Anti-cancer Evaluation of Depsides Isolated from Indonesian Folious Lichens: Physcia millegrana, Parmelia dilatata and Parmelia aurulenta

Cancer is a serious health burden on global societies. The discovery and development of new
anti-cancer therapies remains a challenging objective. Although it has been shown that lichen secondary
metabolites may be potent sources for new anti-cancer agents, the Indonesian- grown folious lichens,
Physcia millegrana, Parmelia dilatata and Parmeila aurulenta, have not yet been explored. In this study
exhaustive preparative high-performance liquid chromatography was employed to isolate the lichen
constituents with spectroscopic and spectrometric protocols identifying nine depsides 9–17, including
the new methyl 4-formyl-2,3-dihydroxy-6-methylbenzoate 13. The cytotoxicity of the depsides towards
cancer cells was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
(MTT) assay. The results indicated lowest toxicity of the depsides towards human A549 lung cancer
cells. Importantly, the di-depsides (11, 12 and 17) showed greatest toxicity, indicating that these
structures are biologically more active than the mono-depsides against the HepG2 liver cancer, A549
lung cancer and HL-60 leukemia cell lines.
Keywords: Indonesia; lichen; Physcia millegrana; Parmelia dilatata; Parmelia aurulenta; depsides;
anti-cancer