The occurrence of fungi on the commercial dietary supplements based on the milk thistle (Silybum marianum (L.) Gaertn.) available on Polish market

Introduction: Milk thistle (Silybum marianum (L.) Gaertn.) is an important medicinal plant, its achenes contain a silymarin, which has a regenerating and stabilizing effect on liver cells. The milk thistle based dietary supplements are among the best-selling plant pharmaceuticals in the US and the UE. Objective: The goal of the experiment was to determine which – if any – fungi contaminated either the whole or ground milk thistle achenes, available on the Polish market. Methods: The mycological analyses were performed on 200 achenes, using deep-freeze blotter method. Ground material was assessed using agar test method. For each sample, 10 Petri dishes were used. The material was applied in five places per one Petri dish, with a micro scoop laboratory spatula. Then, Petri dishes with achenes and ground material were incubated at 20°C under alternating cycles of 12 h NUV light and 12 h darkness. The identification of fungi was performed using stereo microscope and compound microscope, if necessary. Results: The milk thistle achenes were infested with following fungi: Alternaria alternata, Alternaria sp., Aspergillus flavus, Aspergillus spp., Bipolaris sp., Cladosporium spp., Epicoccum nigrum, Fusarium spp., Melanospora simplex, Mucor spp., Penicillium spp., Phoma sp., Rhizopus stolonifer, Sarocladium strictum, Stemphylium botryosum, Trichothecium roseum, Ulocladium consortiale and Verticillium sp. Among them A. alternata predominated. Whereas, milled milk thistle achenes were occupied by Aspergillus flavus, A. niger, Aspergillus spp., Fusarium sp., Mortierella spp., Mucor spp., Penicillium spp. and R. stolonifer. Conclusion: Considering the significant fungal contamination of milk thistle achenes-based dietary supplements, it seems reasonable to introduce a system of achene control due to possible microbiological contamination.