Purification and identification of PA. (A) Purification of antioxidative compounds from S. senanensis leaves. Subcritical water extracts were prepared from the leaves and fractionated by HPLC with MeOH/H2O (17:83). The SOSA was assessed for each fraction, and the highest value detected in fraction 4. (B) Purification of the compound by HPLC. Fraction 4 was further fractionated, and fraction 4-II found to contain the highest SOSA. (C) EI-MS spectra data of purified PA, which was identified using the SDBS. (D–F) HPLC chromatograms of fraction 4-II (D), synthetic PA (E), and a mixture of fraction 4-II and synthetic PA (F), in which the two compounds were co-eluted as a single peak. (G) Chemical structure of PA.