Rumen microbial degradation of bromoform from red seaweed(Asparagopsis taxiformis)and the impact on rumen fermentation and methanogenic archaea

Background The red macroalgae Asparagopsis is an effective methanogenesis inhibitor due to the presence of halogenated methane(CH_(4))analogues,primarily bromoform(CHBr_(3)).This study aimed to investigate the degradation process of CHBr3 from A taxiformis in the rumen and whether this process is diet-dependent.An in vitro batch culture system was used according to a 2×2 factorial design,assessing two A taxiformis inclusion rates[0(CTL)and 2%DM diet(AT)]and two diets[high-concentrate(HC)and high-forage diet(HF)].Incubations lasted for 72 h and samples of headspace and fermentation liquid were taken at 0,0.5,1,3,6,8,12,16,24,48 and 72 h to assess the pattern of degradation of CHBr_(3) into dibromomethane(CH_(2)Br_(2))and fermentation parameters.Additionally,an in vitro experiment with pure cultures of seven methanogens strains(Methanobrevibacter smithii,Methanobrevibacter ruminantium,Methanosphaera stadtmanae,Methanosarcina barkeri,Methanobrevibacter millerae,Methanorhermobacter wolfei and Methanobacterium mobile)was conducted to test the effects of increasing concentrations of CHBr3(0.4,2,10and 50μmol/L).Results The addition of AT significantly decreased CH_(4) production(P=0.002)and the acetate:propionate ratio(P=0.003)during a 72-h incubation.The concentrations of CHBr_(3) showed a rapid decrease with nearly 90%degraded within the first 3 h of incubation.On the contrary,CH_(2)Br_(2) concentration quickly increased during the first 6 h and then gradually decreased towards the end of the incubation.Neither CHBr_(3) degradation nor CH_(2)Br_(2) synthesis were affected by the type of diet used as substrate,suggesting that the fermentation rate is not a driving factor involved in CHBr_(3)degradation.The in vitro culture of methanogens showed a dose-response effect of CHBr3 by inhibiting the growth of M.smithii,M.ruminantium,M.stadtmanae,M.barkeri,M.millerae,M.wolfei,and M.mobile.Conclusions The present work demonstrated that CHBr_(3) from A.taxiformis is quickly degraded to CH_(2)Br_(2)in the rumen and that the fermentation rate promoted by different diets is not a driving factor involved in CHBr_(3)degradation.

Advances in Biomedical Applications of Hydrogels from Seaweed-Derived Sulfated Polysaccharides:Carrageenan,Fucoidan,and Ulvan

Sulfated polysaccharides extracted from seaweeds,including Carrageenan,Fucoidan and Ulvan,are crucial bioactive compounds known for their diverse beneficial properties,such as anti-inflammatory,antitumor,immunomodulatory,antiviral,and anticoagulant effects.These polysaccharides form hydrogels hold immense promise in biomedicine,particularly in tissue engineering,drug delivery systems and wound healing.This review comprehensively explores the sources and structural characteristics of the three important sulfated polysaccharides extracted from different algae species.It elucidates the gelation mechanisms of these polysaccharides into hydrogels.Furthermore,the biomedical applications of these three sulfated polysaccharide hydrogels in wound healing,drug delivery,and tissue engineering are discussed,highlighting their potential in the biomedicine.

Seaweed Fiber Fabricated with Agar Alkali-Free Extracted from Gracilaria lemaneiformis

The sulfate groups in agar structure played a good role in the formation of fiber.However,commercially available agar is usually extracted from red algae by alkali treatment to decrease the content of sulfate group for the purpose of high gel strength.In this paper,an alkali-free method of agar extraction from Gracilaria lemaneiformis was proposed for the wet-spinning purpose.This method is environmentally friendly,reduces the extraction steps,saves energy,and reduces the production cost of agar fiber.The improved agar preparation process not only has higher agar yield,but also has higher molecular weight and sulfate group content,which is beneficial to the preparation and forming of fiber and makes the fiber have higher mechanical strength and elongation.Therefore,this extraction technology has broad application prospect in the textile field.

Effects of Seaweed Bio-organic Fertilizer on Growth and Yield of Winter Wheat

[Objective] This study aimed to investigate the effects of seaweed bio-or- ganic fertilizer on yield and quality of winter wheat. [Method] Seaweed bio-organic fertilizer was applied to leaves of winter wheat according to the dose of 45 kg/hm^2 from jointing stage to maturing stage, and plant height, dry matter accumulation, flag leaf photosynthetic characteristics and grain yield of winter wheat were investigated. [Result] Foliar spraying of seaweed bio-organic fertilizer showed little effect on plant height of winter wheat, thickened stems, promoted dry matter accumulation, in- creased flag leaf photosynthetic rate by 3.16%, and increased yield of winter wheat by 6.85%. [Conclusion] Foliar spraying of seaweed bio-organic fertilizer promoted the intelligent growth, thickened the stems, improved the lodging resistance, significantly increased the panicle weight per plant, and increased the bulk density of winter wheat, as well as improving the physical quality of wheat grain. In addition, foliar spraying of seaweed bio-organic fertilizer promoted the synthesis of chlorophyll and mitigated the decomposition of chlorophyll in winter wheat. Under the background of fertilizer-pesticide double reduction, the test results and data of this study can be promoted in the wheat-growing areas of Shandong Province and even whole China.

Effects of Liquid Seaweed Bio-organic Fertilizer on Seed Germination and Seedling Growth of Vegetables

[Objective] This study aimed to investigate the effects of liquid seaweed bio-organic fertilizer on seed germination and seedling growth of different vegetables. [Method] Serial dilution concentrations of liquid seaweed bio-organic fertilizer were prepared for seed soaking and pot incubation of cucumber, tomato and chili, to ob- serve the effects of liquid seaweed bio-organic fertilizer on seed germination and seedling growth of vegetables. [Result] Compared with the control, germination rate of cucumber and tomato seeds applied with 600-fold liquid seaweed bio-organic fer- tilizer varied significantly; germination rate of chili seeds applied with 400-fold liquid seaweed bio-organic fertilizer varied significantly; germination energy and germination index of chili seeds applied with different dilution concentrations of liquid seaweed bio-organic fertilizer presented no significant differences. In addition, 200-fold and 400-fold liquid seaweed bio-organic fertilizer significantly improved the root length, plant height, plant fresh weight, plant dry weight, chlorophyll content and leaf area of cucumber, tomato and chili seedlings; after treated with 600-fold liquid seaweed bio-organic fertilizer, root length, chlorophyll content and leaf area of cucumber seedlings varied significantly compared with the control, but no significant differences were observed in plant height, plant fresh weight and plant dry weight; after treated with 600-fold liquid seaweed bio-organic fertilizer, root length, chlorophyll content, plant height, plant fresh weight and plant dry weight of chili and tomato varied sig- nificantly compared with the control, but no significant differences were observed in leaf area. [Conclusion] Soaking vegetable seeds with liquid seaweed bio-organic fer- tilizer can significantly improve seed generation rate and seedling growth.

Some Mechanism Seaweeds Employ to Cope with Salinity Stress in the Harsh Euhaline Oceanic Environment

In order to prevent salt damage because seaweed enzymes can only operate under hypohaline conditions (salinity ≈ 6‰ - 12‰) but also obtain for photosynthesis an in the aquatic environment—due to a 10,000 fold strongly limited carbon source—seaweeds developed several mechanisms to meet these vital demands for survival in the harsh euhaline oceanic environment (salinity range: 32‰ - 35‰), we tested this range of adaptation mechanisms in the euhaline oceanic collected water in combination with the seaweed moisture. We obtained under laboratory conditions at 10 bar mechanical pressure for four seaweed species: Ulva lactuca, Caulerpa sertularioides, Caulerpa cf. brachypus (all three green) and Undaria pinnatifidia (brown). Oceanic water and seaweed moisture were measured for salinity, pH and by Inductively Coupled Plasma Spectroscopy (ICP)-techniques concentrations for macro-elements: (Ca, Fe, K, Mg, Mn, Na, P, & S), micro-elements ≈ [HM]: (Al, As, Cd, Co, Cr, Cu, Mo, Ni, Pb & Zn) and nutrients (N-total & P-total). The [seawater compound X]/[oceanic compound X] ration is a reflection of an inward (uptake) or excretion mechanism over the seaweed cellular membrane which is operative. Our observations gave a clear dispersion to salinity stress with on one hand the green seaweed U. lactuca and on the other the brown seaweed U. pinnatifidia. Both Caulerpa spp. took in an intermediate position. Observed in compensatory responses to salinity stress was ranging Ulva sp. both Caulerpa spp.-Undaria sp.: 1) amount pressed seaweed moisture: [ml/g Fresh Weight];2) salinity: (in ‰);3) Na+ storage vacuole volume;4) Na+:K+ ratio (reflection of K+ as osmolyticum);5) ∑[HM] (as osmolyticum);6) pH (seaweed moisture);7) Nutrients (N & P);8) availability of essential metal elements for plants (Cu, Fe, Zn, Mn, Mo, Ni);9) transport direction of micro- and macro-elements. Finally, the role of brown vs. green seaweeds in the evolutionary eukaryotic tree of life in relation to the ability of the brown seaweeds to produce their own osmolyticum will be discussed.

The Application of the Seaweeds in Neutralizing the “Ocean Acidification” as a Long-Term Multifaceted Challenge

The global effects of ocean acidification (OA) on coral reefs are of growing concern. Carbon dioxide released into the atmosphere as a result of burning fossil fuels, not only has an effect on “global warming”, but also on OA which is called the “other CO2 problem”. OA combined with high ocean temperatures has resulted in a massive bleaching of coral reefs in the Indian Ocean and throughout Southeast Asia over the past decade, which is ultimately lethal. Here we discuss the option if innovative seaweed bio-technology—the Ulva lactuca bioreactor option, with its H+ ion-absorbing capacity and its huge green biomass production of around 50 MT/ha/year—which can stabilize our “World Ocean” and our global coral reefs. From our calculations, we came to the conclusion that an area covered with “Ulva lactuca bioreactors” with a production capacity of 250 × 1016 ha of seaweed per year is needed to remove all H+ ions that cause OA in our “World Ocean” since the beginning of the “Industrial Revolution” ≈ 250 years ago. This is a daunting task and therefore we have opted for a multi-faceted approach including variability in seaweed species, avoidance of eutrophication & heavy-metal accumulation, prevention of global warming by more green-biomass production and a better estimation of the huge Kelp seaweed populations in temperate zones in order to protect our coral reefs for the short term.

Research on Aesthetic Implication of Seaweed Residence in Jiaodong

Starting from the analysis on aesthetic implication of seaweed residence in Jiaodong,field study was conducted.With existing residence as the case study,the pervasive and simple ecological value,practical significance and sustainability of traditional residences were explored,so as to provide a theoretical basis and practical reference for new residential design of ecological value.

Antimicrobial potential of selected brown seaweeds from Vedalai coastal waters,Gulf of Mannar

Objective:To evaluate the antimicrobial activity of Turbinaria conoides(T.conoides).Padina gymnospora(P.gymnospora) and Sargassum tenerrimum against human bacterial and fungal pathogens.Methods:The antimicrobial activities of the extracts against various organisms were tested by using disc diffusion method.Results:The methanol extract showed the better result than the other extracts.Whereas,the strong antibacterial inhibition was noted in methanol extracts of P.gymnospora against Bacillus subtilus(26.33±1.86) and the mild inhibition of ethanol extracts from T.conoides against Klebsiella pneumoniae(2.33±0.51).Acetone extraction of P. gymnospora had strong antifungal inhibition against Cryptococcus neoformans(23.00±1.78), and acetone extract of T.conoides had mild inhibition against Aspergillus niger(3.00±0.89). Conclusions:The seven different solvent extracts of seaweeds used in the present study have shown significant bacterial action.Further,a detailed study on the principle compound in the seaweeds which is responsible for antimicrobial activity is still needed and it can be achieved by using advanced separation techniques.

Seaweed glue as a novel polymer depressant for the selective separation of chalcopyrite and galena

The use of seaweed glue(SEG)as a novel polymer depressant for the separation of chalcopyrite from galena with butyl xanthate(BX)as a collector was studied through microflotation experiments.Contact angle,adsorption,dynamic potential,and infrared spectral analyses were conducted to clarify the mechanism underlying the action of SEG on minerals.The results of microflotation experiments indicated that chalcopyrite could be selectively separated from galena by using a SEG depressant concentration of 15 mg·L^-1,BX concentration of 10 mg·L^-1,and methyl isobutyl carbinol concentration of 8.5 mg·L^-1 at pH 8.0.A Cu concentrate with a grading of 23.68wt% was obtained at a recovery rate of 81.52% from mixed minerals with 8.29wt% Cu content.Contact angle analysis showed that the effect of SEG on the wettability of galena was stronger than that on the wettability of chalcopyrite.Adsorption,zeta potential,and FT-IR spectral analyses revealed that SEG and BX were coadsorbed on the surfaces of galena.SEG depressed galena by covering xanthate ions in the functional groups of-COO and mainly underwent weak physisorption on chalcopyrite.These mechanisms account for the ability of SEG to depress galena effectively while enabling chalcopyrite flotation.

Degradation of Extraction from Seaweed and Its Complex with Rare Earths for Organophosphorous Pesticides

On the basis of several experiments carried out in China, it was proved that both seaweed liquid fertilizer and rare earth （RE） could promote the growth of crops and increase their yield. The effects of extraction from seaweed and its complex with RE on the degradation of organophosphorous pesticides and the yield of vegetables were investigated. The resuits showed that the extract and its complex with RE could degrade organophosphorous pesticides in neutral solvent. The residues of the pesticides treated by the extract decreased by 96.88 %, 52.30%, 49.52%, and 22.88 %, respectively, for chlorpyrifos, dichlorvos, omethoate, and dimethoate, and those by the complex decreased by 95.99%, 54.23%, 48.79%, and 25.66%, respectively, when compared with the control. The residues of chlorpyrifos and dimethoate in spinach sprayed with the complex were decreased by 90.64% and 76.56%, respectively, compared with those in spinach from control plots when the interval between spraying and sampling was 8 d. The fresh weight of brassica chinensis and cabbage increased by 28.62% and 18.72%, and their dry weight increased by 44.49% and 14.74%, respectively, compared with those of the controls. The chlorpyrifos and dimethoate residues in brasscia chinese were decreased by 36.36% and 50.00%, respectively, and their rate of decrease in cabbage was 40.00% and 75.00%, respectively, on 5th day after spraying with the complex, when compared with those in the vegetable from control. These results suggest that this complex can increase the agricultural productivity and reduce the use of pesticide residues in the production of vegetables.

In vitro antioxidant activities of selected seaweeds from Southeast coast of India

Objective:In vitro antioxidant activities of three selected Indian seaweeds viz.,Halimeda tuna(H.tuna),Turbinaria conoides(T.conoides) and Gracilaria foliifera(G.foliifera) were evaluated.Methods:Total antioxidant activity,total phenolic content,and reducing power of crude methanol and diethyl ether extracts were determined.Results:Total phenolic content and total antioxidant activity were higher(1.231±0.173 mg GAE/g,1.675±0.361 mg GAE/g) in T.conoides respectively.Reducing power of crude methanol extract increased with concentrations of the extract.The Fourier transform-infra red spectrum analysis revealed the presence of polyphenolic signals.The seaweed extracts displayed moderate antioxidant activity compared to gallic acid standard.Conclusions:The seaweeds could be considered for curing diseases from oxidative deteriorations.

STUDIES ON FREE RADICAL SCAVENGING ACTIVITY IN CHINESE SEAWEEDS PART I. SCREENING RESULTS

Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.

Development of a Seaweed Species-Selection Index for Successful Culture in a Seaweed-Based Integrated Aquaculture System

Integrated multi-trophic aquaculture (IMTA) has been proposed as a concept that combines the cultivation of fed aquaculture species (e.g., finfish/shrimp) with extractive aquaculture species (e.g., shellfish/seaweed). In seaweed-based integrated aquaculture, seaweeds have the capacity to reduce the environmental impact of nitrogen-rich effluents on coastal ecosystems. Thus, selection of optimal species for such aquaculture is of great importance. The present study aimed to develop a seaweed species-selection index for selecting suitable species in seaweed-based integrated aquaculture system. The index was synthesized using available literature-based information, reference data, and physiological seaweed experiments to identify and prioritize the desired species. Undaria pinnatifida, Porphyra yezoensis and Ulva compressa scored the highest according to a seaweed-based integrated aquaculture suitability index (SASI). Seaweed species with the highest scores were adjudged to fit the integrated aquaculture systems. Despite the application of this model limited by local aquaculture environment, it is considered to be a useful tool for selecting seaweed species in IMTA.

Evaluation of Antitumor,Immunomodulatory and Free Radical Scavenging Effects of A New Herbal Prescription Seaweed Complex Preparation

Seaweed Complex Preparation （SCP） is a clinical traditional Chinese medicine preparation which is composed of seven traditional Chinese herbs, and it has been used for treatment of lung cancer, liver cancer and digestive cancer. However, little infor- mation is available about the pharmacodynamic basis. The antitumor, immunomodulatory and free radical scavenging effects of SCP were evaluated in this study. Transplanted tumor in vivo method was used to determine the antitumor effect. The effects on spleno- cyte proliferation and phagocytosis of macrophages in tumor-bearing mice were measured by the MTT method and the phagocytizing cock red blood cell （CRBC） method respectively. The scavenging activities of SCP on DPPH and hydroxyl radicals in vitro were investigated. It was found that the medium-dose and high-dose of SCP could significantly inhibit the growth of transplanted hepatic tumor of murine hepatocarcinoma cell line H22, and promote proliferation of splenocytes and phagocytosis of macrophages. SCP possessed noticeable scavenging activities on DPPH and hydroxyl radicals. The antiturnor effects of SCP might be achieved by im- proving immune system and scavenging free radicals, which is in accordance with the viewpoint of traditional Chinese medicine in promoting the body resistance and eliminating pathogenic factors for cancer treatment.

Edible seaweed-derived constituents: an undisclosed source of neuroprotective compounds

Edible marine algae,or seaweeds,are a rich source of several bioactive compounds including phytosterols,carotenoids,and polysaccharides.Over the last decades,seaweed-derived constituents turned out to not only reside in the systemic circulation,but are able to cross the blood-brain barrier to exert neuro-active functions both in homeostatic and pathological conditions.Therefore,seaweed-derived constituents have gained increasing interest for their neuro-immunomodulatory and neuroprotective properties,rendering them interesting candidates for the management of several neurodegenerative disorders.In particular seaweed-derived phytosterols gained interest for the treatment of neurodegenerative disorders as they potentiate neuroplasticity,enhance phagocytic clearance of neurotoxic peptides and have anti-inflammatory properties.Though,the anti-inflammatory and anti-oxidative properties of other constituents including carotenoids,phenols and polysaccharides have recently gained more interest.In this review,we provide an overview of a selection of the described neuro-active properties of seaweed-derived constituents with a focus on phytosterols.

Evaluation of phenolic contents and antioxidant activities of brown seaweeds belonging to Turbinaria spp.(Phaeophyta,Sargassaceae) collected from Gulf of Mannar

Objective:To evaluate the antioxidant activities and total phenolic contents of brown seaweeds belonging to Turbinaria spp.[Turbinaria conoides(T.conoides)and Turbinaria ornata(T.ornata)collected from Gulf of Mannar of southeastern coast of India in various in vitro systems.Methods:The antioxidant activity was evaluated using different in vitro systems,viz.,I,I-diphenyl-2-picrylhydrazyl(DPPH),2,2'-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid diammonium salt(ABTS),H_20_2/H0 radical scavenging,Fe^(2+)ion chelating ability,and reducing potential.Folin-Ciocalteu method was used to determine the total phenolic content of the extracts,and the results were expressed as mg of gallic acid equivalents(GE)/g of the seaweed extracts.Thiobarbituric acid-reactive substances assay was employed to assess the ability of the seaweed extracts to inhibit lipid oxidation.Results:Ethyl acetate(EtOAc)fraction of T.conoides registered significantly higher phenolic content(105.97 mg GE/g)than that of T.ornata(69.63 mg GE/g).Significantly higher antioxidant potential as determined by DPPH(64.14%)radical scavenging activity was registered in EtOAc fraction of T.ornata.A higher ABTS(?)radical scavenging(IC_(50)3.16μg/mL),Fe^(2+)chelating(IC_(50)0.46 mg/mL),H_2O_2 scavenging(IC_(50)4.25 mg/mL),lipid peroxidation inhibitory(TBARS,IC_(50)0.21 mg/mL),and reducing abilities(IC_(50)52.67 mg/mL)(P<0.05)were realized in EtOAc fraction of T.ornata than other fractions.Conclusions:This study indicated the potential use of T.conoides and T.ornata as candidate species to be used as food supplements/functional foods to increase shelf-life of food items for human consumption,and nutraceuticals to deter deleterious free radical-induced life-threatening diseases.

Antidiabetic and antioxidant activities of red seaweed Laurencia dendroidea

Objective:To investigate antidiabetic and antioxidant activities of the extract and fractions from Vietnamese red seaweed Laurencia dendroidea.Methods:The seaweed Laurencia dendroidea was extracted by using microwave-assisted extraction method in 80%methanol.The seaweed extract was then fractionated using different solvents(n-hexane,chloroform,ethyl acetate,butanol and water).These obtained fractions were evaluated forα-glucosidase inhibitory and antioxidant activities.Antioxidant activities were tested using DPPH,nitric oxide radical scavenging and metal chelating assays.The enzyme inhibition mode was determined using Lineweaver-Burk plot.For acidic and thermal stabilities,the ethyl acetate fraction was treated at pH 2.0 and 100℃,respectively.The residual inhibitory activity of the fraction was calculated based on the initial inhibitory activity.For in vivo antidiabetic activity,mice were divided into four groups,including normal control,diabetic control,diabetic mice treated with ethyl acetate fraction and diabetic mice treated with gliclazide.Blood glucose level of treated mice during acute and prolonged treatments was measured.To evaluate the toxicity of the ethyl acetate fraction,the body weight changes and activities of liver function enzymes(aspartate transaminase,alanine transaminase and gammaglutamyl transferase)were carried out.Results:The extract of Laurencia dendroidea showed strongα-glucosidase inhibitory and DPPH radical scavenging activities.Methanolic concentrations affected bothα-glucosidase inhibitory and antioxidant activities.A 80%aqueous methanol was the suitable solvent for extraction of enzyme inhibitors and antioxidants.Among solvent fractions,ethyl acetate fraction had the highest inhibitory activities againstα-glucosidase with a mixed type of inhibition and the strongest antioxidant activities,and was stable under acidic and thermal conditions.The ethyl acetate fraction treated diabetic mice significantly reduced blood glucose level compared with the diabetic control group(13.16 mmol/L vs.22.75 mmol/L after 3 hours of treatment).Oral administration of ethyl acetate fraction did not exhibit toxicity at a dose of 100 mg/kg body weight as determined by body weight changes and liver biochemical parameters.Conclusions:Laurencia dendroidea could be a potential source for production of antidiabetic and antioxidative agents.

In vitro prebiotic effects of seaweed polysaccharides

Although prebiotic activities of alginate and agar oligosaccharides isolated from seaweeds have been reported, it remains unknown whether seaweed polysaccharides have prebiotic activity. In this study, we isolated polysaccharides from four species of seaweeds, such as Grateloupia fi licina(GFP), Eucheuma spinosum(ESP), Ulva pertusa(UPP), and A scophyllum nodosum(ANP), and characterized their structures and prebiotic ef fects in vitro. The results showed that these polysaccharides were dif ferent in total sugar and sulfate contents as well as monosaccharide composition. GFP and ESP significantly promoted bifi dobacterium proliferation and 0.1% ESP and 0.4% GFP resulted in the highest proliferation rates of beneficial bacteria, whereas UPP and ANP inhibited the growth of beneficial bacteria at all tested concentrations(0.1%–0.5%). The different behaviors of the four seaweed-originated polysaccharides might be refl ected by differences in monosaccharide composition and structure. Therefore, polysaccharides isolated from GFP and ESP could be utilized as prebiotics. However, more studies must be carried out in vivo.

Extraction and Antioxidant Functions of Polysaccharides from Seaweed

Dried seaweed powder was used as the raw material to extract polysaccharides by ethanol precipitation after water bath. Extraction temperature, extrac- tion duration, solution pH and solid to liquid ratio were selected as technical parameters which required to be optimized. With the extraction rate of seaweed poly- saccharides as an index, single-factor experiment and orthogonal experiment were carried out to determine the optimal extraction technique. Seaweed polysaceharides were extracted with the optimal technical parameters to analyze the biological activities. Savage method was used to process seaweed polysaceharide extract. In vitro biological activities of preliminarily purified seaweed polysaeeharides were investigated successively, including reducing ability, antioxidant ability and antibacterial activity. The results showed that there was a positive correlation between polysaccharide concentration and its reducing ability, antioxidant ability and antibacterial activity. Furthermore, there was also a correlation among the reducing ability, antioxidant ability and antibacterial activity of seaweed polysaecharides; the relation- ship between each two of these three indicators was similar to positive linear correlation.