| Centella asiatica (L.) Urb. belongs to the family Umbelliferae (Centella) plant, it has effects that clearing heat and removing dampness, removes toxic substances and promotes subsidence of swelling. It is usually used in treatment of common cold, tonsillitis, infectious hepatitis, dysentery, traumatic injury, furunculosis toxicity, trauma hemorrhage ect as a Chinese folk medicine. Predecessors mainly were focused on study of asiaticoside and madecassoside, but the flavone of Centella asiatica were researched very few. In this essay we have done some studies as follow:1. Centella asiatica contains triterpenoids and flavonoid by qualitative analysis. The aglycone of flavone are quercetin and kaempferol which confirmed by TLC and RP-HPLC methods through hydrolyzed the sample, the hydrolyze sample and unhydrolyze sample were analyzed, the result shows that the flavone exist C. asiatica both in glycosides and aglycone forms at the same time, quantitative analysis show that asiaticoside content is 2.247 %, madecassoside content is 1.341 %, glycosides content is 0.235 % and aglycone content is 0.007 %.2. The raw material of C. asiatica was extracted by boiling water, then water extract was subjected to Diaion column eluted with 75 % ethanol and purified by anhydrous alcohol. After many times silicagel column chromatography, seven compounds were isolated from C. asiatica with gradient elution of chloroform:methanol (20:1 ~ 5:1) and chloroform:methanol:wate (45:15:1 ~ 0:100:0). Five of these structures were elucidated by different kinds of spectrum and chemical methods. They are quercetin, kaempferol, quercetin-3-O-α-L-rhamnopyranoside, asiaticoside and madecassoside.3. We studied on the seasonal variation of total flavone and total triterpene in differenr grouth stage of C. asiatica, the total content of flavone were calculated with quercetin and kaempferol after hydrolysis the sample. The result showed that from March to August the main flavonoids are flavonol aglycone, and the flavonol glycoside is main present in September to December. The ratio of quercetin and kaempferol is almost keep 1:1 in annaual. The content of flavone is aboundand in April to June, reached the highest of 0.242 % in April. The triterpene are appeared in the stage of young bud, the content of triterpene had obviously increased trend from March to September, reached the highest of 6.422 % in September, the ratio of asiaticoside and madecassoside was 1.9:1 in March, and decrease slowly to 1.2:1 in September, then increased to 1.7:1 in December.4. The antioxidation activity of flavone and triterpene in C. asiatica extraction were studied by used DPPH and phosphomolybdate methods, the result showed that the mainly antioxidant components are flavonoids in C. asiatica. Using the content of flavond aglycone as a standard, we test the antioxidation activity of extraction of root, stem and leaf in Centella asiatica. The exist forms and the contents of root, stem and leaf were analyzed through combined with the two exist forms of flavone in C. asiatica: glycoside and aglycone forms. The result showed that the leaf of C. asiatica had the highest content of flavone, the stem was higher, the root extract was lest, but the antioxidation ability of root was more stronger than the stem and the leaf extract based on the same content of flavone. Compared with the same concentration of BHT, the antioxidant ability of the extract of root, stem and leaf in C. asiatica were more stronger than BHT.
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