Twelve biphenyl lignans including a new monoterpene biphenyl lignan (menthylmagnolol, 1) and a new natural product (honokiol 4′-O-β-D-glucoside, 9), along with ten known ones (2-12) were isolated from the cortex of Magnoliae officinalis. Their structures were elucidated by HR-MS and spectroscopic methods including 1D/2D NMR and ECD and so on. To the best of our knowledge, only one natural monoterpene biphenyl lignan in which the monoterpene unit and biphenyl lignan unit were fused via a six-membered ring was reported and compound 1 was the second reported natural product with this structural feature. Their in vitro inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) and Helicobacter pylori were evaluated for the first time. Compounds 3~6 showed significant inhibitory activity against protein PTP1B, with IC₅₀ values of 9.20±1.95, 9.23±1.12, 8.71±0.54 and 6.90±0.70 μM, respectively. Compounds 4~6 and 10 showed significant anti-Helicobacter pylori activity with MIC all of 500 mg/L. The preliminary structure-activity relationship exhibited that the monoterpene units of biphenyl lignans were probably beneficial to improve the inhibitory activities against PTP1B and Helicobacter pylori. The research results indicate that monoterpene biphenyl lignans have development potential as drugs for treating type Ⅱdiabetes and Helicobacter pylori infections.

Key words: Magnolia officinalis, Biphenyl lignans, PTP1B inhibitory activity, anti-Helicobacter pylori activity