Objective To investigate the chemical constituents of the taproots of Brassica rapa (Qiamagu) and evaluate their anti-inflammatory activity. Methods The chemical constituents were systematically isolated and purified using silica gel, ODS, Sephadex LH-20 column chromatography, and preparative HPLC. Their structures were elucidated by comprehensive spectroscopic analyses, including NMR, MS, and UV. The cytotoxicity of the isolates against RAW264.7 murine macrophages was assessed using the CCK-8 assay. The in vitro anti-inflammatory activity was evaluated via the Griess method. Results Twenty-five compounds were isolated from the 70% ethanol extract of B. rapa taproots and identified as 2-C-β-D-glucosyl-indole-3-acetonitrile (1), sinapic acid (2), p-coumaric acid (3), ferulic acid (4), methyl sinapate (5), methyl 4-hydroxycinnamate (6), trans-4-methoxycinnamic acid (7), dimethyl feruloyl malate (8), sinapoyl dimethyl malate (9), p-hydroxybenzaldehyde (10), phenylacetic acid (11), phenylethane-1, 2-diol (12), 3-phenylpropanamide (13), phenylethyl-β-D-glucoside (14), 4-(3-hydroxypropyl) phenyl β-D-glucopyranoside (15), idaeusinol B (16), syringaresinol-4-O-β-D-glucoside (17), equiselignan A (18), phaseic acid (19), abscisic acid (20), roseoside (21), bergapten (22), methylthioadenosine (23), 5-hydroxymethylfurfural (24), and rabdosia acid B (25). The CCK-8 assay demonstrated the cytotoxicity of compounds 16, 22, and 25. To evaluate the anti-inflammatory activity in vitro, the Griess method was employed. The results demonstrated that all tested compounds exhibited varying degrees of inhibitory activity. Conclusion Compound 1 is an indole glucosinolate; compounds 2—9 and 16—18 are phenylpropanoids, compounds 10—12, 14 and 15 are benzene ring derivatives, and compounds 13 and 23 are nitrogen-containing compounds. Among them, compounds 1, 6—9, 13, 15, 16, 18, 19, and 23 are isolated from B. rapa for the first time. In the anti-inflammatory assay, with compounds 8 and 9 demonstrating significant effects, yielding IC₅₀ values of 6.95 and 6.46 μmol/L.

Brassica rapa L.  /  anti-inflammatory activity  /  phenylpropanoids  /  nitrogen-containing compounds  /  2-C-β-D-glucosyl-indole- 3-acetonitrile  /  sinapic acid