The antifungal effect of milk thistle (Silybum marianum) extract: An in vitro study using the agar dilution method
DOI:
https://doi.org/10.31210/spi2026.29.01.19Keywords:
Silybum marianum, milk thistle, antifungal activity, agar dilution method, Candida albicans, Aspergillus nigerAbstract
Silybum marianum, commonly known as milk thistle, is a widely recognized plant for its medicinal properties, especially its hepatoprotective and antioxidant activities, which have been mainly attributed to silymarin. Recently, an increasing number of studies have reported the antimicrobial, including antifungal, activity of milk thistle. This study was designed to examine the antifungal activity of milk thistle extract against two common fungal pathogens, Candida albicans and Aspergillus niger. The crude extract of milk thistle was prepared in three different concentrations (25 %, 50 %, and 100 %), which were directly incorporated into Sabouraud Dextrose Agar (SDA) using the agar dilution method. The results clearly indicated a concentration-dependent inhibition of fungal growth. At a 25 % concentration, moderate inhibition of fungal growth was observed for Candida albicans (35.2±3.1 %), while Aspergillus niger showed minimal inhibition (12.5±2.4 %). At a 50 % concentration, the inhibition increased significantly for both fungal species, with Candida albicans showing 62.8±4.5 % inhibition and Aspergillus niger showing 38.7±3.6 % inhibition. At a 100 % concentration, the maximum growth inhibition was achieved, reaching 85.4±5.2 % for Candida albicans and 64.3 ± 4.8% for Aspergillus niger. Additionally, disk diffusion susceptibility testing confirmed that both the 50 % and 100% extract solutions displayed clear zones of inhibition, categorizing both isolates as sensitive. These results strongly indicate that Silybum marianum possesses substantial inherent antifungal properties. The ability of milk thistle to act as a natural antifungal agent supports its potential application in fields beyond hepatoprotection. Further studies are needed to identify the active antifungal compounds from the crude extract, determine their spectrum of activity against a broader range of fungal pathogens, and assess their possible therapeutic or preservative applications in medicine and agriculture.
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