Chemistry of Leichhardt's Grasshopper, Petasida ephippigera, and its Host Plants, Pityrodia jamesii, P. ternifolia, and P. pungens

Investigation of the strikingly aposematic Leichhardt's grasshopper revealed a number of host-plant-derived components. Chemical study of the three known host plants revealed a diverse array of components. Pityrodia ternifolia and P. pungens contain predominantly sesquiterpenes and sesquiterpene glycosides and P. jamesii is rich in cineole, dihydrochalcones, chalcones, and monoterpene glycosides. Feces from grasshoppers feeding on P. jamesii contain a mixture of hydroxycineoles, of which 3-hydroxycineole is the predominant isomer (68%). No evidence for previously suspected "alkaloidal" toxins was found in either the insect or host plant.     

柚皮苷二氢查尔酮的制备及其呈甜机理研究

利用化橘红醇提水沉法制备柚皮苷,并将柚皮苷催化加氢制备柚皮苷二氢查尔酮,并用SYBYL-X及Discovery Studio 2.5软件对柚皮苷二氢查尔酮的呈甜机理进行了研究。结果表明,化橘红醇提水沉法可以制备纯度大于95%的柚皮苷单体,该单体催化加氢后可制备纯度大于95%的柚皮苷二氢查尔酮,SYBYL-X及Discovery Studio 2.5软件能有效地解释柚皮苷二氢查尔酮的呈甜机理。     

Low-calorie sweeteners in food and food supplements on the Italian market

This study determines the occurrence and concentration levels of artificial low-calorie sweeteners (LCSs) in food and food supplements on the Italian market. The analysed sample set (290 samples) was representative of the Italian market and comprised of beverages, jams, ketchups, confectionery, dairy products, table-top sweeteners and food supplements. All samples were analysed via UPLC-MS/MS. The method was in-house validated for the analysis of seven LCSs (aspartame, acesulfame-K, saccharin, sucralose, cyclamate, neotame and neohesperidin dihydrochalcone) in food and for five LCSs (aspartame, acesulfame-K, saccharin, cyclamate and sucralose) in food supplements. Except for cyclamate in one beverage which exceeded the maximum level (ML) with 13%, all concentrations measured in food were around or below the ML. In food supplements, 40 of the 52 samples (77%) were found to be above the ML, with exceedances of up to 200% of the ML.     

柚皮苷二氢查尔酮的抗氧化活性研究

利用4种常见的抗氧化方法和分子对接,研究柚皮苷二氢查尔酮的抗氧化活性.通过测定酪氨酸酶活性,研究其美白活性,并用MTT试验测定其细胞毒性.试验结果表明:柚皮苷二氢查尔酮有较好的抗氧化性和美白活性,对小鼠黑色素瘤B16细胞的安全浓度为小于等于500μmol/L.     

The Occurrence,Fate and Biological Activities of C-glycosyl Flavonoids in the Human Diet

The human diet contains a wide variety of plant-derived flavonoids, many of which are glycosylated via an O- or less commonly a C-glycosidic linkage. The distribution, quantity, and biological effects of C-glycosyl flavonoids in the human diet have received little attention in the literature in comparison to their O-linked counterparts, however, despite being present in many common foodstuffs. The structural nature, nomenclature, and distribution of C-glycosyl flavonoids in the human diet are, therefore, reviewed. Forty-three dietary flavonoids are revealed to be C-glycosylated, arising from the dihydrochalcone, flavone, and flavan-3-ol backbones, and distributed among edible fruits, cereals, leaves, and stems. C-linked sugar groups are shown to include arabinose, galactose, glucose, rutinose, and xylose, often being present more than once on a single flavonoid backbone and occasionally in tandem with O-linked glucose or rutinose groups. The pharmacokinetic fate of these compounds is discussed with particular reference to their apparent lack of interaction with hydrolytic mechanisms known to influence the fate of O-glycosylated dietary flavonoids, explaining the unusual but potentially important appearance of intact C-glycosylated flavonoid metabolites in human urine following oral administration. Finally, the potential biological significance of these compounds is reviewed, describing mechanisms of antidiabetic, antiinflammatory, anxiolytic, antispasmodic, and hepatoprotective effects.     

甲酸铵催化转移氢化法制备龙血素A和龙血素B

利用催化转移氢化将查耳酮还原为二氢查尔酮,在反应中研究了以甲酸铵作为氢给予体,Pd/C为催化剂,不同溶剂,不同温度及催化剂的量对反应的影响,并对反应条件进行优化,产率在60%以上。此法与直接加氢还原法比较具有安全性高、反应温度低、设备要求低和选择性高、后处理简单等优点,该法在二氢查尔酮的制备中得到较好结果,具有较广泛的用途。     

柚皮苷二氢查耳酮工艺研究

以柚皮苷为原料制备了柚皮苷二氢查耳酮。考察了反应时间、催化剂用量、反应温度、反应压力、搅拌速度等因素对柚皮苷二氢查耳酮收率的影响。实验结果表明,制备柚皮苷二氢查耳酮优化反应条件为:pH值为13,反应温度45℃,反应时间6 h,氢气压力0.5 MPa,雷尼镍(用量为柚皮苷质量的7%)为催化剂,此条件下收率达90.0%。     

新橙皮苷二氢查尔酮的电化学行为研究

采用循环伏安法和线性扫描伏安法研究了新橙皮苷二氢查尔酮在玻碳电极上的电化学行为。在pH=4．8的醋酸／醋酸钠缓冲溶液中,新橙皮苷二氢查尔酮的循环伏安图上呈现出一对氧化还原峰,其电化学过程表现出良好的可逆性。实验结果表明,电化学过程中新橙皮苷二氢查尔酮的电子转移数n为2,参与反应的质子数也为2。新橙皮苷二氢查尔酮的还原峰峰电流与其浓度在2．8×10^-7mol·L^-1至3．1×10^-6mol·L^-1范围内呈现出良好的线性关系。对1．1×10^-6mol·L^-1新橙皮苷二氢查尔酮溶液连续6次测定的RSD为2．2％,检出限为1．1×10^-7mol·L^-1     

新型甜味剂—二氢查尔酮衍生物

对二氢查尔酮类甜味剂的制备和应用作了一简要的概述,介绍了影响此类物质甜度的各个因素和二氢查尔酮衍生物的制备合成方法。同时,对柚皮甙二氢查尔酮和新橙皮甙二氢查尔酮两种甜味剂的性质、用途、合成方法、应用前景做了详细介绍。     

新型甜味剂—橙皮素二氢查耳酮葡萄糖苷的合成研究

以橙皮苷为原料,经化学处理,可转化成具有纯正甜味的,非营养性的题示甜味剂。本文阐述了它的原料来源,产品性能,合成原理及制备方法。