Supercritical fluid extraction of antioxidant and antimicrobial compounds from Laurus nobilis L. Chemical and functional characterization

Extraction of laurel leaves by using supercritical carbon dioxide was carried out on a supercritical fluid (SF) pilot-scale plant. The extraction pressure and temperature were set to 250 bar and 60°C, respectively, using a 4% of ethanol as modifier. The employed apparatus, owing to a two-stage separation, allowed us to obtain two different fractions (F1 and F2), whose antioxidant and antimicrobial activities were investigated. Two different methods, β-carotene bleaching test and DPPH^• free radical–scavenging assay, were carried out to determine the antioxidant activity. Moreover, antimicrobial activity of laurel fractions was tested against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 10145, Escherichia coli ATCC 11775, Candida albicans ATCC 60193 and Aspergillus niger ATCC 16404. Minimum inhibitory concentration (MIC) and minimal bactericidal and fungicidal concentration (MBC) were obtained. Both fractions showed a similar antioxidant activity, although it was slightly higher for the fraction recovered in separator 2. However, antimicrobial activity against the microorganisms tested was only found when fraction 2 was used. Staphylococcus aureus was the most sensitive microorganism to this fraction, with maximal inhibition zones (25 mm) and the lowest MBC values (1.25 mg/ml), whereas the least susceptible was the fungi Aspergillus niger. In order to determine the compounds responsible for the antimicrobial activity, fraction 2 was analysed by GC–MS; results obtained showed that most of the compounds identified in the supercritical extract have been previously described to show antimicrobial activity; among them, the major compound found in the supercritical extract corresponded to a sesquiterpene lactone of the germacrolide type (6-epi-desacetyllaurenobiolide) previously described in laurel.     

Recovery of phenolic compounds from peach pomace using conventional solvent extraction and different emerging techniques

The study compared high-pressure, microwave, ultrasonic, and traditional extraction techniques. The following extraction conditions were implemented: microwave-assisted extraction (MAE) at 900 W power for durations of 30, 60, and 90 s; ultrasonic-assisted extraction (UAE) at 100% amplitude for periods of 5, 10, and 15 min; and high-pressure processing (HPP) at pressures of 400 and 500 MPa for durations of 1, 5, and 10 min. The highest yield in terms of total phenolic content (PC) was obtained in UAE with a value of 45.13 ± 1.09 mg gallic acid equivalent (GAE)/100 g fresh weight (FW). The highest PC content was determined using HPP-500 MPa for 10 min, resulting in 40 mg GAE/100 g, and MAE for 90 s, yielding 34.40 mg GAE/100 g FW. The highest value of antioxidant activity (AA) was obtained by UAE in 51.9% ± 0.71%. The PCs were identified through the utilization of Fourier transform infrared (FTIR) spectroscopy and high-performance liquid chromatography (HPLC). Utilizing multivariate analysis, the construction of chemometric models were executed to predict AA or total PC of the extracts, leveraging the information from IR spectra. The FTIR spectrum revealed bands associated with apigenin, and the application of HPP resulted in concentrations of 5.41 ± 0.25 mg/100 g FW for apigenin and 1.30 ± 0.15 mg/100 g FW for protocatechuic acid. Furthermore, HPLC analysis detected the presence of protocatechuic acid, caffeic acid, p-coumaric acid, and apigenin in both green extraction methods and the classical method. Apigenin emerged as the predominant phenolic compound in peach extracts. The highest concentrations of apigenin, p-coumaric acid, and protocatechuic acid were observed under HPP treatment, measuring 5.41 ± 0.25, 0.21 ± 0.04, and 1.30 ± 0.15 mg/kg FW, respectively.     

不同提取方法对松茸多糖理化性质及抗氧化活性的影响

目的研究不同提取方法对松茸多糖(polysaccharide of Tricholoma matsutake,TMP)的理化性质及抗氧化活性的影响,并以提取得率和抗氧化活性为依据,筛选出最优方法。方法采用热水浸提、超声提取、酶提取和微波提取等4种提取方法,获得4种相应的多糖。利用高效阴离子交换色谱和傅里叶红外光谱对4种多糖的化学特性进行了结构表征。结果 4种多糖的提取得率顺序为热水浸提多糖超声提取多糖酶提取多糖微波提取多糖。在4种多糖中,超声辅助多糖含量最高(48.98%),蛋白含量最低(0.2%)。抗氧化试验结果表明,超声辅助多糖的还原力和·OH的清除力均高于其他3种多糖;从清除DPPH活性来看,超声辅助多糖和热水浸提多糖的EC_(50)分别为1.06和0.98 mg/mL,二者活性相当,均远高于其他2种多糖。结论综合考虑提取得率、多糖含量和抗氧化活性,超声提取为最优方法。4种多糖的单糖组分基本相同,但它们的摩尔比有明显不同。     

Microwave-assisted extraction of phenolic antioxidant compounds from peanut skins

A microwave-assisted extraction system was used to extract phenolic antioxidants from peanut skins. The effects of microwave power (10%, 50%, 90% nominal), irradiation time (30, 90, 150 s) and sample mass (1.5, 2.5, 3.5 g) on total phenolic content (TPC), ORAC (oxygen radical absorbance capacity) level and resveratrol content of peanut skin extracts (PSE) were investigated. Peanut skins were extracted with 37.5 ml of 30% ethanol (EtOH) in water. A response surface method was used to estimate optimum extraction conditions, based on TPC, ORAC level and resveratrol content. The maximum predicted TPC, under the optimised conditions (90% microwave power, 30 s irradiation time and 1.5 g skins), was 143.6 mg gallic acid equivalent (GAE)/g skins. The highest ORAC value was 2789 μmol trolox equivalents (TE)/g skins, which occurred at 90% power, 150 s and 1.5 g of skins. Resveratrol was identified in PSE by LC–MS–MS analysis.     

山茶油中不同形态酚类化合物的分离提取及抗氧化能力评价

以山茶油为原料提取4种形态酚类化合物（游离态、酯化、糖苷态、不溶性结合态）,通过单因素实验优化提取条件,测定了不同形态酚类化合物总酚、总黄酮和缩合单宁含量,并采用DPPH、ABTS、FRAC和ORACFL4种方法评价不同形态酚类化合物抗氧化能力的差异。结果表明：山茶油中酯化、糖苷态及不溶性结合态酚类化合物的最佳水解时间分别为4、1、4 h,最佳液料比（体积比）分别为2∶ 1、1∶ 1、4∶ 1;山茶油中总酚含量（TPC）为（225.74±0.10）μg/g,主要以糖苷态存在,占总TPC的57.02%;山茶油中4种形态酚类化合物抗氧化能力的强弱顺序为糖苷态酚类化合物>不溶性结合态酚类化合物>酯化酚类化合物>游离态酚类化合物。     

Recovery of phytochemical compounds from natural and blanched green broccoli using non-isothermal autohydrolysis

The temperature effect during autohydrolysis of natural and blanched broccoli was studied. For this purpose, the extraction yield, total phenolic content, antioxidant capacity and glucosinolates type and content of the autohydrolysis liquors have been determined. The development of alginate based hydrogels using the autohydrolysis liquid phase as solvent and the corresponding textural characterisation was also evaluated. In all cases, extraction yields rose with the autohydrolysis temperature up to 150 °C and then decreased. For liquors from natural samples, total phenolic content and antioxidant capacity increased with increasing operation temperature. The opposite trend was identified for blanched samples. Comparable values were obtained at 150 °C for liquors from natural samples and those blanched treated at 100 °C. Glucosinolates content decreased with increasing temperature. Glucoiberin, glucoraphanin, gluconapin, glucobrassicin and gluconasturniin were detected. Hydrogels with suitable textural properties were formulated with the extracted liquors at 100 and 150 °C, independently of the blanching treatment.     

Anti-obesity and antioxidant activities of selected medicinal plants and phytochemical profiling of bioactive compounds

The present study describes the screening of eight herbs namely Cosmos caudatus, Pluchea indica, Lawsonia inermis, Carica papaya, Piper betle, Andrographis paniculata, Pereskia bleo, and Melicope lunu based on their anti-obesity and antioxidant activities. Out of all tested herbs, Cosmos caudatus demonstrated excellent anti-obesity and antioxidant potential with pancreatic lipase inhibitory effect (21.7 ± 1.3%) and DPPH radical scavenging activity (IC₅₀ value of 31.98 ± 1.22 µg/mL). Cosmos caudatus was selected for further studies and extracting solvent composition with best anti-obesity and antioxidant potential was identified. Hundred percent Cosmos caudatus ethanolic extract was found to be the most effective and showed highest anti-obesity and antioxidant activities. Moreover, metabolite profiling of Cosmos caudatus extract was also carried out using UHPLC-MS/MS. The analysis depicted the presence of quercetin-3-rhamnoside, catechin, kaempherol, kaempherol glucoside, quercetin, quercetin-3-glucoside, quercetin-O-pentoside, quercetin-rhamnosyl galactoside, quinic acid, 1-caffeyolquinic acid, monogalloyl glucose, and procyanidin B1. Results revealed Cosmos caudatus as promising medicinal plant for the development of new functional food with prodigious applications in obesity.     

On the extraction and antioxidant activity of phenolic compounds from winery wastes

Winery waste (from red winemaking, variety Agiorgitiko) was extracted under various conditions using different solvents. The minimum time required for ensuring maximum extraction of phenols was 180 min at a solvent to sample ratio 9:1 v/w and at pH 1.5. The antioxidant activity of solvent extracts was investigated by DPPH radical scavenging method, by determination of peroxide value on virgin olive oil and by the Rancimat method on sunflower oil. Ethanol extract exhibited the highest antioxidant activity compared to the other solvent extracts, to synthetic food antioxidants BHT, ascorbyl palmitate and to the natural food antioxidant, vitamin E. No correlation was found between antioxidant activity and total phenol content. HPLC analysis of the extracts showed that gallic acid, catechin and epicatechin were the major phenolic compounds in winery waste. Hydroxytyrosol, tyrosol, cyanidin glycosides and various phenolic acids such as caffeic, syringic, vanillic, p-coumaric and o-coumaric acids were also identified.     

Chemical composition and antioxidant activity of quince fruit pulp collected from different locations

This study was carried out to examine the physicochemical and functional characteristics of quince fruit pulp. The matured quince fruits were collected from different locations of Poonch, AJ&;K, Pakistan. Significant differences (P ? 0.05) were found among fruits collected from these locations. The quince pulp has the following characteristics: pH (3.43), total soluble solids (14.22°Brix), acidity (1.25%), carbohydrate (13.38 g/100 g), reducing sugar (5.15 g/100 g), non-reducing sugar (4.61 g/100 g), moisture (84.27 g/100 g), ash (0.62 g/100 g), fat (0.24 g/100 g), protein (0.49 g/100 g), fiber (1.65 g/100 g), ascorbic acid (15.46 mg/100 g), and total phenolic (68.13 mg gallic acid equivalent/100 g) and antioxidant activity (50.05%). This exploration is the basic direction, which highlights the nutritional characteristics of quince fruit grown in AJ&;K, Pakistan.     

高粱不同溶剂提取物的抗氧化活性及抗细胞氧化应激作用

以红高粱为原料,采用测定清除DPPH·和ABTS~+·能力、总抗氧化能力3种方法比较了不同提取溶剂提取物的抗氧化活性,测定了总酚含量,并分析了总酚含量与抗氧化方法的相关性。并研究了高粱多酚对细胞氧化应激的影响。结果表明,60%乙醇提取物中总酚含量最高,达到315.45 mg GAE/100 g DW。DPPH·清除能力达到89.88%,ABTS~+·清除能力达到89.9%,总抗氧化能力为15.93 mmol TEAC/100 g DW,其中ABTS~+·与总酚的相关系数最高,为0.80(P=0.1930.05),但是不显著。高粱多酚质量浓度为2 mg/m L时,对H_2O_2诱导小鼠肝细胞产生MDA抑制率最高,为72.96%。在质量浓度为300μg/m L时,使得PC12细胞的存活率达到94.11%。由此可见,红高粱具有很强的体外抗氧化能力,并对细胞的氧化应激具有保护作用。     

A comparative study of the phenolic compounds and the in vitro antioxidant activity of different Brazilian teas using multivariate statistical techniques

A total of 51 Brazilian teas from the species Camellia sinensis, Peumus boldus, Matricaria recutita, Baccharis trimera, Cymbopogon citratus, Pimpinella anisum, Mentha piperita, and Ilex paraguariensis were analyzed in terms of phenolic compounds, color and in vitro antioxidant capacity using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. Data were processed using principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). Significant (P < 0.01) correlations between antioxidant activity measured by DPPH and FRAP assays with the total phenolic compounds (r = 0.87; r = 0.90, respectively) and flavonoids (r = 0.79; r = 0.77, respectively) were attained. The compounds that displayed significant (P < 0.05) correlations with the antioxidant activity were gallic acid, catechin, epicatechin, procyanidin B2, quercetrin, and caffeine. PCA was a suitable approach to check for similarities among tea samples, explaining up to 50% of data variability. Four groups were suggested using HCA, in which cluster 3 showed the highest content of total phenolic compounds, flavonoids, antioxidant activity, gallic acid, and caffeine. All samples included in this group were from C. sinensis. The overall classification capacity obtained by LDA was 82.00%, in which 100% of samples from I. paraguariensis, C. citratus, M. recutita, and P. boldus were adroitly classified, while 60% of teas from P. anisum, 80% of M. piperita teas, and 88.24% of C. sinensis teas were correctly classified.     

Characterization of aroma potential of apricot varieties using different extraction techniques

Aroma compounds are presents in raw foods, freely and glycosidically-bounded (aroma precursors). In the present work, the volatile fraction of eight varieties of apricot were analyzed using simultaneous distillation extraction (SDE), solid phase extraction (SPE) with reverse phase (C18), liquid–liquid extraction (LLE) and headspace-solid phase microextraction (HS-SPME). The free aroma compounds were identified by GC–MS, finding common compounds such as linalool, α-terpineol, β-ionone and γ-decalactone and specific compounds due to the extraction method used. The ANOVA showed a significant effect in the extraction techniques and on the varieties in the free aromatic fraction from apricot as well. In spite of a large number of volatile compounds extracted by SPE, the technique that allowed for the most number of compounds to be extracted was SPME.     

茶叶籽油中酚类化合物的提取工艺优化及其抗氧化相互作用动力学研究北大核心CSCD

为揭示二元酚类复合物的抗氧化相互作用机制,采用碱解法结合有机溶剂对茶叶籽油中酚类化合物进行提取。通过单因素实验及正交实验优化酚类化合物提取工艺条件,采用超高效液相色谱-串联质谱(UPLC-MS/MS)分析酚类化合物组成,并对7种酚类化合物及其21组二元复合物的DPPH·清除动力学进行研究。结果表明:茶叶籽油中酚类化合物最佳提取工艺条件为乙酸乙酯为萃取剂、NaOH浓度2.0 mol/L、碱解温度45℃、碱解时间5 h、料液比1∶15,在最佳条件下总酚含量可达(91.37±1.83)μg/g;共鉴定出22种酚类化合物,总含量达152.181μg/g,以酚酸类化合物(82.021μg/g)为主;6,7-二羟基香豆素与龙胆酸的复合物具有强协同作用,二元酚类复合物对DPPH·的清除速率受单体相互作用及起主要抗氧化作用酚类化合物的清除速率的影响,同时酚类化合物的相互作用在抗氧化过程中会发生改变。因此,茶叶籽油的耐储藏性与酚类化合物间的抗氧化协同作用密切相关。     

红松树皮多酚的提取工艺及其抗氧化活性的研究

采用酶解预处理结合乙醇浸提法提取红松树皮多酚化合物,并对其抗氧化活性进行了研究。以多酚得率和羟自由基清除率为指标,在单因素实验基础上,采用响应曲面法对红松树皮多酚的提取工艺进行优化,确定最优提取工艺为:加酶量116.70U/g,酶解时间2.60h,酶解温度53.00℃,乙醇添加量49.30%。在该最优提取条件下多酚得率和羟自由基清除率的分别高达11.84%和76.91%。应用电子自旋共振(ESR)法测定抗氧化活性,多酚提取物对羟自由基的清除能力随加入浓度的增加而增加,表明高浓度多酚提取物会提高其抗氧化活性。