Arylbenzofuran Lignans from the Seeds of Arctium lappa and Their Bioactivity

Two new (1 and 2) and two known arylbenzofuran lignans (3 and 4) were isolated from the seeds of Arctium lappa. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-4 were evaluated for their anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity. The results revealed that compound 3 showed good inhibition with IZD of 13.5 +/- 1.5 mm), and compounds 1, 2, and 4 showed weak inhibition with IZD of 9.6 +/- 1.0, 11.6 +/- 1.2, and 10.8 +/- 1.2 mm, respectively. Compounds 1-4 were also tested for the antioxidant activity, and they show good antioxidant activity with an IC50 values of 4.38, 4.22, 3.96, and 4.15 mu g/mL, respectively.