Studies On The Use Of Bioactive Substances From Typical Marine Macroalgae In Zhejiang Coast

Marine macroalgae are widely distributed on the coasts of China,with a wide variety of species and abundant resources.They play an important role in marine ecosystems and environment.Many secondary metabolites from marine macroalgae showed obvious biological activities in anti-tumor,antibacterial and anti-oxidation.In recent years,bioactive substances from marine macroalgae were widely applied in the immune and disease prevention of aquatic animals.The studies on the use of bioactive substances from marine macroalgae are helpful for discovering new bioactive substances,understanding the mechanism of bioactive substances from marine macroalgae,and increasing the utilization of marine macroalgae resources.The coastal reefs in Zhejiang Province are rich in resources,and therefore,marine macroalgae resources are also extremely rich.Take the typical marine macroalgae in Zhejiang coast as the research object and collect several marine macroalgae at four sampling points along the coast of Zhejiang Province.After classification and identification,33 species of marine macroalgae were determined as experimental samples;5 species of solvents were used to extract bioactive substances,and then used to screen for antibacterial activity,WSSV activity and antioxidant activity;the composition and biological activity of marine macroalgae bioactive substances were analyzed,and the relationship between algae activity and chemical composition was further elucidated.The main findings are as follows:1.General situation of research on bioactive substances from marine macroalgae.The main bioactivities and mechanisms of anti-tumor,anti-virus,anti-bacterial and anti-oxidation were introduced.The bioactive substances and utilization of the typical marine macroalgae in Zhejiang coast were systematically described..2.Study on bioactive substances extraction and antibacterial activity of typical marine macroalgae in Zhejiang coast.(1)Collection,identification and morphological description of the macroalgae samples.The samples of macroalgae were collected at four sampling points along the coast of Zhejiang.The total of 33 species of macroalgae used for the experiment were identified,including 8 species of green macroalgae,18 species of red macroalgae,and 7 species of brown macroalgae.The marine macroalgae samples were washed and dried for subsequent experiments.(2)Study on the antibacterial activity of different extraction models.Five kinds of extraction solvents such as hexane,methylene chloride,acetone,85% methanol and 85% ethanol were used to extract bioactive substances.Antibacterial experiment used bioactive substances against Escherichia coli,Aeromonas hydrophila,Pseudomonas aeruginosa,Vibrio alginolyticus and Staphylococcus aureus.The experiment results showed that different extracting solvents had significant effects on the antibacterial activities of macroalgae extracts,and organic solvent extracts exhibited different degrees of antibacterial activity.At the same time,studies have shown that the antibacterial activity of macroalgae extracts is a result of several factors such as the extraction methods,the purity of the bioactive substances,and the target strain.Therefore,the choice of antibacterial active substance extraction solvent needs to be determined by the macroalgae species and the bacteria species.However,due to the good solubility of ethanol,which can dissolve hydrophilic active ingredients,but also can dissolve some lipophilic active ingredients,bioactive substances more diversified,and the cost is low,so this study tends to choose 85% ethanol as the extraction solvent.(3)Preparation of macroalgae ethanolic extracts and screening for their antibacterial activities.The marine macroalgae samples were extracted with 85% ethanol to obtain bioactive extracts.The bioactive extracts were used to conduct antibacterial experiments on the five tested strains.The results showed that 97% of the marine macroalgae samples showed antibacterial activity.Several species of maroalgae showed broad-spectrum antimicrobial activity,such as Chaetomorpha aerea,Polysiphonia urceolata,Symphyocladia latiuscula,Grateloupia carnosa,Grateloupia livida,Pachydictyon coriaceum,Pachydictyon coriaceum and Sargassum fusiforme.The extracts are more active against Staphylococcus aureus.These marine macroalgae with strong antibacterial activity have a certain potential for development,or they may become natural substitutes for antibiotics on the current market.3.Study on the influence on WSSV-infected Scylla Paramamosain by bioactive substances from typical marine macroalgae in Zhejiang coast.(1)Macroalgae extracts inhibited WSSV(white spot syndrome virus)infection.Six species of macroalgae were selected.The 85% ethanol extracts were used for the experiment.The macroalgae extracts solution was injected separately according to the body mass of experimental crabs.The concentration gradients of the extracts were 1 mg/kg,5 mg/kg,and 10 mg/kg.The cumulative mortality of macroalgae extracts against WSSV-infected crabs was observed and recorded.The results showed that the mortality of crabs infected with WSSV was very high,and all died in 204 h without interference.The extract of Sargassum fusiforme can significantly reduce the mortality of WSSV-infected crabs,while other extracts have no obvious effect.This experiment shows that bioactive substances had the potential to be developed as a drug against WSSV,which will provide a safer solution for the prevention and treatment of diseases in the aquatic industry.(2)Study on the effect of macroalgae extracts on the immune activity of the crabs,Scylla Paramamosain.After 24 h of WSSV infection,the hemolymph was collected for the analysis of total hemocyte count(THC),superoxide dismutase(SOD)activity and prophenoloxidase(PO)activity.Experiments showed that macroalgae extracts significantly increase the immune activity of the crabs,thereby effectively enhancing the body's defense against WSSV.Macroalgae extracts can be used as a good immune enhancer for aquatic animals.The immune parameters of the crabs were most obviously improved by the addition of Sargassum fusiforme,and the survival of the crabs infected with WSSV was obvious.4.Antioxidant activity of typical marine macroalgae in Zhejiang coast.(1)Analysis of total polyphenol content of macroalgae.The macroalgae polyphenols were extracted and assayed.The results showed that there were significant differences in the total polyphenols content among different seaweed samples.Among them,the content of polyphenols in the extracts such as Gracilaria lemaneiformis was high.Since polyphenols have a variety of significant biological activities,the macroalgae with high polyphenol content have the potential to be developed to natural antioxidants.(2)Study on the antioxidant activity of macroalgae extracts.Through the determination of the ability to scavenge free radicals of DPPH and ABTs,species with strong antioxidant activity were screened.At the same time,the differences in antioxidant activity,antioxidant capacity and polyphenol content of macroalgae extracts caused by different extraction methods were screened.The results showed that all the extracts from the samples showed antioxidant activities.Among them,the macroalgae such as Polysiphonia urceolata and Ishige okamurai had strong antioxidant activity,indicating that these marine macroalgae can be an important source of natural antioxidant compounds.The study also showed that the extraction solvent had a significant effect on the antioxidant activity of active extracts,indicating that the extraction of antioxidant active substances needs to consider the main components of different macroalgae spicies to select the extraction solvent.The result of TPC is significantly related to antioxidant activity,so TPC can be used as a criterion for the screening of the antioxidant activity of macroalgae to a certain extent.The study found that there is a correlation bwteen the antibacterial activity and ABTs free radical scavenging activity.5.Analysis of bioactive substances from typical marine macroalgae in Zhejiang coast(1)Analysis of macroalgae bioactive substances.Macroalgae had a variety of biological activities related to its contained polysaccharides,polyphenols,fatty acids and other active compounds and other components.The assay was performed and the activity of the material was analyzed by ABTs free radical scavenging assay.The results showed that the contents of soluble polysaccharides,pigments and other substances in macroalgae samples were significantly different.The content of soluble polysaccharides ranged from 6.07±0.80 mg/g to 89.81±2.29 mg/g.The pigment content of different seaweeds varied significantly,ranging from 1.78±0.06 mg/100 g to 186.33±7.06 mg/100 g.Overall,the pigment content of Chlorophyta was the highest,and the pigment content of Phalaenopsis was the lowest.The present study also showed that the macroalgae pigments had antioxidant effects,especially the ABTs radical scavenging activities of the pigment extracts of Ishige okamurai were the strongest,and other macroalgae pigments also showed some antioxidant activity.(2)Analysis of chemical composition of macroalgae with GC-MS.In order to study the relationship between macroalgae activities and their chemical composition,the volatilizable components were analyzed and identified by gas chromatography/mass spectrometry(GC-MS).The results showed that there were many bioactive components in macroalgae volatile compounds,and there were great differences in compounds contained in several macroalgae.In addition,antibacterial compounds such as ?-ionone,Benzaldehyde,and 1-octen-3-one have been found in the paper.