No abstract

Silymarin is a complex of plant-derived compounds obtained from the seed shells of the milk thistle (Silybum marianum). It is used in medicine primarily to protect the liver. The mixture contains mainly flavonolignans, with silybin as a paramount bioactive component of the extract. This article presents the potential health benefits for silymarin as an antifungal drug against five references strains: C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei with MIC (minimum inhibitory concentration) values ranging from 30 to 300 µg/mL. Additionally, this study revealed that the compound suppressed the growth of cells of most of the tested clinical Candida albicans strains with MIC values between 30 and 1200 µg/mL. Based on the fractional inhibitory concentration index (FICI), the combination of silymarin with antifungal drugs caspofungin, fluconazole, and amphotericin B did not significantly change the MIC values for the tested Candida strains. Furthermore, no antagonistic reactions were observed in any combination of drugs. In addition, this substance shows anti-virulence properties including the destabilization of mature biofilm and the inhibition of the secretion of hydrolases. qRT-PCR-based experiments demonstrated that the SAP4 gene involved in virulence was downregulated by silymarin. These results indicate completely new advantages of dietary supplementation with this natural plant extract.

Yarrowia lipolytica as an oleaginous yeast is capable of growing in various non-conventional hydrophobic substrate types, especially industrial wastes. In this study, the content of thiamine (vitamin B1), riboflavin (vitamin B2), pyridoxine (vitamin B6), biotin (vitamin B7) and folic acid (vitamin B9) in the wet biomass of Y. lipolytica strains cultivated in biofuel waste (SK medium), compared to the standard laboratory YPD medium, was assessed. Additionally, the biomass of Y. lipolytica A-101 grown in biofuel waste (SK medium) was dried and examined for B vitamins concentration according to the recommended microbial methods by AOAC Official Methods. The mean values of these vitamins per 100 g of dry weight of Y. lipolytica grown in biofuel waste (SK medium) were as follows: thiamine 1.3 mg/100 g, riboflavin 5.3 mg/100 g, pyridoxine 4.9 mg/100 g, biotin 20.0 µg/100 g, and folic acid 249 µg/100 g. We have demonstrated that the dried biomass is a good source of B vitamins which can be used as nutraceuticals to supplement human diet, especially for people at risk of B vitamin deficiencies in developed countries. Moreover, the biodegradation of biofuel waste by Y. lipolytica is desired for environmental protection.

In the light of the increasing occurrence of antifungal resistance, there is an urgent need to search for new therapeutic strategies to overcome this phenomenon. One of the applied approaches is the synthesis of small-molecule compounds showing antifungal properties. Here we present a continuation of the research on the recently discovered anti-Candida albicans agent 4-AN. Using next generation sequencing and transcriptional analysis, we revealed that the treatment of C. albicans with 4-AN can change the expression profile of a large number of genes. The highest upregulation was observed in the case of genes involved in cell stress, while the highest downregulation was shown for genes coding sugar transporters. Real-time PCR analysis revealed 4-AN mediated reduction of the relative expression of genes engaged in fungal virulence (ALS1, ALS3, BCR1, CPH1, ECE1, EFG1, HWP1, HYR1 and SAP1). The determination of the fractional inhibitory concentration index (FICI) showed that the combination of 4-AN with amphotericin B is synergistic. Finally, flow cytometry analysis revealed that the compound induces mainly necrosis in C. albicans cells.

Since Svf1 is phosphoprotein, we investigated whether it was a substrate for protein kinase CK2. According to the amino acid sequence Svf1 harbours 20 putative CK2 phosphorylation sites. Here, we have reported cloning, overexpression, purification and characterization of yeast Svf1 as a substrate for three forms of yeast CK2. Svf1 serves as a substrate for both the recombinant CK2alpha (Km 0.35 microM) and CK2alpha' (Km 0.18 microM) as well as CK2 holoenzyme (Km 1.1 microM). Different Km values argue that CK2beta(beta') subunit has an inhibitory effect on the activity of both CK2alpha and CK2alpha' towards surviving factor Svf1. Reconstitution of alpha'2betabeta' isoform of CK2 holoenzyme shows that beta/beta' subunits have regulatory effect depending on the kind of CK2 catalytic subunit. This effect was not observed in the case of alpha2betabeta' isoform, which may be due to interaction between Svf1 and regulatory CK2beta subunit (shown by co-immunoprecipitation experiments). Interactions between CK2 subunits and Svf1 protein may have influence on ATP as well as ATP-competitive inhibitors (TBBt and TBBz) binding. CK2 phosphorylates up to six serine residues in highly acidic peptide K199EVIPESDEEESSADEDDNEDEDEESGDSEEESGSEEESDSEEVEITYED248 of the Svf1 protein in vitro. Presented data may help to elucidate the role of protein kinase CK2 and Svf1 in the regulation of cell survival pathways.