Green improved processes to extract bioactive phenolic compounds from brown macroalgae using Sargassum muticum as model.

A comparative study between "alternative" extraction processes such as centrifugal partition extraction (CPE), supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) and classical solid/liquid used in the laboratory are currently focusing on the efficiency (selectivity and productivity) to obtain bioactive phenolic compounds from the phaeophyte Sargassum muticum model. The choice of the best process was based on several measurements: (i) the total phenolic content measured by the colorimetric Folin-Ciocalteu assay, (ii) radical scavenger and antioxidant activities assessed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay, and the β-carotene bleaching method and finally (iii) the method productivity. Irrespective of the solvent used in the processes, alternative methods are always sharply more effective than classical ones. With the exception of SFE which does not allow extracting the totality of the active phenolic compounds, two of the other extraction methods were particularly promising. First, CPE afforded the most important yields in concentrated phenolic compounds (PC) (22.90±0.65% DW) also displaying the best activities (0.52±0.02 and 0.58±0.19 mg/mL for IC50 and AAC700, respectively). Secondly, PLE using an EtOH:water mixture 75:25 (v/v) allowed a good PC extraction (10.18±0.25% DW) with huge efficiency. Despite a lesser activity of the extracts (0.77±0.01 and 1.59±0.15 mg/mL for IC50 and AAC700, respectively) PLE is a green process and potentially complies European norms requirements for the prospective valorization of phenolic compounds from S. muticum in Brittany.

Anaëlle T ，Serrano Leon E ，Laurent V ，Elena I ，Mendiola JA ，Stéphane C ，Nelly K ，Stéphane LB ，Luc M ，Valérie SP ... -  《-》

Exploring the Potential of Invasive Species Sargassum muticum: Microwave-Assisted Extraction Optimization and Bioactivity Profiling.

Silva A ，Cassani L ，Carpena M ，Lourenço-Lopes C ，Grosso C ，Chamorro F ，García-Pérez P ，Carvalho A ，Domingues VF ，Barroso MF ，Simal-Gandara J ，Prieto MA ... -  《Marine Drugs》

Green extraction of antioxidants from different varieties of red grape pomace.

Otero-Pareja MJ ，Casas L ，Fernández-Ponce MT ，Mantell C ，Martínez de la Ossa EJ ... -  《MOLECULES》

Antioxidant activities and phenolic compounds of pigmented rice bran extracts.

This study was carried out to investigate the antioxidant activities and phenolic compounds of pigmented rice (black, red, and green rice) and brown rice brans. Antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) radical cation assay, reducing power, and chelating ability. Phenolic compounds were measured by using HPLC. Pigmented rice brans were extracted by using aqueous mixtures of acetone, ethanol, and methanol to determine the most effective extraction solvent. Of all solvents examined, extract from 40:60 acetone-water mixtures (v/v) provided the highest DPPH radical assay as well as the highest total phenolic and flavonoid content. We finally selected 40% acetone as an extraction solvent for antioxidant study of pigmented rice bran. Antioxidant activities of 40% acetone extracts of pigmented rice bran, measured in the range of 0 to 1500 μg/mL. At 500 μg/mL concentration, red rice bran, which had the highest total phenolic (259.5 μg/mg) and total flavonoid (187.4 μg/mg) contents, showed the highest antioxidant activity: 83.6%, 71.5%, 1.2%, and 16.4% for DPPH radical assay, ABTS radical cation assay, reducing power, and chelating ability, respectively. Red rice bran showed a lower EC(50) value (112.6 μg/mL) than that of butylated hydroxytoluene (144.5 μg/mL) from the DPPH radical assay. The major phenolic acids of red rice bran were ferulic, vanillic and p-coumaric acids. The results indicated pigmented rice bran might be used as a natural antioxidant. The present study revealed black and red rice bran shows high antioxidant activities and they contain high amount of phenolic compounds. Indeed, black and red rice bran could be better raw materials for manufacturing the food with high antioxidant activity.

Jun HI ，Song GS ，Yang EI ，Youn Y ，Kim YS ... -  《-》

Centrifugal partition extraction in the pH-zone-refining displacement mode: an efficient strategy for the screening and isolation of biologically active phenolic compounds.

Centrifugal partition extraction (CPE) was developed for the first time in the pH-zone-refining mode to fractionate a crude bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). The fractionation process was performed at a flow rate of 20mL/min using a biphasic solvent system composed of methyl tert-butyl ether/acetonitrile/water (4:1:5, v/v/v) in the ascending mode. Sodium hydroxide (40mM) and trifluoroacetic acid (30mM) were used as retainer and displacer agents, respectively. In a single run of 67min, 3g of the initial crude extract were successfully separated into fractions selectively enriched in ionizable triterpenes, ellagic acid derivatives and flavonoids. The antioxidant potential of the initial crude extract, isolated compounds and fraction pools was also evaluated by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) stable free radical scavenging assay, providing an interesting view about the effect of the degree of substitution of ellagic acid derivatives on their radical scavenging activity. This study will demonstrate that centrifugal partition extraction used in the pH-zone-refining mode can be proposed as an efficient strategy for the rapid screening of natural phenolic compounds.

Hamzaoui M ，Renault JH ，Reynaud R ，Hubert J ... -  《-》