石榴抗糖尿病生物活性的研究进展

体外和体内实验均证实石榴汁、石榴皮、石榴花、石榴籽和石榴叶等具有抗糖尿病的功效,综述了石榴多个部位的降血糖效果、降血糖活性成分及其作用机制的研究进展。石榴中的多酚类是抗糖尿病的主要活性物质,主要通过提高胰岛素受体敏感性、增强PPAR-γ（Peroxisome proliferator-activated receptor,过氧化酶体增殖物激活受体）的表达、抑制α-葡萄糖苷酶活性等作用达到抗糖尿病的功效,为石榴的进一步开发利用提供参考。      

Antiproliferative and antioxidant activities of Turkish pomegranate (Punica granatum L.) accessions

The objective of this study was to assess antioxidant and antiproliferative activities of four different Turkish pomegranate varieties (Hatay, Hicaz, Adana and Antalya) using an in vitro HepG2 cancer cell model. All the pomegranate extracts employed in this study significantly diminish the proliferation of HepG2 cells in a dose‐dependent manner. The total phenolic acid, anthocyanin and flavonoid contents for each of the four varieties were determined. The Hatay pomegranate variety had the highest total phenolic acid (337.4 ± 2.34 mg/100 g) and flavonoid (58.42 ± 2.25 mg/100 g) contents of the pomegranates examined. Antioxidant activities of the pomegranates were determined using DPPH and ABTS radical scavenging assays. The lack of correlation between colour index value and antioxidant–antiproliferative activities suggested that phenolic acids and flavonoids are predominant compounds influencing pomegranate's bioactivity rather than anthocyanins. Individual phenolic acids found in Hatay pomegranates were determined, using an HPLC system, as gallic acid being the most predominant phenolic compound.     

Storage stability of sterilized liquid extracts from pomegranate peel

Pomegranate marc, a byproduct of commercial juice production, has shown promise as a starting material for the recovery of health promoting phenolic compounds. The stability of aqueous extracts prepared from pomegranate marc was evaluated in preparation to directly using these extracts as nutraceuticals or food additives. The liquid extracts were produced under extraction conditions of 25 °C, water to peel ratio of 50 : 1 (w/w) for 2 min, and then sterilized at 121 °C for 10 s. Storage conditions tested included 3 different pH values (3.5, 5.0, and 7.0) and 2 packaging methods (no light and exposure to light). The extracts were evaluated for industrial (pH, total soluble solid content, and clarity), color, spectral, and antioxidant characteristics over a period of 180 d. The results showed that both pH value and packaging method significantly influenced the industrial and color characteristics of the extracts. The high pH had a negative effect on spectral and antioxidant characteristics. Therefore, the recommended storage conditions are low pH and with dark packaging to maintain the high storage stability. After 180 d of storage, extracts stored at low pH (3.5) in dark packaging still retained 67% and 58% of their total soluble phenolic concentration and antioxidant activity, compared with 61% and 43% for high pH (7.0) samples, and were composed of high concentrations of punicalagins A and B, gallic, and ellagic acids. PRACTICAL APPLICATION: The present research developed an effective recovery of phenolic compounds from pomegranate marc to be used as nutraceuticals or food additives. The aqueous extract product has good quality characteristics with high industrial and color stability, and total phenolic content and antioxidant activity, when stored at pH 3.5 in dark packaging for up to 180 d. The evaluation results of storage stability reported here are important for commercialization.     

石榴花色苷的微波辅助提取及抗氧化活性研究

以陕西临潼甜石榴为试验材料,通过正交试验,采用pH 差示法测定石榴总花色苷含量,优化微波辅助提取石榴花色苷的工艺参数。同时,采用DPPH 法、FRAP 法、ABTS 法、螯合亚铁能力法分析石榴花色苷的体外抗氧化活性。结果表明：微波辅助提取石榴花色苷的最佳工艺参数为溶剂pH1、料液比1:13(g/mL)、提取时间210s、乙醇体积分数70%、微波输出功率360W。此条件下,花色苷得率为184.81μg/g。微波输出功率对石榴汁花色苷的提取得率有显著影响(P ＜ 0.05)。石榴花色苷含量与DPPH 自由基清除率、铁还原力、ABTS+ 自由基清除率和螯合亚铁离子有显著的相关性(相关系数R2 分别为0.9928、0.9925、0.9913、0.9945),呈明显的量效关系,IC50 值分别为2.44、1.14、4.08、101.05mg/L。     

Antioxidant capacity changes of 3 cultivar Chinese pomegranate (Punica granatum L.) juices and corresponding wines

This study investigated the antioxidant capacities that included Ferric reducing antioxidant power (FRAP), 1, 1-diphenyl-2-picryl hydrazine (DPPH), ·OH and O(2·)(-)-scavenging abilities, total polyphenols (TP) and total anthocyanins (TA) in pomegranate (Punica granatum L.) juice (PJ) and pomegranate wine (PW). The correlations among them were also analyzed. Both PJ and PW showed significantly high TP and antioxidant capacities, but some differences existed among these cultivars. There was 1596.67 mg/L TP found in sweet PJ, while sour PJ showed the highest titratable acidity of 35.90 g/L and lowest pH value at 2.56. Red PJ was found to have the highest TA (82.26 mg/L) in the 3 cultivars. Sweet PJ showed higher DPPH-scavenging ability and higher FRAP than others. Both PJ and PW exhibited high and relatively stable ·OH-scavenging abilities, in which sour PJ and sour PW had higher O(2·)(-) scavenging capacity than others. Significant positive correlations were observed among TP, DPPH, and FRAP in both PJ and PW. A high correlation between antioxidant capacities and TP indicated that phenolic compounds were major contributors to the high antioxidant activity of PJ and PW.     

Antioxidant phenolic compounds of pomegranate wines produced by different maceration methods

Various methods were evaluated in the production of ‘Hicaz’ pomegranate wine by microvinification. The chemical, phenolic and antioxidant characteristics of the wines were assessed by measurement of water‐soluble dry matter, acidity, density, alcohol content, volatile acidity, total monomeric anthocyanins, polarized colour intensity and individual phenolic compounds. Three different methods – classical maceration (N), seed‐supplemented maceration (S) and seed + enzyme supplemented maceration (E) – were applied. Total phenolic compounds of pomegranate must and wines (after 18 months of storage) were 1897 mg/L (must), 1663 mg/L (N), 1339 mg/L (E) and 1414 mg/L (S). Phenolic compounds in pomegranate must and wines included gallic acid, vanillic acid, caffeic acid, ferulic acid, p‐coumaric acid, hydroxycinnamic acid, epicatechin and catechin. Total antioxidant capacities (Trolox equivalents) of pomegranate must and wines (N, E and S) were 9.9 mm /L (must), 9.8 mm /L (N), 9.7 mm /L (E) and 9.5 mm /L (S). Copyright © 2017 The Institute of Brewing & Distilling     

Extraction and microencapsulation of bioactive compounds from pomegranate (Punica granatum var. Wonderful) residues

Pomegranate peels and seeds are industrial residues considered interesting sources of punicalagin (PU) and punicic acid (PA), respectively. To optimise their extraction process and protect them against environmental factors, pomegranate residues were extracted with supercritical CO₂ (SC‐CO₂) using a Box–Behnken design and then optimal extracts encapsulated by spray‐drying applying a 2² central composite design. Peel extracts showed a PU content of 0.4–9.5% with optimal extraction conditions of 400 bar, 43 °C and 20% ethanol. On the other hand, SC‐CO₂ seed extracts showed a PA content of 65.1–78.4% with 450 bar, 48 °C and 10% ethanol as optimal extraction parameters. Otherwise, the encapsulation efficiency of SC‐CO₂ extracts was significantly affected by core/wall material ratio and its quadratic effect. This parameter ranged from 35.1% to 72.4% for peel extracts and from 68.2% to 92.7% for seed extracts. Results showed that the proposed technologies are a feasible approach to the integral utilisation of residues from the pomegranate industry.     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

石榴渣多酚提取及抗氧化活性研究

以石榴渣为实验原料,优化石榴渣多酚提取的工艺,并研究它的抗氧化性质。在单因素实验的基础上,利用响应面分析法(Response Surface Methodology,RSM)中的中心组合设计对石榴渣多酚的提取条件进行优化。用传统的溶剂提取法提取石榴渣中的多酚类物质,并利用福林酚法测定其含量。其抗氧化性用DPPH自由基清除能力和还原能力来评价。结果表明,最佳的石榴渣提取工艺条件是:41%的乙醇作溶剂,液料比20 m L/g,在62℃下提取3.5 h时多酚的得率最大为4.88 mg GAE/g,与预测值5.034 mg GAE/g接近。石榴渣多酚有较强的DPPH自由基清除率,且总抗氧化性与提取的石榴渣多酚浓度呈正相关,相关系数为0.9988。      

Evolution of juice anthocyanins during ripening of new selected pomegranate (Punica granatum) clones

 For five new clones of pomegranate, cultivated under homogeneous conditions, changes in juice anthocyanin contents during ripening were studied. Six anthocyanin pigments were found to be responsible for the red color of pomegranate juice. These were quantitatively and qualitatively analyzed by high-performance liquid chromatography and identified as delphinidin 3-glucoside and 3,5-diglucoside, cyanidin 3-glucoside and 3,5-diglucoside and pelargonidin 3-glucoside and 3,5-diglucoside. Generally, there was an increase in juice pigmentation during fruit ripening. In the early fruit-ripening stages, delphinidin 3,5-diglucoside was the main pigment, followed by cyanidin 3,5-diglucoside, while in the later stages, the monoglucoside derivatives cyanidin 3-glucoside and delphinidin 3-glucoside increased considerably. The pelargonidin derivatives were always present in small amounts. Received: 1 March 1999     

Drying kinetics and thermal degradation of phenolic compounds and anthocyanins in pomegranate arils dried under vacuum conditions

The effects of temperature and pretreatment on drying kinetics and thermal degradation of phytonutrients present in pomegranate arils were investigated. The arils were divided into two groups, and half of the samples were pretreated by dipping into 80 °C hot water for 2 min. The drying process was conducted in the vacuum drier at the temperatures of 55, 65 and 75 °C. The fastest drying was completed at 75 °C after pretreatment of the samples. The highest anthocyanin–phenolic compound contents and antioxidant capacity were detected in the arils dried at 55 °C. Seven thin‐layer drying models were used to predict drying curves, and Arrhenius and Eyring–Polanyi models were employed to predict phytonutrient degradation kinetics. Activation energy for drying was 24.26 kJ mol^?1 for pretreated samples and 31.54 kJ mol^?1 for untreated samples. Effective moisture diffusivities were ranged from 1.43 × 10^?9 to 6.03 × 10^?9 m² s^?1.     

Anthocyanin and organic acid profiles of pomegranate (Punica granatum L.) juices from registered varieties in Turkey

This is the first study to analyse the profiles of anthocyanin (ACN) and organic acid (OA) and some physico‐chemical properties of pomegranate juices (PJs) obtained from nine registered varieties in Turkey. HPLC analyses revealed that there were significant differences between ACN contents (28–447 mg L^?1) and profiles (P < 0.01). The PJs contain maximum six ACNs, 3‐glucosides and 3,5‐diglucoside of delphinidin, cyanidin and pelargonidin. The major OA in PJs was citric acid (66–74%), followed by malic (6–12%), succinic (5–19%), nonidentified (0–14%) and tartaric acids (0.1–3.7%). Amongst individual OAs, citric acid had the most significant effects on TA (r = 0.9761), pH (r = 0.9208) values and sourness of PJs. As different from literature, results of this study revealed that malic acid contents of authentic PJs could be higher than 1.5 g L^?1. Consequently, ACN and OA profiles could be successfully used in quality control because all PJs have their own typical ACN and OA profiles.     

响应面法优化石榴叶总酚的亚临界水提取工艺

本研究采用亚临界水萃取法提取石榴叶总酚,并通过响应面法优化其提取工艺参数。在单因素实验的基础上,根据响应面Box-Behnken实验设计原理,采用三因素三水平的分析法,选取提取温度、提取时间、液料比为自变量,考察其对石榴叶提取物中总酚含量的影响,并通过方差分析优化其工艺。结果表明,回归方程对实验拟合较好,可以对石榴叶中总酚含量进行很好的分析和预测;优化后的最佳工艺条件为:提取温度134℃、提取时间31 min、液料比52∶1 m L/g。在该条件下,石榴叶总酚含量为169.24 mg GAE/g,与预测值173.31 mg GAE/g基本一致。通过与溶剂加热回流法相比较,亚临界水提取可明显提高石榴叶总酚的含量,并缩短提取时间。      

Encapsulation of mangosteen pericarp anthocyanin-rich extract by spray drying

Mangosteen pericarp anthocyanin-rich extract (MPA) was encapsulated by maltodextrin dextrose equivalent 20 (MD20) combined with gum arabic (GA), inulin (IN) or pectin (PEC) using spray drying. The highest encapsulation efficiency and anthocyanin content exhibited MD20:PEC and MD20:IN combinations. The MPA-encapsulated powders had a crystalline-mixed amorphous structure. Scanning electron microscopy (SEM) analysis showed smooth, round, fine particles. Fourier transform infrared spectroscopy (FTIR) analysis confirmed entrapment of anthocyanins by carrier agents. Thermogravimetric analysis (TGA) revealed a high thermal stability of encapsulated powders at temperatures <200°C and found that encapsulation reduced thermal degradation of anthocyanins. Incorporation of MPA-encapsulated powders into natural yoghurt produced shelf-stable naturally coloured product but slightly suppressed the multiplication of Lactobacillus bulgaricus. Encapsulation of anthocyanin-rich mangosteen pericarp extract using spray drying presents a viable opportunity for food technologists to utilise this source in the development of functional food products.     

Polyphenol and volatile profiles of pomegranate (Punica granatum L.) fruit extracts and liquors

This work reports on the preparation of new aromatic pomegranate liquors by maceration of pomegranate juice and arils in Arbutus unedo L. distillate. The volatile, anthocyanin and ellagitannin profiles were monitored after each step. Aromatic compounds of pomegranates, such as limonene, 1‐hexenol and trans‐caryophyllene, were detected in trace levels and showed little contribution to the liquor aroma. The main volatiles of the liquors, namely isobutanol, isopentanols, vitispiranes and volatile esters, are given by the fruit distillate. The anthocyanin contents of the pomegranate juice were around 135 mg L^?1 but decreased to about 5% of this value in the final liquors. Anthocyanin diglucoside compounds showed higher stability than their monoglucoside analogs. Punicalagins and punicalins showed contents between 80 and 135 mg L^?1, depending on the used starting pomegranate material. These ellagitannins account for 60% of the total polyphenols. The procedure can be used to prepare aromatic pomegranate liquors with high polyphenol content.     

Antioxidant and Antibacterial Activities of Punica granatum Peel Extracts

ABSTRACT: Pomegranate peels were powdered and extracted with ethyl acetate, acetone, methanol (MeOH), and water for 1 h each at room temperature. Radical-scavenging activity of dried ethyl acetate, acetone, MeOH, and water extracts of pomegranate peels were compared with butylated hydroxyanisole at 5, 10, 25, and 50 ppm by high-performance liquid chromatography method using 1, 1-diphenyl-2-picrylhydrazyl. MeOH extract exhibited stronger radical-scavenging effect than others. MeOH extract showed marked reducing power in potassium ferricyanide reduction method. Antibacterial activity of acetone, MeOH, and water extracts was evaluated by pour plate method against a few Gram-positive and Gram-negative bacteria. Acetone extract showed the highest antibacterial activity, followed by MeOH and water extract.