Hepatoprotective, superoxide scavenging, and antioxidative activities of aromatic constituents from the bark of Betula platyphylla var. japonica - Matsuda, H; Ishikado, A; Nishida, N; Ninomiya, K; Fujiwara, H; Kobayashi, Y; Yoshikawa, M (Bioorg Med Chem Lett, 1998)