柑橘生物活性多甲氧基黄酮及其糖苷类的合成研究

多甲氧基黄酮是广泛存在于柑橘属植物中的一类具有显著抗癌、抗炎等生物活性的天然产物.本工作以间苯二酚和甲氧基取代的苯甲醛为原料,经过溴化、甲基化、芳基亲核取代、Friedel-Crafts乙酰化、羟醛缩合、环化或Algar-Flynn-Oyamada反应、DDQ脱氢、选择性脱甲基化反应,以及随后的糖苷化和脱乙酰化反应,合成了一系列多甲氧基黄酮及其糖苷类化合物1a,1b～4a,4b,5～9.其中1a,1b,2a,2b,3b,4a,4b和5～7,9是全合成的天然产物.此外,在对五甲氧基苯的合成过程中,发现了一种由间二苯酚经溴代、甲基化和芳香亲核取代等三步反应高产率制备有机合成中间体2,3,4,6-四甲氧基苯酚(12)的新方法.所合成新化合物的结构由MS,IR,1H NMR和13C NMR进行了表征.     

Determination of flavanones in Citrus juices by means of one- and two-dimensional liquid chromatography

1-D and 2-D comprehensive (LC×LC) liquid chromatography methods have been developed and compared for the separation and quantification of flavanones in various Citrus juices. 1-D analyses were carried out on a superficially porous C18 column, whereas the 2-D LC approach was composed of a polyethylene glycol silica narrow-bore column packed with totally porous particles in the first dimension (D1) and a superficially porous C18 column in the second dimension (D2). Low-selectivity correlations were ensured by the complementary separation mechanisms offered by the D1 and D2 columns. Quantification was carried out both manually and by means of a software capable of detecting and quantifying each peak from the 2-D plot. Limit of detection (LOD) values as low as 0.023 μg/mL were obtained for hesperidin used as reference material for 1-D LC analyses, whereas values as high as 0.432 μg/mL were obtained by comprehensive LC. This discrepancy can be traced back to the minor sensitivity experienced in comprehensive LC due to both sample dilution in D1 and the high flow rates employed in D2. On the other hand, the separation capabilities of the LC×LC approach allowed to reduce the interferences coming from the matrix and to achieve the separation of some critical pairs, e.g. hesperidin/naringin difficult to accomplish in 1-D LC.     

Differences between elemental composition of orange juices and leaves from organic and conventional production systems

Summary A comprehensive sampling of organic and conventional oranges was carried out in Bebedouro, an important citrus producing region of Brazil. The soils, leaves and fruits of the variety Valencia (Citrus sinensis [L.]Osbeck) budded on Rangpur lime (Citrus limonia Osbeck) were analyzed. The chemical characterization was accomplished by instrumental neutron activation analysis (INAA). Indications for a difference between organic and conventional orange juices and leaves were obtained by applying univariate and multivariate statistical analysis. There were differences between samples for Br, Co, Cs, La and Rb from both systems.     

A fragmentation study of dihydroquercetin using triple quadrupole mass spectrometry and its application for identification of dihydroflavonols in Citrus juices

A mass spectrometric method using electrospray ionization with triple quadrupole and quadrupole time‐of‐flight hybrid (Q‐Tof) mass spectrometry has been applied to the structural characterization of dihydroflavonols. This family of compounds has been studied by liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the first time in this work. A comprehensive study of the product ion MS spectra of the [M+H]⁺ ion of a commercially available standard has been performed. The most useful fragmentations in terms of structural identification are those that involve cleavage of the C‐ring, resulting in diagnostic ions of dihydroflavonol family: ^1,3A, ^1,2B, ^1,2B‐CO, ^0,2A, ^0,2A‐H₂O, ^0,2A‐CO, and ^0,2A‐H₂O‐CO, that allow the characterization of the substituents in the A‐ and B‐rings. In addition to those ions, other product ions due to losses of H₂O and CO molecules from the Y ion were observed. Their fragmentation mechanisms and ion structures have been proposed. The established fragmentation patterns have been used to successfully identity three dihydroflavonols found in tangerine juices for the first time. Copyright © 2009 John Wiley & Sons, Ltd.     

Fatty acid composition of neutral lipid: Classes of Citrus seed oil

The constituents of total lipids and neutral lipid classes, i.e., hydrocarbons, wax esters, sterol esters, triacylglycerols, free fatty acids, 1,3-diacylglycerols, 1,2-diacylglycerols, free sterols, alcohols, and monoacylglycerols of three species of Citrus namely Citrus sinensis, Citrus paradisi, Citrus aurantium were investigated by thin layer and gas chromatography. Palmitic, oleic and linoleic acids were the major components in all the lipids and lipid classes studied.     

Flavonoid composition of the pollen (pollen pellets) fromSalix caprea andS. alba

Chemistry of Natural Compounds -     

Flavonoid profiles of immature and mature fruit tissues of Citrus grandis Osbeck (Dangyuja) and overall contribution to the antioxidant effect

Citrus fruits are a valuable functional food and their peel is used in East Asian folk medicine. In this study, the polar components of the fruit tissues of Citrus grandis Osbeck were analyzed using high‐performance liquid chromatography–tandem mass spectrometry and compared with reported data. Among the 13 characterized compounds, eight flavonoids and one coumarin were identified for the first time in fruit tissues. The total amount of the identified components was the largest for the immature fruit peel, followed by mature fruit peel, mature fruit flesh, and immature fruit flesh. Naringin (2) and neohesperidin (3) were particularly rich in all samples. The antioxidant activity of the flavonoids extracted from fruit tissues increased in a dose‐dependent manner. The activity of the fruit peels was significantly higher than that of the fruit flesh. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Poncirin,a Citrus Flavonoid and Its Aglycone,Isosakuranetin, on the Gut Microbial Diversity and Metabolomics in Mice

Poncirin (PC) and its aglycone, isosakuranetin (IR), occur naturally in citrus fruits. This study aimed to explore the pathways behind the different health benefits of PC and IR by evaluating the effect of these two bioactive flavonoids on the gut microbial diversity and metabolomics of mice. The 16S rRNA gene sequencing was used to analyze the alteration of gut microbiota in mice after PC and IR intervention. The metabolic impact of PC and IR in mice were studied using a metabolomics approach based on LC-MS analysis. Results showed that, after 7 days intervention, PC and IR multiplied the abundance of Parabacteroides in mice’s intestinal tracts by 1.2 and 1.0 times, respectively. PC increased the abundance of Bacteroides by 2.4 times. IR reduced the Allobaculum abundance by 1.0 time and increased Alloprevotella abundance by 1.5 times. When mice were given PC, their fecal acetic acid level increased by 1.8 times, while their isobutyric and isovaleric acid content increased by 1.2 and 1.3 times, respectively. Supplementation with IR had no significant effect on the content of short-chain fatty acids (SCFAs) in the feces of mice. The potential urine biomarkers of mice in the PC group were involved in the digestion and absorption of protein and carbohydrate, as well as the metabolism of amino acids, such as glycine, serine, threonine, tryptophan, D-arginine, D-ornithine, etc. IR mainly affected the amino acid metabolic pathways in mice, including taurine and hypotaurine metabolism, glutathione metabolism, histidine metabolism, D-glutamate metabolism, etc. This study provided valuable clues for future research on the health promoting mechanisms of PC and IR.     

Flavonoid components of propolis

Conclusions The following flavonoids have been isolated from propolis and identified: acacetin (I), 7,4-dimethoxyflavone (II), kaempferide (III), rhamnocitrin (IV), 5,7-dihydroxy-3,4-dihydroxyflavone (V), 3,5-dihydroxy-7,4-dimethoxyflavone (VI), (–)-pinostrobin (VII), and (–)-5-hydroxy-7,4-dimethoxyflavanone (VIII).Khimiya Prirodnykh Soedinenii, Vol. 5, No. 6, pp. 476–482, 1969