In Vitro Antibacterial and Anti-Inflammatory Effects of Novel Insect Fungus Polycephalomyces phaothaiensis Extract and Its Constituents against Propionibacterium acnes

Propionibacterium acnes plays an important role in the pathophysiology of acne vulgaris, the most common chronic inflammatory skin disease of the pilosebaceous unit. This study was conducted to investigate whether the entomopathogenic fungus Polycephalomyces phaothaiensis components have antibacterial and anti-inflammatory effects against P. acnes that may serve for acne treatment. A chemical study by spectroscopic analysis resulted in the identification of seven known compounds. The anti-P. acnes potency of extracts and test compounds was determined by both agar diffusion and broth dilution methods. The ethyl acetate extract from culture broth along with cordytropolone (1) and stipitalide (2) exhibited strong anti- P. acnes activity while (+)-piliformic acid (3) showed weak inhibitory activity. The anti-inflammatory effect of ethyl acetate extract and 1–3 was then examined by the quantification of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α on heat-killed P. acnes induced cytokine production by THP-1 cells. The result demonstrated that the extract and its constituents (1–3) showed a potent significant effect by inhibiting the P. acnes-induced pro-inflammatory cytokines production in THP-1. Our results suggest for the first time that P. phaothaiensis and its constituents (1 and 2) hold therapeutic value for further studies as a new alternative treatment for acne.