The aim of this study was to investigate the in vitro antioxidant and antimicrobial activities from stem bark of Beilschmiedia
madang, and its major compound, a neolignan; (+)-kunstlerone. The antioxidant activity was done using the following assays:
DPPH radical scavenging, β-carotene/linoleic acid bleaching and total phenolic content. The MeOH extract showed the highest
inhibitory activity towards lipid peroxidation (89.6% ± 0.4), phenolic content (163.4 mg GA/g) and DPPH radical scavenging
(IC50 of 63.2 µg/mL). The major compound, (+)-kunstlerone showed a potent antioxidant activity with IC50 of 25.5 µg/mL
comparable to that of ascorbic acid (IC50 of 15.2 µg/mL). Evaluation of the antimicrobial activity was examined by using disc
diffusion and micro dilution (MIC) method. The results revealed that the MeOH extract and (+)-kunstlerone exhibited moderate
activity towards Stretococcus mutans and Aspergillus fumigatus with MIC values 250 µg/mL.