A sustainable application for the extraction of lichen metabolites from Usnea cornuta: nontargeted metabolomics and antioxidant activity

Abstract

In this study, isolation and purification of lichen substances from Usnea cornuta were performed using conventional solvents, green solvents and green technologies. In addition, several lichen compounds were tentatively identified by UHPLC/ESI/MS/MS and usnic acid, diffractaic and galbinic acids were quantified as well. Limonene, ethyl lactate and methanol, were compared regarding their extraction properties and antioxidant capacities, determined by DPPH, ORAC, and FRAP assays. In the ethyl lactate, methanol and limonene extracts, 28 compounds in all, were detected for the first time by high resolution UHPLC-MS/MS fingerprinting. Untargeted metabolomics tentatively identified 14 compounds from the methanolic extract, 4 from limonene extract, and 20 metabolites from ethyl lactate extract. The green extract of ethyl lactate showed a similar antioxidant capacity to toxic methanol extract, except at ORAC assay where it was higher. Therefore, ethyl lactate can replace methanol, to provide more sustainable green chemistry methods.

Microwave-Assisted Semisynthesis and Leishmanicidal Activity of Some Phenolic Constituents from Lichens

“…Galbinic acid (5): This compound was isolated from U. cornuta [22]. From 50 g of dry lichen was macerated with methanol (1.2 L) for 24 h. The crude extract was submitted to flash chromatography and then CC using DCM/MeOH mixtures to yield compound 5 (400 mg): 1 H-NMR (DMSO-d 6 , 300 MHz) δ (ppm); 2.47 (3H, s, CH 3 -8), 5.18 (2H, s, CH 2 -9 ), 10.45(1H, s, H-9), 6.89 (1H, s, H-5), 6.82 (1H, s, H-8 ), 8.34 (1H, s, OH-8 ), 12.06 (1H, s, OH-2 ), 1.99 (3H, s, CH3-O) [9].…”

Evaluation of the toxicity profiles of three families of solvents from biomass: levulinate, lactate and furfural derivatives

“…These solvents are obtained from sustainable sources, such as glucose, sucrose, or lignocellulose, by enzymatic processes, esterification, fermentation, 3 or catalysis, [4][5][6] making their use interesting when ecosustainability is a goal. All this has led to a wide and varying range of applications, highlighting their use as antimicrobial agents, 7 food additives, flavoring agents, 8,9 precursors for environmentally friendly plasticizers, 10 adjuvants in transdermal pharmaceuticals, 11 precursors for biologically active natural products, 12 precursors and intermediates in drug synthesis, 8,13 or even as a green solvent in different processes, [14][15][16] among others. In recent years, due to their associated green properties, they have even been used as components of other green solvents such as deep eutectic solvents, further broadening the scope of their applications.…”