Studies On The Chemical Constituents And Quantitative Determination Of Flavonoids Of Supercritical CO₂ Extracts Of Fistular Onion Stalk

Allium fisturosum L. var. caespitosum Makio originates from western Asia and is widely cultivated in south China. It not only is the edible vegetable and flavoring in daily life,but also can be used as Chinese medicinal herb to prevent and treat diseases. In the previous reseach,the results showed that the SFE of Bulbs of the Allium fisturosum L. var. presented strong activity on lowering blood-lipid. To elucidate the substance foundation of the pharmacology,the chemical constituents and their contents of the Allium fisturosum L. var. had been studied.At first,the SFE of Bulbs of the Allium fisturosum L. var. was studied. Seven chemical fractions were obtained from it using polarity gradient solvents , seven compounds were isolated and purified from four fractions of them by chromatography with silica gel column,Sephadex LH-20 gel column and preparation thin layer. Their structures were elucidated asβ-sitosterol (Ⅰ),(+)Catechin(Ⅳ),(-)Epicatechin(Ⅴ),Astragalin(Ⅵ),3-O-β-D(2-O-β-D-glucopyranosyl) glucopyranosides of kaempferol. They were isolated from this plant for the first time.And then,seven chemical fractions were obtained from the SFE of Bulbs and Leaves of Allium fisturosum L. var. using polarity gradient solvents respectively. The comparisons of the constituents from their three fractions were performed by GC-MS. The results showed that they have the same constituents'type,but the contents of constituents in different parts are obviously different. Steroids are the characteristic chemical constituents in the SFE of Bulbs of Allium fisturosum L. var,the content of the unsaturated fatty acid of SFE of Leaves of Allium fisturosum L. var was a few higher than it of SFE of Bulbs of Allium fisturosum L. var..At last,the spectrophotometry methods to determine the content of total flavonoids of SFE of Bulbs and Leaves of Allium fisturosum L. var. were set up. The results showed that the range of the added standard recovery of the method was from 98.4% to 104.4%, relative standard deviation (RSD) was 2.23%. The average content of total flavonoids of SFE of Bulbs of Allium fisturosum L. var. was 0.921%, and the average content of total flavonoids of SFE of Leaves of Allium fisturosum L. var. was 0.758%. At the same time,The HPLC methods to determine the content of kaempferol and quercetin of SFE of Bulbs and Leaves of Allium fisturosum L. var. were also established. The results indicated that the range of the added standard recovery of the method was from 97.43% to 104.18%, the relative standard deviation (RSD) was less than 3%. The content of kaempferol and quercetin of SFE of Bulbs of Allium fisturosum L. var. were 0.154% and 0.120%, and the content of kaempferol and quercetin of SFE of Leaves of Allium fisturosum L. var. were 0.117% and 0.103%.