| Flavonoids were extracted from perilla's stem and leave by soxhlet extraction, ultrasonication extraction and microwave extraction. After the perilla crude extract was purified by aqueous two-phase extraction and column chromatography, the content of total flavonoids was determined by rutin method, and the components of the compounds were analyzed by full wavelength scan and high performance liquid chromatography (HPLC). Antioxidant activity and antimicrobial activity of flavonoids were studied.The research showed that among the three extraction methods, microwave extraction was the optium method. By the response surface optimization method, the optimal microwave-assisted extraction conditions were as follows:extraction temperature was 71℃, ethanol volume fraction was 61%, the perilla was passed by 20-mu standard sieve, ratio of material to liquid was 1:20, microwave time was 70 min, extraction times was twice. Under these conditions, the yield of flavonoids reached 78.2 mg/g.Flavonoids were purified by aqueous two-phase extraction and column chromatography. Recovery rate of flavonoids of aqueous two-phase extraction was up to 98.46%, but impurities couldn't be removed. Recovery rate of D152 macroporous resin column chromatography was 98.28%, the final product was obtained when loading sample 35mL and using 60%(v/v) ethanol at the elution velocity of 0.8mL/min; on the basis of results of full wavelength scan, the final product only had absorption at the peak of 330nm. The results of HPLC revealed that the major constituents of the subatances were lutin, luteolin.Perilla flavonoids had strong antioxidant activity, and needed to be stored in the dark, acidic conditions (pH2-4). Compared with the natural antibacterial substances, perilla vinegar extract had good antimicrobial activity, it's inhibition rate of the bacteria carried by sushi was up to 81.7%, and it had little effect on the flavor of sushi, could be developed as antistaling agent of sushi. |
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