Antimicrobial activity of honokiol and magnolol isolated from Magnolia officinalis

The antimicrobial activity of honokiol and magnolol, the main constituents of Magnolia: officinalis was investigated. The antimicrobial activity was a ssayed by the agar dilution method using brain heart infusion medium and th e minimum inhibitory concentration (MIC) were determined for each compound using a twofold serial dilution assay. The results showed that honokiol and magnolol have a marked antimicrobial effect (MIC = 25 mug/mL) against Acti nobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella inte rmedia, Micrococcus luteus and Bacillus subtilis, but did not show antimicr obial activity (MIC greater than or equal to 100 mug/mL) for Shigella flexn eii, Staphylococcus epidermidis, Enterobacter aerogenes, Proteus vulgaris, Escherichia coli and Pseudomonas aeruginosa. Our results indicate that hono kiol and magnolol, although less potent than tetracycline, show a significa nt antimicrobial activity for periodontal pathogens. Hence we suggest that honokiol and magnolol might have the potential to be an adjunct in the trea tment of periodontitis. Copyright (C) 2001 John Wiley & Sons, Ltd.