丁香不同提取方法提取物的抗氧化活性

采用微波辅助提取、超声辅助提取和索氏提取3种方法对丁香非挥发性成分进行提取,通过对比单因素实验下不同提取方式得到的总黄酮、总酚含量和抗氧化能力,并结合扫描电镜下丁香粉末的微观结构,选择最佳提取方式;再通过响应面实验优化提取工艺。结果表明,微波辅助提取为最佳提取方式,最优提取工艺条件为微波功率248 W,提取温度52℃,乙醇体积分数72%,提取时间23.5 min,在该条件下总黄酮含量为30.96%±0.44%(309.62±4.41 mg/g),总酚含量70.13%±0.86%(701.34±8.64 mg/g),与预测值相符。DPPH自由基清除能力为99.67%±0.32%、ABTS自由基清除能力为99.81%±0.22%、铁离子还原能力为4.01±0.16 mmol/L、Fe~(2+)螯合能力为30.73%±0.92%、抗脂质过氧化能力为83.44%±1.27%,丁香非挥发性成分提取物具有较好的抗氧化能力。     

用传统和超声提取的松果菊(紫锥菊属)的抗氧化和抗菌活性

Antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by classical and ultrasound solvent extraction were compared. The dry aerial part of plant was extracted by 70% ctha-nol at a solid-to-liquid ratio of 1 : 10 (m/v) and 25℃. The extract obtained by classical solvent extraction contained 29% larger amounts of phenolic compounds and 20% higher content of flavonoids. 2,2-diphenyl-l-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the values of EC50 were (34.16±0.65) μg·ml-1and (65.48±1.12) μg·ml-1 for the extracts obtained by the classical and ultrasound extractions, respectively. The extracts, independent of the extraction technique applied, showed a considerable growth inhibition on Candida albicans and Saccharo-myces cerevisiae, while no growth inhibition zones were observed for Aspergillus niger. The diameters of inhibition zone observed for all the microorganisms were larger for extracts obtained by classical extraction than those by ultrasoud extraction.     

Phenolic compounds from vacuum pyrolysis of wood wastes

Various softwood and hardwood bark residues, primary sludges and softwood sawdust residues were processed by vacuum pyrolysis in a laboratory scale batch reactor. The pyrolysis oil, water, charcoal, and gas were recovered and analyzed. The pyrolysis oils were analyzed in details for their content in phenolic compounds after derivatization to their acetyl derivatives. The influence of temperature, heating rate, feedstock bed thickness, particle size and feedstock water pretreatment on the yield of phenols was investigated. The highest yield of phenols was obtained when hardwood bark was soaked in water for 48 hours and pyrolyzed at a temperature of 450°C and a heating rate of 10°C/min. Pyrolysis performance was evaluated in terms of total phenolic yield and composition.     

玉米须中植物多酚的提取及其抗氧化性研究

研究了玉米须中植物多酚的提取工艺及抗氧化性。以玉米须为原料,采用有机溶剂法提取玉米须中植物多酚,单因素试验优化植物多酚提取工艺条件。结果表明:有机溶剂提取法的最佳条件为:在50℃下,60%甲醇溶液作为提取剂,料液比为1∶60,提取时间4 h;玉米须中植物多酚的浓度达到60 mg/m L对羟基自由基清除率为62.16%,超氧自由基清除率为65.67%。     

Optimization of ultrasound-assisted extraction of bioactive compounds from B. forficata subsp. Pruinosa

Extracts containing bioactive compounds were obtained from Bauhinia forficata leaves by ultrasound-assisted extraction (UAE) with three different solvents (n-hexane, ethyl acetate, and ethanol) and were compared with those obtained by a conventional method (maceration). Box-Behnken experimental design was applied to examine and optimize the effect of the extraction temperature (40°C-60°C), power (20%-80%), and sample to solvent ratio (1:10 to 1:20 (w/v)) on the total phenolic content (TPC), total flavonoid content (TFC), and the ferric reducing antioxidant power (FRAP) of B. forficata leaf extracts. This experimental design generated second-order polynomial models, which accurately describe the experimental data, allowing the prediction of optimal conditions for the investigated responses. Optimal extraction was achieved under the following conditions: 80% power, temperature of 41°C, and a 1:20 sample to solvent ratio. Under these conditions, the experimental yield was 8.33 ± 0.32%, total phenolic content was 59.47 ± 0.71 mg GAE · g_extract⁻¹, total flavonoid content was 62.30 ± 3.38 mg QE · g_extract⁻¹, and the ferric reducing antioxidant power was 726.7 ± 15.7 μmol Fe(II)EQ · g_extract⁻¹, which were close to the predicted values, which validated the models. The major compounds found in B. forficata extracts were tocopherols, phytol, heneicosane, and β-Sitosterol.     

竹笋壳黄酮类化合物的提取及其抗氧化活性的研究

以竹笋壳为原料,采用乙醇浸提法来提取黄酮类化合物。结果表明,竹笋壳黄酮最佳的提取工艺参数:乙醇浓度为60%,浸提时间为3 h,料液比为1∶25,浸提温度为80℃,此时提取量可达到4.393 mg/g。考察了竹笋壳黄酮类化合物提取液对羟基自由基的清除能力。结果表明,当竹笋壳黄酮类提取物的浓度达到60μg/mL时,其对.OH的清除率达到58.02%,表现出良好的抗氧化活性。     

Impact of extraction parameters on chemical composition and antioxidant activity of bioactive compounds from Chinese licorice (Glycyrrhiza uralensis Fisch.) by subcritical water

An efficient extraction of bioactive compounds from licorice was developed using subcritical water. This study aimed at investigating the impacts of parameters on the composition and antioxidant property of the extract. It was found that total phenolics (TP), total flavonoids (TF), glycyrrhizic acid (GL), and antioxidant activity (TAA) were significantly affected by the time, pH, and temperature. The parameters of 20 min and pH 8 were preferred. The maximum values were obtained at 200°C (TF, TP), and 140°C (GL). At 280°C, TAA reached the highest level. Subcritical water extraction was confirmed to be an environmentally-friendly and efficient method.     

雪莲果中绿原酸的提取及其抗氧化性测定

以雪莲果为原料,采用醇提法提取绿原酸,通过对不同乙醇质量分数、提取时间、提取温度、料液的提取效果进行比较分析,确定了最佳提取条件为：乙醇质量分数40%,提取时间2.5 h,提取温度80℃,料液比1∶20（g∶mL）,绿原酸提取量为1.63mg/g。邻二氮菲-Fe2＋法测定雪莲果提取物清除.OH（羟自由基）的能力,结果表明雪莲果中的绿原酸具有一定的抗氧化性。     

响应面法优化闪式提取罗汉松总黄酮及抗氧化活性研究

本研究对罗汉松总黄酮提取工艺及其抗氧化活性进行了研究,采用闪式提取法提取罗汉松总黄酮,并通过单因素法和响应面优化方法,同时考察了罗汉松总黄酮对DPPH•、O2-•和•OH自由基清除作用。结果表明,闪式提取罗汉松总黄酮最佳工艺条件为：乙醇浓度71 %、料液比1:36 (g·mL-1)、提取时间53 s、提取电压为75 V时,罗汉松总黄酮提取率为8.147 %。罗汉松总黄酮对DPPH•、O2-•和•OH具有明显的清除能力,最大清除率分别达到87.13%、58.24%和67.56%,为罗汉松的综合开发利用提供了参考。     

Antioxidant and Antimicrobial Activities of Echinacea (Echinacea purpurea L.) Extracts Obtained by Classical and Ultrasound Extraction

Antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by classical and ultrasound solvent extraction were compared. The dry aerial part of plant was extracted by 70% ethanol at a solid-to-liquid ratio of 1:10 (m/v) and 25°C. The extract obtained by classical solvent extraction contained 29% larger amounts of phenolic compounds and 20% higher content of flavonoids. 2,2-diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the values of EC50 were (34.16±0.65) μg·ml⁻¹ and (65.48±1.12) μg·ml⁻¹ for the extracts obtained by the classical and ultrasound extractions, respectively. The extracts, independent of the extraction technique applied, showed a considerable growth inhibition on Candida albicans and Saccharomyces cerevisiae, while no growth inhibition zones were observed for Aspergillus niger. The diameters of inhibition zone observed for all the microorganisms were larger for extracts obtained by classical extraction than those by ultrasound extraction.     

Antioxidant and Antibacterial Activity of Nutraceutical Compounds from Chlorella vulgaris Extracted in Hydrothermal Condition

Abstract

Water in hydrothermal condition has been used for extraction of nutraceutical compounds from Chlorella vulgaris. Hydrothermal extraction was carried out in a semi-batch and a batch extractor at various temperatures (120–200°C), pressures (2–10 MPa), and extraction times (30–300 min) to extract antioxidant and antibacterial compounds. The effect of extraction condition on the yield of extract was investigated. The antioxidant and antibacterial activity of extracts obtained by hydrothermal extraction were examined. The increasing extraction temperature resulted in higher antioxidant activity, but lower antimicrobial activity. As comparison with hot water extraction, the antioxidant activity of extract obtained by hydrothermal extraction was higher than that obtained by hot water extraction, but the antibacterial activity of the extract obtained by hydrothermal extraction was lower.     

Comparison of Antioxidant Activity of Ethanolic Extracts of Propolis Obtained by Different Extraction Methods

The antioxidant activities of the ethanolic extracts of propolis obtained by different extraction methods (high hydrostatic pressure extraction, leaching at room temperature and heat reflux extraction) were investigated in relationship to their total polyphenol and flavonoid contents by two different assays, namely, the β‐carotene bleaching and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical scavenging assay systems. The results showed that the ethanolic extracts of propolis obtained by high hydrostatic pressure extraction and leaching at room temperature had relatively strong antioxidant activities, which may be correlated with the total polyphenol and flavonoid contents. Antioxidant activities of ethanolic extracts of propolis obtained by high hydrostatic pressure extraction were the same as those of ethanolic extracts of propolis obtained by leaching at room temperature. Leaching at room temperature usually needs a few days, and can take even more than 7 d, while high hydrostatic pressure extraction needs only 1 min. These findings further illustrate that the high hydrostatic pressure extraction has a bright prospect for extracting flavonoids from propolis.     

果蔬抗氧化活性与总酚含量相关性研究

利用β-胡萝卜素-亚油酸乳化液氧化法对杭州市场上常见的41种果蔬进行了抗氧化活性的研究,并测定其总酚的含量。结果表明:大多数果蔬都具有一定的抗氧化活性,其中香椿、芦蒿、莴笋叶、水芹、茼蒿菜、马齿苋、藕的抗氧化活性较强,其总酚含量也较高,说明果蔬抗氧化活性的强弱与果蔬所含的酚类物质有一定的关联性。     

杨梅色素苷的提取及抗氧化性研究

比较了浸提法、热煮法、粉碎法等3种方法提取杨梅色素苷的提取量,并对其抗氧化性能进行了研究。结果表明:浸提法提取效果最好,在510nm处的吸光度为0.198,而粉碎法为0.054;杨梅色素苷浓度与其抗氧化能力、超氧阴离子自由基及羟基自由基的清除能力之间存在明显正相关,当杨梅色素苷浓度为34mg·mL-1时,其对超氧阴离子自由基的清除率达到80%;相同浓度下杨梅色素苷的还原力高于抗坏血酸。     

Antioxidant activity of tocopherols and phenolic compounds of virgin olive oil

The antioxidant effects of hydrophilic phenols and tocopherols on the oxidative stability in virgin olive oils and in purified olive oil have been evaluated. Total hydrophilic phenols and the oleosidic forms of 3,4-dihydroxyphenolethanol (3,4-DHPEA) were correlated (r=0.97) with the oxidative stability of virgin olive oil. On the contrary, tocopherols showed low correlation (r=0.05). Purified olive oil with the dialdehydic form of elenolic acid linked to 3,4-DHPEA, an isomer of oleuropeine aglycon, and 3,4-DHPEA had good oxidative stability. A synergistic effect was observed in the mixture of 3,4-DHPEA and its oleosidic forms with α-tocopherol in purified olive oil by the Rancimat method at 120°C.     

猕猴桃根总黄酮的超声提取及抗氧化活性研究

以湘西“米良猕猴桃”根为原料,采用超声波辅助乙醇提取总黄酮, 通过单因素及正交实验优化提取工艺条件,考察总黄酮对羟基自由基清除效果及对油脂氧化的抑制作用,并与常用抗氧化剂作比较。结果表明,以60%乙醇按照料液比1∶30 (g∶mL) 在60 ℃水浴中超声提取40 min后,猕猴桃根中总黄酮得率为1.5%。该提取物对羟基自由基清除效果随浓度的增大而升高,对食用油脂的氧化有很好的抑制作用。     

Screening the Antioxidant and Antimicrobial Properties of the Extracts from Plantain (Plantago Major L.) Leaves

Abstract

Antioxidant and antimicrobial activities of the extracts obtained by classical (maceration) and ultrasonic (40 kHz) extraction from dry Plantago major leaves were compared. The antioxidant activities of extracts obtained by ultrasonic and classical extraction were 0.87±0.02 and 0.85±0.02 µg/µg DPPH, respectively. Ultrasound positively affected the extractive substance yield and the kinetics of extraction, but the extract obtained by classical extraction contained higher total contents of phenolic compounds and flavonoids than that obtained by ultrasonic extraction. Extracts of P. major showed better antimicrobial activity against the yeasts than against the bacteria.     

Supercritical fluid extraction of Prunus persica leaves and utilization possibilities as a source of phenolic compounds

Mediterranean countries contribute highly on world peach production and tonnes of waste leaves are released due to pruning. The aim of this study was to investigate the utilization possibilities of the leaves by supercritical fluid extraction. A statistical design was used to evaluate the effect of temperature (40–80 °C), pressure (150–300 bar) and concentration of ethanol as co-solvent (6–20%) at a flow rate of 15 g/min and for a duration of 60 min. The most effective variables were found as pressure and co-solvent ratio (p < 0.005). Optimum extraction conditions were elicited as 60 °C, 150 bar and 6% co-solvent yielding a total phenol content of 79.92 mg GAE/g extract, EC₅₀ value of 232.20 μg/ml and a radical scavenging activity of 53.25% which was higher than the value obtained by conventional solvent extraction method (32.23%). Consequently, Prunus persica L. leaves were found as a potential phenolic source for industrial applications.     

Kinetics of the Solid-Liquid Extraction Process of Phenolic Antioxidants and Antioxidant Capacity from Hop (Humulus lupulus L.)

The influence of solvent concentration, pH, temperature, sampler solid ratio, and extraction time on the extractability of total phenolics and antioxidants from hop was investigated. The mechanism of extraction is confirmed to occur in the following steps: first, the dissolution of the phenolic compounds near the particle surface (washing), and second, the diffusion from the solid particles to the bulk of the liquid extract (slow extraction). The process is described mathematically using two concepts of the unsteady diffusion through plant material and Ponomaryov’s empirical equation. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.     

Antioxidant Activity of Alhagi camelorum Phenolics Extracted by Automated and Standard Extraction Techniques

Two extraction techniques, automatic soxtherm apparatus and conventional ultrasonic extraction, were compared in terms of yield, composition, and with special focus on antioxidant activity. In the DPPH test automated extraction showed higher antioxidant potential with IC₅₀ value of 7.5 mg/mL as compared to that of ultrasonic extraction which is 12.5 mg/L, whereas combining both was found to be relatively better. A similar trend in total phenolic and total flavonoid contents was observed. HPLC analysis of both extracts revealed the presence of gallic acid, p-hydroxybenzoic acid, caffeic acid, syringic acid rutin, and ferrulic acid with significant difference in their profile.