Lichen metabolites as potential natural products: a review
Lichens, a unique and complex symbiotic association between fungi and photosynthetic partners (algae and/or cyanobacteria), represent a largely underexplored source of bioactive compounds with significant pharmaceutical, nutraceutical, and industrial potential. They produce a diverse array of secondary metabolites such as usnic acid, atranorin, and vulpinic acid, showing antimicrobial, anticancer, antiviral, antioxidant, herbicidal, insecticidal, antipyretic, and anti-inflammatory activities. The structural uniqueness and chemical diversity of lichen derived metabolites, combined with their ecological divergent distribution make them an invaluable reservoir of natural products for commercial exploitation. In recent years, growing global demand for natural therapeutics, ecofriendly cosmetics, and sustainable agricultural products has intensified interest in lichen bioresources as an alternative. This review aims to provide a comprehensive overview of the major classes of lichen metabolites reported during the period from 1986 to 2026, with particular emphasis on their bioactivities, mechanisms of action, and current and potential future applications. Lichens might become “green gold” if contemporary biotechnological tools like microbial fermentation, metabolic engineering, and synthetic biology are combined with high throughput screening methods, green extraction strategies, and government backed entrepreneurial initiatives.