A novel estimation method of total flavonoids in an edible medicinal mulberry leaves by ultrasound-assisted hydroalcohol-acid extraction and HPLC-DAD
Mulberry leaves have been widely used to produce various health products. In this paper, an efficient procedure of ultrasound-assisted hydroalcohol-acid extraction (UAHAE) was established to estimate the total flavonoids content in mulberry leaves by quantifying their resulting aglycones (quercetin and kaempferol) using HPLC-DAD. Effective hydrolysis of glycosides to aglycones was achieved in an ethanol-HCl-water (7/2/1, v/v/v) solution at 75°C by ultrasound (40 kHz) for 60 min. The average contents of quercetin and kaempferol were 7.12 mg/g and 2.13 mg/g, respectively, in the variety of cultivar MC308, and their recoveries were 105.48% and 105.81%, respectively. The total flavonoid content of most varieties was between 4-10 mg/g, accounting for 80% in 86 species of mulberry leaves. With the increase in leaf maturity, the general trend of the change in flavonoid content was a decrease at first and then an increase. The highest total flavonoid content in commercial mulberry tea (CT 2) is 4.76 mg/g, and the DPPH radical scavenging activities were similar to the distribution of total flavonoids measured by UAHAE in three types of mulberry tea. These finding provide a basis for industrial-scale manufacturing of edible medicinal mulberry leaf products.
From Volume 92 (2019) on, the content of the journal is licensed under the Creative Commons Attribution 4.0 License. Any user is free to share and adapt (remix, transform, build upon) the content as long as the original publication is attributed (authors, title, year, journal, issue, pages) and any changes are labelled.
The copyright of the published work remains with the authors. If you want to use published content beyond what the CC-BY license permits, please contact the corresponding author, whose contact information can be found on the last page of the respective article. In case you want to reproduce content from older issues (before CC BY applied), please contact the corresponding author to ask for permission.