Preparative isolation and purification of alkannin/shikonin derivatives from natural products by high-speed counter-current chromatography

Alkannin and shikonin (A/S) and their derivatives have been found in the roots of several Boraginaceous species and are also produced through plant tissue cultures. The chiral compounds A/S are potent pharmaceutical substances with a wide spectrum of biological and pharmacological activities like wound healing, antimicrobial, anti-inflammatory, anticancer and antioxidant activity. High-speed counter-current chromatography (HSCCC) was applied for the first time to the separation, preparative isolation and purification of A/S and their esters from extracts of Alkanna tinctoria roots, as well as commercial samples. The constituents of HSCCC fractions and their purity were determined by high-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS), since DAD cannot detect oligomeric A/S derivatives that are present in most of the samples containing the respective monomeric derivatives. The purity of HSCCC fractions was compared with the one of fractions isolated by column chromatography (CC) using as stationary phases silica gel and Sephadex LH-20. As shown, the purity of monomeric alkannin/shikonin was greater by HSCCC than CC separation of commercial A/S samples.     

3-Hydroxyglutarate and β,γ-Epoxy Esters as Substrates for Pig Liver Esterase (PLE) and α-Chymotrypsin

The pH dependence of the α-chymotrypsin-catalyzed hydrolysis of dimethyl 3-hydroxyglutarate ( 3 ) has been studied. The e.e. was determined by HPLC analysis of diastereoisomeric camphanoic-acid derivatives. Kinetic resolution of the β,α-epoxy esters 10 and 24 by pig liver esterase has been shown to provide an alternative access to chiral β-hydroxy esters and acids of high optical purity. By this latter method, the unnatural enantiomer of γ-amino-β-hydroxybutyric acid (GABOB) has been synthesized. Finally, dimethyl meso-3,4-epoxyadipate ( 19 ) was hydrolyzed by pig liver esterase with almost 100% selectivity.     

Determination of naturally occurring hydroxynaphthoquinone polymers by size-exclusion chromatography

Summary Polymerization of alkannin, shikonin, and their derivatives, potent pharmaceutical substances, crucially affects their use in pharmaceuticals, cosmetics, and as food colorants, because it leads to loss of their antimicrobial activity, reduction of the lustre of their red coloration, and a decrease in their solubility. In this study size-exclusion chromatography (SEC) has been used for the first time for qualitative and quantitative analysis of monomeric and polymeric hydroxynaphthoquinone alkannin and shikonin derivatives. The purity and degree of polymerization has been determined to evaluate severalAlkanna tinctoria root samples from different geographical sources, and commercial samples of alkannin and shikonin, as pharmaceutical raw materials. Conditions for extraction of hydroxynaphthoquinones fromAlkanna tinctoria roots with olive oil were optimized in terms of polimerization, aiming to improve the biological activity of the final pharmaceutical product, Helixderm.     

紫草萘醌类化合物对乳酸脱氢酶和乙醇脱氢酶的共价修 饰作用

为研究紫草萘醌类化合物的细胞毒性作用机制,从新疆软紫草根中分离出四种紫草萘醌类化合物β,β-二甲基丙烯酰阿卡宁(1),乙酰阿卡宁(2),β-乙酰氧基异戊酰阿卡宁(3)和阿卡宁(4)。研究了四种天然紫草萘醌类化合物对乳酸脱氢酶和乙醇脱氢酶的共价修饰作用。酶活力测定结果表明,这四种紫草萘醌类化合物对两种脱氢酶都具有不同程度的抑制作用;酶分子中游离氨基和巯基修饰率的测定结果表明,紫草萘醌类化合物对两种酶的抑制作用主要是通过与酶分子中的巯基共价结合产生的。     

Alkannin/shikonin mixture from roots of Onosma echioides (L.) L.: extraction method study and quantification

This work reports the extraction procedures of alkannin/shikonin mixture from roots of six populations of Onosma echioides, by means of three extraction techniques: Soxhlet extraction, maceration and rapid solid-liquid dynamic extraction (RSLDE). Five solvents with different polarity (hexane, petroleum ether, chloroform, ethyl acetate, methanol) were also studied. Analysis of the extracts was performed by an HPLC-DAD (diode array detector) system. The most efficient extraction technique was Soxhlet procedure using ethyl acetate for 6 h. Studied samples of O. echioides showed an alkannin/shikonin content in the range of 0.02-0.24 mg/kg. Other naphthoquinone derivatives (deoxyalkannin/deoxyshikonin and 5,8-dihydroxy-2-(4-methyl-6-oxo-5,6-dihydro-2H-pyran-2-yl)-[1,4]naphthoquinone and arnebin-6) were found for the first time in O. echioides and characterized in the extracts using HPLC-MS apparatus equipped with an ESI ionization source.     

β-羰基酰胺类化合物的配位及晶体结构

为确认β-羰基酰胺类化合物与铜离子的配位位点,合成了6种β-羰基酰胺类配体L1～L6,分别与Cu(Ⅱ)进行配位反应.对生成的配合物进行单晶培养,并采用X射线衍射仪测定了单晶结构.结果表明,只有配体L6(2-苯甲酰乙酰苯胺)的铜配合物能够得到单晶.在其单晶中,Cu(Ⅱ)离子与来自2个配体的4个氧原子配位形成长方形的构型;配合物中存在分子内氢键、分子间氢键和π-π相互作用.     

Anti-skin ageing activity of napthoquinones from Arnebia nobilis Reichb.f.

The present isolation and identification of napthoquinones from roots of Arnebia nobilis Reichb.f. can lead to the discovery of new anti-skin ageing ingredient in colour cosmetics. Four compounds have been isolated and purified by rigorous column chromatography. The compounds are identified as β, β-dimethylacryl alkannin (AN-I), acetoxyisovaleryl alkannin (AAN-II), acetyl alkannin (AN-III) and alkannin (AN-IV) by interpretation of spectroscopic data. This study is the first to report the isolation of Acetoxyisovaleryl alkannin (AAN-II) from A. nobilis. The IC₅₀ values of the compounds, determined in human skin cells (human dermal fibroblasts and human keratinocytes) and mouse embryonic fibroblasts (NIH3T3) varied significantly among the four alkannins. Among the four compounds, β-acetoxyisovaleryl alkannin (AAN-II) significantly inhibited hydrogen peroxide (H₂O₂)-induced red blood corpuscle haemolysis and cellular senescence in human dermal fibroblasts. Collagen-I, elastin and involucrin syntheses in human dermal fibroblasts or keratinocytes were up regulated by AAN-II. These results support the potential utility of alkannins as novel anti-ageing ingredients.     

Die Glykoside der Wurzeln von Glossostelma carsoni (N. E. BR.) BULLOCK. Glykoside und Aglykone, 297. Mitteilung

Pentacyclic triterpenes, sterols, cardenolides and pregnane derivatives could be identified in extracts from roots of Glossostelma carsoni (N.E. BR .) Bullock. From the first group, the following substances could be isolated in crystalline form: β-amyrin, lupeol, their 3-O-acetyl derivatives, and 3-O-isovaleryl-β-amyrin. The sterols were isolated in the form of two mixed but crystalline fractions. The less polar fraction was shown to be a mixture of β-sitosterol, campesterol, stigmasterol, and cholesterol (stereoisomers are not excluded); the more polar fraction is probably a mixture of monohydroxy derivatives of the four above mentioned sterols.     

Synthesis and characterization of poly-β-hydroxybutyrate. II. Synthesis of D-poly-β-hydroxybutyrate and the mechanism of ring-opening polymerization of β-butyrolactone

Synthesis of the naturally occurring polyester, D -poly-β-hydroxybutyrate (PHB) was accomplished by using an optically active monomer. Polymerization of D -(+)-β-butyrolactone (β-BL) of 73% optical purity with a catalyst system of Et₃Al–H₂O produced a polymer with a similar optical activity and essentially identical to the natural polymer as isolated from bacterial cells. This paper describes the synthesis and characterization of this optically active polyester along with a suggested mechanism to account for the observed stereospecific polymerization of β-BL with this catalyst system.     

A scalable and expedient method of preparing diastereomerically and enantiomerically enriched pseudonorephedrine from norephedrine

Norephedrine has been efficiently converted into the corresponding diastereomer pseudonorephedrine using a three step, one-pot reaction. The three step process involves treatment of norephedrine with di-tert-butyl dicarbonate (Boc₂O); cyclization by way of mesylate formation at the alcohol; and lithium hydroxide mediated hydrolysis of the oxazolidinone. The diastereomeric purity was determined by HPLC and the enantiomeric purity was determined by optical activity measurements and chiral stationary phase HPLC analysis of the pseudonorephedrine oxazolidinone derivatives.     

三缺位杂多阴离子XW9O34^1^0^-(X=Si,Ge)的稀土衍生物的合成与表征

三缺位杂多阴离子A, α-和A, β-SiW9, A, α-和A, β-GeW9与稀土硝酸盐反应生成A, α-和A, -β[Ln3O3.(X2W9O34)2]^1^7^-(Ln=La, Ce, Pr, Nd, Sm, Eu, Gd,Er)型杂多阴离子。183W NMR结果表明, 配体XW9O34^1^0^-的结构在反应前后并没有发生明显的变化, 本文还对合成化合物的磁性质及氧化还原性质等进行了研究。     

Simultaneous determination of monomeric and oligomeric alkannins and shikonins by high-performance liquid chromatography-diode array detection-mass spectrometry

Alkannin and shikonin (A/S) derivatives have been found in the roots of several Boraginaceous species and are produced through plant tissue cultures. The chiral compounds alkannins and shikonins are potent pharmaceutical substances with a wide spectrum of pharmacological activities such as wound healing, antimicrobial, anti-inflammatory, anticancer and antioxidant. Although oligomeric A/S derivatives have been detected in root extracts and commercial samples their detection and determination through high-performance liquid chromatography has not been reported. Therefore, in the present study a rapid, simple high-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS) method was developed to detect, separate and determine monomeric and oligomeric/polymeric derivatives of alkannin/shikonin simultaneously for the first time. An optimization of HPLC-DAD parameters was performed. Both atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) modes were applied, in order to compare detection of monomeric and oligomeric A/S. Additionally, oligomeric A/S constituents in several samples were identified and the mode of A/S polymerization was proposed.     

Optical resolution of mandelic acid derivatives by column chromatography on crosslinked cyclodextrin gels

Crosslinked α- and β-cyclodextrin gels (α-CD-E and β-CD-E) were used for the chromatographic resolution of racemic mandelic acid and its derivatives. β-CD-E bound L -(+)-isomers preferentially over D -(?)-isomers and resolved DL -methyl mandelate to give a D -(?)-isomer of 100% optical purity in the first fraction. Mandelic acid, ethyl mandelate, and O-methylated mandelic acid yielded resolutions of 65–83% in initial fractions. α-CD-E, on the contrary, bound D -(?)-isomers more strongly than L -(+)-isomers, resolving DL -methyl mandelate to a smaller extent than β-CD-E. Binding of DL -mandelic acid and DL -methyl mandelate on β-CD-E was studied quantitatively by the equilibrium method. β-CD-E has a similar binding capacity to starch with 1:1 stoichiometry but bound much more strongly than starch. β-CD-E has the same mode of selectivity as starch for the asymmetric binding of the mandelic acid derivatives, but α-CD-E has a reverse selectivity to β-CD-E and starch.     

Synthesis of β-pyrazinyl-L-alanine (Paa) and of peptide derivatives

The title compound was prepared via a malonic ester synthesis starting with α-chloromethylpyrazine [2], and ending, after an asymmetric enzymatic hydrolysis of the racemic N-acetyl-β-2-pyrazinylalanine to the L -form of the new amino acid. The optical purity was ascertained by ¹H-NMR analysis at 360 MHz of the diastereoisomeric dipeptides L -pyrazinylalanine-L -leucine and D -pyrazinylalanine-L -leucine. Hydrophobic, steric and electronic parameters for its side chain were also estimated, which can be useful for the quantitative study of structure-activity relationships of biologically active peptide derivatives. The new amino acid could be introduced in the place of phenylalanine in the enkephalin-like pentapeptide [D -alanyl², leucine⁵]enkephalin, thus showing good stability towards the classical methods of peptide synthesis.     

Study on isohexenylnaphthazarins polymerization in alkaline media

The chiral pair alkannin and shikonin (A/S) and their isohexenylnaphthazarin (IHN) esters, which are naturally occurring hydroxynaphthoquinones (HNQ), are potent pharmaceutical substances with a wide spectrum of biological activity. The stability of A/S and their derivatives during process and storage is crucial to their use as drugs, cosmetics and food additives. The influence of alkaline media and of IHN esters hydrolysis was experimentally investigated on IHN polymerization by size exclusion chromatography (SEC). It was proved that during IHN esters hydrolysis, polymeric A/S and IHN are formed. An optimization of the hydrolysis conditions of IHN esters was also approached in terms of polymerization. Hydrolysis of IHN from a pure mixture of pigments proved preferable to that of preliminary root extracts by means of IHN polymerization, even for analytical determination; non-polar solvents are proposed for the extraction of IHN from roots, followed by hydrolysis, aiming to minimize the polymeric IHN and A/S formed. It was also proved that polymerization of IHN in alkaline media and during hydrolysis of IHN esters proceeds through the intermediate formation of semiquinones; after acidification, coupling of semiquinones with phenoxyl radicals results in polymeric IHN structures.     

Synthesis of amicetose by three enantioselective methods

Three methods for the synthesis of the deoxy sugar amicetose (2,3,6-trideoxy-d-erythro-hexopyranoside) are described. All three utilize the known dihydropyran 2-isobutoxy-6-methyl-2,3-dihydro-4H-pyran as an intermediate. Asymmetric hydroboration of the dihydropyran with IpcBH₂ gave enantiomerically enriched isobutyl α and β-amicetosides. Hydroboration with borane–tetrahydrofuran followed by derivatization of the major product (β-anomer) with R-(−)-1-(1-naphthyl)ethylisocyanate gave diastereomeric carbamates which were separated and converted to isobutyl β-d and β-l-amicetosides having high optical purity. Racemic isobutyl β-amicetosides were also resolved by enzymatic transesterification using lipase and an acyl transfer reagent. Porcine pancreatic lipase and lipases from Candida rugosa and Pseudomonas sp. were evaluated in the presence of either vinyl acetate, vinyl butyrate, or trifluoroethyl butyrate as acylating agents. A GC-based method for determining enantiomeric purity of amicetose derivatives was developed.     

竞争包结法研究β-环糊精及其两种衍生物对一些手性脂肪族客体分子的识别作用

以酚酞作为光谱探针 ,采用紫外 可见光谱滴定法测定了 β 环糊精 (β CD)、单 (6 氧 α 麦芽糖 ) β 环糊精 (6 G2 β CD )和单 [2 氧 (2 羟丙基 ) ] β 环糊精 (2 HP β CD )在 2 5℃时 ,pH =10 5缓冲液中(0 0 2 5mol/L)与几种脂肪族手性客体分子所形成超分子配合物的稳定常数 .结果表明 ,多种弱相互作用力协同作用于环糊精的配位过程 ,主 客体间的尺寸匹配决定所形成配合物的稳定性 .环糊精衍生物的取代基影响主体的配位能力 ,对于尺寸较小的客体分子配位能力的大小一般为 2 HP β CD >β CD >6 G2 β CD .另一方面 ,3种环糊精主体化合物对一些脂肪族客体分子也表现出一定的手性识别能力 ,对 (+ ) 异构体给出相对较强的键合能力 ,其中 ,2 HP β CD对 (+ ) /(- ) 樟脑的配位选择性为 1 2 5 .     

Natural (−)-7-methoxy-8-(β, γ-dihydroxyisopentyl)-coumarin

Chemistry of Natural Compounds - The roots ofPrangos ferulaceae (L.) Lindl. have yielded (?)-7-methoxy-8-(β, γ-dihydroxyisopentyl)-coumarin, composition C15H18O5, with mp 128°....     

毛冬青化学成分的研究II: 毛冬青皂苷甲的化学结构

从毛冬青的根皮中分得一种新的三萜皂苷,命名为毛冬青皂苷甲,经^1H NMR、^1^3C NMR、MS、IR、UV和化学转化产物的研究,推定它为3β,19α-二羟基-乌索-12-烯-24,28-二羧酸-28-β-D-葡萄吡喃糖基酯.     

Emulsifying Ability of β-Cyclodextrins for Common Oils

Emulsification of various common oils was investigated using natural β-cyclodextrin (β-CD) and its derivatives as emulsifiers. An oil/water (O/W) emulsion was formed using β-CD, whereas a water/oil (W/O) emulsion was formed using tripropanoyl-β-CD and tributanoyl-β-CD derivatives. Triacetyl-β-CD gave rise to both O/W and W/O emulsions. The type of emulsion was governed by the contact angle (θ_ow), which the precipitate of CD origin make with the oil-water interface.