Encapsulation of polyphenolic grape seed extract in polymer-coated liposomes

Polyphenolic grape seed extract (0.1 w/v%) was encapsulated in liposomes (1% soy lecithin) by high pressure homogenization at 22?500 psi. Liposomes containing grape extract had mean particle diameters of <100 nm compared to control liposomes that contained no extract and that had mean particle diameters of <40 nm. Liposomes with grape seed extract were long-term oxidatively stable, e.g. significantly less hexanal (<15 μmol L(-1)) was formed during storage for 150 days compared to liposomes without extract (>717 μmol L(-1)). Over 80% of the polyphenolic compounds in grape seed extract were incorporated into the liposomal membrane rather than into their interior and compounds remained integrated even if the system pH was changed. Coated liposomes were prepared by alternately adding a cationic polymer (chitosan) and an anionic polymer (citrus pectin). Up to 4 coats could be deposited onto the liposomes without incurring aggregation, i.e. dispersions were physically stable during storage for up to 150 days. Deposition of multiple biopolymer coats onto liposomes decreased the amount of polyphenols that reacted with the Folin-Ciocalteu reagent, suggesting that the polyphenols were no longer exposed to the aqueous phase. Our results hence indicate that polymer-coated liposomes are highly capable carrier systems for polyphenols that may have reduced interactions with ingredients in complex media such as foods.     

Changes in polyphenolic content and antioxidant activity after thermal treatments of grape seed extract and grape pomace

This study was undertaken to investigate the effect of heat treatment on polyphenolic content and antioxidant activity in grape pomace (GP) and grape seed extract (GSE). GP and GSE were heat treated in a furnace or autoclaved at 100 °C for 15, 30 and 60 min. Structural modifications of the polyphenols during thermal processes were determined by HPLC–MS, and the antioxidant activity was determined by ABTS, DPPH and photochemiluminescence methods. In general, furnace thermal treatment of GSE and GP did not affect the total extractable polyphenols content, tannin content, procyanidin components and the antioxidant activity. Autoclave treatment caused an extensive hydrolysis of gallocatechin (70%), catechin (61%), epicatechin (65%), procyanidin B1 (75%) and procyanidin B2 (73%) in GSE, and an increase in gallic acid (71%), gallocatechin (100%) and epicatechin gallate (129%) in GP. Autoclave treatment did not affect the antioxidant activity of GSE or GP. It can be concluded that the effect of autoclave was more severe than furnace heat treatment modifying the phenolic profile in a different manner depending on the grape seed product used. These modifications were not related with changes in antioxidant activity.     

Optimisation of ethanol modified supercritical carbon dioxide on the extract yield and antioxidant activity from Garcinia mangostana L.

Xanthones are an important class of secondary metabolites present in mangosteen fruit pericarp. Herein we have used supercritical fluid technology to extract the active constituents from mangosteen pericarp. Ethanol was added (5% w/w) as a co-solvent to increase the polarity of the CO₂, thus favouring the extraction of xanthones. The maximum extraction yield of 15 wt.% was achieved at a pressure of 280 bar, temperature of 50 °C and a time of 8 h, while without co-solvent the yield was 7.5 wt.%. Conditions for antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay was 280 bar at 50 °C and 5 h. Box–Behnken design was used to study the efficiency of extraction pressure (180, 280, and 380 bar), temperature (40, 50, and 60 °C) and time (2–8 h) on the total extraction yields and their radical scavenging activity. Experimental results of the total extract yield and radical scavenging activity were close to the predicted values calculated from the polynomial response surface models equations (R² = 0.99 and 0.98).     

Antioxidant and hepatoprotective activity of ethanolic extract of leaves of Solidago microglossa containing polyphenolic compounds

The antioxidative and hepatoprotective potential of Solidago microglossa D.C, a widely used medicinal plant from Brazil was investigated. The leaf extract showed inhibition against thiobarbituric acid reactive species (TBARS) induced by different prooxidants (10 μM FeSO₄ and 5 μM sodium nitroprusside SNP) in rat liver, brain and phospholipid homogenates from egg yolk. Moreover, the free radical scavenging activities of the extract was evaluated by the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC_50, 3.8 ± 0.5 μg/ml) and hydroxyl radical on benzoic acid hydroxylation (IC_50, 32.3 ± 1.3 μg/ml) and deoxyribose (IC_50, 39.1 ± 2.4 μg/ml) assays. The ethanolic extract showed significant hepatoprotective activity against paracetamol (250 mg/kg) induced liver damage in mice in a dose dependent manner. The phenolic composition and their quantification by high performance liquid chromatography (HPLC) resulted in the identification of gallic acid and flavonoids: quercetrin (quercetin-3-O-rhamnoside), rutin (quercetin-3-O-rutinoside) and quercetin.     

Changes in polyphenol and polysaccharide content of grape seed extract and grape pomace after enzymatic treatment

Grape seed extract and grape pomace are rich sources of polyphenols. The aim of this study was to evaluate the release of polyphenols, the solubilisation of carbohydrate, and the antioxidant capacity of these grape by-products after enzymatic reaction with carbohydrases (cellulolytic and pectinolytic activities) and tannase for 24 h. The use of tannase in these by-products, and pectinase in grape pomace changed the galloylated form of catechin to its free form, releasing gallic acid and increasing the antioxidant activity. In grape pomace, cellulase treatment was not efficient for phenolic release and antioxidant activity improvement. The addition of carbohydrases to grape pomace, either alone or in combination, degraded the cell wall polysaccharides, increasing the content of monosaccharides. These results provide relevant data about the potential of pectinase, tannase and combinations of enzymes on the release of polyphenols and monosaccharides from grape by-products, improving the antioxidant capacity and the nutritional value.     

Antioxidant and antiproliferative activity of polyphenols in novel high-polyphenol grape lines

Health-beneficial effects of grape and wine consumption have been linked to the presence of various polyphenols including anthocyanins in these products. The anthocyanin levels of red grape varieties can vary significantly and there is an interest in developing grape varieties with high anthocyanin levels. In this study, antioxidant and antiproliferative effects of grape anthocyanins from a group of selected grape lines designated as V 72, V 83 and V 103 developed through traditional breeding of the parent lines Lomanto and Seibel 8357, were investigated. The total anthocyanin levels in the different “Vintinto” lines (V) ranged from 119 mg/100 g fresh weight to 963 mg/100 g fresh weight. HPLC–MS analysis of the anthocyanin fractions of grapes in three selected high-polyphenol lines showed predominantly the glucosides of delphinidin, cyanidin, peonidin, petunidin and malvidin with lesser amounts of acetoyl glucosides and coumaroyl glucosides. Anthocyanin fractionation based on hydrophobicity and subsequent evaluation of antioxidant activities showed varying efficiencies in scavenging superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. However, antiproliferative activity of these fractions evaluated using the estrogen receptor positive MCF-7 cells were very similar. High polyphenol grapes and products derived from such grapes may be useful as a concentrated source of dietary polyphenols.     

葡萄籽提取物生理活性及其提取研究

葡萄籽提取物具有多种生理活性而成为有关科研工作者的研究热点。综述了葡萄籽提取物生理活性及其提取分离研究进展,并对葡萄籽提取物的开发利用前景进行了展望。      

Antithrombotic activity of 12 table grape varieties. Relationship with polyphenolic profile

The synthesis of tissue factor (TF) by monocytes/macrophages activated by inflammatory agents is of utmost importance in the pathogenesis of thrombotic diseases and substances inhibiting TF synthesis represent novel and promising antithrombotics. We investigated the effect of 12 table grape varieties (white, red and black) on TF synthesis and the possible relation with the phenolic profile.     

Evaluation of total phenol content and antioxidant properties of encapsulated grape seed extract in yoghurt

The effect of encapsulated (En) and nonencapsulated (NE) grape seed extract (GSE) at 1% level added to milk before its fermentation was evaluated on the physicochemical properties, total phenolic content and antioxidant activity of the resulting yoghurt. Encapsulated GSE resulted in a product comparable to the control, based on sensory properties, acidity, water‐holding capacity, viscosity and colour, along with a threefold increase in total phenolic content and fourfold increase in antioxidant activity. The GSE addition resulted in no effect on the viability of Streptococcus thermophilus and Lactobacillus bulgaricus subsp. delbrueckii counts. The product with NE‐GSE had poor sensory properties and lesser polyphenol stability during storage as compared to En‐GSE yoghurt.     

葡萄籽提取物体外抗氧化活性的研究

通过测定DPPH自由基的清除率、羟自由基的清除率、还原力以及螯合金属的能力,并与天然抗氧化剂VC、VE、儿茶素、蜂胶和合成抗氧化剂BHT、TBHQ、PG进行比较,研究葡萄籽提取物(Grape seed extract,GSE)的抗氧化活性。结果显示:GSE具有较强的DPPH自由基清除能力、还原能力和螯合金属铁离子的能力,均高于VE、蜂胶、BHT;GSE清除羟自由基的能力较弱,低于VC、VE、儿茶素、蜂胶、BHT、TBHQ。表明GSE的抗氧化机理与自由基、还原力和螯合金属离子有关。     

Influence of heating on the polyphenolic content and antioxidant activity of grape seed flour

Abstract: The production of grape seed flour (GSF) from a waste product generated during winemaking, is of interest in product development applications due to its potential health benefits. However, before GSF can used in baking as a source of additional antioxidants, research on its heat stability is required. The overall objective of this study was to assess changes in phenolic content and antioxidant activity of GSF during heating. Merlot GSF was heated at 5 temperatures (120 to 240 °C) for 0 to 90 min. At each time/temperature combination, total phenolic content (TPC), total flavanoid content (TFC), Trolox equivalent antioxidant capacity (TEAC), 2,2 diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, and ferric ion reducing antioxidant power (FRAP) of the extracts were determined. Specific polyphenolic compounds, including catechin, gallocatechin, epicatechin, and gallic acid were also measured. Results showed that when Merlot GSF was heated to ≥180 °C, significant decreases in the TPC and antioxidant activity, measured using FRAP, DPPH, and TEAC, were observed. Longer heating times also caused a reduction in antioxidant capability. Catechin and epicatechin content decreased with increasing heating temperature while gallocatechin and gallic acid content increased. Both catechin and epicatechin content had strong positive correlations (r > 0.91) with TPC and TFC, as well with FRAP and TEAC, suggesting that the GSF antioxidant activity is related to the presence of these particular compounds. Overall, while a decrease in antioxidant content was observed during heating, this occurred at higher baking temperatures. Thus GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content. Practical Application: In order for Merlot grape seed flour (GSF) to be used in baking as a source of additional antioxidant compounds, the impact of heating on the polyphenolic compounds in the GSF needed to be examined. Thermal treatment of Merlot GSF caused significant decreases in the TPC, antioxidant power, and specific polyphenolic compounds when heated ≥180 °C. Thus while antioxidant content decreased with higher heating temperatures, this occurred at higher baking temperatures. Thus, GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content.     

光皮木瓜多酚粗提液的抗氧化活性研究

以光皮小瓜多酚醇提物、水提物为研究究对象,在测定提取液中多酚含量的基础上,研究了多酚粗提液的还原能力以及清除超氧阴离子自由基（O2）、羟基自由基（&#183;OH）和亚硝酸根（NO2-）的能力。结果表明：在试验浓度范围内,木瓜多酚粗提液有强的还原能力,且醇提物对（O2）、&#183;OH和NO2的最大清除率分别达78．29％、83．97％和55．64％;水提物为96．64％、89．64％和81．23％。这说明木瓜多酚粗提液具有较强的综合抗氧化能力,是一种有开发价值的天然抗氧化剂。     

Effects of red grape skin and seed extract supplementation on atherosclerosis in Watanabe heritable hyperlipidemic rabbits

Epidemiological studies have suggested an association between consumption of red wine and other polyphenolic compounds and prevention of cardiovascular diseases. In the present study, Watanabe heritable hyperlipidemic (WHHL) rabbits were used to investigate the effects of polyphenols in a red grape skin and seed extract (GSE) on the development of atherosclerosis. WHHL rabbits received either semisynthetic diet (casein based) or semisynthetic diet added GSE over a period of 15 wk. Plasma lipids and aortic cholesterol accumulation were measured. Feeding semisynthetic diet was associated with increasing hypercholesterolemia, which was developing slower in GSE group compared to the controls as recorded by significantly lower plasma cholesterol in dosage week 7 (males: P < 0.05, females: P < 0.01) and 11 (males: P < 0.01). Aortic atherosclerosis evaluated as the cholesterol content in aortic tissue was comparable in the control and GSE-dosed females, but it was significantly reduced in the abdominal part of GSE-dosed male compared to the controls (P < 0.05). In conclusion, feeding GSE extract to WHHL rabbits had no significant effects in females but was associated with transient less hypercholesterolemic response to semisynthetic diet and, furthermore, retarded the development of aortic atherosclerosis in males as demonstrated by significantly lower cholesterol content in the abdominal part.     

Antioxidant activity of grapefruit seed extract on vegetable oils

The antioxidant activities of a grapefruit seed extract (GFSE) which contains tocopherols, citric acid and ascorbic acid, were investigated in vegetable oils. Different amounts of GFSE in powder were dissolved in a mixture of soybean oil–sunflower oil. The oxidation was carried out in an AOM equipment at temperatures of 98·7°C, 75°C and 66·5°C. The results indicated prooxidant effects of GFSE at 97·8°C and 75°C possibly due to a blockade effect of a hydroxyl compound by tocopherol. The inhibitor reaction orders at these temperatures were 0·902 and 0·465, respectively, while at 66·5°C the oxidation rate was inverse to GFSE concentration with reaction order of −0·420. These results seem to indicate different reaction mechanisms depending on temperature conditions. The blockade effects were explained on the basis of a proposed complex between tocopherol and citric acid molecules. © 1998 SCI.     

Classification and fingerprinting of kiwi and pomelo fruits by multivariate analysis of chromatographic and spectroscopic data

The fingerprinting capacity of two analytical techniques, HPLC and UV–Vis spectroscopy in the case of fruits samples (kiwi and pomelo) has been investigated. The multivariate exploratory techniques were used for sample discrimination according to the fruit species and subspecies. The combination of principal component analysis with linear discriminant analysis is opening new directions in the fingerprinting analysis. The classifications obtained were independent by the analytical techniques, which signalise that both of them may be successfully employed in the fingerprinting methodologies if they are combined with appropriate chemometric methods. One of the biggest advantages of the proposed chemometric method is the ability to discriminate different types and species and subspecies of fruits in just one analysis, which indicates that it is one of the simplest and less time consuming methods. It is strongly sustained by the good results obtained in the case of kiwi and pomelo fruit samples that were simultaneously analysed.     

Effect of heating conditions of grape seeds on the antioxidant activity of grape seed extracts

This study was carried out to evaluate the effect of heating and physical conditions of grape seeds on the antioxidant activity of their extracts. Two forms of grape seeds, whole and powdered forms, were heated at four different temperatures −50, 100, 150 and 200 °C. After heating, grape seeds were extracted with 70% ethanol (0.1 g grape seed/10 mL of 70% ethanol), and total phenol contents (TPC), radical scavenging activity (RSA) and reducing power of the extracts were determined. Thermal treatment of grape seed increased the antioxidant activity of extracts. The maximum TPC and RSA of whole grape seed extract (WGSE) were achieved when the seeds were heat-treated at 150 °C for 40 min, while that of powdered grape seed extract (PGSE) were at 100 °C for 10 min, and were greater than that of the non-treated control. Also, the reducing powers of WGSE and PGSE slightly increased at the conditions. According to the GC-MS analysis, several low-molecular-weight phenolic compounds such as azelaic acid, 3,4-dihydroxy benzoic acid, and o-cinnamic acid were newly formed in the WGSE heated at 150 °C for 40 min. There were slight differences in the kinds of phenolic compounds between non-heated and heated GSE. In HPLC analysis, the contents of gallocatechin gallate and caffeine in GSE significantly increased by heat treatment. These results indicated that antioxidant activity of GSE was affected by heating conditions (temperature and time) and physical conditions of grape seeds at the time of heat treatments.     

葡萄籽多酚化合物抗氧化能力与抗癌细胞增殖活性的评价

目的:探讨葡萄鲜果及酿酒皮渣中葡萄籽提取物中的酚类化合物含量,抗氧化特性及对癌细胞增殖的抑制作用。方法:乙醇法提取葡萄籽中多酚化合物,分光光度计法测定三大酚类化合物参数(总酚、类黄酮类、黄烷-3-醇类)及3种抗氧化性能参数(DPPH及ABTS自由基清除能力,FRAP分析)。体外培养肝癌细胞HepG2,建立细胞模型,不同浓度的提取物作用于癌细胞后,采用四甲基偶氮唑盐比色法(MTT法)检测多酚提取物对癌细胞增殖的抑制作用。结果:不同样品葡萄籽所含酚类化合物、抗氧化性能、抗癌细胞增殖能力均不同,酿酒皮渣的葡萄籽中仍含有大量的多酚化合物,其中欧亚种赤霞珠鲜果及酿酒皮渣中葡萄籽所含酚类化合物、抗氧化能力及抗癌细胞增殖活性高于圆叶葡萄Noble鲜果及酿酒皮渣。结论:葡萄鲜果与酿酒皮渣中的葡萄籽多酚化合物具有抗氧化能力及抗癌细胞增殖活性。     

Antioxidant activity of polyphenolic compounds extracted from defatted raw and dry heated Tamarindus indica seed coat

The antioxidative properties and total phenolic contents of raw and dry heated seed coat of Tamarindus indica were examined. The raw and dry heated samples were extracted with methanol followed by 70% acetone, after treating with petroleum ether, solvents were removed using rotary vacuum evaporator and the extracts which contain residual moisture were freeze-dried, respectively. Methanol extracts for both raw and dry heated seed coat samples contained higher level of total phenolics and tannins than the aqueous acetone extracts. The extracts were screened for their potential antioxidant activities using such as O₂⁻, OH, α,α-diphenyl-β-picrylhydrazyl (DPPH), ABTS⁺, FRAP and linoleic acid emulsion model systems. At different concentration of respective solvent extracts, the maximum level of superoxide anion radical scavenging activity (79-85%) was observed at 200 μg of both the raw and dry heated seed coat extracts in the reaction mixture. The DPPH radical and ABTS cation radical scavenging activities were well proved with the ferric reducing antioxidant capacity of the extracts. Interestingly, among the extracts, methanol and aqueous acetone extracts of dry heated sample showed the highest hydroxyl radical scavenging activity of 56.6 and 45.7%, respectively. All extracts, exhibited good antioxidant activity (64.5-71.7%) against the linoleic acid emulsion system and the values were lower and higher than the synthetic antioxdiant, BHA and ascorbic acid, respectively.     

Characterisation of genuine and derived cranberry proanthocyanidins by LC–ESI-MS

Cranberry proanthocyanidins (PACs) were characterised by HPLC (after thiolysis) and LC–ESI-MS analysis after fractionation by normal-phase chromatography. According to the HPLC retention time and mass spectra of compounds released after depolymerisation reaction, PACs are based on epicatechin and dimer A2 units along with catechin (minor component) and epigallocatechin (trace amounts). Fractionation at semi-preparative scale on normal phase allowed to remove other phenolic compounds than PACs (flavonols, phenolic acids and anthocyanins) and to separate the PACs according to their polymerisation degrees. Six fractions were eluted. PAC concentration, mean degree of polymerisation and percentage of A-type bonds were calculated for these six fractions by HPLC after thiolysis. Whereas the three first fractions contained phenolic acids and flavonols, the three latest fractions were enriched in PACs. Genuine PACs (A and B-types) from DP2 to DP16 were detected by LC–DAD-ESI-MS analysis. Fragmentation on ion trap spectrometer allowed us to determine the position of A-type bonds. Derived PACs were also observed: anthocyanin ethyl-bridged PACs (monomer to tetramer) in the three last fractions, flavonol-ethyl-PACs (monomer and dimer) in the third fraction and pyranoanthocyanin derivatives in the last fraction.