六种果皮原料果胶的理化及凝胶特性比较

为了解不同品种水果的果皮(柚子皮、西番莲皮、脐橙皮、石榴皮、榴莲皮)以及向日葵盘所提取果胶的理化和质构特性,研究了不同原料果胶的得率、色泽、果胶酸含量、甲氧基含量、酯化度、黏度及质构特性,特别是采用高效液相色谱准确测定了各类果胶的分子量。结果表明:柚子皮、向日葵盘和脐橙皮果胶质量分数较高,分别为18.06%、14.61%和14.43%;西番莲皮果胶质量分数为8.76%;而石榴皮及榴莲皮果胶质量分数较低(均<3%)。从分子量看,石榴皮、脐橙皮果胶分子量较大(>1000kDa),向日葵盘果胶分子量最小(483kDa)。此外,几种果胶的溶胶均属低黏度值果胶(<25厘泊),且在pH值为7.0时黏度最大、在pH值为5.0时黏度最小。结合凝胶质构分析表明:石榴皮果胶分子量最大,凝胶强度最大,但为高甲氧基果胶,且得率较低;而向日葵盘果胶分子量最小,但得率较高,且为低甲基果胶,在非糖及含糖体系中均可形成性能优良的凝胶,因此是生产果胶的良好原料。该文为果胶的生产及应用提供参考。     

The origin of mangosteen: A review

Genetic Resources and Crop Evolution - Mangosteen (Garcinia mangostana var. mangostana) is an obligate apomictic species which does not require a fertilization process to produce seeds. The absence...     

Antioxidant activity of A-type proanthocyanidins from Geranium niveum (Geraniaceae)

Geranium niveum S. Watson (Geraniaceae) is a medicinal herb widely used by the Tarahumara Indians of Mexico. This species is rich in proanthocyanidins and other phenolics. Previous in vitro assays have demonstrated that proanthocyanidins exhibited antiinflammatory, antiviral, antibacterial, enzyme-inhibiting, antioxidant, and radical-scavenging properties. In view of its medicinal use and chemical composition, the aim of the present study was to determine the in vitro antioxidant activity of the extracts and two proanthocyanidins (geranins A and D) from the roots of G. niveum by using seven different assay systems, namely, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2*-), hydrogen peroxide (H2O2), hydroxyl radical (OH*), hypochlorous acid (HOCl), and singlet oxygen ((1)O2). Two known antioxidants, resveratrol and ascorbic acid, were used as positive controls. The results showed that geranins A and D and the extracts were able to scavenge ABTS, DPPH, O2*-, OH*, and HOCl. The scavenging ability of geranins A and D was similar to that of resveratrol and ascorbic acid in the following assays: ABTS, O2*-, and HOCl. The scavenging capacity of ascorbic acid for DPPH was higher than that of both geranins and resveratrol. On the other hand, the OH* scavenging action of both geranins and resveratrol was similar. The methanol-CHCl3 (1:1) extract had a higher ability to scavenge ABTS, DPPH, and O2*- radicals than the chloroform extract. In turn, the latter was more potent than the methanol-CHCl3 (1:1) extract as OH* or HOCl scavenger agent. Neither geranins A and D nor the extracts were able to scavenge H2O2 and (1)O2. In conclusion, G. niveum roots have proanthocyanidins with powerful radical scavenging in vitro activity. This property may partially explain the wide use of this plant in the Tarahumara indigenous system of medicine for the treatment of gastrointestinal illnesses (other than spasms), pain, and fevers associated with oxidative stress.     

A-type proanthocyanidins from lychee seeds and their antioxidant and antiviral activities

Two new A-type trimeric proanthocyanidins with two doubly bonded interflavanoid linkages, litchitannin A1 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→8)-catechin] (1) and litchitannin A2 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→6)-epicatechin] (2), were isolated from lychee (Litchi chinensis Sonn. cv. Heiye) seeds together with aesculitannin A (3), epicatechin-(2β→O→7,4β→8)-epiafzelechin-(4α→8)-epicatechin (4), proanthocyanidin A1 (5), proanthocyanidin A2 (6), proanthocyanidin A6 (7), epicatechin-(7,8-bc)-4β-(4-hydroxyphenyl)-dihydro-2(3H)-pyranone (8), and epicatechin (9). Their structures were elucidated on the basis of spectroscopic and chemical evidence. It is the first time that compounds 1-4, 7, and 8 have been reported in this species. Compounds 1-9 showed more potent antioxidant activity than L-ascorbic acid with ferric reducing antioxidant power (FRAP) values of 3.71-24.18 mmol/g and IC50 values of 5.25-20.07 μM toward DPPH radicals. Moreover, litchitannin A2 (2) was found to exhibit in vitro antiviral activity against coxsackie virus B3 (CVB3) and compounds 3 and 6 displayed antiherpes simplex virus 1 (HSV-1) activity.     

Antioxidant oligomeric proanthocyanidins from sea buckthorn (Hippophae rhamnoides) Pomace

After flavonol glycosides, monomeric flavan-3-ols, and dimeric and trimeric proanthocyanidins were fractionated from an extract of sea buckthorn (Hippophae rhamnoides) pomace by Sephadex LH-20 gel chromatography, oligomeric proanthocyanidins were eluted. The oligomeric fraction accounted for 84% of the total proanthocyanidins and 75% of the total antioxidant activity of the sea buckthorn pomace extract. To elucidate the structure of the oligomeric fraction, it was depolymerized by acid catalysis in the presence of phloroglucinol. The structure of the resulting flavan-3-ol monomers and flavan-3-ol-phloroglucinol adducts was determined by electrospray ionization mass spectrometry (ESI-MS) and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. Quantitative high-performance liquid chromatography investigations demonstrated (+)-gallocatechin as the predominating subunit in the oligomeric fraction. This observation was confirmed by ESI-MS, matrix-assisted laser desorption/ionization mass spectrometry, and (13)C NMR spectroscopy. The results showed that the majority of the flavan-3-ol subunits possessed a 2,3-trans configuration. The oligomers consisted mainly of prodelphinidin subunits whereas procyanidins were present in smaller amounts, indicating a very uncommon composition of the sea buckthorn proanthocyanidins. The mean degree of polymerization of the oligomeric proanthocyanidins was between 6 and 9.     

原花色素研究进展

原花色素是葡萄中一类重要的多酚类次生代谢化合物,是影响葡萄酒品质的重要因子之一.该文从原花色素的结构、性质、生理功能、葡萄果实中的分布及存在形式等几个方面对近年来研究成果进行了综述,并讨论了葡萄酒中原花色素的来源、对葡萄酒品质的影响及提高葡萄酒中原花色素含量的工艺措施,指出了存在的问题及今后的研究方向.     

Rapid fractionation of grape seed proanthocyanidins.

A rapid method that permits separation of grape seed proanthocyanidins according to their polymerization degrees has been developed. This method was based on liquid/liquid extraction and relative solubility of these compounds in different solvents (water, ethyle acetate, methanol, and chloroform). The different fractions obtained were then analyzed by various HPLC techniques (normal phase, reversed phase after thiolysis, and gel permeation) to determine their mean degree of polymerization (DP) and molecular weight profiles. Results show that this method can be used on a preparative scale to separate these polymers according to their sizes.     

Historical review and notes on the correct scientific name for seashore mangosteen

Taxonomic name for “seashore mangosteen” has been known as Garcinia hombroniana and was first established by Pierre (Flore Forestiere de la Cochinchine 1-2. pl. 54–98 Paris, 1882–1885). The distribution of this species is wide and can be found in the Malay Peninsula, upper part of Borneo, and in Andaman and Nicobar islands but not in the Indonesian islands. Instead, many other names are used in Indonesian islands for species that resembles G. hombroniana. This study reviews relevant taxonomic literatures accompanied by observation on herbarium specimens to see whether G. hombroniana is a valid taxonomic name to be used since many more species resembling it were used elsewhere. Historically, when Pierre created G. hombroniana, he placed it together with two Linnaeus species, G. celebica and G. cornea within section Kiras based on the characteristics of male flowers, fruits and geographical distribution. However, no surviving type specimens for G. celebica and G. cornea were found and this has created confusion on the true identities of both Linnaeus species, which have then resulted into many newly-established species. In addition, many early taxonomic classifications including the work of Linnaeus and Pierre have used poor characters for their species delimitation. Morphological evidences based on the literature and herbarium specimens suggested that there are no clear cut discontinuities in morphological characters or any characters exclusive to certain geographical areas between G. hombroniana with G. celebica and G. cornea. Because of that, the valid name that should be used is G. celebica as it was published much earlier. In addition to that, other names including G. benthamii, G. fabrilis, G. ferrea, G. rumphii, G. jawoera, G. kingii, G. krawang, G. kurzii and G. speciosa should simply be synonyms of G. celebica.     

Immunomodulatory and antitumor activities of grape seed proanthocyanidins

Proanthocyanidins are naturally occurring compounds that are widely available in many kinds of plants; particularly, the grape seeds are a rich source of proanthocyanidins. Grape seed proanthocyanidins (GSPs) have been demonstrated to possess a wide range of health beneficial properties. This study was carried out to elucidate the molecular mechanisms involved in the antitumor therapeutic and immunomodulating effects of GSPs through in vivo and in vitro models. The results showed that GSPs could significantly inhibit the growth of Sarcoma 180 tumor cells in vivo and remarkably increase thymus and spleen weight of Sarcoma 180-bearing mice and upgrade the secretion level of tumor necrosis factor-α (TNF-α) in serum. Moreover, GSPs could stimulate lymphocyte transformation, enhance lysosomal enzyme activity and phagocytic capability of peritoneal macrophages, and remarkably promote the production of TNF-α. These results suggested that GSPs could improve functional activation of the immune system, and the antitumor effects of GSPs were achieved by immunostimulating properties.     

Identification of two novel proanthocyanidins in green Tea.

The isolation and structural elucidation of epiafzelechingallate-(4beta-->8)-epicatechingallate (EAG-4beta-->8-ECG) and epiafzelechingallate-(4beta-->6)-epicatechingallate (EAG-4beta-->6-ECG) in green tea samples are described. The combination of various 2D NMR techniques allowed a full structural determination of the underivatized proanthocyanidins even though broadening of the signals did not allow observation of some key correlations that characterize the location of the interflavonoid linkage. The differences in the NMR spectra of the new compounds allowed formulation of criteria for the discrimination between the 4-->6 and 4-->8 isomers in this type of compound.     

Floral Trifolium proanthocyanidins: polyphenol formation and compositional diversity

Recent studies on the biosynthesis of proanthocyandins have identified key genes and enzymes in the formation of 2,3-cis-flavan-3-ols (epiafzelechin, epicatechin, and epigallocatechin). However, the enzymes that catalyze the polymerization of monomer units remain unknown. Studies of proanthocyanidin synthesis have involved the reference plant, Arabidopsis thaliana, forage legumes, tobacco, and grape. For this paper the floral proanthocyanidins of 10 Trifolium species were studied to identify candidates with contrasting proanthocyanidin chemistry, for the identification of factors involved in polymerization. Proanthocyandins were present in the floral portions (3.1-12.2 g/100 g of dry matter) of Trifolium spp. Thiolyic cleavage of proanthocyanidin fractions liberated flavan-3-ol extension units dominated by cis stereochemistry. The terminal units' stereochemistry of T. michelianum was exclusively trans (catechin), that of T. hirtum mixed trans (catechin and gallocatechin), and that of T. vesiculosum equal proportions of trans and cis (catechin and epicatechin). Compositional dispersion for oligomers was determined by MALDI-TOF MS, which showed a range of ions up to approximately 2200 Da. The three Trifolium spp. highlighted, all annuals, may warrant investigation for insights into proanthocyanidins biosynthesis.     

Structural identification and distribution of proanthocyanidins in 13 different hops

Ten newly isolated hop proanthocyanidin oligomers and flavan-3-ol monomers from 13 different hops have been identified as gallocatechin, gallocatechin-(4alpha-->8)-catechin, gallocatechin-(4alpha-->6)-catechin, catechin-(4alpha-->8)-gallocatechin, catechin-(4alpha-->6)-gallocatechin, afzelechin-(4alpha-->8)-catechin, catechin-(4alpha-->8)-catechin-(4alpha-->8)-catechin, epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-catechin, catechin-(4alpha-->8)-gallocatechin-(4alpha-->8)-catechin, and gallocatechin-(4alpha-->8)-gallocatechin-(4alpha-->8)-catechin, together with seven previously isolated oligomers, namely, catechin, epicatechin, epicatechin-(4beta-->8)-catechin, epicatechin-(4beta-->8)-epicatechin, catechin-(4alpha-->8)-catechin, catechin-(4alpha-->8)-epicatechin, and epicatechin-(4beta-->8)-catechin-(4alpha-->8)-catechin. These compounds were subjected to acid-catalyzed degradation in the presence of phloroglucinol or by partial or complete acid-catalyzed degradation and reaction with benzyl mercaptan followed by desulfurization. The resultant adducts when compared to authentic samples by high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry and high-performance liquid chromatography-electrospray ionization tandem mass spectrometry served to identify the precursors. The composition of proanthocyanidins from 13 different hops was similar, but the concentration of individual compounds showed some differences, which indicated that hop proanthocyanidin profiles are affected by geographic origin and are variable depending on the cultivars.     

Grape seed proanthocyanidins prevent plasma postprandial oxidative stress in humans

Postprandial hyperlipemia is a well-defined risk factor for atherosclerosis. A reasonable contributing mechanism could involve the postprandial increase of plasma lipid hydroperoxides (LPO) affecting the oxidant/antioxidant balance and increasing the susceptibility of LDL to oxidation. Wine has been shown to prevent both these events. The present study was designed to investigate the effect of supplementing a meal with grape seed proanthocyanidins (the main phenolic antioxidant of red wine) on plasma postprandial oxidative stress. In two different sessions, 8 healthy volunteers consumed the same test meal rich in oxidized and oxidizable lipids without (control) or with 300 mg of a proanthocyanidin-rich grape seeds extract (GSE). Lipid hydroperoxide concentration, antioxidant status, and LDL resistance to oxidative modification were measured in postprandial plasma. The content of LPO in chylomicrons was 1.5-fold higher after the control meal than after the GSE-supplemented meal. Plasma LPO increased only after consumption of the control meal. The plasma antioxidant capacity increased in the postprandial phase only following the GSE supplemented meal. LDL isolated 3 h after the control meal tended to be more susceptible to oxidative modification (but the difference did not reach statistical significance). An opposite trend was observed following the GSE supplemented meal. In conclusion, the supplementation of a meal with GSE minimizes the postprandial oxidative stress by decreasing the oxidants and increasing the antioxidant levels in plasma, and, as a consequence, enhancing the resistance to oxidative modification of LDL.     

Analysis of the oxidative degradation of proanthocyanidins under basic conditions

Proanthocyanidin isolates from grape (Vitis vinifera L. cv. Pinot noir) skin and seed underwent oxidative degradation in solution (10 g/L) under basic conditions while exposed to atmospheric oxygen. Degradation was monitored by reversed-phase HPLC following acid-catalyzed cleavage in the presence of excess phloroglucinol (phloroglucinolysis) and by high-performance gel permeation chromatography. All isolates degraded under these conditions and followed second-order kinetics for over 1 half-life, consistent with an oxidation reaction. The conversion of proanthocyanidins to known subunits (conversion yield) when measured by phloroglucinolysis showed a dramatic decline over the course of the reaction. With the exception of (+)-catechin extension subunits, all individual subunits decreased in concentration during the oxidation process, also following second-order kinetics for over 1 half-life. Skin proanthocyanidins degraded the fastest due to the presence of (-)-epigallocatechin extension subunits. Seed procyanidins were degraded with and without flavan-3-ol monomers. Flavan-3-ol monomers slowed the rate of seed procyanidin degradation. The mean degree of polymerization (mDP) determined by phloroglucinolysis indicated a large decrease in mDP as the reaction progressed; yet, by GPC, the size distribution of all proanthocyanidins changed little in comparison. The conversion yield could be an important parameter to follow when using phloroglucinolysis as a means for determining proanthocyanidin mDP, and when monitoring the oxidative degradation of proanthocyanidins.     

HPLC determination of extractable and unextractable proanthocyanidins in plant materials

This study developed a method for the determination of extractable and unextractable proanthocyanidins. Extractable proanthocyanidins were separated according to their degree of polymerization using normal phase HPLC. Unextractable proanthocyanidins were measured after acid-catalyzed depolymerization as flavan-3-ols (terminal units) and benzylthioethers (external units). Electrospray ionization mass spectrometry (ESI-MS) was used for the identification of proanthocyanidins in the samples. Hubaux-Vos detection limits were 0.01-0.15 ng/injection for extractable proanthocyanidins, with recovery rates from 69 to 91%. Detection limits for unextractable proanthocyanidin derivatives were 0.002-0.035 ng/injection with 80% recovery. The developed method was applied to the analysis of several fruit and berry samples. Results showed great variation in the proportion of unextractable proanthocyanidins in total proanthocyanidin content between samples, being highest in the green variety of table grape (63%) and lowest in the apple cultivar 'Valkeakuulas' (4.1%). The method reported herein is reliable and gives valuable information on the nature of proanthocyanidins in plant-derived foods.     

The extraction of anthocyanins and proanthocyanidins from grapes to wine during fermentative maceration is affected by the enological technique

The effect of three enological techniques (low temperature prefermentative maceration, must freezing with dry ice, and the use of a maceration enzyme) on the extraction of anthocyanins and proanthocyanidins from must to wine during fermentative maceration was studied to determine the extent to which these compounds are extracted and to assess the changes on their qualitative composition due to enological technique applied. The results showed that the dry ice treatment led to wines with high color intensity and high anthocyanin content, the maximum rate of extraction being observed the first 6 days of fermentative maceration. Regarding the effect of the different techniques on the quantitative and qualitative composition of proanthocyanidins, only the dry ice treatment seemed to favor the extraction of high molecular weight skin proanthocyanidins. The low temperature prefermentative maceration treatment led to the highest concentration of proanthocyanidins at the moment of pressing; however, this treatment, contrary to expectations, led to wines with the highest content of seed-derived proanthocyanidins. The use of the maceration enzyme also increased the concentration of proanthocyanidins during all of the fermentative process, as compared to a control wine, although the increase was not only due to skin proanthocyanidins but also seed proanthocyanidins. We have demonstrated in this study that maceration enzymes also facilitate seed phenolic extraction.     

Quantitative fractionation of grape proanthocyanidins according to their degree of polymerization.

A method was developed for the fractionation of grape (seed or skin) proanthocyanidins according to their degree of polymerization. After precipitation in chloroform/methanol (75:25, v/v), the grape proanthocyanidins were deposited onto an inert glass powder column and sequentially dissolved in several fractions by increasing proportions of methanol in the solvent. Each fraction from each proanthocyanidin source was quantified and characterized after acidic degradation with phenylmethanethiol (i.e., thiolysis). The comparison of data from total extract and successive fractions showed that a quantitative separation was achieved so that estimation of polymer size distribution in relation to other compositional characteristics (proportions of prodelphinidin units, galloylation rate) was thus possible. Mean degree of polymerization of separated proanthocyanidins ranged increasingly from 4.7 to 17.4 in seed (8.1 for total extract) and from 9.3 to 73.8 in skin (34.9 for total extract). The method proposed is very interesting for the study of grape proanthocyanidins according to their degree of polymerization because it gives both qualitative and quantitative information especially on the highly polymerized forms, which were not fractionated by previous techniques.     

Composition of grape skin proanthocyanidins at different stages of berry development.

The composition of grape (Vitis vinifera L. cv. Shiraz) skin proanthocyanidins has been determined at different stages of berry development. Beginning approximately 3 weeks after fruit set and concluding at commercial ripeness, the composition of isolated skin proanthocyanidins was determined using the following analytical techniques: elemental analysis, UV-Vis absorption spectroscopy, reversed-phase HPLC after acid-catalysis in the presence of excess phloroglucinol, gel permeation chromatography, electrospray ionization mass spectrometry (ESI-MS), and (13)C NMR. On the basis of these analyses, berry development was correlated with an increase in proanthocyanidin mean degree of polymerization, an increase in the proportion of (-)-epigallocatechin extension subunits, and increases in the level of anthocyanins associated with the proanthocyanidin fraction. Additionally, data acquired from ESI-MS of the isolates following acid-catalysis in the presence of excess phloroglucinol is consistent with pectin-bound proanthocyanidins.     

Ripening-induced changes in grape skin proanthocyanidins modify their interaction with cell walls

Proanthocyanidins were isolated from the skins of Cabernet Sauvignon grapes at different stages of grape development in order to study the effect of proanthocyanidin modification on the interaction with grape cell wall material. After veraison, the degree of proanthocyanidin polymerization increased, and thereafter was variable between 24 and 33 subunits as ripening progressed. Affinity of skin cell wall material for proanthocyanidin decreased with proanthocyanidin ripeness following veraison. A significant negative relationship (R2=0.93) was found for average proanthocyanidin molecular mass and the proportion of high molecular mass proanthocyanidin adsorbed by skin cell wall material. This indicated that as proanthocyanidin polymerization increased, the affinity of a component of high molecular mass proanthocyanidins for skin cell wall material declined. This phenomenon was only associated with skin proanthocyanidins from colored grapes, as high molecular mass proanthocyanidins of equivalent subunit composition from colorless mutant Cabernet Sauvignon grapes had a higher affinity for skin cell wall material.     

沙枣果肉原花青素的提取、纯化及抗氧化性能的研究

该文对沙枣果肉中原花青素的提取工艺进行了研究,通过单因素试验,在中心组合试验基础上得出了提取沙枣果肉原花青素的最佳工艺条件：提取温度76℃、提取时间86 min、乙醇浓度72％、提取液pH值5.0、料液比1∶9、提取3次。在此条件下提取率达95.9%。采用固相萃取法对沙枣果肉提取物中原花青素进行纯化,产物纯度为89.91％,原花青素的得率为4.23％;同时对纯化后沙枣果肉原花青素的抗氧化性能进行了测定,结果显示沙枣果肉原花青素有较好的抗脂氧化能力。