′,9-epoxylignan-9′-ol-7-one), 5 ((+)-8-hydroxypinoresinol), 6 ((+)-8-hydroxymedioresinol), 8 ((2R,3R)-2β-(4″-hydroxy-3″-methoxybenzyl)-3α-(4′-hydroxy-3′-methoxybenzyl)-γ-butyrolactone 2-O-(β-D-glucopyranoside), 12 ((+)-8-methoxyisolariciresinol), 13 (α-conidendrin), 14 (boehmenan) and 15 (7R,8R,7′E-7′,8′-didehydro-4,7,9,9′- tetrahydroxy-3-methoxy-8-O-4′-neolignan) were reported from the Illicium genus for the first time, and compounds 1 (simulanol), 7 ((+)-secoisolariciresinol monoglucoside), 10 ((+)-9-O-β-D-glucopyranosyl lyoniresinol), 11 ((+)-isolariciresinol), 18 (neoanisatin), 19 (veranisatin A), 20 (4,5-d₂-8′-oxo-dihydrophaseic acid) and 22 (Oligandrumin A) were firstly isolated from the plant. Their structures were elucidated on the basis of NMR spectroscopic and mass spectrometric data. Moreover, the chemotaxonomic significance of the isolated compounds is discussed.     

Oligosaccharides from “standardized intermediates”. Synthesis of a branched tetrasaccharide glycoside isomeric with the blood-group B,type 2 determinant

Building-block derivatives of the component monosaccharides were used to construct the tetrasaccharide glycoside 15, in which an α- d-Galp-(1→4)- d-Gal linkage replaces the α-(1→3) linkage of the human blood-group B, type 2, determinant structure. The initial coupling of 2-O-benzoyl-3,6-di-O-benzyl-4-O-(tetrahydropyran-2-yl)-α- d-galactopyranosyl chloride to allyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β- d-glucopyranoside was followed by selective deprotection of the disaccharide product, either at O-4′ (to give 8) or O-2′ (to give 3). The conversion of 8 into 15 involved successive coupling with tetra-O-benzyl-α- d-galactopyranosyl bromide ( 8 → 11), O-debenzoylation at O-2′ ( 11 → 12), coupling with tri-O-benzyl-α- l-fucopyranosyl bromide ( 12 → 14), and O-debenzylation by hydrogenolysis ( 14 → 15). Alternatively, 3 was α- l-fucosylated to give 6, and 6 was selectively deprotected at O-4′ to give 7. However, attempts to α- d-galactosylate 7 were unsuccessful. The unsubstituted forms of the intermediate disaccharide ( 8) and trisaccharide ( 12) glycosides were obtained by appropriate deblocking procedures.     

Chemical constituents from the leaves of Cinnamomum parthenoxylon (Jack) Meisn. (Lauraceae)

Phytochemical investigation of the ethanolic extract from the leaves of Cinnamomum parthenoxylon (Jack) Meisn. led to the isolation of (3R, 4R, 3′R, 4′R)-6,6′-dimethoxy-3, 4, 3′, 4′-tetrahydro-2H, 2′H-[3, 3′]bichromenyl-4, 4′-diol (1), 4-hydroxybenzaldehyde (2), 1,2,4-trihydroxybenzene (3), kaempferol-3-O-α-l-rhamnoside (4), herbacetin (5), quercetin-3-O-α-l-rhamnoside (6), daucosterol (7), and β-sitosterol (8). The structures were established by extensive analysis of their MS and NMR spectroscopic data and comparison with literature data. In the present research, all of the isolated compounds 1–8 are reported for the first time in the species C. parthenoxylon. Compounds 1–6 were firstly isolated from genus Cinnamomum. Compounds 1, 3, 5 and 6 have not been reported from any species in Lauraceae family. The chemotaxonomic significance of the isolated compounds is discussed.     

Enantiotopically Selective Oxidation of 1,5-Diols with Gluconobacters Preparation of (S)-Mevalonolactone

(±)-(2Z,4E)-α-Ionylideneacetic acid (2) was enantioselectively oxidized to (?)-(l′S)-(2Z,4E)-4′-hydroxy-α-ionylideneacetic acid (3), (+)-(1′R)-(2Z,4E)-4′-oxo-α-ionylideneacetic acid (4) and (+)-abscisic acid (ABA) (1) by Cercospora cruenta IFO 6164, which can produce (+)-ABA and (+)-4′-oxo-α-acid 4. This metabolism was confirmed by the incorporation of radioactivity from (±)-(2-¹⁴C)-(2Z,4E)-α-acid 2 into three metabolites. (?)-4′-Hydroxy-α-acid 3 was a diastereoisomeric mixture consisting of major 1′,4′-trance-4′-hydroxy-α-acid 3a and minor 1′,4′-cis-4′-hydroxy-α-acid 3b. These structures, 3a and 3b, were confirmed by ¹³C-NMR and ¹H-NMR analysis. Also, the enantioselectivity of the microbial oxidation was reexamined by using optically pure α-acid (+)-2 and (?)-2, as the substrates.     

Equimolar oxymercuration of D-glucal triacetate with mercuric perchlorate and its application to the synthesis of 2′-deoxy disaccharides

A search for appropriate reaction conditions for the equimolar methoxymercuration of D-glucal triacetate was made by using various mercuric salts, bases, and reaction solvents. Under optimum conditions with mercuric perchlorate, sym-collidine, and acetonitrile, D-glucal triacetate underwent methoxymercuration with an equimolar amount of methanol to afford methyl 3,4,6-tri-O-acetyl-2-deoxy-2-perchloratomercuri-β-D-glucopyranoside (1, 26%) and its α-D-manno isomer (2, 49%). Equimolar oxymercuration of D-glucal triacetate with partially protected sugars, followed by subsequent demercuration of the products with sodium borohydride, afforded α- and β-linked 2′-deoxy disaccharide derivatives in moderate yields. The partially protected sugars used were 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose and 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose, and the corresponding products were O-(3,4,6-tri-O-acetyl-2-deoxy-α-D-arabino-hexopyranosyl)-(1→6)-1,2,3,4-tetra-O-acetyl-D-glucopyranose(4, 23%) and its β-linked isomer (5, 11%) from the former, and O-(3,4,6-tri-O-acetyl-2-deoxy-α-D-arabino-hexapyranosyl)-(1→6)-1,2:3,4-di- O-isopropylidene-α-D-galactopyranose (9, 29%) and its β-linked isomer (10, 10%) from the latter. Deacetylation of these 2′-deoxy disaccharides was effected with methanolic sodium methoxide, but deacetonation was unsuccessful owing to simultaneous cleavage of the glycosidic linkage.     

Further applications of selective displacements in an unsymmetrical ditriflate. Synthesis of new triamino and tetraamino disaccharides of the trehalose type

Although the known ring-opening with sodium azide in 2,3-anhydro-4,6-O-benzylidene-α-d-allopyranosyl 2,3-anhydro-4,6-O-benzylidene-α-d-allopyranoside gave mainly symmetrical 2-azido-4,6-O-benzylidene-2-deoxy-α-d-allopyranosyl 2-azido-4,6-O-benzylidene-2-deoxy-α-d-allopyranoside (2), the unsymmetrical 2,3′-diazido isomer 3 having the α-d-altro, α-d-gluco configuration was shown to be a second product that can be conveniently isolated on a preparative scale. The ditriflate 4 derived from 3 was subjected to regioselective displacement in the altro moiety with sodium azide, followed by displacement with sodium benzoate in the gluco moiety, to give a 2,3,3′-triazide having the α-d-manno, α-d-manno configuration. Alternatively, 4 was subjected to displacement first with benzoate and then with azide, thus providing the regioisomeric 2,3,2′-triazide of the same configuration. The ditriflate obtained from 2 furnished the corresponding 2,3,2′,3′-tetraazido derivative. Minor proportions of elimination products also arose in these reactions. The protected azido sugars were converted by standard methods into the 2,3,2′- and 2,3,3′-triamino derivatives and the 2,3,2′,3′-tetraamino derivative of α-d-mannopyranosyl α-d-mannopyranoside.     

Two new glycosides and one new neolignan from the roots of Cynanchum stauntonii

Three new compounds including one C₂₁-steroidal glycoside, one methylglycoside, and one neolignan, named as Deoxyamplexicogenin A-3-O-yl-4-O-(4-O-α-l-cymaropyranosoyl-β-d-digitoxopyranosoyl)-β-d-canaropyranoside (1), Methyl-O-α-l-cymaropyranosoyl-(1 → 4)-β-D-digitoxopyranoside (2), and (+)-(7S, 8R, 7′E)-5-hydroxy-3, 5′-dimethoxy-4′, 7-epoxy-8, 3′-neolign-7′-ene-9, 9′-diol 9′-ethyl ether (3), respectively, were isolated from the roots of Cynanchum stauntonii. The structure elucidations were achieved by in-depth spectroscopic examination, mainly including the experiments and analyses of multiple 1D- and 2D-NMR and HRESIMS and CD analysis and qualitative chemical tests. Cytotoxicity activities of compounds 1–3 were evaluated against five tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, and A2780) in cell based assays where they were found to be inactive.     

3′,6′-anhydro-6-O-corynomycoloyl trehalose: Synthesis and identification as the impurity in synthetic cord factor preparations

Acylation of 2,3,4,2′,3′,4′-hexa-O-benzyl-6,6′-di-O-methanesulphonyl-α-α-trehalose (1) with a reduced amount of potassium corynomycolate yielded a mixture which consisted mainly of 2,3,4,2′,3′,4′-hexa-O-benzyl-6-O-corynomycoloyl-6′-O-methanesulphonyl-α,α-trehalose (2). Catalytic hydrogenolysis of 2 gave the mono-mesylate 4 which was converted into 3′,6′-anhydro-6-O-corynomycoloyl-α,α-trehalose (5) but treatment with sodium hydride. The structure of 5 was studied by mass-spectroscopy. Compound 5 was found to be identical with the byproduct obtained in the acylation of 6,6′-di-O-p-toluenesulphonyl-α,α-trehalose with potassium corynomycolate.