Tzumin A and B, two new lignan derivatives from the barks of Sassafras tzumu

Two new lignan compounds, 5′-allyl-2,2′-dihydroxy-[1,1′-biphenyl]-5-carboxylic acid (1) and 4,4′-diallyl-[1,1′-biphenyl]-2,2′-diol (2), together with four known compounds (3–6), were isolated from the barks of Sassafras tzumu. The new compounds were determined by NMR (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, NOESY/ROESY), and MS analysis. Compounds 1–3 showed potent AChE inhibitory activities, with IC₅₀ values of 2.00, 1.81 and 1.91 μM, respectively.