A novel compound from celery seed with a bactericidal effect against Helicobacter pylori

Objectives The aim was to purify and characterise an antimicrobial component from celery (Apium graveolens) seeds, which have been used for centuries as a herbal medicine with reported antibacterial effects. Methods A crude alcoholic extract of celery seeds was fractionated by organic solvent extractions, column chromatography and HPLC. Fractions were assayed for antimicrobial activity against the gastric pathogen Helicobacter pylori and other bacteria. The purified antibacterial component was characterised via MS and NMR. Preliminary investigation of its mechanism of action included morphological studies, incorporation of macromolecular precursors, membrane integrity and two‐dimensional protein electrophoresis. Key findings The purified component, termed ‘compound with anti‐Helicobacter activity’ (CAH), had potent bactericidal effects against H. pylori; the minimum inhibitory concentration and minimum bactericidal concentration were 3.15 μg/ml and 6.25–12.5 μg/ml, respectively. CAH (M_r = 384.23; empirical formula C₂₄H₃₂O₄) had specific inhibitory effects on H. pylori and was not active against Campylobacter jejuni or Escherichia coli. MS and NMR data were consistent with a dimeric phthalide structure. The results appeared to rule out mechanisms that operated solely by loss of membrane integrity or inhibition of protein or nucleic acid synthesis. Conclusions CAH may be suitable for further investigation as a potent agent for treating H. pylori infections.