| Alpinia Officinarum Hance(AOH)is medicinal and edible plant which is precious.It is rich in various functional ingredients,such as essential oils and flavonoids.At present,there are many worldwide researches and reports on active ingredients of AOH roots,making full use of the value,but stems and leaves are directlydiscarded,and various ingredients contained are not effectively utilized,resulting in waste of resourses.In order to make full use of those active ingredients in the stems and leaves of AOH and improve the utilization efficiency of AOH resources,in this paper,the extraction and purification process of flavonoids from stems and leaves of AOH were optimized,increasing the extraction amount and purity of flavonoids,and then the biological activity and stability of flavonoids were studied.The main contents of this paper are as follows:(1)Extraction process of flavonoids from stems and leaves of AOH The flavonoids were extracted from stems and leaves of AOH by single factor and response surface optimization experiments and orthogonal optimization experiments.The results showed that the extraction amount of flavonoids by ultrasonic method was higher than that of traditional solvent method.The optimum conditions for ultrasonic extraction of flavonoids were as follows: ultrasonic treatment time was 10 min,ultrasonic output power was 900 W,the ratio of material to liquid was 1:50(g:m L),the extraction temperature was 40 °C,and the ethanol concentration was 50%.Under this condition,the extraction amount of flavonoids was is 108.63 mg/g,which was the highest amout.(2)Isolation and purification of flavonoids from stems and leaves of AOH By comparing the static adsorption rates and desorption rates of eight kinds of macroporous resins AB-8,D-101,XDA-6,LSA-12,S-8,XAD-2,HPD-600 and LX-213,AB-8 resin is the most suitable kind of resin for the purification of flavonoids in the stems and leaves of AOH.Through the static test,the optimum p H of the adsorbent was determined to be 6,and the optimum eluent was 60% ethanol.By studying the dynamic purification process of flavonoids,the optimal dynamic purification conditions were as followed: the concentration of flavonoids in the sample solution: 1 mg/m L,the flow rate of the sample solution: 1 BV/h,the flow rate of elution: 2 m L/min.Under the optimal purification conditions,the purity of purified flavonoids reached 77.37%,while the purity before purification was only 37.63%.(3)Biological activity and stability of flavonoids from stems and leaves of AOH The antioxidant properties of flavonoids in the stems and leaves of AOH were studied by comparing the flavonoids before purified,the purified flavonoids and VC to the removal of DPPH·?ABTS · and the ability to reduce iron ions.Knowing from the results of antioxidant tests,the antioxidant capacity of flavonoids before purification was close to that of VC,and the antioxidant capacity of flavonoids after purification was higher;when the sample concentration of solute was 0.04 mg/m L,the DPPH· radical scavenging rate of purified flavonoids was 90%,while that of flavonoids before purified and VC was only 80%,indicating that the flavonoids before purified obtained from the stems and leaves of AOH and the purified flavonoids have strong antioxidant capacity,which can be significantly improved by purification.The inhibition activity on ?-amylase of flavonoids from stems and leaves of AOH was determined to determine the strength of hypoglycemic function.The results showed that the highest inhibition rates on ?-amylase of flavonoids before purified?purified flavonoids and acarbose were 51.93%,82.11%,and 89.25%,which showed that the purified flavonoids had strong hypoglycemic function.In addition,the stability of flavonoids from the stems and leaves of AOH were studied,and effects of light,temperature and p H on them were determined.The results showed that the flavonoids decreased by 15.95% after 7 days of illumination;The content of flavonoids above 60 °C will be decreased;When the p H of the solvent was 6~7,the flavonoids were relatively stable,and the stability in the strong acidic solution and the strong alkaline solution is poor. |
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