Abstract: The total flavonoids in Exocarpium citri Grandis were extracted using the optimum ultrasonic extraction conditions and were further separated by ethyl acetate to yield lipid-soluble and water-soluble parts. The inhibitions of these different extracts on nitrosation were studied. The lipid-soluble extract was purified by chromatography on silica gel and the water-soluble extract was purified by macroporous adsorption resin. The structures of the flavonoids were identified and their inhibitions on nitrosation were experimented. The results showed that the extraction yield of the flavonoids was as high as 26.42%. The lipid-soluble and water-soluble extracts had some inhibition effects on nitrosation such as nitrosodimethylamine synthesis and sodium nitrite, in which the inhibition of the water-soluble extract was stronger than the lipid-soluble extract. In the four flavonoids, naringin had stronger inhibition than the others, the maximum blocking rate to nitrosodimethylamine synthesis was as high as 94.7%, while the highest removal rate to sodium nitrite was 92.3%.

Key words: Exocarpium citri Grandis, flavonoids, extraction and isolation, inhibition on nitrosation