Studies On Chemical Constituents And Bioactivities Of Scytosiphon Lomentaria

Scytosiphon lomentaria is widely distributed in the north and south waters ofChina, which is often intaked as a kind of valuable marine vegetable by thecoastal residents. S. lomentaria is classified as medicinal seaweed by ChineseMateria Medicaμ, which has anti-tumor, recovering of cardiovascular disease, clearingheat and detoxification, and other effects. Because of its good taste and medicinalactivity, its limited production can not satisfy the demand. In recent years, itscultiviation technology has been successfully established. Thus itsproduction will increase dramatically with the development and widespread of itscultivation techniques. In order to form a complete industrial chain, the researches ofits nutritional components, medicinal value and bioactive substances are urgentlyneeded.This paper deals with the analysis of basic components, alginate, fucoidanand polyphenol contents of S. lomentaria, the study of the anti-diabetic properties,whitening and moisturizing abilities and antioxidant activities of enzymatic extractsfrom S. lomentaria, so as to provid a theory basis for the development ofnatural active substances of S. lomentaria.1. The chemical compositions of S. lomentaria were moisture of8.51%, ash of30.63%, crude protein of19.71%, crude fat of5.48%, alginate of16.30%, solublefiber of7.35%, insoluble fiber of21.58%. The compositions of insoluble fiber werecellulose of8.50%, hemicellulose of8.66%and lignin of4.42%.The effects of water extraction, acid extraction and composite enzyme extractionon the efficiency and chemical compositions of fucoidan were studied. The resultsshowed that the yield of water extraction was the highest of7.27%. Thepolysaccharide content of crude fucoidan by acid extraction was the highest of56.77%. The fucoidan content of crude fucoidan by Celluclast extraction was thehighest of10.61%. The concents of sulfate groups in the crude fucoidan were20.63% by water extraction,20.72%by acid extraction,18.90%by Viscozyme extraction, and18.40%by Celluclast extraction, respectively.The effects of phenolic compounds by hot-water extraction, hot-water extractionfollowed by ethanol precipitation, ethanol extraction and water extraction followed byethanol precipitation were studied. The results showed that the highest amount ofphenolic compounds was obtained by the hot-water extract. The total phenols contentswere hot-water extraction of4.1mg catechin equivalents (CatE)/g dry sample,hot-water extraction followed by ethanol precipitation of2.8mg/g, ethanol extractionof2.5mg/g, and water extraction followed by ethanol precipitation of1.8mg/g.2. One-factor-at-a-time experiment was adopted to optimize the bleachingcondition of alginates from S. lomentsrius. The results indicated that the optimalbleaching condition was as follows. The sodium hypochlorite solution of4%with pHof10.5was added to the alginate solution with a ratio of3:600, and heated at35°Cfor40min. Under to the optimal bleaching conditions, the extracting rate of alginatewas11.57%and the purity was84.66%.The rheological characteristics of sodium alginate solution were studied. Thesodium alginate solution from S. lomentsrius behaved as pseudoplastic fluid. Itsviscosity decreased with increasing of shearing rate or temperature. The viscosity ofthe sodium alginate solution also was influenced by different addition level of salt orsucrose. The viscosity decreased with different amount of sodium chloride, evendecreased dramatically when the addition quantity was larger. A small amountof sucrose increased of the alginate viscosity, but the increase slowed down with theconcentration increasing of sucrose. On the contrary, the alginate viscosity decreasedwhen the sucrose concentration was20%. The sodium alginate solution hadthixotropism，which showed a bigger thixotropic loop with the higher concentration.The sodium alginate solution from S. lomentsrius possessed viscoelasticity, whichprimarily behaved viscocity in the low frequency area system and elasticity in thehigher one.3. The effects of enzymatic extracts from S. lomentaria against-amylase and-glucosidase were stuied. Alcalase extraction at6mg/mL showed an excellent inhibitory activity against-amylase (77.10%, IC50=0.36), and the activity wasdose-dependent. The inhibition rate of Celluclast, Viscozyme and water extracts were72.59%,64.51%,55.47%at6mg/mL, and their IC50values were0.83,1.21,1.52mg/mL, respectively. All the extracts displayed a considerable inhibitory activityagainst-glucosidase in a lower concentration. The IC50values of Alcalase, Celluclast,Viscozyme and water extracts were0.58、1.09、0.27、0.20mg/mL, respectively.The hpyerglycemic activities of enzymatic extracts from S. lomentaria instreptozotocin-induced diabetic mice were studied. The Alcalase assistant extraction(AAE) supplement groups showed a decrease in the fasting-blood glucose level fromthe2ndweek and the fasting-blood glucose level was significantly lower than that ofdiabetic control group when treated for three weeks (p <0.05). The fasting-bloodglucose level of diabetic mice treated with AAE at amount of800mg/kg·bwdecreased by33.12%at3rdweek, showing the best hypoglycemic effect. Compared tothe control group, the plasma insulin level and the HOMAβ-cell were significantly (p<0.01) increased and the glycated serum protein (GSP) significantly (p <0.01)decreased in diabetic mice treated with two different concentrations of AAE (400,800mg/kg·bw). There was no significant differences between the plasma insulin levelsamong the above two groups and normal group (p>0.05).4. The effects of enzymatic extracts from S. lomentaria against tyrosinase werestudied. When L-tyrosine was used as the substrate, all the extracts demonstratedinhibitory effect on tyrosinase, and the inhibitory activity was dose-depended. Amongthe tested samples, Alcalase assistant extract (AAE) showed the highest inhibitoryeffect on tyrosinase activity of37.76%. When DOPA was used as a substrate, theresults were similar to that of using L-tyrosine as the substrate.The moisture absorption and retention abilities of enzymatic extracts from S.lomentaria were studied. All tested samples had observably ability to attract moisture,which were even stronger than that of the positive control of glycerol. Besides WE,most extracts had higher moisture-retention ability than those of glycerol. AAE notonly had good moisture-absorption ability under the low relative humidity (43%), butalso the highest moisture-retention ability when the wet sample was putting in the silica gel desiccator.The antioxidant activities of enzymatic extracts from S. lomentaria were stuiedin vitro. The enzymatic extracts exhibited good scavenging activities on free radicals,especially in DPPH radical scavenging assay. All extracts except AAE had superior orsimilar scavenging activity on DPPH radical compared with the commercialantioxidant of BHT.