Biology subjects

Junka, A. F.

Publications and source records attributed to Junka, A. F..

4 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↗

bioRxiv2023

Chronic Wound Milieu Challenges Essential Oils' Antibiofilm Activity

The treatment of infected non-healing wounds poses a significant challenge to contemporary medicine. Essential oils (EOs) are being increasingly investigated as potential antibiofilm agents for the management of biofilm-related wound infections. However, their in vitro antimicrobial activity reported in literature does not necessarily reflect the actual in vivo activity due to, among others, methodological imperfections of performed tests. In our study, we cultivated a Staphylococcus aureus biofilm in a novel IVWM (In Vitro Wound Milieu) medium designed to simulate the wound environment and compared it with biofilms cultured in the standard microbiological Tryptic Soy Broth (TSB) medium. We examined and compared critical biofilm properties such as morphology, biomass, metabolic activity, cell count, thickness, and spatial distribution of live and dead cells. Subsequently, staphylococcal biofilms and planktonic cells cultured in both media were exposed to the activity of thyme or rosemary EOs (T-EO, R-EO, respectively). We found that morphology of biofilms cultured in IVWM resembled more the morphology of biofilms visualized in the non-healing wounds than biofilms cultured in TSB. The biomass, metabolic activity, cell number, and the ratio of live to dead cells of S. aureus biofilms were all lower in IVWM compared to the TSB medium. Additionally, while EOs demonstrated overall significant anti-staphylococcal activity, their efficacy varied depending on the medium used. Generally, EOs displayed lower antimicrobial activity (against planktonic cells) in the IVWM than in the TSB medium. Interestingly, T-EO caused a higher reduction of biofilm cells in IVWM than in the TSB medium, in contrast to R-EO. Our findings suggest that EOs hold promise as agents for the treatment of biofilm-related wound infections. However, it is crucial to apply in vitro conditions that closely reflect the wound infection site to gain an accurate insight into the real-world activity of these antimicrobial/antibiofilm agents.

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↗