Effects of different extraction methods on phenolic compounds and antioxidant activity in Hemerocallis flower

Hemerocallis fulva is one of the most popular flowers rich in bioactive substances, such as polyphenols, flavonoids, and alkaloids anthraquinones, particularly on antioxidant, antidepressant and anticancer. The extraction of phenolic compounds and antioxidant properties can also greatly contribute to the popularization of H. flower in the agricultural industry. However, only a few reports were focused on the extraction, forms and antioxidant activities of phenolic compounds in the H. flower. The present study aims to explore the effects of different extraction on the content, composition and antioxidant activity of phenolic compounds in various Hemerocallis flowers. Five kinds of flowers with different colors (yellow, orange, red-orange, jujube red, and bright red) were selected as raw materials. Three processing treatments (ultrasound, enzymolysis-ultrasound, and fermentation-ultrasound) were also utilized to determine the content of total flavonoids, total polyphenols, and scavenging rate of free radicals. Furthermore, high-performance liquid chromatography was adopted to identify the free, conjugated, and bound fractions of phenolic compounds, where the relationship was also established between phenolic compounds and antioxidant activity. Specifically, the types of total flavonoids and polyphenols were as follows: 'Hongyingwu', '63#', 'Jianzhuanglilan', 'Meiguixiniu', and 'Taiyangwu'. The results showed that there was a significant difference (P © 2021, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.