Comparison of the Effect of Amino Acids and Their Derivatives on the Growth of Some Dermatophytes: An In Vitro Study

Amino acids have different effects on the growth of some dermatophytes. Some may increase whereas others maydecrease their growth. The concentration of some amino acids is also an important factor for their effects.
To investigate the effects of L-amino acids on the growth of six species of dermatophytes including Epidermophyton floccosum, Microsporum gypseum, Microsporum canison, Trichophyton rubrum, Trichophyton schoienlinii and Trichophyton verrucosum, two concentrations (1 and 0.1 mg/ml) of the 23 L-amino acids and some of their derivatives were added to sabouraud glucose agar media of these dermatophytes. The experiment was carried out three times. After 3 weeks for Trichophyton verrucosum and Trichophyton schoenleinii, and 2 weeks for the rest of dermatophytes, the mean diameter of each colony was measured and compared with the control whose media was not treated with amino acids.
The results showed the higher inhibitory effects of L-Cysteine hydrochloride, L-Cysteine, L-Aspartic acid, L-Glutamic acid, DL-Tryptophan and L-Tyrosine on the studied dermatophytes. The other amino acids had less inhibitory or even stimulatory effects on the growth of the dermatophytes.
By using the properties of these effective amino acids, antifungal drugs may be synthesized more effective with lower cost and less side effects against different dermatophytes.