A systematic review on biological activities of prenylated flavonoids

Context: Prenylated flavonoids are a unique class of naturally occurring flavonoids that exist especially for the plant's self- defensive strategy. This special class of flavonoids increases the bioactivities of their backbone flavonoids with non- prenylation; therefore, prenylated flavonoids have more potential to be developed and utilized. Objective: The number, position and type of the prenyl group on the flavonoids backbone structure may have close relationships with the bioactivities of flavonoids. Methods: PubMed and WEB OF KNOWLEDGE (R) were used to search articles published in English between 1 January 2002 and 31 December 2012, which discuss the structure- activity relationship between prenylated flavonoids and their bioactivities. Results: It is proposed that the prenyl- moiety makes the backbone compound more lipophilic, which leads to its high affinity with cell membranes. The prenylation brings the flavonoids with enhancement of antibacterial, anti- inflammatory, antioxidant, cytotoxicity, larvicidal as well as estrogenic activities. However, it is reported that the prenyl- moiety decreases the bioavailability and plasma absorption of prenylated flavonoids. Conclusion: The prenyl group affects the bioactivities of flavonoids in certain ways, while the action mechanisms and the structure-activity relationship as well as more in vivo studies even clinical validation trials need to be further investigated.