The phenolic compound
pyrogallol is the functional unit of many
polyphenols and currently there has been a growing interest in using this compound in human and animal health owing to its health-promoting effects. The
biological actions of
pyrogallol moiety (and
polyphenols) in inducing health benefitting effects have been studied; however, the mechanisms of action remain unclear yet. Here, we aimed at unravelling the underlying mechanism of action behind the protective effects of
pyrogallol against
bacterial infection by using the gnotobiotically-cultured brine shrimp Artemia franciscana and pathogenic bacteria Vibrio harveyi as host-pathogen model system. The gnotobiotic test system represents an exceptional system for carrying out such studies because it eliminates any possible interference of microbial communities (naturally present in the experimental system) in mechanistic studies and furthermore facilitates the interpretation of the results in terms of a cause effect relationship. We provided clear evidences suggesting that
pyrogallol pretreament, at an optimum concentration, induced protective effects in the brine shrimp against V. harveyi
infection. By pretreating brine shrimp with
pyrogallol in the presence or absence of an
antioxidant enzyme mixture (
catalase and
superoxide dismutase), we showed that the Vibrio-protective effect of the compound was caused by its prooxidant action (e.g. generation of
hydrogen peroxide, H2O2). We showed further that generation of prooxidant is linked to the induction of
heat shock protein Hsp70, which is involved in eliciting the
prophenoloxidase and
transglutaminase immune responses. The ability of
pyrogallol to induce protective immunity makes it a potential natural
protective agent that might be a potential preventive modality for different host-pathogen systems.