Fungicidal and Bactericidal Properties of Bisabolol and Dragosantol

Abstract

Abstract α-Bisabolol, a natural plant sesquiterpene alcohol, and dragosantol, a racemic mixture of synthetic bisabolol, were studied for their fungicidal properties separately against the nongerminated and germinating conidia of several species of Aspergillus and Fusarium which represent problems in agriculture and medicine. Bactericidal assays against Pseudomonas aeruginosa and Staphylococcus aureus were also performed. Compared to the controls, both compounds displayed statistically significant (p < 0.001) lethality for the tested microorganisms. α-Bisabolol and dragosantol produced nearly 98% viability loss against the germinating conidia of A. flavus, A. fumigatus, A. niger, A. terreus, F. oxysporum, F. solani, and F. verticillioides (formerly F. moniliforme) at, or below, 10 μM. The viability of nongerminated F. oxysporum conidia was significantly reduced. Both compounds showed very rapid and significant reduction of P. aeruginosa viability at 7.5 μM. Staphylococcus aureus was more resistant to these compounds though significant viability loss occurred after 2 h incubation at 12.5 μM. Minimum inhibition concentration studies (NCCLS Method-38A) showed that bisabolol inhibited the growth of clinical isolates of the dermatophytic pathogens Trichophyton tonsurans (2–8 μg/mL), T. mentogrophytes (2–4 μg/mL), T. rubrum (0–1 μg/mL) and Microsporum canis (0.5–2.0 μg/mL). Results showed α-bisabolol and dragosantol have potent fungicidal and bactericidal properties against the tested strains. Because both compounds are safe for use in cosmetics, the data presented here suggest potential utility as antimicrobials in cosmetics, food and as a topical antifungal treatment Key Word Index: Arnica longifolia Aster hesperius Chrysothamnus nauseosus essential oilsα-bisabololdragosantolantimicrobial