Herbal Extracts Reduce Bacterial Adhesion in Respiratory Pathogens

Two phytoneering extracts, BNO 1016 and BNO 1030, demonstrated strain-specific anti-adhesive activity against typical respiratory pathogens in an experimental study published in Clinical Phytoscience. The research evaluated how these herbal preparations influence the initial attachment of bacteria and fungi to human erythrocytes, a critical step in the development of bacterial biofilms. Biofilms are complex structures that complicate the treatment of chronic upper respiratory tract infections, such as rhinosinusitis and tonsillitis, by providing a protective matrix that enhances resistance to antibiotics and immune responses. By targeting the adhesion phase, the study aimed to identify potential mechanisms by which these extracts may limit early microbial colonization and reduce the biomass available for biofilm formation.

The study was conducted at the Department of Microbiology, Virology and Immunology of Ivano-Frankivsk National Medical University. It utilized clinical isolates obtained from the nasopharynx of seven patients diagnosed with acute rhinosinusitis and acute tonsillitis. The microbial strains included Staphylococcus aureus, Staphylococcus epidermidis, two strains of Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus dysgalactiae ssp. equisimilis, and Candida albicans. Identification of these pure cultures was performed using morphological, cultural, and biochemical characteristics, supported by VITEK 2 test systems. The study protocol was approved by the Bioethics Committee of the university, and written informed consent was obtained from all participants prior to inclusion.

The experimental design employed a human erythrocyte adhesion model to simulate the interaction between pathogens and host cells. The extracts BNO 1016, known commercially as Sinupret Extract, and BNO 1030, known as Imupret, were applied at a 1:5 dilution to reflect the expected dilution by mucosal secretions in vivo. BNO 1016 is a dry combined extract containing five medicinal plants, including primrose flowers, verbena herb, elderberry flowers, sorrel herb, and gentian root. BNO 1030 is an aqueous extract consisting of seven medicinal plants, such as marshmallow root, chamomile flowers, horsetail herb, walnut leaves, yarrow herb, oak bark, and dandelion herb. Both products are manufactured by Bionorica SE and are registered in Ukraine for the treatment of upper respiratory tract diseases.

Adhesion was quantified using three specific metrics: the average adhesion index (AAI), the adhesion coefficient (AC), and the microbial adhesion index (MAI). AAI reflects the average number of microbial cells attached to the surface of one red blood cell. AC represents the percentage of red blood cells that have at least one adherent microorganism. MAI is an integral indicator calculated by dividing AAI by AC and multiplying by 100, providing a comprehensive measure of adhesion intensity that accounts for both the number of adherent cells and the proportion of cells involved in the process. Microscopic evaluation was performed using Romanowsky–Giemsa staining, with at least 100 erythrocytes evaluated per sample to ensure statistical robustness.

The results indicated that BNO 1016 significantly reduced AAI and MAI in several strains, including S. aureus, S. pyogenes, S. dysgalactiae ssp. equisimilis, S. epidermidis, and C. albicans. For S. aureus, the AAI decreased from 1.82 to 1.42, and the AC dropped from 88 to 80. In S. pyogenes, the AAI fell from 3.30 to 1.78, while the AC decreased from 92 to 76. However, BNO 1016 showed no significant inhibitory effect on either strain of S. pneumoniae, suggesting that pneumococci may possess intrinsic resistance to this specific anti-adhesive modulation. The reduction in MAI for S. epidermidis was notable, decreasing from 3.28 to 2.09, despite no significant change in AAI or AC, indicating a shift in adhesion intensity patterns.

BNO 1030 exhibited a more selective anti-adhesive profile. It significantly decreased AAI and MAI in S. epidermidis, S. dysgalactiae ssp. equisimilis, S. pneumoniae (M), and C. albicans. For S. epidermidis, the AAI dropped from 2.56 to 2.00, and the MAI decreased from 3.28 to 2.17. In S. dysgalactiae ssp. equisimilis, the MAI reduction was substantial, falling from 3.20 to 2.27. Unlike BNO 1016, BNO 1030 did not significantly alter the AC for any of the tested strains, with values remaining statistically unchanged from control levels. No inhibitory effect was observed for S. aureus or S. pneumoniae (H) with BNO 1030, highlighting the strain-specific nature of the extract’s activity.

The degree of MAI suppression varied across the different pathogens. BNO 1016 demonstrated the highest suppression against S. epidermidis, with a 36.3% reduction in MAI, followed by S. pyogenes at 34.8%. BNO 1030 showed a 33.8% reduction in MAI for S. epidermidis and a 29.1% reduction for S. dysgalactiae ssp. equisimilis. Both extracts exerted weak but detectable effects on C. albicans, with BNO 1030 showing a slightly higher suppression rate of 9.8% compared to 7.3% for BNO 1016. The lack of effect on S. pneumoniae (H) by both extracts suggests that this strain may utilize adhesion mechanisms that are not targeted by the active components in these phytocomplexes.

The study’s findings are consistent with the hypothesis that herbal preparations may influence the pathogenesis of chronic upper respiratory tract infections by interfering with the initial stages of biofilm formation. Biofilm formation involves four main stages: cell adhesion, microcolony formation, biofilm maturation, and dispersion. By reducing adhesion, these extracts may limit the establishment of microcolonies, thereby preventing the development of mature biofilms that are resistant to conventional therapies. The use of clinically relevant isolates from patients with acute rhinosinusitis and tonsillitis adds ecological validity to the findings, as these strains represent the actual pathogens encountered in clinical practice.

Limitations of the study include the small number of strains tested and the use of in vitro models that do not fully replicate the complex interactions between microorganisms, the immune system, and the host microbiota in vivo. The study evaluated only three adhesion parameters and did not investigate the molecular mechanisms underlying the anti-adhesive effects, such as changes in adhesin expression or quorum sensing. Furthermore, the absence of a pharmacological positive control limits the ability to compare the efficacy of these extracts with established anti-biofilm agents. The 1:5 dilution was chosen to mimic in vivo conditions, but the actual concentration at the site of infection may vary depending on local secretions and application methods.

Future research should expand the range of microorganisms to include multidrug-resistant strains and anaerobic flora, which are often involved in chronic biofilm infections. Molecular characterization of the mechanisms of action is needed to understand how these phytopreparations interfere with cell-cell binding interactions. Investigating the synergy of herbal medicines with antibiotics or probiotics could provide insights into combination therapies that enhance therapeutic effectiveness and reduce the risk of relapse. The current findings support the potential role of BNO 1016 and BNO 1030 in the phytotherapeutic management of upper respiratory tract infections, particularly in contexts where biofilm formation contributes to treatment resistance.

The study underscores the importance of considering adhesion as a target for therapeutic intervention in chronic respiratory infections. While the extracts showed variable effects across different species, the consistent reduction in MAI for several key pathogens suggests a meaningful impact on the initial biomass available for biofilm development. As the prevalence of multidrug-resistant bacteria continues to rise, exploring alternative therapeutic options that target biofilm formation becomes increasingly relevant for clinical practice.

Subject of Research: The effect of phytoneering extracts BNO 1016 and BNO 1030 on the adhesion of typical respiratory pathogens: an experimental study

Article Title: The effect of phytoneering extracts BNO 1016 and BNO 1030 on the adhesion of typical respiratory pathogens: an experimental study

Article References: Vasyl, P., Rоman, K., & Ivanna, K. (2026). The effect of phytoneering extracts BNO 1016 and BNO 1030 on the adhesion of typical respiratory pathogens: an experimental study. Clinical Phytoscience, 12(1), Article 3. https://doi.org/10.1186/s40816-026-00419-3

Image Credits: AI Generated

DOI: 10.1186/s40816-026-00419-3

Keywords: effect, phytoneering, extracts, adhesion, typical, respiratory, pathogens, experimental, scientific research