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Keywords = placodiolic acid

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22 pages, 3815 KB  
Article
Unravelling Novel Phytochemicals and Anticholinesterase Activity in Irish Cladonia portentosa
by Shipra Nagar, Maria Pigott, Wirginia Kukula-Koch and Helen Sheridan
Molecules 2023, 28(10), 4145; https://doi.org/10.3390/molecules28104145 - 17 May 2023
Cited by 5 | Viewed by 2592
Abstract
Acetylcholinesterase inhibitors remain the mainstay of symptomatic treatment for Alzheimer’s disease. The natural world is rich in acetylcholinesterase inhibitory molecules, and research efforts to identify novel leads is ongoing. Cladonia portentosa, commonly known as reindeer lichen, is an abundant lichen species found [...] Read more.
Acetylcholinesterase inhibitors remain the mainstay of symptomatic treatment for Alzheimer’s disease. The natural world is rich in acetylcholinesterase inhibitory molecules, and research efforts to identify novel leads is ongoing. Cladonia portentosa, commonly known as reindeer lichen, is an abundant lichen species found in Irish Boglands. The methanol extract of Irish C. portentosa was identified as an acetylcholinesterase inhibitory lead using qualitative TLC-bioautography in a screening program. To identify the active components, the extract was deconvoluted using a successive extraction process with hexane, ethyl acetate and methanol to isolate the active fraction. The hexane extract demonstrated the highest inhibitory activity and was selected for further phytochemical investigations. Olivetolic acid, 4-O-methylolivetolcarboxylic acid, perlatolic acid and usnic acid were isolated and characterized using ESI-MS and two-dimensional NMR techniques. LC-MS analysis also determined the presence of the additional usnic acid derivatives, placodiolic and pseudoplacodiolic acids. Assays of the isolated components confirmed that the observed anticholinesterase activity of C. portentosa can be attributed to usnic acid (25% inhibition at 125 µM) and perlatolic acid (20% inhibition at 250 µM), which were both reported inhibitors. This is the first report of isolation of olivetolic and 4-O-methylolivetolcarboxylic acids and the identification of placodiolic and pseudoplacodiolic acids from C. portentosa. Full article
(This article belongs to the Special Issue Bioactive Compounds from Natural Sources II)
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7 pages, 1151 KB  
Article
Mycousfurans A and B, Antibacterial Usnic Acid Congeners from the Fungus Mycosphaerella sp., Isolated from a Marine Sediment
by Jihye Lee, Jusung Lee, Geum Jin Kim, Inho Yang, Weihong Wang, Joo-Won Nam, Hyukjae Choi, Sang-Jip Nam and Heonjoong Kang
Mar. Drugs 2019, 17(7), 422; https://doi.org/10.3390/md17070422 - 19 Jul 2019
Cited by 15 | Viewed by 5218
Abstract
Mycousfurans (1 and 2), two new usnic acid congeners, along with (−)-mycousnine (3), (−)-placodiolic acid (4), and (+)-usnic acid (5), were isolated using high-performance liquid chromatography-ultraviolet (HPLC-UV)-guided fractionation of extracts of Mycosphaerella sp. isolated from [...] Read more.
Mycousfurans (1 and 2), two new usnic acid congeners, along with (−)-mycousnine (3), (−)-placodiolic acid (4), and (+)-usnic acid (5), were isolated using high-performance liquid chromatography-ultraviolet (HPLC-UV)-guided fractionation of extracts of Mycosphaerella sp. isolated from a marine sediment. The planar structures of 1 and 2 were elucidated using 1D and 2D NMR spectra. The relative configurations of the stereogenic carbons of 1 and 2 were established via analysis of their nuclear Overhauser spectroscopy (NOESY) spectra, and their absolute configurations were determined using a comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1 and 2 were found to have antibacterial activity, showing moderate activity against Kocuria rhizophila and Staphylococcus aureus. Full article
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