Dokument

Summary:
Allium species like garlic (Allium sativum) and kitchen onion (Allium cepa) have been used since ancient times as vegetable, spice and remedy for different diseases. For these purposes, usually their bulbs and green plant are of interest. Wild Allium species have also been used in a similar manner. The antimicrobial activity of these plants is believed to be related to their allicin content, other thiosulfinates, and their sulphuric transformation products. In this thesis, we investigate antifungal activities of 51 Allium spp. belonging to 9 subgenera against 4 plant pathogenic fungi and 3 human pathogens (dermatophytes). The plant pathogenic fungi under considerations are Mucor hiemalis, Aspergillus flavus, A. niger and Penicillium italicum. The investigated human pathogens are Epidermophyton floccosum, Cryptococcus neoformans and Basidiobolus ranarum. To this end, we test dilution series of ethyl acetate extracts obtained from Allium bulbs on the above-mentioned fungi using three different methods as (i) potato dextrose agar (PDA) micro-dilution susceptibility testing, (ii) disk diffusion method, and (iii) double-dish chamber method. We show that among the tested Allium samples, A. sativum from the subgenus Allium, with the total average MIC of 0.25mg/mL, represents the highest anti-fungal activity against all the tested human and plant pathogenic fungi. In addition, our investigation reveals that A. stipitatum belonging to the subgenus Melanocrommyum with a total average minimum inhibitory concentration of 0.55mg/mL exhibits a significant effect towards all the pathogens. We also show that E. floccosum has the highest susceptibility, while P. italicum demonstrates greater resistance towards Allium extracts and miconazole. Our results indicate that extractions of Allium spp. have antifungal activity and might be promising not only in ‘biological’ treatment of fungal-associated plant diseases, but also as natural remedies in order to cure fungal skin infections. The effect seems to be partially related to volatile sulphur compounds, and other compounds like saponins and flavonoids must be considered.

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