Optimized Extraction and Determination of Dihydromyricetin Content from Local and Introduced Ampelopsis grossedentata to Zhejiang Province

In March 2015, leaves of Ampelopsis grossedentata were collected in Guangxin, Guizhou and Hubei, and A. grossedentata a HPLC method was established for the determination of dihydromyricetin in the leaves of Ampelopsis grossedentata , and the contents in the old and young leaves from 4 germplasm (Guangxi, Guizhou, Hubei and Hubei large leaf provenances) introduced in Zhejiang were analyzed . The results showed the optimal extraction conditions of dihydromyricetin from the leaves of Ampelopsis grossedentata were as follows: liquid-solid ratio 20∶1, extraction solvent 75% ethanol, extraction temperature 40℃, extraction three times under 500 W ultrasonic power and 20 kHz frequency, 25 min each time, and under these conditions, the extraction rate of dihydromyricetin could reach 16.21%. The fitting equation of the standard sample of the HPLC method for dihydromyricetin was y = 218.74x, R2 = 0.999 7, and the average recovery was 98.88%, which could well meet the needs of the study. The dihydromyricetin content in young leaves from Hubei provenance was the highest, up to 291.87mg·g-1, but there was no significant difference among the three provenances. The content of dihydromyricetin in young leaves from large leaf provenances was the lowest, which was significantly different from the other three provenances (P＜0.01). The difference of dihydromyricetin content between young leaves and old leaves was very significant (P＜0.01), and the difference was the largest in Guizhou provenances. The content of dihydromyricetin content in young leaves was 2.07 times that of old leaves. Therefore, it was suggested to pick and process young leaves in actual tea production.