Study On Aqueous Two-phase Extraction Coupling Technique Of Flavonoid Of Lotus Leaf And Its Microencapsulation And Application

Lotus leaf resources are rich in our country,except for individual provinces,all over the country are distributed.Because flavonoid are easily oxidized,and the solubility in water is very small,the utilization rate of lotus leaf is not high,which result in a lot of waste of resources.In this paper,a new aqueous two-phase extraction coupling technology was used to separate and purify the total flavonoid of lotus leaf,and flavonoid of lotus leaf were microencapsulated to expand the application range of flavonoid.Firstly,the flavonoid of lotus leaf were extracted by a new two-phase aqueous phase extraction.Effects of ethanol concentration,phosphate concentration,pH,phase volume ratio and extraction times on the extraction rate of flavonoid were studied by single factor test.At the same time,DPPH free radical scavenging capacity assay and skin irritation test were used to evaluate the antioxidant activity and safety of lotus leaf flavonoid extraction.The best extraction process was as follows:43%ethanol(V/V),0.35 g/mL dipotassium hydrogen phosphate,original pH,the yield of flavonoid was3.6%and the purification rate was 80.5%.DPPH free radical scavenging capacity assay and skin irritation test showed that the antioxidant ability of lotus leaf flavonoid was strong,and it was not irritating to the skin of rats.Then,lotus leaf flavonoid liposomes were prepared by thin film dispersion method,the encapsulation efficiency was used as the main index to optimize the preparation process of flavonoid liposomes by orthogonal design.At the same time,the content of flavonoid and the encapsulation efficiency of liposomes were determined by roporous resin enrichment combined with UV method.The optimum conditions were as follows:anhydrous ethanol as the organic phase,the phosphate buffer(pH 6.8)as the aqueous phase,and the volume ratio of the organic phase to the aqueous phase was 2:1,the quality ratio of flavonoid and soybean lecithin was 1:5,the quality ratio of soybean lecithin and cholesterol was 6:1,embedding temperature was 50 ~o C.The colour of flavonoid liposomes was pale yellow,the particles were distributed evenly in the suspension,the average particle size was 553.49 nm,and the maximum encapsulation efficiency was 36.56%.At the same time,the stability test and the DPPH free radical scavenging rate test showed that the liposome embedding technique could significantly improve the stability of lotus leaf flavonoid without changing its biological activity.The experimental results showed that the new aqueous two-phase extraction coupling technology can be used for the separation and purification of flavonoid,which could overcome the problem of flavonoids in the extraction process easy to oxidative deterioration,at the same time the method has the advantages of a simple process,low energy consumption,low cost,pollution-free,high product yield and purity.The membrane dispersion method of the optimized process was suitable for the preparation of flavonoid liposomes with stable properties.At the same time,the encapsulation efficiency of flavonoid liposomes was determined by enrichment of macroporous resin and UV,which could be used as an indicator for the preparation of flavonoid detection method.The optimized film dispersion method was suitable for the preparation of flavonoid liposomes with stable properties.The encapsulation efficiency of flavonoid liposomes was determined by the enrichment of roporous resin and ultraviolet spectrophotometry.