Filamentous fungi produce a multitude of secondary metabolites, some of them known as mycotoxins, which are toxic to vertebrates and other animal groups in low concentrations. Among them, penitrems, which belong to the group of indole-diterpene mycotoxins, are synthesized by Penicillium and Aspergillus genera and exhibit potent tremorgenic effects. This is the first complex study of the penitrems A–F production under the influence of different abiotic factors, e.g., media, incubation time, temperature, pH, light, water activity, and carbon and nitrogen source as well as oxidative and salt stress. For this purpose, penitrems A–F were isolated from Penicillium crustosum cultures and used as analytical standards. Among the carbon sources, glucose supplemented to the media at the concentration of 50 g/L, showed the strongest inducing effect on the biosynthesis of penitrems. Among nitrogen sources, glutamate was found to be the most favorable supplement, significantly increasing production of these secondary metabolites. CuSO4-promoted oxidative stress was also shown to remarkably stimulate biosynthesis of all penitrems. In contrast, the salt stress, caused by the elevated concentrations of NaCl, showed an inhibitory effect on the penitrem biosynthesis. Finally, cheese model medium elicited exceptionally high production of all members of the penitrems family. Obtained results give insides into the biosynthesis of toxicologically relevant penitrems A–F under different environmental factors and can be utilized to prevent food contamination.

The genus Stachybotrys produces a broad diversity of secondary metabolites, including macrocyclic trichothecenes, atranones, and phenylspirodrimanes. Although the class of the phenylspirodrimanes is the major one and consists of a multitude of metabolites bearing various structural modifications, few investigations have been carried out. Thus, the presented study deals with the quantitative determination of several secondary metabolites produced by distinct Stachybotrys species for comparison of their metabolite profiles. For that purpose, 15 of the primarily produced secondary metabolites were isolated from fungal cultures and structurally characterized in order to be used as analytical standards for the development of an LC-MS/MS multimethod. The developed method was applied to the analysis of micro-scale extracts from 5 different Stachybotrys strains, which were cultured on different media. In that process, spontaneous dialdehyde/lactone isomerization was observed for some of the isolated secondary metabolites, and novel stachybotrychromenes were quantitatively investigated for the first time. The metabolite profiles of Stachybotrys species are considerably influenced by time of growth and substrate availability, as well as the individual biosynthetic potential of the respective species. Regarding the reported adverse effects associated with Stachybotrys growth in building environments, combinatory effects of the investigated secondary metabolites should be addressed and the role of the phenylspirodrimanes re-evaluated in future research.

Human protein kinase CK2 is an emerging target for drug design. Overexpression of CK2 is closely related to many types of human cancer. It was shown that elevated levels of CK2 protect tumor cells from apoptosis [1]. Inhibition of CK2 activity can lead tumor cells into apoptosis, whereas viability of healthy cells is not affected [2]. Up till now, one ATP competitive inhibitor of CK2, silmitasertib, is in clinical trials phase II [3]. Here we report on the screening of natural compounds isolated from Stachybotrys chartarum [4]. Twelve phenylspirodrimanes and three triphenylphenols were investigated on inhibitory activity towards CK2 using a CE-based assay [5]. Triphenyl phenolestachybotrychromene C, phenylspirodrimanes stachybotrydial acetate and acetoxystachybotrydial acetate with IC50 ­values of 0.3 µM, 0.7 µM and 1.9 µM, respectively, were identified as potent CK2 inhibitors. Effect of these compounds on the proliferation of breast cancer cells MCF-7 was determined using an EdU assay. For comparison, viability of breast cancer cells MCF-7 as well as lung cancer cells A427 and epidermal cancer cells A 431 was tested using the MTT assay. In particular, acetoxystachybotrydial acetate turned out to be the most active compound. After treatment of MCF-7 cells with 1 µM for 24 h cell proliferation was blocked almost completely (99%), whereas cell viability was decreased only by 63%. Here we describe phenlyspirodrimanes as new class of CK2 inhibitors, among them acetoxystachybotrydial acetate which has proved to be the most potent representative of this series. References Faust M, Montenarh M. Cell Tissue Res 2000; 301:329-340. Ruzzene M, Pinna LA. Biochim Biophys Acta 2010; 1804:499-504. Gowda C et al. Curr Pharm Des 2017; 23:95-107. Gratz A et al. Electrophoresis 2010; 31:634–640. Jagels A et al., Mycotoxin Res. 2018; 34: 179-185.