Structure-antioxidant activity relationships of flavonoids within three species of Indonesian artocarpus

Using the DPPH method, the antioxidant properties of six flavonoids with various basic chemical structures from the three species of Artocarpus (A. nangkadak, A. champeden, and A. altilis) were investigated. In addition, the flavonoids Cudraflavone C (flavone), artocarpin (flavone), and artocapanon (flavane), which have distinct basic structures but the same hydroxylation pattern (2' and 4'-OH in the B-ring, respectively), were given special consideration. Since all three flavonoids showed comparable antioxidant activity against DPPH, it can be said that the presence of the 7-OH group, the 2' and 4'-OH groups in the B ring, and the 2,3-double bond is a sign of strong antioxidant potency. Moreover, prenyl groups and structural modification involving these groups to flavonoids, such as cyclization of the 3-prenyl to make a pyranohydrobenzoxanthone type (cycloartocarpine, cyclomorusin, cyclocommunol) can decrease antioxidant activities.