Phenylpropanoid glycosides from the seeds of Michelia hedyosperma

The seed of Michelia hedyosperma Law (Magnoliaceae) is a commonly used spice by the local people living in the south of Yunnan province, China. From which, six new phenylpropanoid glycosides, michehedyosides A–F (1–6) were obtained, in addition to six known compounds, eugenol, eugenol 4-O-β-d-glucopyranoside, martynoside, alaschanioside C, 3,4-methylenedioxycinnamyl alcohol, and (+)-pinoresinol 4-O-β-d-glucoside. Their structures were elucidated on the basis of detailed spectroscopic analyses and chemical methods.     

Solubility enhancement of steviol glycosides and characterization of their inclusion complexes with gamma-cyclodextrin

Steviol glycosidesrebaudioside (reb) A, C and D have low aqueous solubilities. To improve their aqueous solubilities, inclusion complex of steviol glycosides, reb A, C and D and gamma cyclodextrin were prepared by freeze drying method and further characterized by means of differential scanning calorimetry, Fourier transform infrared spectroscopy and Raman spectroscopy. The effect of gamma cyclodextrin on chemical shifts of the steviol glycosides was also studied in proton NMR experiments as well as in solid state (13)C CP/MAS NMR experiments. These results indicated that the steviol glycosides were clearly in inclusion complex formation with the gamma cyclodextrin which also results in solubility enhancement of these steviol glycosides. Phase solubility studies showed that amounts of soluble reb A, C and D increased with increasing amounts of gamma cyclodextrin indicating formation of 1:1 stoichiometric and higher order inclusion complexes.     

香料前体香叶醇-β-D-葡萄糖苷的合成

报道了一种合成香叶醇葡萄糖苷的新方法。考察了糖苷化反应的多种影响因素（合成方法、反应温度、摩尔比）,得出最佳合成条件：采用相转移催化法,反应温度为60℃,反应物摩尔比n（溴代四乙酰葡萄糖：）n（香叶醇）为1.6∶1,反应时间为10 h,收率可达64%。该合成方法操作简单、反应条件温和、不污染环境,有较好的工业应用前景。     

A novel mechanism for the promotion of quercetin glycoside absorption by megalo α-1,6-glucosaccharide in the rat small intestine

The presence of an α-1,6-glucosaccharide enhances absorption of water-soluble quercetin glycosides, a mixture of quercetin-3-O-β-d-glucoside (Q3G, 31.8%), mono (23.3%), di (20.3%) and more d-glucose adducts with α-1,4-linkage to a d-glucose moiety of Q3G, in a ligated small intestinal loop of anesthetized rats. We prepared α-1,6-glucosaccharides with different degrees of polymerization (DP) enzymatically and separated them into a megalo-isomaltosaccharide-containing fraction (M-IM, average DP = 11.0) and an oligo-isomaltosaccharide-containing fraction (O-IM, average DP = 3.6). Luminal injection of either saccharide fraction promoted the absorption of total quercetin-derivatives from the small intestinal segment and this effect was greater for M-IM than O-IM addition. M-IM also increased Q3G, but not the quercetin aglycone, concentration in the water-phase of the luminal contents more strongly than O-IM. The enhancement of Q3G solubilization in the luminal contents may be responsible for the increases in the quercetin glucoside absorption promoted by α-1,6-glucosaccharides, especially that by M-IM. These results suggest that the ingestion of α-1,6-glucosaccharides promotes Q3G bioavailability.     

Do Enemies of Herbivores Influence Plant Growth and Chemistry? Evidence from a Seminatural Experiment

It is predicted that enemies of insect herbivores may influence the effects of herbivores on their host plants by affecting the choice of plant genotypes. To examine the effect of predators, we conducted two experiments, each with a different caterpillar species (Junonia coenia and Pyrrharctia isabella). Under seminatural conditions, we provided a choice between two genotypes of plantain (Plantago lanceolata) with different levels of iridoid glycosides and used Podisus maculiventris stinkbugs as predators. There were four treatments: no herbivores and no predators, low density of herbivores and no predators, high density of herbivores and no predators, and high density of herbivores plus predators. The caterpillars had little effect on plant growth but did influence the iridoid glycoside concentration. For the Junonia experiment, the concentration of iridoid glycosides was less for plots with a low density of caterpillars (with no predators) compared to the other treatments of caterpillar density. In the Pyrrharctia experiment, catalpol was induced by a high density of caterpillars (with no predators). There were no increases in total iridoid glycosides associated with either herbivore species. The presence of predators had no effect on plant growth or total iridoid glycoside pattern. The lack of effect by predators seems to reflect the relatively large variation in iridoid glycoside concentration among leaf ages, and the herbivores ability to respond to that variation, such that the difference in iridoid glycoside concentrations in the plant genotypes was less important.     

PU硬泡用淀粉乙二醇糖甙聚醚的制备与性质

通过控制反应条件得到了在粘度和羟值上具有较好重复性的淀粉乙二醇糖甙聚醚。在 1 2 5～ 1 30℃、催化剂为 0 .76%硫酸、甙化 30 min,醚化率为 7mol的条件下 ,得到了一系列产品。聚醚的平均偏移在 :羟值± 4,粘度±80 0厘泊 ( 32℃ )。从糖甙混合物中蒸馏得到的回收乙二醇 ,未经纯化再次使用 ,研究了其可重复使用性能。结果表明 ,回收乙二醇的重复使用没有影响聚醚的性能 ,所得糖甙聚醚的性能满足 PU硬质泡沫的制备要求。     

白藜芦醇糖苷类衍生物的设计与合成

以白藜芦醇及其类似物紫檀芪为原料,采用Schmidt成苷法、相转移催化法,分别与溴代糖和乙酰氨基糖反应,得紫檀芪乙酰葡萄糖苷和(E)-5,4'-二叔丁基二甲基硅基-3-(2"-乙酰氨基-3",4",6"-三乙酰葡萄糖二苯乙烯,其结构经红外光谱、核磁共振氢谱和质谱表征.     

Purification of stevia extract by chitosan precipitation and reversed-phase chromatography

To improve the shortness of the current purification technology of steviol glycosides (SG) extract, a two-step purification procedure consisting of chitosan precipitation and reversed-phase chromatography (RPC) was investigated. The impurity-to-SG ratio in the SG extract obtained from non-destructive soaking was 5:1 ~ 6:1. It was found that 80.90% of the impurities could be removed by RPC using 20% (v/v) ethanol solution as the eluent with a high SG recovery of 96.98%. When 25% ethanol was applied, the SG recovery was reduced to 71.23%. An adsorption test using D280 anionic resin suggested that the impurities were negatively charged; thus, chitosan was used to co-precipitate the impurities. An optimal decolourisation result of ~ 70% was obtained at 0.06 g·g⁻¹ (w/w, to solids in extract) chitosan addition, shaking at 28 °C for 1 h. Afterwards, the extract was further purified by RPC. The total removal rate of impurities was increased to 91.20%, and the SG recovery was 85.15%.     

多元醇葡萄糖苷的合成及应用

本文综述了多元醇葡萄糖苷的合成方法，介绍了它们的特点及应用，并且结合我国实际说明了开发此类表面活性剂的可行性和必要性。     

Iridoid glycosides as oviposition stimulants for the buckeye butterfly,Junonia coenia (Nymphalidae)

Females ofJunonia coenia (Nymphalidae), a specialist on plants that contain iridoid glycosides, were found to use aucubin and catalpol, iridoid glycosides typical of a host plant,Plantago lanceolata (Plantaginaceae), as oviposition cues. Incorporating dried ground leaf material or pure iridoid glycosides into agar disks proved to be a very effective method of testing. In no-choice tests and choice tests, females laid more eggs on disks withP. lanceolata leaf material or iridoid glycosides, compared to agar controls. There was variation among individual females in preference for disks withP. lanceolata leaf material versus disks with iridoid glycosides. Females given a choice of three different concentrations of iridoid glycoside (0.2, 0.5, 1.0%) in the agar disks and a control laid more eggs on the disk with the highest concentration of iridoid glycoside.