Biological Activities and Syntheses of Steroidal Saponins: the Shark-Repelling Pavoninins

Steroidal saponins are complex compounds that have a steroid attached to a carbohydrate moiety. They are natural surfactants and detergents and exhibit a number of biological effects. Steroidal saponins have shown membrane-permeabilizing, hypocholesterolemic, immunostimulant, and anticancer properties. They have also been found to affect the growth, food intake and reproductive capabilities of animals. Furthermore, they have been shown to act as antiviral and antifungal agents. They have been isolated from many plants and some animals, especially sea cucumbers and starfish. Fish belonging to the species Pardachirus pavoninus excrete a mixture of six steroidal N-acetylglucosaminides, pavoninins 1–6, with shark-repelling properties. We report syntheses of the C-15α pavoninin-4 by both direct synthesis from diosgenin and by remote functionalization. A general solution for the glycosylation of hindered alcohols was developed using glycosyl fluorides as good glycosyl donors. The syntheses of two C-16β structural analogs of OSW-1 are described.     

纤维素酶催化与三液相萃取偶联制备盾叶薯蓣皂苷元

利用三液相萃取与酶催化转化耦合技术对盾叶薯蓣中薯蓣皂苷进行水解,并分离提取薯蓣皂苷元。考察了几种甾体皂苷和水解下的葡萄糖在三液相中的分配、酶的分配以及酶活力在三液相体系中的保留情况,并对比了三液相、有机相、水相中纤维素酶催化转化与薯蓣皂苷元的生成情况。实验结果表明,正己烷/1,4-二氧六环/硫酸铵三液相体系能够满足酶催化和产物分离同步进行的要求,使薯蓣皂苷元分配在正己烷相,底物和酶保留在1,4-二氧六环相,大部分葡萄糖进入硫酸铵相,反应进行96h薯蓣皂苷元的得率为69.4%,比有机相、水相酶催化分别提高一倍和27.6倍,显示出耦合技术的明显优势。     

Is the Membrane Lipid Matrix a Key Target for Action of Pharmacologically Active Plant Saponins?

This study was focused on the molecular mechanisms of action of saponins and related compounds (sapogenins and alkaloids) on model lipid membranes. Steroids and triterpenes were tested. A systematic analysis of the effects of these chemicals on the physicochemical properties of the lipid bilayers and on the formation and functionality of the reconstituted ion channels induced by antimicrobial agents was performed. It was found that digitonin, tribulosin, and dioscin substantially reduced the boundary potential of the phosphatidylcholine membranes. We concluded that saponins might affect the membrane boundary potential by restructuring the membrane hydration layer. Moreover, an increase in the conductance and lifetime of gramicidin A channels in the presence of tribulosin was due to an alteration in the membrane dipole potential. Differential scanning microcalorimetry data indicated the key role of the sapogenin core structure (steroid or triterpenic) in affecting lipid melting and disordering. We showed that an alteration in pore forming activity of syringomycin E by dioscin might be due to amendments in the lipid packing. We also found that the ability of saponins to disengage the fluorescent marker calcein from lipid vesicles might be also determined by their ability to induce a positive curvature stress.     

Elicitation of Diosgenin Production in Trigonella foenum-graecum (Fenugreek) Seedlings by Methyl Jasmonate

The effects of methyl jasmonate (MeJA), an elicitor of plant defense mechanisms, on the biosynthesis of diosgenin, a steroidal saponin, were investigated in six fenugreek (Trigonella foenum-graecum) varieties (Gujarat Methi-2, Kasuri-1, Kasuri-2, Pusa Early Branching, Rajasthan Methi and Maharashtra Methi-5). Treatment with 0.01% MeJA increased diosgenin levels, in 12 days old seedlings, from 0.5%–0.9% to 1.1%–1.8%. In addition, MeJA upregulated the expression of two pivotal genes of the mevalonate pathway, the metabolic route leading to diosgenin: 3-hydroxy-3-methylglutaryl-CoA reductase (HMG) and sterol-3-β-glucosyl transferase (STRL). In particular, MeJA increased the expression of HMG and STRL genes by 3.2- and 22.2-fold, respectively, in the Gujarat Methi-2 variety, and by 25.4- and 28.4-fold, respectively, in the Kasuri-2 variety. Therefore, MeJA may be considered a promising elicitor for diosgenin production by fenugreek plants.     

Pathways for the steroidal saponins conversion to diosgenin during acid hydrolysis of Dioscorea zingiberensis C. H. Wright

Diosgenin is an important starting material for the synthesis of steroidal hormone drugs in pharmaceutical industry. Acid hydrolysis of Dioscorea zingiberensis C. H. Wright (DZW) was the key step in the conversion of steroidal saponins to diosgenin in its manufacture factories. The pathways for the conversion of steroidal saponins to diosgenin during acid hydrolysis of DZW were studied experimentally. Three intermediate products and one byproduct were identified. The conversion pathways were from raw steroidal saponins zingiberensis newsaponin (1), deltonin (2), prosapogenin A of dioscin (3) to three intermediate products diosgenin-triglucoside (4), diosgenin-diglucoside (5) and trillin (6), and then to the product diosgenin (7) and byproduct 25-spirosta-3, 5-dienes (8). A maximum diosgenin yield of 2.5% was achieved when reacting in 0.8 M sulfuric acid for 6 h at 120 °C, while the intermediate products were just exhausted. After 6 h, the diosgenin yield decreased, due to the conversion of diosgenin to 25-spirosta-3, 5-dienes (8). The knowledge of the pathways for the conversion of steroidal saponins to diosgenin provide a scientific basis for assessing the performance of acid hydrolysis reaction in diosgenin manufacture factories by monitoring the content of three intermediate products (4-6). It also gives an alternative method for the synthesis of diosgenyl saponins (4-6) from plant material.     

葫芦巴护肤品配制及性能测试

为探索葫芦巴在护肤品中的应用,以葫芦巴种子提取物为原料,配制保湿霜、抗氧化霜、保湿水,对配制的3种护肤品进行了理化指标、稳定性、保湿能力、抗氧化能力、防晒功效、安全性和抑菌性测试。结果表明,保湿霜和抗氧化霜、保湿水的感官和理化指标符合我国行业标准QB/T1857-2013、QB/T2660-2004的要求。葫芦巴种子提取物的添加使得护肤品具有抗菌性,葫芦巴护肤品具有较好的保湿效果和防晒效果,同时葫芦巴抗氧化霜能有效清除皮肤表面的自由基,其与小麦胚芽油、葡萄籽油、维生素E共同作用对2,2-联氮-双(3-乙基苯并噻唑-6-磺酸)自由基（ABTS+·）、羟基自由基（·OH）、超氧自由基（·O2-）的清除率分别达95.2%、68.2%、85.5%。     

米曲霉直接转化盾叶薯蓣生产薯蓣皂苷元

利用米曲霉直接转化盾叶薯蓣制备了薯蓣皂苷元,转化中最重要的影响因素是pH、接种量和培养温度. 在pH 6.0的66.7 mmol/L Na2HPO4-KH2PO4缓冲液中,8%接种量、37℃培养84 h后提温至50℃继续转化8 h的条件下,薯蓣皂苷元得率可达17.06 mg/g,是粗酶液转化的6.77倍. 转化过程中甾体的总摩尔数分别是微波辅助提取和酸水解的1.73和1.47倍. 转化产物经质谱和核磁共振鉴定与薯蓣皂苷元同质. 直接微生物转化法优于酶解法.     

大孔吸附树脂分离纯化胡芦巴中总皂苷工艺

通过对11种大孔吸附树脂对比研究,筛选出了一种对胡芦巴中总皂苷具有最佳吸附解吸性能的树脂,并对该树脂的静态和动态吸附性能进行了研究,确定了树脂纯化总皂苷的工艺参数。结果表明,HPD-400A型树脂对总皂苷有良好吸附分离性能,Freundlich等温吸附模型较Langmuir模型更适宜描述树脂对胡芦巴总皂苷的吸附;吸附分离总皂苷的工艺条件:树脂柱径高比为1∶10,上柱液质量浓度为1.358 mg/mL,流速为2 BV/h,解吸流速1 BV/h,解吸液为体积分数60%的乙醇,洗脱剂用量为1.5 BV。经大孔树脂纯化前总固物中总皂苷质量分数为11.38%,纯化后总固物中总皂苷质量分数为42.76%,纯度提高了近4倍。     

二次酸水解法从黄姜中提取薯蓣皂甙元的工艺

薯蓣皂甙元是合成甾体激素药物和甾体避孕药物的重要原料,是黄姜中的主要活性物质。采用正交实验的方法,探讨了经过二次酸水解法从黄姜中提取薯蓣皂甙元的工艺条件,结果表明该方法提取的薯蓣皂甙元产率达到了2.41%,比直接水解法(2.20%)提高了9.55%。另外,采用熔点、元素分析法、红外、核磁等一系列的手段对产品进行表征,结果表明该法是可行的,提取的薯蓣皂甙元的质量纯度达到了工业的要求。     

苦良姜中薯蓣皂甙元的提取及应用

介绍了从苦良姜中提取薯蓣皂甙元的工艺以及以薯蓣皂甙元为原料合成甾体激素等药物的方法     

响应面法超声波提取胡芦巴薯蓣皂苷元的研究

采用超声波法对胡芦巴中薯蓣皂苷元的提取工艺过程进行了研究。在单因素实验基础上根据中心组合实验设计原理,采用四因素五水平的响应面分析法对提取工艺进行了优化。通过响应面实验及回归分析得出最佳工艺条件为:原料粒径50目,料水质量比1∶16.2,浸泡7 h后,在频率20 kHz、功率200 W超声强度下提取35 min,胡芦巴中薯蓣皂苷元的提取率可达87.65%。验证实验表明,所得二次模型方程能较好地预测实验结果。     

Effect of dietary fat saturation of absorption and intestinal secretion of cholesterol by the hypercholesterolemic rat

The fate of an oral dose of [4-¹⁴C] cholesterol given to rats grown on diets with 20% safflower oil or 20% hydrogenated coconut oil was determined by analysis of digestive tract, feces and tissues. The pattern of isotope distribution did not support the view that rats fed a saturated fat absorb less cholesterol than those fed an unsaturated fat. Fasted animals growth on the diet with 5% of these two fats and beef fallow showed no clear difference in the amount of digitonin-peecipitable sterol in their intestines. A shorter transit time for intestinal contents was observed with the saturated fat groups. It is concluded that neither absorption of cholesterol from the gut nor secretion of β-hydroxy sterol into the gut accounts for the hypocholesterolemic effect of polyunsaturated fat. Journal Paper No. 4951 AES, Purdue University.     

Resistance in the Plant, <Emphasis Type="Italic">Barbarea vulgaris</Emphasis>, and Counter-Adaptations in Flea Beetles Mediated by Saponins

Three saponins and two sapogenins had differential effects on food consumption in five near-isogenic flea beetle lines, which differ in their ability to utilize a novel host plant, Barbarea vulgaris (Brassicaceae). The ability to live on this plant is controlled by major, dominant R-genes in the flea beetle, Phyllotreta nemorum (Coleoptera: Chrysomelidae: Alticinae). A susceptible genotype (rr) is unable to live on the plant, whereas resistant genotypes (RR and Rr) can utilize the novel host plant. Among compounds isolated from B. vulgaris, hederagenin cellobioside (hederagenin-3-O-(4-O-β-D-glucopyranosyl)-β-D-glucopyranoside) inhibited feeding, whereas the effect of oleanolic acid cellobioside was much weaker. The aglycones (sapogenins) were inactive. Although hederagenin cellobioside was active against all flea beetle lines, its effect on food consumption was much stronger on the susceptible genotype (rr) compared to the resistant genotype (Rr). Susceptible and resistant flea beetle genotypes were equally sensitive to a non-host saponin, α-hederin (hederagenin-3-O-(2-O-α-L-rhamnopyranosyl)-α-L-arabinopyranoside). These results suggest that R-alleles in flea beetles might be specific adaptations to defensive saponins in B. vulgaris. A possible mechanism of action of the R-alleles might be to encode for an enzyme (e.g. a glucosidase), which is able to cleave glycosidic bonds in hederagenin cellobioside, but not in α-hederin. The potential role of saponins as defensive compounds in B. vulgaris and as targets for counter-adaptations in flea beetles and other insects is discussed.     

The Obscure Effect of Tribulus terrestris Saponins Plus Inulin on Liver Morphology,Liver Fatty Acids,Plasma Glucose,and Lipid Profile in SD Rats with and without Induced Type 2 Diabetes Mellitus

Diabetes is a predictor of nonalcoholic fatty liver disease (NAFLD). There are data suggesting that Tribulus terrestris (TT) saponins act as antidiabetic agents and protect against NAFLD. The effect of saponins may be increased by fermentable fibers such as inulin. The aim of the present study was to investigate the influence of TT saponins and TT saponins plus inulin on the plasma lipid profile and liver fatty acids of rats with induced diabetes mellitus type 2 (T2DM). The study was performed on 36 male Sprague–Dawley rats divided into two main groups: control and diabetic. Animals of the diabetic (DM) group were fed a high-fat diet and injected with streptozotocin (low doses). Animals of the control group (nDM) were on a regular diet and were injected with buffer. After the injections, the animals were split into subgroups: three non-diabetic (nDM): (i) control (c-C); (ii) saponin-treated rats (C-Sap); (iii) rats treated with saponins + inulin (C-Sap + IN), and three diabetic subgroups (DM): (iv) control (c-DM); (v) saponin-treated rats (DM-Sap); (vi) rats treated with saponins + inulin (DM-Sap + IN). Liver fatty acids were extracted and analyzed by gas chromatography, and plasma glucose and lipids were measured. The study showed significant changes in liver morphology, liver fatty acids, plasma lipid profile, and plasma glucose. In summary, supplementation with TT saponins or saponins with inulin for one month decreased the level of steatosis in rats with induced type 2 diabetes. Moreover, there were favorable effects on the plasma lipid profile in the rats. However, additional supplementation with inulin had a negative effect on liver morphology (with a microvesicular type of steatosis) in the non-diabetes group. Moreover, supplementation with inulin had a negative effect on plasma glucose in both diabetic and non-diabetic rats. These data show that a diet enriched with fermentable fibers reveals different effects in different organisms, and not all sources and forms of fiber are beneficial to health.     

黄姜资源清洁高效利用研究进展

黄姜皂素是合成甾体类药物的重要中间体,传统的皂素生产工艺废液、废渣污染重,而且造成资源浪费。简介了黄姜皂素的用途与传统生产工艺,重点对主产皂素且联产鼠李糖、黄色素等多种产品的黄姜清洁高效利用工艺进行了综述。     

Antinutritional effects and ecological significance of dietary condensed tannins may not be due to binding and inhibiting digestive enzymes

The digestive enzymes alkaline phosphatase and 5-nucleotide phosphodiesterase, solubilized from bovine intestinal mucosa and purified to homogeneity, were found to be strongly inhibited in vitro by condensed tannins (proanthocyanidins) purified from sorghum seeds and from quebracho. Tannin inhibition was prevented and reversed by the detergent Triton X-100 (protein-binding agent), by soluble polyvinylpyrrolidone (tannin-binding agent), or by phosphatidylcholine (membrane component). When tested as a crude particulate membrane fraction more characteristic of their in vivo condition, both enzymes were inhibited much less than either purified enzyme at the same tannin concentration. Because the enzymes appear to be relatively insensitive to inhibition by tannin in conditions which mimic in vivo conditions, and because the proportion of the dietary tannin which is available to interact with these enzymes in the digestive tract is likely to be rather small, we suggest that the antinutritional effects and ecological significance of dietary tannins are not due to tannin inhibition of these or other digestive enzymes by direct binding to them.     

薯蓣皂甙元的研究进展

薯蓣皂甙元是合成多种甾体激素类药物和甾体避孕药的重要医药化工原料,被誉为"药中黄金"。由于植物资源分布的优势,中国是薯蓣皂甙元的主要生产国,年产量约3 000 t,占世界总产量的60%,其中2/3直接出口。该文对薯蓣皂甙元的相关研究进行了总结,内容包括薯蓣属植株生物合成薯蓣皂甙元的机理及影响因素研究、薯蓣皂甙元的提取分离和鉴定检测方法,以及其药理毒理功效,以期为高值、高效地开发利用薯蓣皂甙元的药用价值提供参考。     

Chemical composition of lucerne leaf extract (EFL) and its applications as a phytobiotic in human nutrition

Lucerne, a valuable plant grown mainly for animal feed, is rich in protein, minerals (Ca, Cu, Fe, Mg, Mn, P, Zn, Si), vitamins (A, B, C, D, E, K, U), phytochemical substances (carotene, chlorophyll, coumarins, isoflavones, alkaloids, saponins), contains secondary metabolites of plants (phytoestrogens: isoflavones and coumestrol), and antinutritional components (phytates, L-canavanine, saponins). It may be used as a dietary supplement in human nutrition. The proteins found in lucerne are comprised of numerous exogenous and semi-exogenous amino acids which are desirable for human body. Extract from the leaves of alfalfa (EFL - l'Extrait Foliaire de Luzerne) practically does not contain mycotoxins and pesticide pollutants. It is a completely natural product, safe even in a long-term supplementation. Extract from the leaves of alfalfa has a positive, multidirectional impact on the human body. It increases the level of estrogen, prevents atherosclerosis, helps blood circulation and strenghtens immunity, protects against the development of dangerous diseases of the digestive tract, combats anemia and many other health ailments. The results of preclinical studies indicate that alfalfa leaf extract enriched with vitamin C (EFL) can be a dietary supplement supporting the human body in fighting malnutrition, ischemic diseases, and various disorders of digestive tract. It also strengthens and enhances immunity.     

Characterization of Flavonoid Glycosides from Fenugreek (Trigonella foenum-graecum) Crude Seeds by HPLC–DAD–ESI/MS Analysis

Fenugreek (Trigonella foenum-graecum) is a medicinal plant which is widely used for its pharmacological properties. In this study the phenolic composition of fenugreek crude seeds originating from Morocco has been investigated. Extraction was performed from defatted seeds by a hydromethanolic solution using an Accelerated Solvent Extractor. HPLC technique coupled to negative ion electrospray ionization mass spectrometry and diode array detection was employed to identify the polyphenol in the obtained extract. The obtained results allowed the detection of 32 phenolic compounds among which various flavonoid glycosides and phenolic acids have been tentatively identified on the basis of their UV and MS spectra, and comparisons with standards when available, as well as with literature data. A systematic study of the obtained MS spectra and the observed fragmentation showed that most of the identified compounds were acylated and non-acylated flavonoids with apigenin, luteolin and kaempferol as aglycons. Hydroxycinnamic acids mostly dominated by caffeic acid derivatives were also detected. The quantitative analysis of the identified compounds showed that the phenolic composition of the studied crude fenugreek seeds was predominantly acylated and non-acylated flavone derivatives with apigenin as the main aglycon.