Abstract
Plants usually produce many secondary metabolites with antifungal and microbicide activity. 1 They would be the best source for obtaining a variety of drugs and a possible way to treat diseases caused by multi–drug-resistant microorganisms. 2 Some medicinal plants exert strong antifungal properties and could be conveniently used as a promising alternative source for presently problematic antifungal treatment in many areas with respect to their natural origin. 3 Furthermore, multiplication by in vitro culture is a very important methodology to obtain a great number of homogeneous plants in a short period of time, and an important system to optimize and increase the secondary metabolites production. Thus, Thymus mastichina and Mentha rotundifolia were micropropagated for evaluation of antifungal capacity.
The effect of four different concentrations (5, 10, 20, and 25 mg/mL) of extracts from Thymus and Mentha plants was tested against Aspergillus fumigatus, by the method of mycelial growth. 4 Antifungal activity was assayed on the third, fifth, and seventh day. The mold was grown on potato dextrose agar, and a mycelial disk of 4 mm diameter of the test A. fumigatus taken from 4-day-old fungi culture was placed at the center of the medium. Radial growth of colonies was measured at two points along the diameter of the plate, and the mean of these two readings was taken as the diameter of the fungal colony. After incubation at 25°C in darkness, growth zones were measured. The growth of the colonies in control sets was compared with various treatments and the difference was converted into percent inhibition [(C − T)×100/C], where C and T are the radial diameters of the colony in control and treatment, respectively. The percentage of A. fumigatus growth inhibition is expressed as a mean of three replicate tests for each treatment.
One-way analysis of variance followed by Tukey's test with P=.05 were used to detect significant differences in inhibition fungi.
Our results showed that extracts from Thymus and Mentha may be particularly useful against A. fumigatus. T. mastichina exhibited antifungal activity against the tested fungus at two different concentrations, 20 and 25 mg/mL. The highest antifungal activity was exhibited at 25 mg/mL in Thymus. No enhancing effect was observed for the Mentha extract against A. fumigatus at higher concentrations.
There is little information about Thymus and Mentha and their derivatives in the fungal cell which promote the fungistatic or fungicide effect. 5 Considering the fact that in vitro results cannot be directly extrapolated to ex vitro effects suggests that the use of plant extracts such as Thymus and Mentha against Aspergillus sp. has potential as a topical antifungal agent, as they offer a cheap and effective module for therapeutic and/or preventive purposes.
Our concern is the first time that antifungi activity was evaluated in Thymus and Mentha plants obtained by in vitro culture.