Anti-oxidant and anti-inflammatory cyclic diarylheptanoids from Alnus japonica stem bark

A new cyclic diarylheptanoid namely alnuheptanoid B (3), along with four known cyclic diarylheptanoids: myricanone (1), ()-S-myricanol (2), myricanone 5-O--D-glucopyranoside (4), and ()-S-myricanol 5-O--D-glucopyranoside (5) were isolated from the EtOAc fraction of Alnus japonica Steud (family: Betulaceae) stem bark. Their structures were established by different spectroscopic analyses, as well as optical rotation measurement. Compounds 1, 2, 4, and 5 are isolated for the first time from A. japonica. The antioxidant and anti-inflammatory activities of compounds (1-5) were assessed using DPPH assay and carrageenin induced rat paw edema model, respectively. They displayed significant antioxidant activity in relation to propyl gallate (standard antioxidant) at concentration 50 µM. Compound 2 demonstrated anti-inflammatory effect at a dose 10 mg/kg compared with indomethacin (positive control).