Study On The Sugar Components Of Root And Dynamic Change Of Total Flavonoids Of Leaves From Smallanthus Sonchifolius

Yacon(Smallanthus Sonchifolius) is dicotyledonous herbage from helianthus of the composite,which was originally cultivated in South America in the Andean highlands with altitude of 880-3500 m from Ecuador to the northwest of Argentina.Yacon is rich in active ingredients including polysaccharides,flavonoids,phenolic acids and essential oil,and also has comprehensive utilization value in edibility,medicine and environmental protection. Yacon has unique pharmacological activities,such as hypoglycemic effect,antibacterial activity,antioxidant effect and anti-inflammation effect which were close related to the polysaccharides and flavonoids in yacon.Thus,the sugar components of yacon roots durning storage as well as the extraction and dynamic change of total flavonoids from leaves of yacon were systematically studied.The main results were described as follows:1.Sugars in fruits of yacon were extracted by hot-water extraction method,and its composition and content was measured by HPLC.The results argued that the main components of sugar extracted from roots of yacon after introduction included fructose, glucose,sucrose,GF₂ and GF₃.Furthermore,the contents of GF₂ and GF₃ were reach to 31.52 mg/g,39.55 mg/g,respectively.2.The results of sugar components changes of yacon roots in different storage conditions indicated that fructo-oligosaccharide could easily decompose into fructose, glucose and sucrose during storage,whereas the degradation speed of fructo-oligosaccharide stored at 4℃was slower than that stored at room temperature.3.The main factors with effects on the extraction of total flavonoids of yacon leaves were ethanol concentration(A),microwave power(B),extraction time(C) and solid-to-liquid ratio(D).Based on the results of single-factor experiment,three better levels of these factors were chosen for L₉(3⁴) orthogonal test.The results showed that the order of the factors with effects on extraction rates of the total flavonoids was as follows:ethanol concentration,liquid-to-solid ratio,extraction time,microwave power.Furthermore,the optimum conditions of microwave extraction of total flavonoids from leaves of yacon were as follows(A₂B₁C₂D₂):ethanol concentration was 55%,microwave power was 280 W, extraction time was 9 min,liquid-to-solid ratio was 1:60 and repeated the extraction for 3 times.4.The dynamic changes of total flavonoids content of yacon leaves from three different areas were compared in this study.The results suggested that the total trend of dynamic change of total flavonoids content was basically consistent,which all showed the change of "low-high-low".There was a concentration peak of total flavonoids of yacon leaves during fast-growing period(August),and its concentration peak of the total flavonoids was 15.27%,14.07%and 18.78%,respectively.After August,the total flavonoids content of yacon leaves decreased continuously.However,the total flavonoids content of yacon leaves from Ya'an and Pengzhou slightly increased in November after entering to the end of flowering.Therefore,the accumulation of the total flavonoids from yacon leaves was closely related to the growth and development of yacon.5.The total flavonoids contents of yacon leaves from Ya'an,Pengzhou and Xichang during different periods were comparatively analyzed in this study.The results showed that there was an extremely significant difference in the total flavonoids content of yacon leaves during different periods.In August,the average of total flavonoids content of yacon leaves was significantly higher than other periods.There was also an extremely significant difference in the total flavonoids content of yacon leaves from different areas.The average of total flavonoids content of yacon leaves from Xichang was extremely higher than those from Ya'an and Pengzhou,while that from Ya'an was extremely higher than that from Pengzhou.Thus,the external environment such as climate and soil also had an important impact on the accumulation of total flavonoids of yacon leaves.