Antifungal activity of the volatiles of Agathosma betulina and Coleonema album commercial essential oil and their effect on the morphology of fungal strains Trichophyton rubrum and T. mentagrophytes

Abstract

The side effects of skin disease antibiotics and lengthy periods of therapy are major shortcomings of both old and newly developed ranges of antifungals. Hence, there is a need to develop an effective, cheap and readily available antifungal of a natural origin to combat skin diseases. The aim of this study was to investigate the effect of Agathosma betulina and Coleonema album essential oil (EO) on the growth and morphology of two fungal strains (Trichophyton rubrum and T. mentagrophytes) responsible for ringworm, and analyse the components of the EO of both plants. There was inhibition/reduction of fungal growth in all plates exposed to EO volatiles. However, the rates of inhibition varied among the fungal species, EO and different volumes tested. The volatiles from A. betulina EO showed a remarkable inhibitory effect with the highest inhibition recorded at 40μl. The best inhibition was recorded in T. rubrum exposed to volatiles at 40μl of A. betulina EO with a fungal growth index of 2.3%, indicating its ability of strong fungicidal effects. The mode of action of the EO volatiles was elucidated using electron microscopy. The volatiles inhibited fungal growth by inhibiting the production of spores. Agathosma betulina EO (40μl) resulted in the destruction of hyphae and spores of T. rubrum. The major components of the EO of A. betulina were limonene (29.8%), menthone (21.6%), and isomenthone (14.7%), while of C. album were pinene (27.4%), and myrcene (14.5%).