Influence of Oxidation and Dialysis of Phlorotannins on Bioactivity and Composition of Ultrasound-Assisted Extracts from Ascophyllum nodosum

The isolation and chemical characterization of phlorotannins has gained special attention in recent years due to their specific health-promoting benefits. Flow-cell ultrasound-assisted extraction (90 W/cm2 of sonication power, 2 min of retention time and 20 g solvent/g algae of liquid–solid ratio) was carried out by using double-distilled water (WE) and acetone:water mixture (AWE) as extraction solvents. The AWE showed a higher total polyphenols content (TPC), carbohydrates (CHOs) and antioxidant activities than WE. However, when the WE was purified by using Amberlite XAD16 column, the purified WE (PWE) showed similar a TPC, decreased CHOs and increased antioxidant activity compared to WE. The oxidation of the PWE extract was evaluated under natural, forced and severe oxidation condition for 120 h. Only severe oxidation conditions were able to significantly reduce TPC and antioxidant activities. PWE was dialyzed (20, 10, 3.5 and 2 kDa). The main bioactive fraction of phlorotannins was obtained from 10 to 20 kDa. CHOs were distributed in fractions below 20 kDa. MALDI-TOF analysis was performed for PWE, PD20 and PD2 extracts to analyze the degree of polymerization of phlorotannins, which ranged from 4 to 17 phloroglucinol units/molecule. Fragmentation patterns allowed the proximate identification of several phlorotannins in Ascophyllum nodosum extractsThis work was supported by the Ministry of Science and Innovation of Spain and European Regional Development Fund (ERDF) of European Union by the research project (RTI2018–095919–B–C2R) and Xunta de Galicia, Spain (Consolidation Project ED431B 2019/01).S

Determination of thermal transitions of gluten-free chestnut flour doughs enriched with brown seaweed powders and antioxidant properties of baked cookies

A protocol for determining the characteristic temperatures of thermomechanical transitions on gluten-free flour doughs is proposed. This protocol is based on the mathematical analysis of experimental curve of storage modulus (G0 ) vs temperature obtained by means of Dynamic Mechanical Thermal Analysis (DMTA) technique. Doughs at constant consistency of chestnut flour with different levels (3, 6 and 9% flour basis, f.b.) of brown seaweed (Bifurcaria bifurcata, Fucus vesiculosus and Ascophyllum nodosum) powders addition, 2% f.b. of guar gum and 1.8% f.b. of salt with different water absorption were used to test the proposed protocol. The ranges of temperatures corresponding to starch gelatinization (59–97 C), amylopectin crystallites melting (82–101 C), reversible dissociation of lipid-amylose complexes (107–128 C) and amylose melting (133–171 C) showed a strong dependence with water absorption of samples. Doughs with the same water absorption submitted to starch gelatinization during mixing were also analysed to corroborate the protocol suitability. Total polyphenols content and radical scavenging activity of extracts from chestnut flour-seaweed powder blends and seaweed-enriched chestnut cookies baked at 180 C were determined. Extraction assisted with ultrasounds was carried out employing acetone-water (70:30 v/v) solution as solvent during 4 min with a liquid/solid ratio of 30 w/w. Seaweed powder addition had a positive effect on antioxidant properties of doughs before baking. However, the seaweed powder addition effect on baked products (cookies) is not clear due to antioxidant activity is overlapped by Maillard's products generated during bakingThis work was supported by the Ministry of Economy and competitiveness of Spain and European Regional Development Fund (ERDF) of European Union by the research project (CTQ 2013–43616/P)S

Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts

Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed’s health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid–liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.This work was funded by the Ministry of Science and Innovation of Spain and European Regional Development Fund (ERDF) of European Union by the research project (RTI2018-095919-B-C2).S

Impact of drying on the sodium alginate obtained after polyphenols ultrasound-assisted extraction from Ascophyllum nodosum seaweeds

Ultrasound-assisted extraction (UAE) of polyphenols from the brown seaweeds Ascophyllum nodosum leaves a solid phase where alginates can be extracted. This study characterizes alginates extracted after the UAE process, with and without an intermediate drying stage at different temperatures (50 and 90 °C) producing sequentially two bioactive compounds from a unique raw material. FT-IR and 1H NMR analyses showed the high purity of alginates with features in the range of commercial alginates. Drying at high temperature decreased average block length and viscosity average molecular weight (Mv) of alginate from 428 to 133 kg/mol. Steady-shear curves (shear-thinning behaviour) and viscoelasticity (liquid like character) features depended clearly on Mv. Solutions of alginates with high Mv were more viscous and the elastic character was more relevant. Cox-Merz rule was only accomplished within the semi-dilute regimes of alginate concentration. Tested process conditions allow the production of alginates with different propertiesS

Polyphenols extraction kinetics from Ascophyllum nodosum seaweed employing water and saltwater: effect of ultrasound sonication

Saltwater (S), with the same ionic strength of seawater, was employed as solvent to extract polyphenols from seaweeds. Aqueous extracts were chemically characterized by means of total polyphenols (TPC), carbohydrates (CHOS) and uronic acids (UA) content and antioxidant capacities (DPPH, ABTS and FRAP). S-extracts showed lower TPC than those obtained with distilled water (D) using two different extraction methods, conventional solid-liquid extraction (SLE) and ultrasound-assisted extraction (UAE). The antioxidant capacities of both non-sonicated extracts did not show significant (p < 0.05) differences. SLE kinetics employing both solvents (D and S) were successfully modelled by Peleg's model, and equilibria were achieved after 15 min. Long-time UAE (15 min) increased phytochemical content in both D- and S-extracts with respect to SLE. Extracts showed three main (A, B, and C) regions from RP-HPLC profiles with different peak areas and shapes. Normalized regions areas from RP-HPLC were related to antioxidant activities by linear regressions and showed that B-region was the main responsible of phytochemical features of the extracts. SLE with saltwater promoted the leaching of other compounds (mainly proteins) that formed intermolecular complexes. These interactions were notoriously diminished with UAE. At these conditions, saltwater can be employed as eco-friendly solvent according to the green chemistry principlesS

A comparison between bark extracts from Pinus pinaster and Pinus radiata: Antioxidant activity and procyanidin composition

5 pages, 4 tables.-- Printed version published Feb 2007.The composition and antiradical activity of procyanidins from the bark of two kinds of pine, Pinus pinaster and Pinus radiata, were compared. Both the total bark extract and the fraction soluble in both water and ethyl acetate (OW) were evaluated, because of their promising results in previous experiments.Results showed that P. radiata bark was richer in total phenols and also in procyanidins, catechin always being the main unit, so terminal as extensional. For P. pinaster, epicatechin was the predominant extension unit. The mean degree of polymerization (mDP) was higher for the latter. Interestingly, opposite results were encountered for the corresponding OW fractions, where P. radiata showed a mDP of 2.9 vs. 2.3 of P. pinaster. It was also found that the higher the mDP the higher was the specific antiradical activity. The different procyanidin composition and specific antiradical activity of the two kinds of barks, and particularly their OW fractions, may lead to the design of efficient natural antioxidants with application in the food industry.We thank the Spanish Ministry of Science and Technology for Project No. PPQ2003-06602-C04, Subprojects 1 and 2.Peer reviewe

Procyanidins from pine bark: Relationships between structure, composition and antiradical activity

10 pages, 5 figures.-- Printed version published Feb 2007.Barks of Pinus pinaster and Pinus radiata were studied as source of procyanidins; these raw materials, considered a byproduct of forestal industry, were extracted with ethanol. The extract was partially fractionated to obtain an aqueous fraction (FA) containing a great part of the procyanidins from barks and with potential application to both food and medical fields. FAs were rich in polyphenols, 65–87% of which were procyanidins; the mean degree of polymerization (mDP) was 7.9 for radiata (rFA) and 10.6 for pinaster (pFA) varieties.The aqueous fractions were chromatographed on Sephadex LH-20 to obtain specific fractions differing in DP and composition. These fractions were analysed by thiolysis with cysteamine, followed by RP-HPLC. Results showed that (+)-catechin was the main terminal unit for both barks and also the main extension unit for radiata. In contrast (-)-epicatechin was predominant as extension unit in pinaster and this could have implications for applications in oils, emulsions and biological systems.In terms of antiradical activity, expressed as specific antiradical units, the entire rFA gave the best results, together with rF5. For P. pinaster bark, the best results were achieved for fractions F5–F8, with DP 7–22. The whole fraction from radiata represents an economic alternative of great interest because the fractionation costs can be avoided.We thank Spanish Ministry MCyT for Project PPQ2003-06602-C04-01 and 02.Peer reviewe