Evaluation of the Effects of Fucoidans from Fucus Species and Laminaria hyperborea against Oxidative Stress and Iron-Dependent Cell Death

Fucoidans are algal polysaccharides that exhibit protective properties against oxidative stress. The aim of this study was to investigate different fucoidans from brown seaweeds for their ability to protect against iron-dependent oxidative stress (ferroptosis), a main hallmark of retinal and brain diseases, including hemorrhage. We investigated five new high-molecular weight fucoidan extracts from Fucus vesiculosus, F. serratus, and F. distichus subsp. evanescens, a previously published Laminaria hyperborean extract, and commercially available extracts from F. vesiculosus and Undaria pinnatifida. We induced oxidative stress by glutathione depletion (erastin) and H₂O₂ in four retinal and neuronal cell lines as well as primary cortical neurons. Only extracts from F. serratus, F. distichus subsp. evanescens, and Laminaria hyperborea were partially protective against erastin-induced cell death in ARPE-19 and OMM-1 cells, while none of the extracts showed beneficial effects in neuronal cells. Protective fucoidans also attenuated the decrease in protein levels of the antioxidant enzyme GPX4, a key regulator of ferroptosis. This comprehensive analysis demonstrates that the antioxidant abilities of fucoidans may be cell type-specific, besides depending on the algal species and extraction method. Future studies are needed to further characterize the health-benefiting effects of fucoidans and to determine the exact mechanism underlying their antioxidative abilities.     

Dietary Supplementation of Astaxanthin Improved the Growth Performance,Antioxidant Ability and Immune Response of Juvenile Largemouth Bass (Micropterus salmoides) Fed High-Fat Diet

High-fat diet (HFD) usually induces oxidative stress and astaxanthin is regarded as an excellent anti-oxidant. An 8-week feeding trial was conducted to investigate the effects of dietary astaxanthin supplementation on growth performance, lipid metabolism, antioxidant ability, and immune response of juvenile largemouth bass (Micropterus salmoides) fed HFD. Four diets were formulated: the control diet (10.87% lipid, C), high-fat diet (18.08% lipid, HF), and HF diet supplemented with 75 and 150 mg kg⁻¹ astaxanthin (HFA1 and HFA2, respectively). Dietary supplementation of astaxanthin improved the growth of fish fed HFD, also decreased hepatosomatic index and intraperitoneal fat ratio of fish fed HFD, while having no effect on body fat. Malondialdehyde content and superoxide dismutase activity were increased in fish fed HFD, astaxanthin supplementation in HFD decreased the oxidative stress of fish. The supplementation of astaxanthin in HFD also reduced the mRNA levels of Caspase 3, Caspase 9, BAD, and IL15. These results suggested that dietary astaxanthin supplementation in HFD improved the growth performance, antioxidant ability and immune response of largemouth bass.     

The effect of algal protein diets on the regeneration of serum and liver proteins in protein depleted rats

The protein quality of algaeSpirulina platensis was evaluated biochemically in adult albino rats by serum protein regeneration studies. Rats depleted for 12 days were repleted for 15 days with diets containing 10% protein derived from algae, methionine supplemented algae, or casein. On protein depletion, the activity of the hepatic enzymes, succinic dehydrogenase and alanine aminotransferase, were lowered while the activity of alkaline phosphatase increased. Protein repletion with algal and casein diets resulted in an increased activity of succinic dehydrogenase and alanine amino transferase and a decrease in alkaline phosphatase activity. However, the levels of these three enzymes were lower with the algal than with the casein diets. Algal diets regenerated serum protein effectively though to a slightly lesser extent than casein.     

Immune Status and Hepatic Antioxidant Capacity of Gilthead Seabream Sparus aurata Juveniles Fed Yeast and Microalga Derived β-glucans

This work aimed to evaluate the effects of dietary supplementation with β-glucans extracted from yeast (Saccharomyces cerevisiae) and microalga (Phaeodactylum tricornutum) on gene expression, oxidative stress biomarkers and plasma immune parameters in gilthead seabream (Sparus aurata) juveniles. A practical commercial diet was used as the control (CTRL), and three others based on CTRL were further supplemented with different β-glucan extracts. One was derived from S. cerevisiae (diet MG) and two different extracts of 21% and 37% P. tricornutum-derived β-glucans (defined as Phaeo21 and Phaeo37), to give a final 0.06% β-glucan dietary concentration. Quadruplicate groups of 95 gilthead seabream (initial body weight: 4.1 ± 0.1 g) were fed to satiation three times a day for 8 weeks in a pulse-feeding regimen, with experimental diets intercalated with the CTRL dietary treatment every 2 weeks. After 8 weeks of feeding, all groups showed equal growth performance and no changes were found in plasma innate immune status. Nonetheless, fish groups fed β-glucans supplemented diets showed an improved anti-oxidant status compared to those fed CTRL at both sampling points (i.e., 2 and 8 weeks). The intestinal gene expression analysis highlighted the immunomodulatory role of Phaeo37 diet after 8 weeks, inducing an immune tolerance effect in gilthead seabream intestine, and a general down-regulation of immune-related gene expression. In conclusion, the results suggest that the dietary pulse administration of a P. tricornutum 37% enriched-β-glucans extract might be used as a counter-measure in a context of gut inflammation, due to its immune-tolerant and anti-oxidative effects.     

In Vivo Nutritional Assessment of the Microalga Nannochloropsis gaditana and Evaluation of the Antioxidant and Antiproliferative Capacity of Its Functional Extracts

Nannochloropsis gaditana is a microalga with interesting nutritional and functional value due to its high content of protein, polyunsaturated fatty acids, and bioactive compounds. However, the hardness of its cell wall prevents accessibility to these components. This work aimed to study the effect of a treatment to increase the fragility of the cell wall on the bioavailability of its nutrients and functional compounds. The antioxidant and antiproliferative capacity of functional extracts from treated and untreated N. gaditana was assessed, and the profile of bioactive compounds was characterized. Furthermore, to study the effect of treatment on its nutrient availability and functional capacity, an in vivo experiment was carried out using a rat experimental model and a 20% dietary inclusion level of microalgae. Functional extracts from treated N. gaditana exhibited higher antioxidant activity than the untreated control. Furthermore, the treated microalga induced hypoglycemic action, higher nitrogen digestibility, and increased hepatic antioxidant activity. In conclusion, N. gaditana has interesting hepatoprotective, antioxidant, and anti-inflammatory potential, thus proving itself an ideal functional food candidate, especially if the microalga is treated to increase the fragility of its cell wall before consumption.     

The Biochemical Composition and Antioxidant Properties of Fucus vesiculosus from the Arctic Region

Fucus vesiculosus is one of the most prominent brown algae in the shallow waters of the seas of the Arctic region (Barents (BS), White (WS), Norwegian (NS), and Irminger (IS)). The aim of this study was to determine the biochemical composition of F. vesiculosus from the Arctic at different reproductive phases, and to evaluate the antioxidant properties of F. vesiculosus extracts. The amounts of monosaccharides, phlorotannins, flavonoids, and ash and the mineral composition significantly varied in the algae. A strong correlation was established between monosaccharide, phlorotannin, and flavonoid accumulation and water salinity (Pearson’s correlation coefficients r = −0.58, 0.83, and 0.44, respectively; p < 0.05). We noted a negative correlation between the antioxidant activity and the amount of the structural monosaccharides of fucoidan (r = −0.64). A positive correlation of phlorotannins and flavonoids with antioxidant power was confirmed for all samples. The ash accumulation was relatively lower in the sterile phase for the algae from the BS and WS. The correlation between the Metal Pollution Index (MPI) and the reproductive phases was medium with high fluctuation. Meanwhile, the MPI strongly correlated with the salinity and sampling site. The gradient of the MPI values across the sea was in the following ranking order: BS < WS < NS < IS. Taken together, and based on our data on the elemental contents of F. vesiculosus, we believe that this alga does not accumulate toxic doses of elements. Therefore, the Arctic F. vesiculosus could be safely used in food and drug development as a source of active biochemical compounds and as a source of dietary elements to cover the daily nutritional requirements of humans.     

Biobased Solvents for Pressurized Liquid Extraction of Nannochloropsis gaditana Omega-3 Lipids

To develop greener extraction alternatives for microalgae biomass, ultrasound assisted extraction (UAE) and pressurized liquid extraction (PLE) with different biobased solvents were investigated, demonstrating that both techniques are useful alternatives for algal lipid extraction. Specifically, Nannochloropsis gaditana lipids were extracted by UAE and PLE at different temperatures and extraction times with sustainable solvents like 2-Methyltetrahydrofuran (2-MeTHF) and its mixtures with ethanol and other alcohols. The best oil yields for both PLE and UAE of N. gaditana were achieved with the mixture of 2-MeTHF:ethanol (1:3), reaching yields of up to 16.3%, for UAE at 50 °C and up to 46.1% for PLE at 120 °C. Lipid composition of the extracts was analyzed by HPLC-ELSD and by GC-MS to determine lipid species and fatty acid profile, respectively. Different fractionation of lipid species was achieved with PLE and solvent mixtures of different polarity. Thus, for the extraction of glycolipids, ethanolic extracts contained higher amounts of glycolipids and EPA, probably due to the higher polarity of the solvent. The optimized method was applied to microalgae Isochrysis galbana and Tetraselmis chuii showing the potential of mixtures of biobased solvents like 2-methyl-THF and ethanol in different proportions to efficiently extract and fractionate lipids from microalgal biomass.     

Evaluation of Ultrasound,Microwave, Ultrasound–Microwave,Hydrothermal and High Pressure Assisted Extraction Technologies for the Recovery of Phytochemicals and Antioxidants from Brown Macroalgae

This study aims to explore novel extraction technologies (ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), ultrasound–microwave-assisted extraction (UMAE), hydrothermal-assisted extraction (HAE) and high-pressure-assisted extraction (HPAE)) and extraction time post-treatment (0 and 24 h) for the recovery of phytochemicals and associated antioxidant properties from Fucus vesiculosus and Pelvetia canaliculata. When using fixed extraction conditions (solvent: 50% ethanol; extraction time: 10 min; algae/solvent ratio: 1/10) for all the novel technologies, UAE generated extracts with the highest phytochemical contents from both macroalgae. The highest yields of compounds extracted from F. vesiculosus using UAE were: total phenolic content (445.0 ± 4.6 mg gallic acid equivalents/g), total phlorotannin content (362.9 ± 3.7 mg phloroglucinol equivalents/g), total flavonoid content (286.3 ± 7.8 mg quercetin equivalents/g) and total tannin content (189.1 ± 4.4 mg catechin equivalents/g). In the case of the antioxidant activities, the highest DPPH activities were achieved by UAE and UMAE from both macroalgae, while no clear pattern was recorded in the case of FRAP activities. The highest DPPH scavenging activities (112.5 ± 0.7 mg trolox equivalents/g) and FRAP activities (284.8 ± 2.2 mg trolox equivalents/g) were achieved from F. vesiculosus. Following the extraction treatment, an additional storage post-extraction (24 h) did not improve the yields of phytochemicals or antioxidant properties of the extracts.     

Induction of Phlorotannins and Gene Expression in the Brown Macroalga Fucus vesiculosus in Response to the Herbivore Littorina littorea

Mechanisms related to the induction of phlorotannin biosynthesis in marine brown algae remain poorly known. Several studies undertaken on fucoid species have shown that phlorotannins accumulate in the algae for several days or weeks after being exposed to grazing, and this is measured by direct quantification of soluble phenolic compounds. In order to investigate earlier inducible responses involved in phlorotannin metabolism, Fucus vesiculosus was studied between 6 and 72 h of grazing by the sea snail Littorina littorea. In this study, the quantification of soluble phenolic compounds was complemented by a Quantitative real-time PCR (qRT-PCR) approach applied on genes that are potentially involved in either the phlorotannin metabolism or stress responses. Soluble phlorotannin levels remained stable during the kinetics and increased significantly only after 12 h in the presence of grazers, compared to the control, before decreasing to the initial steady state for the rest of the kinetics. Under grazing conditions, the expression of vbpo, cyp450 and ast6 genes was upregulated, respectively, at 6 h, 12 h and 24 h, and cyp450 gene was downregulated after 72 h. Interestingly, the pksIII gene involved in the synthesis of phloroglucinol was overexpressed under grazing conditions after 24 h and 72 h. This study supports the hypothesis that phlorotannins are able to provide an inducible chemical defense under grazing activity, which is regulated at different stages of the stress response.     

Profiling of the Molecular Weight and Structural Isomer Abundance of Macroalgae-Derived Phlorotannins

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.     

Valorization of the Red Algae Gelidium sesquipedale by Extracting a Broad Spectrum of Minor Compounds Using Green Approaches

Until now, the red algae Gelidium sesquipedale has been primarily exploited for agar production, leaving an undervalued biomass. In this work, the use of eco-friendly approaches employing ultrasound-assisted extraction (UAE) and green solvents was investigated to valorize the algal minor compounds. The green methods used herein showed an attractive alternative to efficiently extract a broad spectrum of bioactive compounds in short extraction times (15 to 30 min vs. 8 h of the conventional method). Using the best UAE conditions, red seaweed extracts were characterized in terms of total phenolics (189.3 ± 11.7 mg GAE/100 g dw), flavonoids (310.7 ± 9.7 mg QE/100 g dw), mycosporine-like amino acids (MAAs) (Σ MAAs = 1271 mg/100 g dw), and phycobiliproteins (72.4 ± 0.5 mg/100 g dw). Additionally, produced algal extracts exhibited interesting antioxidant and anti-enzymatic activities for potential applications in medical and/or cosmetic products. Thus, this study provides the basis to reach a superior valorization of algal biomass by using alternative methods to extract biologically active compounds following eco-friendly approaches. Moreover, the strategies developed not only open new possibilities for the commercial use of Gelidium sesquipedale, but also for the valorization of different algae species since the techniques established can be easily adapted.     

Influence of Fucoidan Extracts from Different Fucus Species on Adult Stem Cells and Molecular Mediators in In Vitro Models for Bone Formation and Vascularization

Fucoidans, sulfated polysaccharides extracted from brown algae, are marine products with the potential to modulate bone formation and vascularization processes. The bioactivity and safety of fucoidans are highly associated with their chemical structure, which may vary with algae species and extraction method. Thus, in depth evaluation of fucoidan extracts in terms of endotoxin content, cytotoxicity, and their detailed molecular biological impact on the individual cell types in bone is needed. In this study, we characterized fucoidan extracts from three different Fucus species including Fucus vesiculosus (Fv), Fucus serratus (Fs), and Fucus distichus subsp. evanescens (Fe) for their chemical features, endotoxin content, cytotoxicity, and bioactive effects on human outgrowth endothelial cells (OEC) and human mesenchymal stem cells (MSC) as in vitro models for bone function and vascularization. Extracts contained mainly high molecular weight (HMW) fucoidans and were free of endotoxins that may cause inflammation or influence vascularization. OEC tolerated fucoidan concentrations up to 200 µg/mL, and no indication of cytotoxicity was observed. The inflammatory response, however, investigated by real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) and endothelial barrier assessed by impedance measurement differed for the individual extracts. MSC in comparison with endothelial cells were more sensitive to fucoidans and showed partly reduced metabolic activity and proliferation at higher doses of fucoidans. Further results for MSC indicated impaired osteogenic functions in alkaline phosphatase and calcification assays. All tested extracts consistently lowered important molecular mediators involved in angiogenesis, such a VEGF (vascular endothelial growth factor), ANG-1 (angiopoietin 1), and ANG-2 (angiopoietin 2), as indicated by RT-PCR and ELISA. This was associated with antiangiogenic effects at the functional level using selected extracts in co-culture models to mimic bone vascularization processes during bone regeneration or osteosarcoma.     

In Vitro Chemopreventive Potential of Phlorotannins-Rich Extract from Brown Algae by Inhibition of Benzo[a]pyrene-Induced P2X7 Activation and Toxic Effects

Phlorotannins are polyphenols occurring exclusively in some species of brown algae, known for numerous biological activities, e.g., antioxidant, antiproliferative, antidiabetic, and antiallergic properties. Their effects on the response of human lung cells to benzo[a]pyrene (B[a]P) has not been characterized. Our objective was to in vitro evaluate the effects of a phlorotannin-rich extract obtained from the brown algae Ascophyllum nodosum and Fucus vesiculosus on B[a]P cytotoxic effects. The A549 cell line was incubated with B[a]P for 48 and 72 h in the presence or absence of the brown algae extract. Cytochrome P450 activity, activation of P2X7 receptor, F-actin disorganization, and loss of E-cadherin expression were assessed using microplate cytometry and fluorescence microscopy. Relative to control, incubation with the brown algae extract was associated with lower B[a]P-induced CYP1 activity, lower P2X7 receptor activation, and lower reactive oxygen species production. The brown algae extract inhibited the alterations of F-actin arrangement and the downregulation of E-cadherin expression. We identified a phlorotannins-rich extract that could be deeper investigated as a cancer chemopreventive agent to block B[a]P-mediated carcinogenesis.     

Valorization of Sargassum muticum Biomass According to the Biorefinery Concept

The biorefinery concept integrates processes and technologies for an efficient biomass conversion using all components of a feedstock. Sargassum muticum is an invasive brown algae which could be regarded as a renewable resource susceptible of individual valorization of the constituent fractions into high added-value compounds. Microwave drying technology can be proposed before conventional ethanol extraction of algal biomass, and supercritical fluid extraction with CO₂ was useful to extract fucoxanthin and for the fractionation of crude ethanol extracts. Hydrothermal processing is proposed to fractionate the algal biomass and to solubilize the fucoidan and phlorotannin fractions. Membrane technology was proposed to concentrate these fractions and obtain salt- and arsenic-free saccharidic fractions. Based on these technologies, this study presents a multipurpose process to obtain six different products with potential applications for nutraceutical, cosmetic and pharmaceutical industries.     

Algicidal Effects of a High-Efficiency Algicidal Bacterium Shewanella Y1 on the Toxic Bloom-Causing Dinoflagellate Alexandrium pacificum

Alexandriumpacificum is a typical toxic bloom-forming dinoflagellate, causing serious damage to aquatic ecosystems and human health. Many bacteria have been isolated, having algicidal effects on harmful algal species, while few algicidal bacteria have been found to be able to lyse A. pacificum. Herein, an algicidal bacterium, Shewanella Y1, with algicidal activity to the toxic dinoflagellate A. pacificum, was isolated from Jiaozhou Bay, China, and the physiological responses to oxidative stress in A. pacificum were further investigated to elucidate the mechanism involved in Shewanella Y1. Y1 exhibited a significant algicidal effect (86.64 ± 5.04% at 24 h) and algicidal activity in an indirect manner. The significant declines of the maximal photosynthetic efficiency (F_v/F_m), initial slope of the light limited region (alpha), and maximum relative photosynthetic electron transfer rate (rETRmax) indicated that the Y1 filtrate inhibited photosynthetic activities of A. pacificum. Impaired photosynthesis induced the overproduction of reactive oxygen species (ROS) and caused strong oxidative damage in A. pacificum, ultimately inducing cell death. These findings provide a better understanding of the biological basis of complex algicidal bacterium-harmful algae interactions, providing a potential source of bacterial agent to control harmful algal blooms.     

Antioxidant Enzymes and Oxidative Stress in the Erythrocytes of Iron Deficiency Anemic Patients Supplemented with Vitamins

Background: Iron deficiency anemia is one of the major causes of morbidity and mortality worldwide. Evidences from epidemiological and clinical studies suggest a possible correlation between antioxidant levels and the anemic disease risk. The present work is to investigate antioxidant levels and lipid peroxidation in anemic patients. Methods: A number of 30 patients (15 males and 15 females) were selected for the study. Likewise, 30 age- and gender-matched healthy volunteers (15 males and 15 females) were selected with their informed consent. Patients and healthy subjects were supplemented with vitamins C and E for 15 days. The lipid peroxidation both in plasma and erythrocyte lysates was determined by thiobarbituric acid reactive substances and lipid peroxides. The antioxidant vitamins A, C, and E and total antioxidant activity were also analyzed. The antioxidant enzyme superoxide dismutase, catalase, and glutathione peroxidase were also determined. Results: Based on analysis, we found that the increase in lipid peroxidation was higher in the anemic subjects before vitamin supplementation, which was statistically significant at P<0.05. The antioxidant enzymes were higher in the patients before antioxidant supplementation when compared with patients after vitamin supplementation. Conclusion: Our data revealed higher oxidative stress before vitamin supplementation in iron deficiency anemic patients and after supplementation, lower lipid peroxidation and increased antioxidant vitamins were achieved. Key Words: Iron deficiency anemia, Lipid hydroperoxides (LOOH), Vitamin C, Vitamin E, Thiobarbituric acid reactive substances (TBARS)     

Redox Status and Neuro Inflammation Indexes in Cerebellum and Motor Cortex of Wistar Rats Supplemented with Natural Sources of Omega-3 Fatty Acids and Astaxanthin: Fish Oil,Krill Oil,and Algal Biomass

Health authorities worldwide have consistently recommended the regular consumption of marine fishes and seafood to preserve memory, sustain cognitive functions, and prevent neurodegenerative processes in humans. Shrimp, crabs, lobster, and salmon are of particular interest in the human diet due to their substantial provision of omega-3 fatty acids (n-3/PUFAs) and the antioxidant carotenoid astaxanthin (ASTA). However, the optimal ratio between these nutraceuticals in natural sources is apparently the key factor for maximum protection against most neuro-motor disorders. Therefore, we aimed here to investigate the effects of a long-term supplementation with (n-3)/PUFAs-rich fish oil, ASTA-rich algal biomass, the combination of them, or krill oil (a natural combination of both nutrients) on baseline redox balance and neuro-inflammation indexes in cerebellum and motor cortex of Wistar rats. Significant changes in redox metabolism were only observed upon ASTA supplementation, which reinforce its antioxidant properties with a putative mitochondrial-centered action in rat brain. Krill oil imposed mild astrocyte activation in motor cortex of Wistar rats, although no redox or inflammatory index was concomitantly altered. In summary, there is no experimental evidence that krill oil, fish oil, oralgal biomass (minor variation), drastically change the baseline oxidative conditions or the neuro-inflammatory scenario in neuromotor-associated rat brain regions.     

Assessment of the Antimicrobial Activity of Algae Extracts on Bacteria Responsible of External Otitis

External otitis is a diffuse inflammation around the external auditory canal and auricle, which is often occurred by microbial infection. This disease is generally treated using antibiotics, but the frequent occurrence of antibiotic resistance requires the development of new antibiotic agents. In this context, unexplored bioactive natural candidates could be a chance for the production of targeted drugs provided with antimicrobial activity. In this paper, microbial pathogens were isolated from patients with external otitis using ear swabs for over one year, and the antimicrobial activity of the two methanol extracts from selected marine (Dunaliella salina) and freshwater (Pseudokirchneriella subcapitata) microalgae was tested on the isolated pathogens. Totally, 114 bacterial and 11 fungal strains were isolated, of which Staphylococcus spp. (28.8%) and Pseudomonas aeruginosa (P. aeruginosa) (24.8%) were the major pathogens. Only three Staphylococcus aureus (S. aureus) strains and 11 coagulase-negative Staphylococci showed resistance to methicillin. The two algal extracts showed interesting antimicrobial properties, which mostly inhibited the growth of isolated S. aureus, P. aeruginosa, Escherichia coli, and Klebsiella spp. with MICs range of 1.4 × 10⁹ to 2.2 × 10¹⁰ cells/mL. These results suggest that the two algae have potential as resources for the development of antimicrobial agents.     

Total phenolic contents and antioxidant properties of buckwheat fermented by three strains of Agaricus

The aim of this work was to evaluate the effects of solid-state fermentation (SSF) with three strains of Agaricus (Agaricus blazei Murrill SH26, Agaricus bisporus AS2796 and Agaricus bisporus G1) on the total phenolic contents and antioxidant properties of buckwheat (Fagopyrum esculentum Möench). The results showed that the total phenolic contents of the fermented buckwheat varied with fermentation time and the starter organisms. The total phenolic content of buckwheat fermented with strain SH26 reached its maximum value of 18.07 mg/g after the fermentation of 21 days, which was 3.96 times higher than that of control. The ethanolic extracts of buckwheat fermented by strains SH26 and AS2796 exhibited enhanced antioxidant properties in comparison with the control. However, the ethanolic extracts of buckwheat fermented by strain G1 exhibited less antioxidant properties in comparison with the control. The ethanolic extracts of buckwheat fermented with strain SH26 exhibited the highest reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and ferrous ion chelating ability, respectively. The ethanolic extracts of buckwheat fermented with strain AS2796 exhibited the highest superoxide anion radical scavenging ability.