Antimicrobial activity of the volatile constituents of Perilla frutescens and its synergistic effect with polygodial

The steam distillate of the green leaves of Perilla frutescens has broad antimicrobial activity assumed from its use as food and food additives. The steam distillate mainly consists of perillaldehyde, limonene, beta-caryophyllene, alpha-bergamotene, and linalool. The most abundant, perillaldehyde, inhibits moderately a broad range of both bacteria and fungi. Perillaldehyde works in polygodial not only against fungi but also against both Gram-positive and Gram-negative bacteria. Synergistic effects are evaluated by the fractional inhibition concentration method.