Antioxidative activity and anti-inflammatory effects of diarylheptanoids isolated from Alnus hirsuta

Two diarylheptanoids, 1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-beta-d-xylopyranoside (I) and 1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-d-xylopyranoside (II), were isolated from the bark of Alnus hirsuta. Compounds I and II exhibited strong antioxidative activity against 1,1-diphenyl-2-picrylhydrazyl radicals, with IC50 values of 8.36 +/- 0.54 and 8.67 +/- 1.46 mu M, respectively. In addition, we demonstrated that compounds I and II inhibited the production of nitric oxide and reactive oxygen species and the expression of proinflammatory molecules such as inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-induced macrophages. According to our results, the two diarylheptanoids isolated from the bark of A. hirsuta exhibited significant antioxidative activity and anti-inflammatory effects and may be useful in the pharmaceutical industry for alleviating oxidative stress.