Antibacterial activity of 4-oxo-(E)-2-hexenal from adults and nymphs of the heteropteran, Dolycoris baccarum (Heteroptera: Pentatomidae).

We identified 4-oxo-(E)-2-hexenal (4-OHE) as a common component of the secretion from both Dolycoris baccarum nymphs (66.5 ± 34.7 µg/bug) and adults (87.4 ± 48.0 µg/bug) by GC/MS. We also found that this compound inhibited the growth of bacteria starting at 10 µg. The stronger antibacterial activity of 4-OHE than that of (E)-2-hexenal and (E)-2-octenal might be explained by the reactivity of α,β-unsaturated aldehydes with nucleophilic molecules.