Fungal infection with opportunistic fungi can cause a serious problem for immunocompromised persons such as organ-transplant recipients, cancer, and HIV/AIDS patients. Control of these organisms using natural products is an interesting strategy to avoid the use of heavy chemotherapy in patients.

This study aimed to use the extract of Forsskaolea tenacissima L. and Xanthium spinosum L. to suppress the growth of Candida albicans and Geotrichum candidum and to investigate their potential mode of action.

Different plant extracts were tested for their antifungal activity using disc diffusion method and their mode of action was explored using the scanning electron microscopy (SEM) and gas chromatography-mass spectrometry (GC-MS).

The results showed that chloroform extract of X. spinosum was the most effective against G. candidum, inhibiting its growth at very low concentration (38μg/mL). Chloroform extract of F. tenacissima was the most effective against C. albicans, with a minimum inhibitory concentration of 39μg/mL. SEM demonstrated the fungitoxicity of the plant extracts against both pathogens. C. albicans treated with plant extract were invaginated and ruptured and the treated mycelia of G. candidum were distorted and squashed. GC-MS analysis showed that the chloroform extract of both plants had 13 different compounds.

Due to these promising results, these extracts should be further investigated and tested on different strains of C. albicans and G. candidum towards validation of their efficacy as a natural drug.