Biology subjects

Dudek, B.

Publications and source records attributed to Dudek, B..

5 recordsLinked to original sources

bioRxiv2025

Isoquinoline Alkaloids from Traditional Medicinal Plants of the Papaveraceae as a Third Line of Defense Against Bacterial Ocular Infections

There is an evident need for novel ophthalmic therapeutics that operate outside the conventional antibiotic and chemically synthetized antiseptic paradigms. Medicinal plants represent a chemically rich and cost-effective source of bioactive compounds, though their use requires careful toxicological assessment. In this study, extracts from four Papaveraceae species - Chelidonium majus (roots), Corydalis cheilanthifolia (aerial parts and roots), Glaucium flavum (aerial parts and roots), and Fumaria officinalis (herb) - were investigated across three experimental levels: in silico, in vitro, and in vivo, using the Galleria mellonella larval model. Chemical profiling identified several isoquinoline alkaloids, including berberine, coptisine, protopine, chelidonine, allocryptopine, glaucine, and tetrahydropalmatine. In silico assessment suggested low systemic toxicity but possible blood-brain barrier permeability for some compounds. In vitro antimicrobial testing against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 15442, performed using broth microdilution and bacterial-cellulose-based diffusion assays, demonstrated moderate but reproducible activity, particularly for Ch. majus and C. cheilanthifolia extracts. Cytotoxicity testing on fibroblast cell lines showed no significant toxicity in applied concentrations. In vivo testing showed that all extracts, except C. cheilanthifolia (herb_1) and Ch. majus (root) were virtually non-lethal to larvae, indicating a favorable safety profile. To evaluate their suitability for ocular application, wettability tests were performed using commercial tear substitute formulations. The incorporation of the C. cheilanthifolia_herb2 extract at bactericidal concentrations did not alter these physicochemical properties. Overall, the Papaveraceae extracts demonstrated moderate antibacterial activity and low cytotoxicity in an ophthalmologically relevant concentrations, supporting their potential use as adjuvant components in eye drop formulations - enhancing therapeutic efficacy, reducing required antiseptic dosage, and potentially lowering the risk of resistance development.

microbiology↗

bioRxiv2025

Establishing Essential Oil Stewardship Through the Case of Rosemary and Thyme Oils Against Staphylococcus aureus

Essential oils (EOs) have long been studied for their antimicrobial properties, yet most investigations rely on simplistic models, limited strain panels, and anecdotal interpretations - failing to meet the standards expected of modern anti-infective agents. Advancing beyond this tradition, we implement a framework developed over several years of systematic investigation. Using this approach, we assessed the antibiofilm activity of Rosmarinus officinalis L. and Thymus vulgaris L. EOs against a panel of clinical Staphylococcus aureus isolates obtained from non-healing wounds. By applying infection-relevant conditions, such as wound-mimicking media and surfaces, strain-level resolution, and both contact and volatile exposure, we revealed substantial inter-strain variability in susceptibility, challenging the notion of EOs as uniformly effective agents. This variability was quantified using robust statistics, lending confidence to the reproducibility and translational relevance of the findings. These results underscore the need for Essential Oil Stewardship: a reproducible, interdisciplinary framework for EO testing, interpretation, and clinical translation. Our work demonstrates that such approach is feasible and sets the foundation for its broader adoption. The key message from this study is that EOs cannot meaningfully support or complement antibiotics and antiseptic agents in combating infections unless they are evaluated with the same methodological rigor.

microbiology↗

bioRxiv2025

Toward Essential Oil Stewardship Strain-Resolved Evaluation of Thyme Oil Activity Against Pseudomonas aeruginosa

AbstractThe rising interest in essential oils (EOs) as antimicrobial agents demands evaluation frameworks that move beyond anecdotal efficacy and toward structured, reproducible assessment. In this study, we examined the strain-dependent response of Pseudomonas aeruginosa to Pharmacopoeia-grade Thyme Essential Oil (TEO) or polyhexamethylene biguanide antiseptic (PHMB), using a panel of ten genetically diversified strains in planktonic and biofilm form and by complementary in vitro models. Despite uniform test conditions, we observed striking inter-strain variability: TEO Minimal Inhibitory Concentrations (MICs) differed by up to 1000-fold, and biofilm susceptibility profiles ranged from full tolerance to near-complete eradication. Notably, strains with low metabolic activity and sparse cell populations--but high matrix biomass--exhibited reduced responsiveness to TEO, while susceptibility to PHMB was more consistent, though not absolute. These findings highlight the critical influence of both microbial phenotype and agent formulation on antimicrobial outcomes. Rather than framing EOs as superior or inferior alternatives, our results advocate for their integration into a stewardship paradigm--one that values standardization, model-based evaluation, and informed formulation. In this context, we position essential oil stewardship not as a constraint, but as a necessary evolution for their credible inclusion in antimicrobial strategies.

microbiology↗

bioRxiv2024

No Miracle, Just a Mineral: The Not-So-Magical Antimicrobial World of Chlorine Dioxide

This study evaluates the in vitro antimicrobial efficacy and cytotoxicity of acidified sodium chlorite (ASC), a source of chlorine dioxide. Despite its controversial promotion in alternative medicine as a cure-all solution, known as "Miracle Mineral Solution" (MMS), the data on its factual medicinal activity is very limited. Therefore, we aimed to elucidate the activity of ASC against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, Streptococcus mutans, Pseudomonas aeruginosa, Escherichia coli, and Lactobacillus sp. The study also investigated the in vitro cytotoxic effects of ASC towards eukaryotic fibroblasts and in in vivo model of Galleria mellonella larvae. Our findings demonstrate that these concentrations of ASC which can effectively eradicate biofilms, also pose potential health risks due to their in vitro and in vivo cytotoxicity. It implies that ASC applied in human can lead to damage to the mucous membrane of the gastrointestinal tract. This research contributes to the ongoing debate on the safety and efficacy of chlorine dioxide in clinical applications, highlighting the need for precise dosing to avoid mucosal damage in therapeutic contexts.

microbiology↗

bioRxiv2021

The processing of staphylococcal biofilm images from Fluorescence and Confocal Microscopy to assess in vitro efficacy of antiseptic molecules

The staphylococcal biofilms are major causative factors of non-healing wound infections. Their treatment algorithms recommend the use of locally applied antiseptic agents to counteract the spread of infection. The efficacy of antiseptics against biofilm is assessed in vitro by a set of standard quantitative and semi-quantitative methods. The development of software for image processing allowed to obtain quantitative data also from microscopic images of biofilm dyed with propidium iodine and SYTO-9 reagents, differentiating dead cells from the live ones. In this work, the method of assessment of the impact of antiseptic agents on staphylococcal biofilm in vitro, based on biofilms processed images, was proposed and scrutinized with regard to clinically-relevant antiseptics. Taking into account the fact that in vitro results of the efficacy of antiseptic agents against staphylococcal biofilm are frequently applied to back up their use in hospitals and ambulatory units, our work should be considered an important tool providing reliable, quantitative data with this regard.

microbiology↗