Antimicrobial properties of natural phenols and related compounds: obtusastyrene and dihydro-obtusastyrene.

Factors influencing the antimicrobial properties of obtusastyrene and dihydro-obtusastyrene were studied. Both of these compounds were soluble in acetone, alcohol, and olive oil. In water, they were soluble at concentrations of 34 and 53 mug/ml, respectively. The minimal inhibitory concentrations against gram-positive bacteria and yeast were below 100 mug/ml. The compounds were not effective against gram-negative bacteria at 200 mug/ml or lower concentrations. With initial populations of cells greater than 10(6)/ml, the concentrations of these compounds required to prevent growth were greater than with lower cell populations. Changing the pH of the growth medium did not decrease the effectiveness of these two compounds in the pH range of 3 through 8. Both obtusastyrene and dihydro-obtusastyrene were rapidly bactericidal to Staphylococcus aureus and Bacillus cereus at 25 mug/ml.