Microwave-assisted Extraction Ampelopsis Dihydromyricetin And Mechanism

Dihydromyricetin(DMY) is a kind of flavonoid, which has many prominent biological activities, such as anticarcinogenic ,antioxidant ,promoting blood circulation to remove blood stasis ,clearing away heat ,relieving vexation ,tranquilizing the mind ,cooling the blood to relieve carbuncles,treating hemorrhages, etc. So it has the immense potential to be developed into drug,functional food and health-care food. It is showed that dihydromyricetin is the main component that occupies 15%~20% (w/w) of Ampelopsis grossedentata dry tender leaves, especially reach 40% (w/w) in the core leaves. In order to take fully advantage of our herbal resources, the research on the microwave assisted extraction of dihydromyricetin from Ampelopsis grossedentata and its mechanism has been developed, which was supported by Natural Science Foundation of Guangdong Province (No. 030509). 1. Extraction techniques using microwave assisted extraction (MAE) and the conventional extraction methods at room temperature (ERT) were evaluated for the extraction of dihydromyricetin from ampelopsis, and the radiation time, temperature, the solid/liquid ratios and the size of herbal particle were valued to compare the extraction yield rate of dihydromyricetin. It is showed that microwave-assisted extraction method has decreased the extraction time from 30min to 15 min, and the extraction efficiency has been improved for 50%. Optimal extraction conditions were also obtained through the orthogonal test as follows: the extracting temperature was 95 ℃,the extracting time was 15min,and the solid/liquid ratio was 1:20. 2. The procedure of breaking the cell wall of ampelopsis leaves in MARS5 before extracting dihydromyricetin at room temperature was considered to enhance the whole extraction. The influence of microwave treatment time and the microwave output power on the yield of dihydromyricetin were investigated . The most favorable experimental conditions included an output power of 750w and microwave treatment time of 4 min. Compared with the conventional extraction method, the microwave-assisted extraction method which was conducted with the lowest output power(300w) and irradiation time(2min) could provided the highest yields(about 28.48 % )of dihydromyricetin, while using the conventional method can only reach 24.10%. So, the extraction efficient has been improved 20%, give the impression of the prominent merit. 3. By watching the extent of the cellular rupture through transmission electron telescope, the mechanism of microwave-assisted extraction has been proposed in this paper. With the increase of the microwave output power and the irradiation time, the increasing disruption of cellular structures was found before the irradiation time reached 3min or the microwave power reach 600w. Once exceed this point, the disruption of the cell was no longer obvious.