TLC-Bioautographic and LC-MS/MS Detection of Antimicrobial Compounds from Four Semipolar Extracts of Cladonia Species

Abstract

To continue the study of Sumatran lichen, six species of the genus Cladonia were screened for phytochemicals and their antibacterial bioactivity. The procedure included sequential extraction (semi polar solvent), antibacterial activity tests using the agar diffusion method, and microdilution to determine the minimum inhibitory concentration (MIC) value of each extract. The study also involved the thin layer chromatography (TLC)-bioautography method and liquid chromatography-mass spectrometry (LC-MS/MS) analysis (in positive mode), which aimed to provide information about the composition and activity of individual components of the extracts that have an antibacterial effect. The test results indicated that all studied Cladonia lichen semipolar extracts had an antibacterial effect, while five of them had very strong bacterial growth inhibition activity (MIC range values 2.5 to 10 mg/mL). Additionally, the identities of compounds found in lichen with broad inhibition, which include the depside and depsidone groups, were confirmed by LC-MS/MS. Based on existing test data, C. scabriuscula, C. crispata, C. rappii, and C. macilenta are potential antibacterial candidates.