Preventive Potential and Safety Considerations of Plantago lanceolata: A Narrative Review of Ethnopharmacological and Preclinical Evidence

Abstract

Background: Plantago lanceolata L. (ribwort plantain) is traditionally used for respiratory and wound care. Its main bioactive constituents include iridoids such as aucubin and catalpol, phenylethanoid glycosides such as acteoside and plantamajoside, flavonoids, tannins, and polysaccharides, which have been associated with antioxidant, anti-inflammatory, antimicrobial, and barrier-supporting effects. Aim: This review aims to synthesise ethnopharmacological, phytochemical, preclinical, environmental, and allergological evidence on the preventive potential and safety considerations of P. lanceolata, with particular attention to the distinction between pollen-related allergenic risk and leaf-based medicinal preparations. Methods: A narrative review was conducted using studies indexed in PubMed/NCBI, Web of Science, Scopus, and MDPI journals. Relevant literature on ethnobotany, phytochemistry, antimicrobial and antifungal activity, cytotoxicity, allergenicity, environmental biomonitoring, safety, and standardisation was considered. Results: Leaf extracts of P. lanceolata contain steroids, flavonoids, tannins, saponins, glycosides, and phenolics. Experimental studies report antibacterial and antifungal activity, including effects against Candida albicans and Malassezia spp. Methanolic extracts have shown preliminary in vitro cytotoxic effects against A549 lung cancer cells and enhanced activity of methotrexate or cytarabine, while relatively preserving macrophage viability. Immunoproteomic studies identify multiple IgE-reactive pollen allergens, indicating a clinically relevant respiratory allergy risk mainly related to airborne pollen. The plant may also accumulate environmental pollutants, emphasising the need for controlled sourcing. Conclusion: P. lanceolata shows promising but not yet clinically established preventive potential, particularly for barrier integrity, infection control, and inflammation modulation. Current evidence remains largely ethnopharmacological and preclinical, while direct clinical trials are limited. Translation to practice requires standardised, contaminant-tested, pollen-reduced preparations, dose–response studies, safety evaluation in at-risk groups, clear allergy labelling, and pharmacovigilance. Major Findings: The review highlights the dual relevance of P. lanceolata as a source of bioactive leaf constituents and as a pollen-related allergen. Its preventive use remains promising but preliminary and requires stronger clinical validation and quality control.