Biology subjects

Stevanoska, M.

Publications and source records attributed to Stevanoska, M..

3 recordsLinked to original sources

bioRxiv2026

Chemical probes reveal individualized gut microbiome biotransformation capacity and the impacts of ex vivo fermentation conditions

The gut microbiome transforms endogenous and exogenous chemicals, contributing to bioactivation or detoxification via the formation of metabolites with altered bioactivity. Most high content microbiome assays infer function from genetic composition rather than direct assessment of biotransformation activity, and it remains difficult to predict functional consequences of environmental factors and experimental variation. Therefore, we developed an anaerobic fecal fermentation workflow that couples targeted LC-MS/MS quantification of dynamic profiles of 20 chemical probes with untargeted metabolomics to profile human microbiome biotransformation capacity and used it to assess the impact of experimental conditions on biotransformation profiles. Across five donors and 240 fermentations, inoculum density and growth medium composition strongly influenced probe transformation rates, whereas the biotransformation capacities of fecal slurries frozen at -80{degrees}C did not differ from fresh fecal samples. Individual donors could be uniquely stratified on the basis of biotransformation profile data in a way that was not recapitulated by 16S rRNA taxonomic structure or predicted functional pathways. Finally, expected biotransformation products and metabolic trends could be confirmed with untargeted metabolomics characterization. This scalable platform directly profiles gut microbial biotransformation activity, supporting wider applications of standardized microbiome functional phenotyping in humans and quantitative models of microbiome-competent biokinetics assessment in pharmacology and toxicology.

microbiology↗

bioRxiv2026

Bidirectional interactions between gut microbiota and fluorochemical biotransformation and bioactivity

Fluorinated chemicals are increasingly prevalent in pharmaceuticals and agrochemicals, yet their influence on the human gut microbiome and the potential for microbial biotransformation to alter therapeutic and toxicological profiles remain poorly understood. Here, we investigated the bidirectional relationship between 15 structurally diverse fluorinated chemicals and the gut microbiota by using an ex vivo high-throughput fermentation system. Screening revealed that flutamide, fluazinam, and pretomanid were consistently biotransformed across the donor microbiomes, while other compounds showed substantial inter-individual variability in degradation. Furthermore, exposure to fluorinated chemicals induced compound-specific shifts in microbial diversity and community composition, demonstrating their capacity to alter gut microbial ecology. Using a computational workflow combining in silico biotransformation predictions with untargeted LC-MS/MS analysis, we identified nitroreduction as the primary gut microbial transformation across all three compounds. Single-strain experiments confirmed that the nitroreduction of flutamide to flu-6, previously attributed only to hepatic metabolism, is a widespread capacity among gut bacterial strains. Finally, in vitro cytotoxicity assays and in silico modelling further revealed flu-6 to be a less hepatotoxic derivative than the parent compound, suggesting a potential detoxifying role for the gut microbiota. Together, these findings establish an integrated ex vivo, in vitro, and in silico approach for assessing the bidirectional interactions between fluorinated chemicals and the gut microbiome.

pharmacology and toxicology↗

bioRxiv2024

Predicting in vivo concentrations of dietary hop phytoestrogens by physiologically based kinetic modeling

Hop extracts containing prenylated polyphenols such as 8-prenylnaringenin (8-PN) and its precursor isoxanthohumol (iXN) are popular among women seeking natural alternatives to hormone therapy for postmenopausal symptoms. Due to structural similarities with estrogens, these compounds act as estrogen receptor agonists. Especially 8-PN, described as the most potent phytoestrogen known to date, poses a potential risk for endocrine disruption. Therefore, its use as a hormone replacement raises concerns for human health. However, a significant challenge in assessing the potential endocrine-disruptive effects of hop polyphenols is the lack of data on their toxicokinetics. Particularly, information on in vivo concentrations in target tissues is lacking. To address this gap, we developed a physiologically based kinetic (PBK) model tailored to female physiology. The model was used to predict the levels of hop polyphenols in human blood and target tissues under realistic exposure scenarios. The predictions suggest that iXN and 8-PN concentrations in target tissues reach the low nanomolar range after dietary supplementation. This study enhances our understanding of the safety profile of hop polyphenols and highlights the need for further research into their use as an alternative to hormone therapy in menopausal women.

pharmacology and toxicology↗