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 lichenforming 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 Uludag, ˘ 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