| Ampelopsis grossedentata, also named Vine Tea, is an important class of wooden vine plant. The process of making tea can produce a lot of discarded stems. Every 10000 tons of Vine tea production will produce 600 tons of waste stems in the Wuling mountain areas. DMY is a kind of additive for food, medicine and pharmaceutical intermediates, and it is an important active ingredient of Ampelopsis grossedentata. Nowadays, high purity DMY mainly extracted from Ampelopsis grossedentata leaves, causing its price expensive. So extracting DMY from discarded stems of Ampelopsis grossedentata, can not only improve economic benefits of planting and processing, but also have important practical significance. This paper conducted a comprehensive study of extracting and separating DMY from Ampelopsis grossedentata discarded stems. The results are as follows:(1) Established the method of HPLC to determine DMY, established the method of UV to determine flavonoids, and the DMY and flavonoids of the different parts of vine tea were determined. HPLC measurement conditions: column Kromasil C18, the mobile phase: acetonitrile: 0.05% phosphoric acid(18:82), flow rate of 1.0 m L/min, column temperature of 27.8℃, the detection wavelength was 292 nm; the standard curve equation was obtained: C = 0.000019S-2.726383, R2 = 0.9998, C(20.3, 203 ∈μg/m L). UV measurement conditions: 310 nm detection wavelength, 340 nm reference wavelength, Al Cl3 as chromogenic agent; obtained standard curve equation: C = 18.509 ΔA-0.19679, R2 = 0.9998, C(4, 24 μg/m L∈). The measurement results were: DMY and flavonoid content of leaves was the highest, its contents were 7.79%, 15.01%; The parts of DMY accounted for the highest proportion of flavonoids was tender stem, a ratio of 64.31%; Vine tea aboveground DMY and flavonoid content was greater than the underground part.(2) We studied the enzymatic extracting DMY process. Obtained the optimum conditions: type enzyme complex enzyme, p H=4.46, temperature 45℃, enzyme dosage 2.0%, liquid ratio was 1:20. Under this condition, DMY extraction rate was 30.65%, purity was 23.40%. And compared with the hot water extraction and ultrasonic assisted extraction, enzymatic extraction was the best results.(3) Activated carbon separating DMY process was studied in this paper. On the basis of single factor experiments, response surface obtained the optimum conditions of ZX-1 activated carbon: p H=2.09, temperature 50.51℃, activated carbon dosage 19.80%. Under this condition, the yield of DMY was 96.99%,the purity increased from 23.40% to 33.29%.(4) The technology conditions of extracting DMY were determined. The optimum parameters: ethyl acetate extraction, extraction time of 8.52 min, extraction temperature 59.26℃, solid-liquid ratio 0.013 g/m L. Under this condition, the yield of DMY was 86.01%, the purity increased from 33.29% to 66.01%.(5) DMY crystallization process was studied in this paper. DMY crystallization using ethanol concentration gradient method, orthogonal experiment obtained the optimum conditions: time 96 h, crystallization temperature 7℃, the solvent concentration 16.67%. Under this condition, after the three times of crystallization, the yield of DMY was 79%, with the purity higher than 98%.(6) 98% DMY structural was identified by UV, HPLC, IR, 1H-NMR, 13C-NMR. DMY standards and samples had the same absorption spectra, the same HPLC peak time, IR spectra consistent, the same 1H-NMR, 13C-NMR chemical shifts; which showed DMY standards and samples had the same structure. They were the same substance.(7) Expanded experiment was carried out based on pilot experiment, determined the industrialized production process of extracting DMY from Ampelopsis grossedentata discarded stems. |
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