Inhibition of oral pathogens and collagenase activity by seaweed extracts.

Fifty-seven species of common seaweed from the Coast of Korea were screened for antimicrobial (i.e. inhibition of Prevotella intermedia and Porphyromonas gingivalis growth) activity. As a source of bioactive compounds, seaweeds can produce many secondary metabolites with a variety of activities. Using the agar diffusion method, only 17 species (29.8%) showed inhibitory activity. Of these, methanol extracts of Enteromorpha linza, Sargassum sagamianum, and Ulva pertusa showed strong inhibitory effects against both P. intermedia and P. gingivalis. The MIC values of E. linza, S. sagamianum, and U. pertusa extracts against P. intermedia were 625, 78 and 625 microg ml(-1) and those against P. gingivalis were 312, 156 and 625 microg ml(-1), respectively. When these three species' extracts were separated into five fractions according to their polarity, the main active agents were determined to be phenolic compounds. We then compared the antimicrobial activities of these phenolic compounds against various periodontal pathogens using a MIC test. Phenolic compound containing extracts at concentrations of 10 to 100 microg ml(-1) showed a moderate to significant inhibitory effect on collagenase 1,2 and 3 activity.