Antifungal activity of oxidative damaging agents in combination with metal cations against Trichophyton rubrum isolated from a dermatological patient

Abstract

Trichophyton rubrum is a causative agent responsible for human chronic dermatophytosis worlwide. It is a common causative agent of the dermatophyte infections and resistant to many antifungal drugs. Oxidative damaging agents belong to a strong antimicrobial group and have been intensively investigated. The synergistic oxidative damage can occur if the agents react with metal cations. Therefore, in this study the antifungal activity of formulas containing the two oxidative damaging agents, including hydrogen peroxide (H₂O₂) and 8-hydroxyquinoline (8HQ), in combination with metal cations has been determined to examine the synergistic damage in T. rubrum isolated from the skin of a dermatological patient. The isolate was identified by morphology observations, biochemical tests and sequence analysis of ITS1-4 gene, in comparison with the similar ITS nucleotide sequences of others. The obtained results showed that the isolated fungal strain had physiological and biochemical characteristics of T. rubrum with more than 99% identity of the T. rubrum CBS 392.58 ITS sequence with OL347577 accession numbers. The antifungal tests indicated that the combinations of 2 mM Cu²⁺ + 0.05% H₂O₂; 2 mM Cu²⁺+ 0.005% 8HQ; 2 mM Cu²⁺ + 0.005% 8HQ + 0.05% H₂O₂ exerted the best antifungal activity against the isolated T. rubrum with the diameter of inhibition zones of 22, 25 and 28 mm, respectively. Among the combinations containing Zn²⁺, the only formula of 2 mM Zn²⁺ + 0.05% H₂O₂ exhibited the desired effect, while the combinations containing Fe²⁺ did not show any activity. Thus, our study suggested a potential use of Cu²⁺ + 0.05% H₂O₂; 2 mM Cu²⁺+ 0.005% 8HQ and 2 mM Cu²⁺ + 0.005% 8HQ + 0.05% H₂O₂ formulas as new potential antifungal agents against T. rubrum due to their synergistic oxidative damage.