Antifungal Activities and Chemical Compositions of Essential Oils from Leaves of Four Eucalypts

Abstract

Essential oils from the leaves of 4 eucalypts species, i.e., Eucalyptus urophylla, E. grandis, E. camaldulensis, and E. citriodora, were extracted by hydrodistillation. Compositions of the essential oils were analyzed and identified. Their biological activities with respect to antifungal activity were examined. Yields of the essential oils in descending order were E. camaldulensis (3.48 mL 100 gm^(-1)), E. urophylla (3.14 mL 100 gm^(-1)), E. grandis (3.01 mL 100 gm^(-1)), and E. citriodora (1.89 mL 100 g^(-1)). Components of individual essential oils identified that 51 compounds were present in E. urophylla, with γ-terpinene predominant: E. grandis had 65 identified compounds with 1, 8-cineole being the richest fraction; there were 62 compounds identified from the essential oil of E. camaldulensis with 1, 8-cineole as the main component; and for E. citriodora, 35 compounds were identified with citrionellal as the dominant components. Anti-mildew tests of the 4 eucalypt essential oils indicated that E. citriodora had the best efficacy, and was extensively effective against all tested mildew species. E. urophylla, on the other hand, had the poorest efficacy. On the wood decay fungus tests, the same was observed for E. citriodora essential oil, and this indicated that it might be an excellent choice as a wood preservative. The main reason for its effectiveness was the presence of citronellal and citronellal which had obvious benefits in fighting mildew and fungi.