白薇中C21甾体皂苷类成分分析与伪品鉴别研究

本文建立了HPLC-ELSD法用以测定中药白薇中四种C21甾体皂苷类化合物含量,分析两种植物来源的白薇药材中C21甾体皂苷类化合物含量差异,并通过色谱特征分析其与易混淆品白前和徐长卿的成分差异.结果表明在不同批次直立白薇和蔓生白薇样品中C21甾体皂苷含量差异很大.本方法简便,灵敏、准确、重现性好,适用于中药白薇主要皂苷成分测定和真伪药材鉴别.     

甾体C7-羟基化研究进展

生物羟基化被用作研究甾体代谢机制和制备羟基甾体的工具,许多真菌微生物菌具有甾体C7-羟基化能力,而C7-羟基甾体具有许多重要的生物活性。在分子水平上,人们已经发现了7α-羟基化酶及其基因。就以上几个方面做一简单综述,并对此领域的发展趋势进行展望。     

甾体微生物转化C11β-羟基化的研究进展

C11β-羟基化是甾体微生物转化中难以实现的一步反应。对甾体C11β-羟基化的机理及部分生理生化问题进行了讨论,对蓝色犁头霉和新月弯孢霉催化转化甾体C11β-羟基化的应用研究特点及其催化转化反应产物氢化可的松的工业生产现状及相关问题进行了评述,并对此技术开发前景进行了预测。     

徐长卿中的一个新的C21甾体配糖体

从传统中药徐长卿（Cynanchum paniculatum Ktag)根茎的乙酸乙酯提取物中分离得到1个新的C21甾体配糖体,经1D,2D-NMR波谱分析,确定其结构为新白薇甙元C3-O-β-D-夹竹桃吡喃糖甙（1）。     

甾体微生物转化反应关键酶3-甾酮-Δ1-脱氢酶的研究进展

3-甾酮-Δ~1-脱氢酶是甾体化合物微生物代谢的关键酶,负责催化3-酮基类甾体化合物A环上的C1,2位脱氢反应。其不仅在甾体母核的早期降解途径中发挥重要作用,而且能通过A环C1,2位上双键的导入显著提高甾体化合物的生理活性。本文详细阐述了3-甾酮-Δ~1-脱氢酶在微生物中的种属分布和序列特征、酶的生物学特性、生理作用、催化机理以及分子改造等,为深入研究该酶在甾体生物转化领域中的应用提供重要参考。     

白首乌化学成分与药理活性研究进展

白首乌类植物含有C21甾体酯甙类、磷脂类、苯乙酮甙类等化学成分,具有抗氧化、调节免疫功能、抗肿瘤、抗缺氧、降血脂等多种药理活性.主要综述了近年来白首乌类植物化学成分及药理活性研究进展概况.     

萝藦科马利筋族植物化学成分研究进展(Ⅱ)

综述了到目前为止,从马利筋族植物中发现的黄酮、强心甙、生物碱、萜类、苯衍生物类等成分的种类及其分布,并介绍了一些化合物的药理作用以及黄酮类和C21甾体化合物在鹅绒藤属化学分类中的作用.     

牛奶菜属植物化学成分研究进展

萝藦科牛奶菜属植物全世界约100种,中国产22种5变种,化学成分主要包括C21甾体类、三萜类和环醇类等.本文综述了牛奶菜属植物化学成分的研究进展,为该属植物的进一步研究开发提供参考.     

中国薯蓣属植物中的甾体皂苷及甾体皂苷元

中国薯蓣属(Dioscorea L.)植物含有约21种甾体皂苷元,其中大部分种类含有3β-羟基皂苷元,少数种类含有3α-羟基皂苷元。从薯蓣属13种植物中共分离出59个甾体皂苷成分,按化学结构可将这些甾体皂苷分为4种类型。约有17种薯蓣属植物含有甾体皂苷元(主要为薯蓣皂苷元),均为根茎组(Sect.Stenophora)种类。在查阅大量资料的基础上,对各种类所含的甾体皂苷元和甾体皂苷成分及各成分的化学结构进行了归纳和综述。     

南山藤属植物化学成分及生物活性研究进展

萝藦科南山藤属植物广泛分布于亚洲和非洲南部,全株药用,临床应用广泛。化学结构类型包括甾体、苯丙素、寡糖等,其中C21甾体类成分为该属植物中主要化学结构类型,并具有抗肿瘤、抗抑郁、抗炎及免疫调节等作用。本文对南山藤属植物化学成分及生物活性进行综述,以期为更好地开发和利用南山藤属植物资源提供参考。     

Biosynthesis of a C21 steroid conjugate in an insect. The conversion of [14C]cholesterol to 5-[14C]pregnen-3 beta,20 beta-diol glucoside in the tobacco hornworm, Manduca sexta

Following injection into Manduca sexta (L.) female pupae (day 16), [14C]cholesterol was converted to a C21 steroid conjugate, 5-[14C]pregnen-3 beta,20 beta-diol glucoside. The conjugate was isolated from ovaries and eggs and contained three glucose units at least one of which is attached to C-20. The distribution of the other two glucose units remains to be determined. Other than the dealkylation of C-24 alkane or alkene substituents, side-chain cleavage of sterols is uncommon to insects. Here we report the first definitive proof of the biosynthesis of a C21 steroid conjugate from cholesterol in an insect species. The capability of M. sexta to so readily convert cholesterol to a C21 steroid suggests a physiological role for 5-pregnen-3 beta,20 beta-diol in this species.     

Determination of deletion sizes in the MHC-linked complement C4 and steroid 21-hydroxylase genes by pulsed-field gel electrophoresis

In man, the genes encoding the complement component C4 (C4A, C4B) of the immune system and the steroid 21-hydroxylase enzyme (CYP21A, CYP21B) of adrenal steroid biosynthesis are located in the major histocompatibility complex (MHC). Frequent gene deletions and duplications have been described in the C4 and CYP21 genes, particularly in patients with autoimmune diseases and congenital adrenal hyperplasia. Here we report the determination of deletion sizes in 11 chromosomes with six different deletions. The deletions spanned the C4A+CYP21A, C4B+CYP21A, and C4B+CYP21B gene pairs as determined by standard Southern blot analysis. The deletion size fell within the range of 30-38 kb in all the chromosomes, as determined by pulsed-field gel electrophoresis. Because the deletion sizes in most other gene clusters are more heterogeneous, the results suggest the involvement of a specific mechanism in the generation of C4+CYP21 deletions.     

Five new C21 steroidal glycosides from Cynanchum komarovii Al.Iljinski

Five new C21 steroidal glycosides, namely, komarosides D (1), E (2), F (3), G (4), and H (5), along with two known C21 steroidal glycosides cynatratoside E (6) and hancoside A (7), were isolated from the ethanol extract of the roots of Cynanchum komarovii Al.Iljinski (Asclepiadaceae). Their structures were determined by physiochemical and spectroscopic analysis. Among these glycosides, five had an aberrant 13,14:14,15-disecopregnane-type skeleton, and the other two had normal four-ring C21 steroid skeletons. The existence of more than one type of C21 steroid skeleton in one species is rare in the plants of the family Asclepiadaceae, and this has chemotaxonomic significance for this species.     

Identification and quantification of C21 steroidal saponins from Radix Cynanchi Atrati by high-performance liquid chromatography with evaporative light scattering detection and electrospray mass spectrometric detection

High-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-ESI/MS) and evaporative light scattering detection (HPLC-ELSD), respectively, has been performed for the simultaneous identification and quantification of six C(21) steroid saponins, including cynanversicoside A, B, D, G, glaucoside C and glaucogenin C-3-O-beta-d-thevetopyranoside in Radix Cynanchi Atrati. The extraction of the C(21) steroidal saponins was performed using a B-811 Buchi Universal Extraction System in Warm Solvent Mode, and the analyte was concentrated by column chromatography before HPLC analysis. The chromatographic separation was performed on an Agilent Zorbax Extend C(18) analytical column efficiently using gradient elution with acetonitrile and water. The method was validated with acceptable linearities (r > 0.9991) and recoveries (98.2-101.3%). The limits of detection of the C(21) steroid saponins were from 0.2 microg for glaucogenin C-3-O-beta-d-thevetopyranoside to 0.5 microg for cynanversicoside B. The intra- and inter-day precisions of the method were evaluated and were less than 5.0%. The method was successfully used to analyse 20 batches of Radix Cynanchi Atrati. The content of C(21) steroid saponins in the plant material varied significantly from habitat to habitat, confirming the necessity to control the quality of Radix Cynanchi Atrati during its preparation and application in the clinic.     

DNA polymorphism unique for a complotype with deletion of HLA-linked C4B and 21-hydroxylase B genes causing congenital adrenal hyperplasia

Summary Defects in the enzyme steroid 21-hydroxylase (21-OH) result in congenital adrenal hyperplasia (CAH), a frequent disorder of steroid biosynthesis. The gene encoding the enzyme, 21-OHB, has been mapped adjacent to the complement component C4B gene in the human HLA gene complex. DNA-level analyses of patients with CAH have shown that the 21-OHB gene has often been deleted, but the detection of 21-OHB delections in heterozygotes is often problematic because it is based on relative band intensities. We here report a DNA polymorphism in the C4A91 gene unique to one particular type of 21-OHB deletion occurring solely with a complement phenotype BfF C4A91 B null, shown earlier to be frequent in CAH patients. This marker makes direct detection of the 21-OHB deletion in heterozygotes possible.     

Duplication of the CYP21A2 gene complicates mutation analysis of steroid 21-hydroxylase deficiency: characteristics of three unusual haplotypes

Steroid 21-hydroxylase deficiency, the primary cause of congenital adrenal hyperplasia, is caused by defects of the CYP21A2 gene. As a complement to hormonal measurements, mutation analysis of CYP21A2 is an important tool in the diagnosis of steroid 21-hydroxylase deficiency. Contemporary mutation-detection protocols based on the polymerase chain reaction often depend on the assumption that no more than one CYP21A2 gene is present on each chromosome 6. We describe three haplotypes with two CYP21A2 genes on the same chromosome, with defects typical of salt-losing steroid 21-hydroxylase deficiency in one of those genes, but not necessarily in the other. The frequency of these haplotypes in the general population is 6/365 (1.6%), so they are no less common than other haplotypes that indeed carry steroid 21-hydroxylase deficiency. Chromosomes that carry two CYP21A2 genes therefore represent a significant pitfall in the molecular diagnosis of steroid 21-hydroxylase deficiency. We recommend that, whenever CYP21A2 mutation analysis of an individual who is not a known carrier of steroid 21-hydroxylase deficiency is performed, the overall structure of the CYP21/ C4 region (the RCCX area) is determined by haplotyping to avoid erroneous assignment of carrier status.     

Metabolic fate of [3H]deoxycorticosterone and [14C]progesterone--I. Early tissue metabolites and analysis of 21-hydroxysteroids by high pressure liquid chromatography

Rabbits injected with mixtures of [3H]deoxycorticosterone and [14C]progesterone had significant levels of both 3H and 14C in several tissues and fluids extracted 10-45 min later. The distribution of radioactivity between 21-deoxysteroid, 21-hydroxysteroid, steroid acid and steroid glucuronide fractions was determined by alumina adsorption chromatography. Steroid acids derived from both steroids accumulated in the liver, kidney and urine, but were quantitatively less significant in the bile, duodenum, uterus, spleen and lung and were detected in the blood for the first time. Different 21-hydroxysteroid profiles were detected in the tissue and fluid extracts by reverse and straight phase high pressure liquid chromatography. [3H]Deoxycorticosterone accumulated in the kidney, lung, spleen and uterus, whereas tetra and hexahydro reduced metabolites predominated in the liver, bile and duodenum. By contrast, [14C]progesterone was metabolised to more polar 21-hydroxylated metabolites which were detected in the liver, kidney and urine. These results show the influence of a steroid 21-hydroxyl function, when administered, as opposed to being formed in in vivo, on the metabolic fate and excretory pathways of 21-hydroxysteroids by the rabbit.     

Extraction of a steroid transport system from Pseudomonas testosteroni membranes and incorporation into synthetic liposomes

A steroid binding protein has been extracted from Pseudomonas testosteroni membranes with an organic solvent system. This protection binds some C19 and C21 steroids but not C18 steroids. When this protein is incorporated into synthetic lipid vesicles constructed from P. testosteroni phospholipids, the vesicles perform concentrative uptake of testosterone in the presence of the ionophore valinomycin. This steroid binding protein is thus believed to be the steroid permease of this organism.     

Effect of spin state on reduction of cytochrome P-450 (P-450C21) from bovine adrenocortical microsomes

The effect of spin state on cytochrome P-450 reduction was studied with a reconstituted system consisting of P-450C21 and NADPH-cytochrome P-450 reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4) purified from bovine adrenocortical microsomes. The absolute high spin contents of substrate-free, progesterone-bound and 17 alpha-hydroxyprogesterone-bound P-450C21 were estimated from the analysis of thermally induced difference spectra to be 25, 78 and 94% at 25 degrees C, respectively, in 50 mM potassium phosphate buffer (pH 7.2) containing 20% glycerol, 0.1 mM EDTA and 0.5% Emulgen 913. The effect of the high spin content on P-450C21 reduction by NADPH in the reconstituted system was analyzed by a steady-state method and by a stopped-flow method at 25 degrees C. The steady-state results showed that the rate of P-450C21 reduction was not affected by the high spin content of substrate-bound P-450C21 but was very slow without a steroid substrate. Biphasic reduction of P450C21 containing two first-order processes was observed in the stopped-flow experiment in the presence of either of the steroid substrates, but the reduction was very slow without the substrate. There were no significant differences in the rate and the amount of the fast phase of reduction between 17 alpha-hydroxyprogesterone-bound and progesterone-bound P-450C21. Both kinetic studies indicate that the spin state does not control the electron transfer from NADPH to P-450C21 via NADPH-cytochrome P-450 reductase but the presence of substrate is essential for the reduction of P-450C21.