Optimization of extraction process for total flavonoids from leaves of Aquilaria sinensis by response surface method and purification technology

The leaves of Aquilaria sinensis were extracted by ethanol solution, with rutin as reference substance and nitrate as chromogenic agent, the absorbance of the extract in the 510 nm wave was determined. In the single factor experiment, the effects of ethanol concentration, extraction temperature, solid-liquid ratio and extraction time on the extraction rate of total flavonoids were studied. On the basis of single factor experiment, the optimum conditions were studied by the response surface methodology. The total flavonoids in leaves of Aquilaria sinensis were separated and purified by macroporous adsorption resin. By comparing the saturated adsorption capacity, adsorption rate and desorption rate of three kinds of resins D101, AB-8, and S-8, the resin with the best separation and purification effect was obtained, and the relationship between the adsorption time and the adsorption rate was studied. The results showed that: 1) the optimal extraction conditions were 80% ethanol, 65 ℃, liquid to solid ratio of 20:1 (mL/g) and 3 hours as extraction time. Under this condition, the yield of total flavonoids was 4.83%. 2) Non-polar and low- polar macroporous adsorption resin were more suitable for the separation and purification of total flavonoids from the leaves of Aquilaria sinensis. 3) D101 macroporous adsorptive resin had best adsorption ability. The purity of flavones increased to 2.8 times.