Phenylpropanoids from red kohlrabi sprouts inhibits nitric oxide production in RAW 264.7 macrophage cells

The sprouts of red kohlrabi (Brassica oleracea var. gongylodes) were extracted with methanol, and the concentrated extracts were successively partitioned with ethyl acetate, n-butyl alcohol (n-BuOH), and H₂O. From the n-BuOH fraction, four phenylpropanoids were isolated through repeated silica gel and ODS column chromatographies. On the basis of physico-chemical and spectroscopic data including NMR, MS, and IR, the isolated compounds were identified as 3-(3,4,5-trimethoxyphenyl)-2E-propenoic acid methyl ester (1), (E)-sinapic acid methyl ester (2), (E)-sinapoyl glucoside (3), and lawsoniaside B (4). Moreover, the compounds dose-dependently inhibited NO production in RAW 264.7 cells with IC₅₀ values of 41.22 (1), 38.32 (3), and 22.65 (4) μM, respectively. With further studies, these compounds may be potentially useful in developing new anti-inflammatory agents.