Screening of Bioactive Properties in Brown Algae from the Northwest Iberian Peninsula

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

Sargassum muticum (SM) poses a serious environmental issue since it is a fast-expanding invasive species occupying key areas of the European shoreline, disrupting the autochthonous algae species, and disturbing the ecosystem. This problem has concerned the general population and the scientific community. Nevertheless, as macroalgae are recognized as a source of bioactive molecules, the abundance of SM presents an opportunity as a raw material. In this work, response surface methodology (RSM) was applied as a tool for the optimization of the extraction of bioactive compounds from SM by microwave-assisted extraction (MAE). Five different parameters were used as target functions: yield, total phenolic content (TPC); and the antioxidant measurements of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and β-carotene bleaching (BC). After the optimal extraction conditions were determined (time = 14.00 min; pressure = 11.03 bar; ethanol = 33.31%), the chemical composition and bioactivity of the optimum extract was evaluated to appraise its antioxidant capability to scavenge reactive species and as a potential antibacterial, antidiabetic, antiproliferation, and neuroprotective agent. The results lead to the conclusion that MAE crude extract has bioactive properties, being especially active as an antiproliferation agent and as a nitric oxide and superoxide radical scavenger.

Unraveling the Bioactive Potential of Camellia japonica Edible Flowers: Profiling Antioxidant Substances and In Vitro Bioactivity Assessment

In recent years, the search for novel natural-based ingredients by food and related industries has sparked extensive research aimed at discovering new sources of functional molecules. Camellia japonica, traditionally known as an ornamental plant, has gained attention due to its diverse array of bioactive compounds with potential industrial applications. Although C. japonica flowers are edible, their phytochemical profile has not been thoroughly investigated. In this study, a phenolic profile screening through an HPLC-ESI-QQQ-MS/MS approach was applied to C. japonica flower extracts, revealing a total of 36 compounds, including anthocyanins, curcuminoids, dihydrochalcones, dihydroflavonols, flavonols, flavones, hydroxybenzoic acids, hydroxycinnamic acids, isoflavonoids, stilbenes, and tyrosols. Following extract profiling, their bioactivity was assessed by means of in vitro antioxidant, antimicrobial, cytotoxic, and neuroprotective activities. The results showed a multifaceted high correlation of phenolic compounds with all the tested bioactivities according to Pearson's correlation analysis, unraveling the potential of C. japonica flowers as promising sources of nutraceuticals. Overall, these findings provide insight into the valorization of C. japonica flowers from different unexplored cultivars thus diversifying their industrial outcome.

Phytochemical compounds with promising biological activities from Ascophyllum nodosum extracts using microwave-assisted extraction

Phytochemical-rich antioxidant extracts were obtained from Ascophyllum nodosum (AN) using microwave-assisted extraction (MAE). Critical extraction factors such as time, pressure, and ethanol concentration were optimized by response surface methodology with a circumscribed central composite design. Under the optimal MAE conditions (3 min, 10.4 bar, 46.8 % ethanol), the maximum recovery of phytochemical compounds (polyphenols and fucoxanthin) with improved antioxidant activity from AN was obtained. In addition, the optimized AN extract showed significant biological activities as it was able to scavenge reactive oxygen and nitrogen species, inhibit central nervous system-related enzymes, and exhibit cytotoxic activity against different cancer cell lines. In addition, the optimized AN extract showed antimicrobial, and anti-quorum sensing activities, indicating that this extract could offer direct and indirect protection against infection by pathogenic microorganisms. This work demonstrated that the sustainably obtained AN extract could be an emerging, non-toxic, and natural ingredient with potential to be included in different applications.

Approaches of marine compounds and relevant immune mediators in Autism Spectrum Disorder: Opportunities and challenges

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that affects social skills, language, communication, and behavioral skills, significantly impacting the individual's quality of life. Recently, numerous works have centered on the connections between the immune and central nervous systems and the influence of neuroinflammation on autism symptomatology. Marine natural products are considered as important alternative sources of different types of compounds, including polysaccharides, polyphenols, sterols, carotenoids, terpenoids and, alkaloids. These compounds present anti-inflammatory, neuroprotective and immunomodulatory activities, exhibiting a potential for the treatment of many diseases. Although many studies address the marine compounds in the modulation of inflammatory mediators, there is a gap regarding their use in the regulation of the immune system in ASD. Thus, this review aims to provide a better understanding regarding cytokines, chemokines, growth factors and immune responses in ASD, as well as the potential of bioactive marine compounds in the immune regulation in ASD. We expect that this review would contribute to the development of therapeutic alternatives for controlling immune mediators and inflammation in ASD.

Camellia japonica Flowers as a Source of Nutritional and Bioactive Compounds

In recent decades, plants have strengthened their relevance as sources of molecules potentially beneficial for health. This underpinning effect also arises from the extensive research that has been conducted on plants that are typically undervalued, besides being scarcely used. This is the case with Camellia japonica in Galicia (NW Spain), where, despite its abundance, it is exclusively used for ornamental purposes and has been studied only for its proximate composition. Thus, the present study was conducted on several additional parameters in the flowers of eight C. japonica varieties. Our results show that camellia has a high nutritional value, with carbohydrates as the most abundant macronutrients followed by a moderate protein content (4.4-6.3 g/100 g dry weight) and high levels of polyunsaturated fatty acids (especially ω-3 fatty acids, which represent 12.9-22.7% of the total fatty acids), raising its potential for use for nutritional purposes. According to the thermochemical characterization and elemental composition of camellia, the raw material has poor mineralization and low nitrogen content, but high percentages of volatile matter and high carbon-fixation rates, making it a promising alternative for biofuel production. Furthermore, preliminary analysis reveals a high concentration of different bioactive compounds. As a result of these findings, camellias can be used as food or functional ingredients to improve the nutritional quality of food formulations.

Kinetic Extraction of Fucoxanthin from Undaria pinnatifida Using Ethanol as a Solvent

Fucoxanthin (Fx) has been proven to exert numerous biological properties, which makes it an interesting molecule with diverse industrial applications. In this study, the kinetic behavior of Fx was studied to optimize three variables: time (t-3 min to 7 days), temperature (T-5 to 85 °C), and concentration of ethanol in water (S-50 to 100%, v/v), in order to obtain the best Fx yield from Undaria pinnatifida using conventional heat extraction. The Fx content (Y1) was found through HPLC-DAD and expressed in µg Fx/g of algae sample dry weight (AS dw). Furthermore, extraction yield (Y2) was also found through dry weight analysis and was expressed in mg extract (E)/g AS dw. The purity of the extracts (Y3) was found and expressed in mg Fx/g E dw. The optimal conditions selected for Y1 were T = 45 °C, S = 70%, and t = 66 min, obtaining ~5.24 mg Fx/g AS; for Y2 were T = 65 °C, S = 60%, and t = ~10 min, obtaining ~450 mg E/g AS; and for Y3 were T = 45 °C, S = 70%, and t = 45 min, obtaining ~12.3 mg Fx/g E. In addition, for the selected optimums, a full screening of pigments was performed by HPLC-DAD, while phenolics and flavonoids were quantified by spectrophotometric techniques and several biological properties were evaluated (namely, antioxidant, antimicrobial, and cholinesterase inhibitory activity). These results could be of interest for future applications in the food, cosmetic, or pharmaceutical industries, as they show the Fx kinetic behavior and could help reduce costs associated with energy and solvent consumption while maximizing the extraction yields.

Nutritional and Health Benefits of the Brown Seaweed Himanthalia elongata

Himanthalia elongata is a brown seaweed containing several nutritional compounds and bioactive substances including antioxidants, dietary fibre, vitamins, fatty acids, amino acids, and macro- and trace- elements. A variety of bioactive compounds including phlorotannins, flavonoids, dietary fucoxanthin, hydroxybenzoic acid, hydroxycinnamic acid, polyphenols and carotenoids are also present in this seaweed. Multiple comparative studies were carried out between different seaweed species, wherein H. elongata was determined to exhibit high antioxidant capacity, total phenolic content, fucose content and potassium concentrations compared to other species. H. elongata extracts have also shown promising anti-hyperglycaemic and neuroprotective activities. H. elongata is being studied for its potential industrial food applications. In new meat product formulations, it lowered sodium content, improved phytochemical and fiber content in beef patties, improved properties of meat gel/emulsion systems, firmer and tougher with improved water and fat binding properties. This narrative review provides a comprehensive overview of the nutritional composition, bioactive properties, and food applications of H. elongata.

First Insight into the Neuroprotective and Antibacterial Effects of Phlorotannins Isolated from the Cell Walls of Brown Algae Fucus vesiculosus and Pelvetia canaliculata

Phaeophyceae (brown algae) essentially contribute to biotopes of cold and temperate seas. Their thalli are rich in biologically active natural products, which are strongly and universally dominated with phlorotannins—polyphenols of complex and diverse structure based on multiple differently arranged phloroglucinol units and well known as strong antioxidants with a broad spectrum of biological activities. In the algal cells, phlorotannins can either accumulate in the cytoplasm or can be secreted into the cell wall (CW). The biological activities of extractable intracellular phlorotannins have been comprehensively characterized, whereas the properties of the CW-bound polyphenol fraction are still mostly unknown. Recently, we identified dibenzodioxin bonding as the principal structural feature of the CW-bound phlorotannins in fucoid algae, whereas soluble intracellular phlorotannins rely on aryl and ether bonds. However, profiles of biological activity associated with these structural differences are still unknown. Therefore, to the best of our knowledge, for the first time we address the antioxidant, cytotoxic, neuroprotective, and antibacterial properties of the CW-bound phlorotannin fractions isolated from two representatives of the order Fucales—Fucus vesiculosus and Pelvetia canaliculata. The CW-bound phlorotannins appeared to be softer antioxidants, stronger antibacterial agents and were featured with essentially less cytotoxicity in comparison to the intracellular fraction. However, the neuroprotective effects of both sub-cellular phlorotannin fractions of F. vesiculosus and P. canaliculata were similar. Thus, due to their lower cytotoxicity, CW-bound phlorotannins can be considered as promising antioxidants and neuroprotectors.

Applications of Antioxidant Secondary Metabolites of Sargassum spp

Sargassum is one of the largest and most diverse genus of brown seaweeds, comprising of around 400 taxonomically accepted species. Many species of this genus have long been a part of human culture with applications as food, feed, and remedies in folk medicine. Apart from their high nutritional value, these seaweeds are also a well-known reservoir of natural antioxidant compounds of great interest, including polyphenols, carotenoids, meroterpenoids, phytosterols, and several others. Such compounds provide a valuable contribution to innovation that can translate, for instance, into the development of new ingredients for preventing product deterioration, particularly in food products, cosmetics or biostimulants to boost crops production and tolerance to abiotic stress. This manuscript revises the chemical composition of Sargassum seaweeds, highlighting their antioxidant secondary metabolites, their mechanism of action, and multiple applications in fields, including agriculture, food, and health.

Effect of solid-state fermentation and ultrasonication processes on antimicrobial and antioxidant properties of algae extracts

Algal biomass (AB) is prospective source of valuable compounds, however, Baltic Sea macroalgae have some challenges, because of their high microbial and chemical contamination. These problems can be solved, by using appropriate technologies for AG pre-treatment. The aim of this study was to evaluate the influence of two pre-treatments, solid-state fermentation with the Lactiplantibacillus plantarum LUHS135 and ultrasonication, on the antioxidant and antimicrobial characteristics of macro- (Cladophora rupestris, Cladophora glomerata, Furcellaria lumbricalis, Ulva intestinalis) and Spirulina (Arthrospira platensis) extracts. Also, combinations of extracts and LUHS135 were developed and their characteristics were evaluated. The total phenolic compound content was determined from the calibration curve and expressed in mg of gallic acid equivalents; antioxidant activity was measured by a Trolox equivalent antioxidant capacity assay using the DPPH^• (1,1-diphenyl-2-picrylhydrazyl), ABTS^•+ 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (Ferric Reducing Ability of Plasma) discoloration methods. Antimicrobial activity was measured by using agar well diffusion assay and in a liquid medium. The highest DPPH^• and ABTS^•+ was shown by C.rupestris and F.lumbricalis extract × LUHS135 combinations, the highest FRAP - by non-pretreated C.rupestris and F.lumbricalis extract × LUHS135 combinations. Ultrasonicated samples inhibited four out of seven tested pathogens. Finally, the tested pre-treatments showed good perspectives and can be recommended for AB valorization.

Antioxidant and Antimicrobial Activity of Algal and Cyanobacterial Extracts: An In Vitro Study

Algae and cyanobacteria, other than their nutritional value, possess different beneficial properties, including antioxidant and antimicrobial ones. Therefore, they can be considered functional ingredients in animal feed and natural substitutes for antibiotics. The aim of this study was to evaluate the antioxidant and antimicrobial capacity against porcine O138 E. coli of Ascophyllum nodosum, Chlorella vulgaris, Lithotamnium calcareum, Schizochytrium spp. as algal species and Arthrospira platensis as cyanobacteria. The antioxidant capacity was determined by ABTS Radical Cation Decolorization Assay testing at three different concentrations (100%; 75%; 50%). The growth inhibition effect of the extracts at concentrations of 25%, 12.5%, 6%, 3% and 1.5% against porcine O138 E. coli was genetically characterized by PCR to detect the presence of major virulence factors; this was evaluated by following the microdilution bacterial growth method. The ABTS assay disclosed that Ascophyllum nodosum was the compound with the major antioxidant properties (57.75 ± 1.44 percentage of inhibition; p < 0.0001). All the extracts tested showed growth inhibition activity at a concentration of 25%. Among all extracts, A. nodosum was the most effective, showing a significant growth inhibition of E. coli; in particular, the log10 cells/mL of E. coli used as a control resulted in a significantly higher concentration of 25% and 12.5% after 4 h (8.45 ± 0.036 and 7.22 ± 0.025 log10 cells/mL, respectively; p < 0.005). This also suggests a dose-dependent relationship between the inhibitory activity and the concentration. Also, a synergistic effect was observed on antioxidant activity for the combination of Ascophyllum nodosum and Lithotamnium calcareum (p < 0.0001). Moreover, to determine if this combination could affect the viability of the IPEC-J2 cells under the normal or stress condition, the viability and membrane integrity were tested, disclosing that the combination mitigated the oxidative stress experimentally induced by increasing the cell viability. In conclusion, the results obtained highlight that the bioactive compounds of algal species are able to exert antioxidant capacity and modulate O138 E. coli growth. Also, the combination of Ascophyllum nodosum and Lithotamnium calcareum species can enhance their bioactivity, making them a promising functional feed additive and a suitable alternative to antibiotics.

Impacts of Oxidative Stress and PI3K/AKT/mTOR on Metabolism and the Future Direction of Investigating Fucoidan-Modulated Metabolism

The critical factors for regulating cancer metabolism are oxidative stress and phosphoinositide-3-kinase/AKT serine-threonine kinase/mechanistic target of the rapamycin kinase (PI3K/AKT/mTOR). However, the metabolic impacts of oxidative stress and PI3K/AKT/mTOR on individual mechanisms such as glycolysis (Warburg effect), pentose phosphate pathway (PPP), fatty acid synthesis, tricarboxylic acid cycle (TCA) cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS) are complicated. Therefore, this review summarizes the individual and interacting functions of oxidative stress and PI3K/AKT/mTOR on metabolism. Moreover, natural products providing oxidative stress and PI3K/AKT/mTOR modulating effects have anticancer potential. Using the example of brown algae-derived fucoidan, the roles of oxidative stress and PI3K/AKT/mTOR were summarized, although their potential functions within diverse metabolisms were rarely investigated. We propose a potential application that fucoidan may regulate oxidative stress and PI3K/AKT/mTOR signaling to modulate their associated metabolic regulations. This review sheds light on understanding the impacts of oxidative stress and PI3K/AKT/mTOR on metabolism and the future direction of metabolism-based cancer therapy of fucoidan.

Effect of Extraction Temperature on Pressurized Liquid Extraction of Bioactive Compounds from Fucus vesiculosus

This study was aimed at investigating the effect of low polarity water (LPW) on the extraction of bioactive compounds from Fucus vesiculosus and to examine the influence of temperature on the extraction yield, total phenolic content, crude alginate, fucoidan content, and antioxidant activity. The extractions were performed at the temperature range of 120-200 °C with 10 °C increments, and the extraction yield increased linearly with the increasing extraction temperature, with the highest yields at 170-200 °C and with the maximum extraction yield (25.99 ± 2.22%) at 190 °C. The total phenolic content also increased with increasing temperature. The extracts showed a high antioxidant activity, measured with DPPH (2,2-Diphenyl-1-picrylhydrazyl) radicals scavenging and metal-chelating activities of 0.14 mg/mL and 1.39 mg/mL, respectively. The highest yield of alginate and crude fucoidan were found at 140 °C and 160 °C, respectively. The alginate and crude fucoidan contents of the extract were 2.13% and 22.3%, respectively. This study showed that the extraction of bioactive compounds from seaweed could be selectively maximized by controlling the polarity of an environmentally friendly solvent.

Evaluation of the Biological Potential of Himanthalia elongata (L.) S.F.Gray and Eisenia bicyclis (Kjellman) Setchell Subcritical Water Extracts

Neuroprotection is a need that remains unmet in treating chronic neurodegenerative disorders, despite decades of extensive research. To find new neuroprotective compounds, extracts of Himanthalia elongata (L.) S.F.Gray and of Eisenia bicyclis (Kjellman) Setchell were obtained through subcritical water extraction applying a four-step temperature gradient. The fractions obtained were screened against brain enzymes involved in neurodegenerative etiology, namely in Alzheimer’s and Parkinson’s diseases, and against reactive oxygen and nitrogen species, all contributing factors to the progression of neurodegeneration. Results showed no significant enzyme inhibition but strong radical scavenging activities, particularly in the fourth fraction, extracted at the highest temperature (250 °C), highlighting their ability to retard oxidative and nitrosative stresses. At higher temperatures, fractions were composed of phenolic compounds and Maillard reaction products, a combination that contributed to their antioxidant activity and, consequently, their neuroprotective properties. All fractions were evaluated for the presence of iodine, 14 organochlorine and 7 organophosphorus pesticides, and pharmaceuticals used in Alzheimer’s and Parkinson’s diseases (14), psychiatric drugs (8), and metabolites (8). The fractions studied did not present any of the screened contaminants, and only fraction 1 of E. bicyclis should be used with caution due to iodine content.

Thermochemical Characterization of Eight Seaweed Species and Evaluation of Their Potential Use as an Alternative for Biofuel Production and Source of Bioactive Compounds

Algae are underexplored resources in Western countries and novel approaches are needed to boost their industrial exploitation. In this work, eight edible seaweeds were subjected to their valorization in terms of nutritional characterization, thermochemical properties, and bioactive profile. Our results suggest that seaweeds present a rich nutritional profile, in which carbohydrates are present in high proportions, followed by a moderate protein composition and a valuable content of ω-3 polyunsaturated fatty acids. The thermochemical characterization of seaweeds showed that some macroalgae present a low ash content and high volatile matter and carbon fixation rates, being promising sources for alternative biofuel production. The bioactive profile of seaweeds was obtained from their phenolic and carotenoid content, together with the evaluation of their associated bioactivities. Among all the species analyzed, Porphyra purpurea presented a balanced composition in terms of carbohydrates and proteins and the best thermochemical profile. This species also showed moderate anti-inflammatory activity. Additionally, Himanthalia elongata extracts showed the highest contents of total phenolics and a moderate carotenoid content, which led to the highest rates of antioxidant activity. Overall, these results suggest that seaweeds can be used as food or functional ingredient to increase the nutritional quality of food formulations.

Pigment Composition of Nine Brown Algae from the Iberian Northwestern Coastline: Influence of the Extraction Solvent

Brown algae are ubiquitously distributed in the NW coastline of the Iberian Peninsula, where they stand as an underexploited resource. In this study, five solvents were applied to the extraction of pigments from nine brown algae, followed by their determination and quantification by HPLC-DAD. A total of 13 compounds were detected: Six were identified as chlorophylls, six were classified as xanthophylls, and one compound was reported as a carotene. Fucoxanthin was reported in all extracts, which is the most prominent pigment of these algae. Among them, L. saccharina and U. pinnatifida present the highest concentration of fucoxanthin (4.5-4.7 mg∙g-1 dry weight). Ethanol and acetone were revealed as the most efficient solvents for the extraction of pigments, showing a maximal value of 11.9 mg of total pigments per gram of dry alga obtained from the ethanolic extracts of H. elongata, followed by the acetonic extracts of L. ochroleuca. Indeed, ethanol was also revealed as the most efficient solvent according to its high extraction yield along all species evaluated. Our results supply insights into the pigment composition of brown algae, opening new perspectives on their commercial exploitation by food, pharmaceutical, and cosmeceutical industries.

RP-HPLC-DAD determination of the differences in the polyphenol content of Fucus vesiculosus extracts with similar antioxidant activity

Significant quantities of bioactive compounds have been found in the chemical composition of seaweeds. This source of natural antioxidants such as polyphenols appears to attenuate lipid peroxidation caused by oxidative stress, preventing the harmful effects of a number of injuries including ischemia-reperfusion (I/R). Conventional extraction (CE) has been used for years as a traditional method for obtaining bioactive components from seaweeds. However, recent studies highlight ultrasonic-assisted extraction (UAE) as an alternative and more eco-friendly technique. Therefore, the two methods were optimised and compared to obtain a Fucus vesiculosus extract (FVE) with high antioxidant activity and polyphenol content. The highest antioxidant activity was obtained after 1 h at 25 °C for conventional extraction, and after 5 min at 35 °C for ultrasonic-assisted extraction. Higher concentrations of polyphenols were obtained with the optimal conditions in conventional extraction (13.61 mg PGE/g seaweed), but no significant differences were observed between the antioxidant activity obtained with UAE (89.33%) and CE (89.74%). The characterization of the polyphenols present in both optimised extracts was carried out and compared with reverse-phase high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). The following compounds were identified: phloroglucinol, gallic acid, catechin, vanillic acid, epicatechin, protocatechuic acid, rutin, gentisic acid, chlorogenic acid, caffeic acid, coumaric acid and ferulic acid. RP-HPLC-DAD results also showed higher concentrations of polyphenols in optimised extracts with CE. Consequently, CE was found to be more effective than UAE in providing extracts with higher concentrations of polyphenols, but UAE constitutes an efficient and more eco-friendly methodology for obtaining a FVE with the highest antioxidant activity.

Phytochemical Fortification in Fruit and Vegetable Beverages with Green Technologies

BACKGROUND

Phytochemical, bioactive and nutraceutical compounds are terms usually found in the scientific literature related to natural compounds found in plants linked to health-promoting properties. Fruit and vegetable beverages (mainly juice and smoothies) are a convenient strategy to enhance the consumption of horticultural commodities, with the possibility of being fortified with plant byproducts to enhance the content of bioactive compounds.

OBJECTIVE

This review aims to analyse the different green technologies applied in beverage processing with a fortification effect on their health promoting compounds.

RESULTS

Fortification can be performed by several strategies, including physical elicitors (e.g., processing technologies), plant/algae extract supplementation, and fermentation with probiotics, among others. Thermal processing technologies are conventionally used to ensure the preservation of food safety with a long shelf life, but this frequently reduces nutritional and sensory quality. However, green non-thermal technologies (e.g., UV, high-pressure processing, pulsed electric fields, ultrasounds, cold plasma, etc.) are being widely investigated in order to reduce costs and make possible more sustainable production processes without affecting the nutritional and sensory quality of beverages.

CONCLUSIONS

Such green processing technologies may enhance the content of phytochemical compounds through improvement of their extraction/bioaccessibility and/or different biosynthetic reactions that occurred during processing.