Study On The Separation, Structures And Antioxidant Activity Of Flavone From Lotus Epicarp

Lotus epicarp is a part of Nuelumbo nucifera Gaertn,which is often discarded as the inedible part.In order to use resources and increase the added value of products,the flavones were extracted and separated from lotus epicarp,and the structures of flavones were studied by means of the size exclusion chromatography, TLC,GC and HPLC-MS/MS.The antioxidant activity of lotus epicarp flavones（LF） was researched by a series tests in vitro.The results as follow:1.Decision of the optimal extraction parameters about LFThe optimal extraction parameters were determined by the L9（3⁴） orthogonal test when the ethanol as extraction solvent,and the yield rate of flavonoid as a index determined.The temperature was 88.38℃,the concentration of ethanol was 51.34%,and the extraction time was 40 min.2.Separation and purification of LFFirst LF were purified by macroporous resin in order to remove the sugar and other impurities in the crude extraction which can not be adsorbed by the resin,then Toyopearl HW-40S size exclusion chromatography was used for secondary purification,and six fractions——LF-F1～LF-F6 were obtained.3.Analysis of components and structure of LFThe components of LF-F2 were analyzed by HPLC.By means of HPLC and HPLC- MS/MS,two kinds of flavonol glycoside were found in LF-F2,which were rutin,quercetin,hypericin.And four kinds of aglycones were found in LF-F2,which were quercetin,kaempferol,myricetin and isorhamnetin.4.Research of the antioxidant activity of LF（1） The total antioxidant capacity（T-AOC） of LF-F2 was higher than that of the crude sample LF,the T-AOC of the crude LF sample was 89.52 U/mL,whereas that of LF-F2 was 187.92 U/mL.（2） The inhibition abilities on hydroxyl radicals of the crude LF sample was 70.28U/mg,and that of the LF-F2 was 93.01 U/mg.The IC₅₀ of scavenging the superoxide anion radical,hydroxyl radicals,hydrogen peroxide and inhibiting oxidative damage on DNA were 420±8,40±1,0.6±0.18 and 8.3± 0.09μg/mL separately.（3） The ability of scavenging DPPH·of the LF-F2 was better than that of BHT,but the antioxidant activety of the LF-F2 was inferior than that of BHT inβ-carotene/linoleic acid emulsions.The inhibition abilities on hydroxyl radicals of the LF-F2 was better than that of Vc,however the reductive capability on Fe³⁺ of the LF-F2 was inferior than that of Vc.In a word,all results showed that LF-F2 was a good antioxidant in a series of tests in vitro.