Absorption of acylated anthocyanins in purple-fleshed sweet potato (Ipomoea batatas cv. Ayamurasaki) in rats was studied to obtain evidence that the acylated anthocyanins themselves could exert a physiological function in vivo. Peonidin 3-caffeoylsophoroside-5-glucoside (Pn 3-Caf*sop-5-glc) in purple-fleshed sweet potato was directly absorbed into rat and present as an intact acylated form in plasma. After oral administration of the purple-fleshed sweet potato anthocyanin (PSA) concentrate containing 38.9 micromol of Pn 3-Caf*sop-5-glc/kg of body weight, Pn 3-Caf*sop-5-glc was detected in the plasma, and the C(max) value and t(max) were estimated as 50.0 +/- 6.8 nmol/Lof plasma and 30 min, respectively. Furthermore, the plasma antioxidant capacity was significantly elevated from 58.0 +/- 12.0 to 89.2 +/- 6.8 micromol of Trolox equivalent/L of plasma 30 min after the administration of the PSA concentrate.