In vitro antibacterial and anti-inflammatory properties of seaweed extracts against acne inducing bacteria, Propionibacterium acnes

This study was conducted to evaluate the antimicrobial activities of common seaweeds from the coast of South Korea against the etiologic agents of acne vulgaris. Fifty-seven species of seaweed were screened for potential antimicrobial activity. Methanol extracts of 13 species (22.8%) showed inhibitory effects against Propionibacterium acnes. The aqueous extracts of only two species (3.5%) showed antimicrobial activity. When tested with the agar disk diffusion method, Ecklonia cava, E. kurome, Ishige sinicola, and Symphyocladia latiuscula had the strongest inhibitory effects. However, these four seaweed extracts showed no antibacterial activity against Staphylococcus epidermidis at 5 mg disk-1. The minimum inhibitory concentration (MIC) values of E. cava and E. kurome were both 0.31 mg ml-1 and the MIC values of l. sinicola and S. latiuscula were 0.26 and 0.21 mg ml-1, respectively. Among whole plants of E. cava and E. kurome, extracts of the pinnate blade had the highest inhibitory activity on bacterial growth. In cytotoxicity assays, methanol extracts of E. cava, E. kurome, and I. sinicola showed no effect on cell viability at concentrations of 200 microg ml-1. However, the methanol extracts of S. latiuscula reduced cell viability rates to 50% at the same concentration. Additionally, methanol extracts of E. cava, E. kurome, and I. sinicola potently inhibited the in vitro production of nitric oxide. These results suggest that the methanol extracts from these three species may be useful in the development of therapeutic agents for acne vulgaris. Further investigations to determine the bioactive compound are in progress.