... Volume: Page: ... 2.4 Hz, H-5)] and confirmed the presence of a hydroxy group [δ 8.04 (1H, br s, OH-6)] on ring A, an NH proton [δ 9.89 (1H, br s)] on ring B, and a proton [δ 7.16 (1H, s, H-4)], a methoxy group [δ 3.93 (3H, s, OCH 3 -3)], and a p-hydroxybenzyl group ...