Antibacterial activity of buckwheat honey added with ferrous lactate against Pseudomonas aeruginosa

Hydroxyl radical (OH center dot) in honey has been identified to cause damage to bacteria that degrades DNA, stalls growth and even kills cells. This study investigated the action model of OH center dot induced by exogenous ferrous iron. Our data showed that ferrous lactate augmented the antibacterial activity of buckwheat honey by producing OH center dot that targeted at components in the respiratory system and the metabolic system such as NADH dehydrogenases and 6-phosphogluconate dehydratases in Pseudomonas aeruginosa. After buckwheat honey was pretreated with ferrous lactate, the activities of NADH dehydrogenases and 6-phosphogluconate showed 79.9% and 99.7% reduction respectively. Activities of these enzymes were much less affected if OH center dot was scavenged by alpha-tocopherol. OH center dot in buckwheat honey also increased malondialdehyde production from 0.54 to 6.87 nmoL/g and seriously damaged the cell membrane in P. aeruginosa. This damage ramped up the membrane permeability and increased protein leakage from 0.02 to 1.87 mu g/mg. Our results indicate that in such action model exogenous ferrous lactate brings on cell decomposition and increases bactericidal activity of buckwheat honey.