https://orcid.org/0000-0002-9117-4713
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Abstract
An extensive phytochemical study of a foliose lichen from Indonesia, Parmelia cetrata, resulted in the successful isolation of 13 phenol and depside derivatives (1–13) including the previously unreported depsides 3′-hydroxyl-5′-pentylphenyl 2,4-dihydroxyl-6-methylbenzoate (7), 3′-hydroxyl-5′-propylphenyl 2,4-dihydroxyl-6-methylbenzoate (8) and 3′-hydroxyl-5′-methylphenyl 2-hydroxyl-4-methoxyl-6-propylbenzoate (9). The anti-infective activity of isolated compounds was evaluated against the gram-negative bacterium Aliivibrio fischeri and the nematode Caenorhabditis elegans. 2,4-Dihydroxyl-6-pentylbenzoate (5) and lecanoric acid (6) induced growth inhibition of A. fischeri with inhibition values of 49% and 100% at a concentration of 100 µM, respectively. The antibacterial activity might be due to their free carboxyl group. A phenolic group at C4 also contributed to the antimicrobial activity of the depsides as shown for compounds 7 and 8, which caused 89% and 96% growth inhibition at 100 µM, respectively. Lecanoric acid (6) in addition possesses significant anthelmintic effects causing 80% mortality of C. elegans at 100 µg/mL.
Graphical Abstract
Acknowledgements
ASN thanks Mr. Aang Yudianto for assisting the field trip to collect the lichen in the high altitude region of Klocing-Bondowoso Indonesia. ASN also thanks the University of Jember and the Leibniz Institute of Plant Biochemistry, Halle (Germany), for research support. Furthermore, the authors acknowledge technical assistance by Gudrun Hahn (NMR), Anke Dettmer (bioassays) and Anja Ehrlich (HPLC).
Disclosure statement
No potential conflict of interest was reported by the author(s).