Study On Antioxidant Biological Activity Of Scytosiphon Lomentaria

Scytosiphon lomentaria（Lyngbye.）Link, a large economic seaweed, is a precioussea-vegetable eaten by coastal residents all the time because of its delicious taste andhigh nutritional value. After years of systematic researches, the life history, thetechniques about sporophyte preservation, industrial breeding and artificial cultivationof S. lomentaria increasingly perfect. The cultivating scale of S. lomentaria willfurther expand while the yield will increase progressively in the future. In aspect ofthe research of bioactivity is necessary to keep pace with the marine aquaculture.However, the research of natural bioactivator of S. lomentaria is still in an initial stage.There are still many studies to be carried out. Especially the antioxidant activities of S.lomentaria require a fairly systematic evaluation.Plenty of studies have revealed that most of the economic seaweeds, containing alot of biologically active compounds, possess strong antioxidant activity. To evaluatethe antioxidant activities of S. lomentaria comprehensively, five assays wereperformed by determining total polyphenols contents, investigating the free radicalscavenging activity, reducing power and the inhibitory effect on lipid peroxidation,which can provide fundamental data for the research of bioactivities and exploring theapplication value of S. lomentaria. In the future, the research outcomes can be appliedto exploit natural food antioxidants, health care for human food and disease treatmentdrugs, which will certainly bring us great economic and social value, moreover,conducive to health and the improvement of people’s living standard preferably. Forthis purpose, we have done some research on antioxidant biological activity of S.lomentaria as follows:Firstly, one type of bioactive compounds which was called polyphenols extractedfrom S. lomentaria by ethanol extraction process for optimizing the extractionconditions through the orthogonal experiment on the basis of single factor experiments. Folin-Ciocalteu Colorimetry was applied for determining the totalpolyphenols content of S. lomentaria quantitatively. The credibility of the method wasevaluated by stability test, precision test, repeatability test and the standard additionrecovery test. The optimum extraction conditions were obtained as follows:50%ofalcohol concentration,65℃of extraction temperature,120min of extraction time,1:25(g·ml^-1)of extraction ratio of solid to liquid and2times of extraction. According tothe optimal conditions, results showed that the average total polyphenols content (Theresults were expressed as mg of gallic acid equivalents（GAE）·g^-1dry weight（DW）.)ofthe S. lomentaria was6.006±0.023mg（GAE）·g^-1（DW） with corresponding RSD of0.94%. This method was relatively convenient with higher accuracy and credibility.Secondly, in vitro antioxidative activities of water extracts and alcohol extractswith three concentration from S. lomentaria were evaluated systematically using thechemical approaches in terms of hydroxyl radical scavenging activity, superoxideanion radical scavenging activity,1,1-diphenyl-2-picrylhydrazyl （DPPH） radicalscavenging activity, reducing power and suppression activity of lipid peroxidation.The results represented that the crude extracts from S. lomentaria exhibited strongreducing power and scavenging activity on hydroxyl and DPPH radicals, and theactivity increased with increment of concentration of the extracts, whereas the effectof ethanol extracts from S. lomentaria was superior to water extracts on scavengingsuperoxide anion radical ability and inhibitory activity of lipid peroxidation, evenpromoting lipid peroxidation and generation of superoxide anions.Thirdly, the antioxidant activities of S. lomentaria were compared with otherseaweeds as well in terms of total phenolics content, free radical scavenging activity,reducing power, and inhibitory effect on lipid peroxidation.The extracts of differentseaweeds varied remarkably in their antioxidant activities.The result demonstratedthat the extracts of S. lomentaria exhibited more prominent effects in total phenolicscontent, reducing power, hydroxyl radical and superoxide anion radical scavengingactivity among the seaweeds. However, when it came to lipid peroxidant inhibitorycapacity, the effect of Porphyra sp., Laminaria japonica Aresch and Undariapinnatifida （Harv.）Suringar were much better than S. lomentaria. Considering that single assay can’t reflect the antioxidant activities of S.lomentaria completely. This study performed one comprehensive evaluation byvarious assays. Based on the above results, we can draw the conclusion that theextracts of S. lomentaria have significant advantages in total phenolics content,reducing power and the capacity to scavenge the reactive oxygen free radicals, whichis attributed to its better antioxidant biological activities. Therefore S. lomentariabeing one of valuable seaweeds should be cultivated and utilized vigorously.