A Comprehensive Review of Structures, Structure-activity Relationships, Extractions, and Bioactivities of Flavonoids from Citrus medica

Background: Citrus medica is a kind of medicinal and edible plant. It not only contains rich nutrients but also has a variety of therapeutic functions, including relieving pain, harmonizing the stomach, removing dampness, reducing phlegm, cleaning the liver, and relieving qi in traditional Chinese diagnosis. Methods: The references of C. medica were mainly collected from the online database, such as PubMed, SciFinder, Web of Science, Google Scholar, Elsevier, Willy, SpringLink, and CNKI. The other related references were sorted by consulting books and documents. Results: This review summarized and analyzed the different types of flavonoids of C. medica, including flavone-O-glycosides, flavone-C-glycosides, dihydroflavone-O-glycosides, flavonol aglycones, flavonoid aglycones, dihydroflavonoid aglycones, and bioflavonoids. The extraction methods of flavonoids were summarized in this review. Meanwhile, the multiple bioactivities of these flavonoids, including anti-atherosclerotic, hypolipidemic, anti-oxidant, hypoglycemic, and other activities. Their structure-activity relationships were reviewed and discussed in this paper. Conclusions: This review summarized the different extraction methods of diverse flavonoids with multiple bioactivities of C. medica, and their structure-activity relationships were discussed in this paper. This review may provide a valuable reference for researching and exploiting C. medica.