Clove extract and eugenol suppress inflammatory responses elicited by Propionibacterium acnes in vitro and in vivo

Acne vulgaris is a multifactorial inflammatory disease involving an activation of the immune response to Propionibacterium acnes. The aim of this study is to determine the effects of clove (Syzygium aromaticum L.) extract and eugenol against P. acnes-induced inflammatory responses. The results showed that treatments of ethanolic clove extract (ECE) or eugenol at noncytotoxic concentrations significantly suppressed P. acnes-stimulated NF-κB-mediated tumor necrosis factor-α, interleukin (IL)-1β, and IL-8 productions and matrix metalloproteinase-9 expression in THP-1 cells in vitro. In order to investigate their effects in vivo, histological assessment was examined in the P. acnes-induced mouse ear edema model. The concomitant intradermal injection of ECE and eugenol resulted in reduction of ear swelling in mice along with microabscess. These observations demonstrate that ECE and eugenol inhibit P. acnes-induced inflammatory responses and suggest that ECE and eugenol might be a beneficial agent in treatment of skin inflammation induced by P. acnes.