Inhibitory effect of essential oils on apical growth of Aspergillus fumigatus by vapour contact

Abstract

The inhibitory effect of seven essential oils on the apical growth of hyphae of Aspergillus fumigatus was studied using a bio cell tracer by vapour contact in a sealed vessel. Based on the inhibitory pattern, these essential oils were classified into three groups. The first group, composed of citron, lavender and tea tree oils, stopped the apical growth in a loading dose of 63 micrograms ml-1 air, but allowed the regrowth of the hyphae after removal of the vapour, indicating fungistatic action. The second group, consisting of perilla and lemon-grass oils, stopped the apical growth in a loading dose of 6.3 micrograms ml-1 air, and did not allow the regrowth after gaseous contact at 63 micrograms ml-1 air, indicative of fungicidal action. The third group, consisting of cinnamon bark and thyme oils, retarded the growth in a dose of 6.3 micrograms ml-1 air, stopped it in a dose of 63 micrograms ml-1 air, and incompletely suppressed regrowth of the hyphae. Gas chromatographic analysis revealed that vapours of essential oils were absorbed on fungal mycelia and agar medium most abundantly by the first group, followed by the second and third groups, reflecting the volatility of the respective groups. Suppression of the apical growth by vapour contact was ascribed to the direct deposition of essential oils on fungal mycelia, together with an indirect effect via the agar medium absorbed.

Antimicrobial and Antifungal Activity of Volatile Extracts of 10 Herb Species against Glomerella cingulata

“…First, volatile extracts tend to show broader antibacterial, cytotoxic, and antiviral properties than do non-volatile ones (Sivropoulou et al, 1997). Secondly, the antifungal activity of many non-volatile plant extract components is very low (Farag et al, 1989), while the antifungal of volatile components tends to be high (Inouye et al, 2000). Thirdly, volatile components are effective against antibiotic-resistant bacteria because their antibacterial mechanism differs from those of antibiotic agents (Fanaki & EI-Nakeed, 1997).…”

Effect of Sealing and Tween 80 on the Antifungal Susceptibility Testing of Essential Oils

“…GC analysis was performed using a Model 353B Gas Chromatogram (GL Sciences, Tokyo) and the capillary column (HP-Innowax (0.2 mm X 30 m) or DB-5 (0.5 mm X 30 mj). The GC conditions were described already (10). Concentrations of essential oils were estimated from the peak areas of the respective major components using the respective calibration lines.…”

“…A. fumigatus IFM41392 and T. mentagrophytes TIMM 1189 were grown at 27 C on Sabouraud dextrose (Difco) agar slants and 1/10 Sabouraud dextrose agar slants (Takashio medium), respectively, until they were judged to have mature conidia. Then, conidia suspensions were prepared as described (10). A suspension of C. albicans was prepared utilizing the reference procedure reported (18).…”

Evaluation of Antifungal Activity of Some Plant Extracts and their Applicability in Extending the Shelf Life of Stored Tomato Fruits

“…The same concentrations of oregano essential oil were prepared by dissolving the requisite amounts in 25 mL of 0.05% Tween-80 and then mixing with 475 mL of sterile distilled water. The control sets were prepared similarly using equal amounts of sterilized water in place of the essential oil [6]. Tomatoes were dipped into the solutions (rosemary or oregano essential oil) for 1 min at room temperature (~ 25°C) and air dried.…”

“…Recently, medicinal plants and their extracts have gained importance as potential antimicrobial agents because they are generally assumed to be more acceptable and less hazardous than synthetic compounds [2]. Numerous studies have documented the antifungal properties of plant products [5][6][7][8][9][10][11][12][13]. In in vivo studies, emulsions of oils of thyme and oregano at 5000 ppm and 10000 ppm as dip treatments reduced disease development in tomatoes inoculated with Botrtytis cinerea and Alternaria arborescens [14].…”