Powder X-ray diffraction (PXRD) analysis of usnic acid in five selected lichen species from Sri Lanka

Abstract

Cancer remains a global health problem despite the continuous development of anticancer therapies. The discovery of anticancer drugs from diverse natural sources has recently gained a focus. Lichens are a widespread symbiotic association between fungal and photosynthetic partners, and they are known to produce a diverse array of secondary metabolites with promising anticancer effects. Usnic acid (UA), a dibenzofuran derivative, is a key secondary metabolite found only in lichens and has shown anticarcinogenic effects on a variety of human cancer cell types. This study was conducted to investigate the presence of UA in five selected lichen species, which has previously been detected by thin layer chromatography (TLC), using a powder X-ray diffraction data analysis (PXRD) approach. Lichen samples representing Lepraria sp., Physcia sp., Lecanora sp., Parmotrema sp. and Graphis sp. were collected from Peradeniya, Sri Lanka, and crude acetone extracts for PXRD analysis were prepared following a standard protocol.