Evaluation for Antioxidative Properties of Phlorotannins Isolated from the Brown Alga <i>Eisenia bicyclis</i>, by the H-ORAC Method

The antioxidative properties of phlorotannins isolated from the brown alga Eisenia bicyclis were measured using the H-ORAC (Hydrophilic Oxygen Radical Absorbance Capacity) method. The ORAC values of phloroglucinol and it’s oligomers: eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, 8,8’-bieckol, were 2.57 ± 0.14, 4.97 ± 0.36, 9.82 ± 0.70, 8.97 ± 0.89, 10.22 ± 0.85, 8.62 ± 0.92 μmol Trolox equivalent/μmol, respectively. With the exception of eckol, the ORAC values of tested phlorotannins were higher than those of the well-known antioxidants (epigallocatechin gallate, resveratrol and L-ascorbic acid) used as positive controls. As a result of comparing with known ORAC values, it was found that the dieckol and fucofuroeckol A had stronger antioxidant activity than representative polyphenols (e.g., kaempferol, quercetin, myricetin and chlorogenic acid) derived from terrestrial plants.

The Influence of Phlorotannins and Bromophenols on the Feeding Behavior of Marine Herbivorous Gastropod <i>Turbo cornutus</i>

The influence of phlorotannins and bromophenols on the feeding behavior of marine herbivores was determined using bioassay of Turbo cornutus. It was found that phloroglucinol and its oligomers isolated from the brown alga Eisenia bicyclis (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8’-bieckol) had a deterrent effect against feeding behavior of T. cornutus in the concentration of algal body, respectively. In the case of the examination of 0.1 mM concentration, although fucofuroeckol A and phlorofucofuroeckol A significantly reduced feeding by T. cornutus, phloroglucinol and 8,8’-bieckol did not show any significant influence on feeding behavior, and eckol and dieckol had stimulating activity. 2,4-Dibromophenol and 2,4,6-tribromophenol, which are major components of extracellular secretions from Eisenia and Ecklonia species, caused the death, the torpidity, and the decreased appetite of T. cornutus at the concentration of 0.1 mM. In addition, 2,4-dibromophenol had strong feeding deterrent activity at the concentration of 1 μM. These results indicate that phlorotannins and bromophenols act as chemical defense agents of brown algae against environmental stresses such as the herbivore attack.

STUDIES ON EXTRACTION PROCEDURE AND ANTIOXIDATIVE ACTIVITY OF PHLOROTANNINS FROM SARGASSUM KJELLMANIANUM

Known only in phaeophyceae, phlorotannins (brown algal polyphenols) are natural products with potential uses in pharmacology. This study yielded an extraction procedure to obtain high purity,high purity, high molecular weight phlorotannins from Sargassum kjellmanianum, and revealed the characteristics of their infrared and flourescence spectra. The antioxidative activity of phlorotannins, which was about 2.6 times as strongas that of 0.02% BHT (tert - butyl - 4 - hydroxytoluen). showed potential for preventing oil rancidification.

Analysis on Composition and Antioxidative Properties of Phlorotannins Isolated from Japanese Eisenia and Ecklonia Species

The composition and antioxidative properties of crude phlorotannins isolated from Japanese Eisenia and Ecklonia species including cultured E. kurome were analyzed. As a result of liquid chromatography mass spectrometry analysis, it was suggested that the phlorotannins were composed of compounds containing 3 - 7 phloroglucinol units for Eisenia species and 3 - 8 phloroglucinol units for Ecklonia species. The antioxidant properties of phlorotannins were evaluated using the hydrophilic oxygen radical absorbance capacity (H-ORAC) assay, the measurements of superoxide anion radical scavenging activity (SOSA) with electron spin resonance method, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power assay. It was clarified that the phlorotannins contained H-ORAC values of 8.9 × 103 - 1.0 × 104 μmol-Trolox equivalents (TE)/g, SOSA of 1.5 × 104 - 2.9 × 104 superoxide dismutase units/g, DPPH radical scavenging activity of 4.7 × 103 - 5.5 × 103 μmol-TE/g, and reducing power of 6.5 × 102 - 7.0 × 102 mg-ascorbic acid equivalents/g, and had excellent antioxidative properties.

Antioxidant Activities of Crude Phlorotannins from Sargassum hemiphyllum

Brown algae are well known as a source of biologically active compounds, especially those having antioxidant activities, such as phlorotannins. In this study we examined the antioxidant activities of crude phlorotannins extracts（CPEs） obtained from Sargassum hemiphyllum（SH） and fractionated according to the molecular weights. When CPEs were administrated at a dose of 30 mg/kg to Kunming mice pre-treated with carbon tetrachloride（CCl4）, the levels of oxidative stress indicators in the liver, kidney and brain were significantly reduced in vivo. All the components of various molecular weight fractions of CPEs exhibited greater scavenging capacities in clearing hydroxyl free radical and superoxide anion than the positive controls gallic acid, vitamin C and vitamin E. Particularly, the components greater than 30 k D obtained from ethyl acetate phase showed the highest antioxidant capacities. These results indicated that SH is a potential source for extracting phlorotannins, the algal antioxidant compounds.

Preparation and characterization of pH-responsive metal-polyphenol structure coated nanoparticles

In this paper,tannic acid(TA)and Fe~(3+)were added to form a layer of metal-polyphenol network structure on the surface of the nanoparticles which were fabricated by zein and carbon quantum dots(CQDs)encapsulating phlorotannins(PTN).pH-Responsive nanoparticles were prepared successfully(zein-PTN-CQDs-Fe-~Ⅲ).Further,the formation of composite nanoparticles was confirmed by a series of characterization methods.The zeta-potential and Fourier transform infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form nanoparticles.The encapsulation efficiency(EE)revealed that metal-polyphenol network structure could improve the EE of PTN.Thermogravimetric analysis and differential scanning calorimetry experiment indicated the thermal stability of zein-PTN-CQDs-Fe~Ⅲnanoparticles increased because of metal-polyphenol network structure.The pH-responsive nanoparticles greatly increased the release rate of active substances and achieved targeted release.

Anti-methanogenic potential of seaweeds and seaweed-derived compounds in ruminant feed:current perspectives,risks and future prospects

With methane emissions from ruminant agriculture contributing 17%of total methane emissions worldwide,there is increasing urgency to develop strategies to reduce greenhouse gas emissions in this sector.One of the proposed strategies is ruminant feed intervention studies focused on the inclusion of anti-methanogenic compounds which are those capable of interacting with the rumen microbiome,reducing the capacity of ruminal microorganisms to produce methane.Recently,seaweeds have been investigated for their ability to reduce methane in ruminants in vitro and in vivo,with the greatest methane abatement reported when using the red seaweed Asparagopsis taxiformis(attributed to the bromoform content of this species).From the literature analysis in this study,levels of up to 99%reduction in ruminant methane emissions have been reported from inclusion of this seaweed in animal feed,although further in vivo and microbiome studies are required to confirm these results as other reports showed no effect on methane emission resulting from the inclusion of seaweed to basal feed.This review explores the current state of research aiming to integrate seaweeds as anti-methanogenic feed additives,as well as examining the specific bioactive compounds within seaweeds that are likely to be related to these effects.The effects of the inclusion of seaweeds on the ruminal microbiome are also reviewed,as well as the future challenges when considering the largescale inclusion of seaweeds into ruminant diets as anti-methanogenic agents.

穴状昆布中的phlorotannins对HIV-1逆转录酶和蛋白酶的抑制作用

穴状昆布Ecklonia cava Kjellman是一种海洋褐藻。曾报道该植物的乙酸乙酯提取部位对RNA依赖的DNA聚合酶(RDDP)有较强的抑制作用。作者以生物活性为导向，从穴状昆布中分离出4个均含二苯并[1，4]二氧芑结构的phlorotannins类化合物1～4，研究了它们对HIV-1逆转录酶(RT)和蛋白酶的抑制作用。

Antioxidant activity of phlorotannins from brown algae

The antioxidant activity of the phlorotannins extracted from five marine algaespecies(Saccharina latissima,Alaria esculenta,Laminaria digitata,Fucus vesiculosusand Ascophyllum nodosum)was studied.Three phlorotannin groups,including soluble,membrane-bound,and extracted membrane-bound phlorotannins obtained by two solvent extraction methods were investigated for their DPPH radical scavenging activity.F.vesiculosusand A.nodosumshowed the highest phlorotannin yield(14.83 mg-extract/g-algae and 12.80 mg-extract/g-algae,respectively)among the five algaespecies.Their soluble phlorophannin(SP),membrane-bound phlorotannin(MP)and extracted membrane-bound phlorotannin(eMP)extracts all showed equal or greater DPPH radical scavenging activity than the commercial antioxidants of butylated hydroxytoluene and ascorbic acid.The antioxidant potential that combines phlorotannin yield and antioxidant activity of the MP extracts of F.vesiculosusand A.nodosum(5890mL/g and 5278 mL/g algae,respectively)were higher than those of SP and eMP,suggesting that the MPs of F.vesiculosusand A.nodosumhad great potential to be used as antioxidants.Different extraction methods also showed significantly different effects on the antioxidant activity of the phlorotannin extracts.

The role of seaweed as a potential dietary supplementation for enteric methane mitigation in ruminants: Challenges and opportunities

Seaweeds are macroalgae,which can be of many different morphologies,sizes,colors,and chemical profiles.They include brown,red,and green seaweeds.Brown seaweeds have been more investigated and exploited in comparison to other seaweed types for their use in animal feeding studies due to their large sizes and ease of harvesting.Recent in vitro and in vivo studies suggest that plant secondary compound-containing seaweeds(e.g.,halogenated compounds,phlorotannins,etc.)have the potential to mitigate enteric methane(CH_(4))emissions from ruminants when added to the diets of beef and dairy cattle.Red seaweeds including Asparagopsis spp.are rich in crude protein and halogenated compounds compared to brown and green seaweeds.When halogenated-containing red seaweeds are used as the active ingredient in ruminant diets,bromoform concentration can be used as an indicator of antimethanogenic properties.Phlorotannin-containing brown seaweed has also the potential to decrease CH_(4) production.However,numerous studies examined the possible anti-methanogenic effects of marine seaweeds with inconsistent results.This work reviews existing data associated with seaweeds and in vitro and in vivo rumen fermentation,animal performance,and enteric CH4 emissions in ruminants.Increased understanding of the seaweed supplementation related to rumen fermentation and its effect on animal performance and CH_(4) emissions in ruminants may lead to novel strategies aimed at reducing greenhouse gas emissions while improving animal productivity.

6,6’-Bieckol induces apoptosis and suppresses TGF-β-induced epithelial-mesenchymal transition in non-small lung cancer cells

Objective:In this study,the aim was to investigate the inhibitory effect of 6,6’-bieckol on the migration and epithelial-mesenchymal transition(EMT)of non-small cell lung cancer(NSCLC)cells,and explore its potential molecular mechanisms.Methods:Cell migration was measured using a CCK8,wound healing,and transwell migration assay.Apoptosis was determined using an Annexin V/propidium iodide staining.Western blotting and immunofluorescence were used to examine the expression level of apoptosis-related proteins and EMT marker proteins.Results:The results showed that 6,6’-bieckol inhibited migration and induced apoptosis of NSCLC cells.Furthermore,6,6’-bieckol had significantly up-regulated the E-cadherin and down-regulated Snail1 and Twist1 transcriptional levels.6,6’-Bieckol might inhibit TGF-β-induced EMT by down-regulating Snail1 and Twist1 and up-regulating E-cadherin in lung cancer cells.Conclusion:It is suggested that 6,6’-bieckol has the potential to be developed as a therapeutic candidate for lung cancer.