The NO production of inducible NO-synthase (iNOS) is part of the cellular, unspecific immune system and of many inflammatory processes. NO is cytotoxic in high concentrations and can damage cells. Compounds with inhibitory effects on NO production can be considered as anti-inflammatory drugs.In this diploma thesis, active fractions of the dichloromethane extract of Hansenia weberbaueriana (Fedde ex H. Wolff) Pimenov & Kljuykov, comb. nov. (= Notopterygium incisum C.C. Ting & H. T. Chang), which had shown inhibitory activity on NO production in RAW 264.7 macrophages stimulated with LPS/IFN?, were further fractionated by preparative HPLC. Falcarindiol, 9-epoxy-falcarindiol, falcarindiol-8-acetate, crithmumdiol, notopterol, ostruthin, 3(4-hydroxy-3-methoxyphenyl)-2-prop-2-enoic acid-3-propyl-pent-3-enyl, 5,7-dimethoxycoumarin, 5-methoxy-furocoumarin, phenylethylferulate and (E)-3-hydroxy-4,5-dimethoxy-stilben were isolated and identified. 3-(4-Hydroxy-3-methoxyphenyl)-2-prop-2-enoic acid-3-propyl-pent-3-enyl is a new substance and the polyacetylenes 9-epoxy-falcarindiol and crithmumdiol were isolated from Hansenia weberbaueriana (= Notopterygium incisum) for the first time. Testing in the iNOS assay showed that the polyacetylenes falcarindiol (IC50 20 M), 9-epoxy-falcarindiol (IC50 8 M), falcarindiol-8-acetate (IC50 30 M), crithmumdiol (IC50 15 M), and the new 3-(4-hydroxy-3-methoxyphenyl)-2-prop-2-enoic acid-3-propyl-pent-3-enyl (IC50 35 M) have an inhibitory potential on NO production in LPS/IFN? stimulated RAW 264.7 macrophages. Notopterol, phenylethylferulate and (E)-3-hydroxy-4,5-dimethoxystilben did not show any inhibitory activity on NO production. Whereas the inhibitory activity of falcarindiol has been known from literature, the inhibitory activity of the rest of the tested substances is reported for the first time.