Screening of bioactivity-oriented extraction approach and quality control standards of lotus leaf extracts with dual functions

Abstract

In the present study, various lotus leaf extracts were prepared by multiple methods, characterized by 12 alkaloids, 14 flavonoids, and superoxide anion radical scavenging (OS) and xanthine oxidase inhibitory (XOI) activities, and divided into 3/4 groups with different characteristics. Both alkaloids and flavonoids contributed to XOI activity of representative lotus leaf extract. Norcoclaurine, O-nornuciferine, N-nornuciferine, nuciferine, luteolin, diosmetin, quercetin, and quercetin-3-O-glucuronide were defined as quality control standards for lotus leaf extracts with dual OS and XOI activities. Enzymatic hydrolysis coupled with ultrasound-assisted extraction method using 50% (v/v) ethanol was the most favorable approach for preparing food-grade lotus leaf extract with dual functions. Network pharmacology revealed that this extract having abundant alkaloids and flavonoids (especially flavonoid aglycones) could improve hyperuricemia by multiple actions on uric acid synthesis and transport, inflammation response, oxidative stress and lipid metabolism. Our study provided crucial data about clear quality control standards for plant-based functional food with potential hypouricemic effect.