Exploring vitamin D3 profile of epiphytic lichen forming fungi in forest ecosystems: Influence of habitat-dependent ecological variables

Vitamin D is critically important for sustainable human health, and the rising prevalence of deficiency-related diseases has increased interest in natural sources. This study explores the potential of epiphytic lichen-forming fungi, known for their unique metabolites, as a novel biosource of vitamin D₃ for pharmaceutical and nutraceutical applications. Fourteen epiphytic lichen species were collected using a stratified sampling method from four mountainous forests in the Marmara Region of Türkiye. Vitamin D₃ contents of the samples were analysed in relation to six ecological variables: study area layer, stand type, tree species, altitude, aspect, and air humidity and temperature. Extraction methods including maceration, Soxhlet, and supercritical CO₂ techniques were applied, followed by HPLC analysis. Olive oil-based maceration was identified as the most efficient extraction method. One-way ANOVA showed significant associations between vitamin D₃ content and lichen species (p = 0.024), layer, stand, and tree species. Concentrations ranged from 0.6 to 20.33 μg/g, with Bryoria fuscescens, Evernia prunastri, and Pseudevernia furfuracea yielding the highest values. The highest vitamin D₃ levels were detected in Uludağ, especially in coniferous forests dominated by Pinus nigra. The results indicated that forest layer, stand, altitude, and tree species significantly influence vitamin D₃ amounts, while aspect and humidity do not. This is the first study to comprehensively report natural vitamin D₃ content in lichens, filling an important scientific gap and demonstrating their potential as an eco-sustainable resource for vitamin D₃ production