Lichen Depsidones with Biological Interest

Abstract

Depsidones are some of the most abundant secondary metabolites produced by lichens. These compounds have aroused great pharmacological interest due to their activities as antioxidants, antimicrobial, and cytotoxic agents. Hence, this paper aims to provide up-to-date knowledge including an overview of the potential biological interest of lichen depsidones. So far, the most studied depsidones are fumarprotocetraric acid, lobaric acid, norstictic acid, physodic acid, salazinic acid, and stictic acid. Their pharmacological activities have been mainly investigated in in vitro studies and, to a lesser extent, in in vivo studies. No clinical trials have been performed yet. Depsidones are promising cytotoxic agents that act against different cell lines of animal and human origin. Moreover, these compounds have shown antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungi, mainly Candida spp. Furthermore, depsidones have antioxidant properties as revealed in oxidative stress in vitro and in vivo models. Future research should be focused on further investigating the mechanism of action of depsidones and in evaluating new potential actions as well as other depsidones that have not been studied yet from a pharmacological perspective. Likewise, more in vivo studies are prerequisite, and clinical trials for the most promising depsidones are encouraged.

Antioxidant, Cytotoxic, and Rheological Properties of Canola Oil Extract of Usnea barbata (L.) Weber ex F.H. Wigg from Călimani Mountains, Romania

“…Thus, from the depsides group, atranorin shows antimicrobial, anti-proliferative, cytoprotective, anti-inflammatory, and antioxidant activities [ 26 ]; lecanoric acid has antimicrobial [ 27 ], anti-proliferative [ 28 ], and antioxidant [ 29 ] effects; diffractaic acid shows analgesic-antipyretic [ 23 ], hepatoprotective [ 30 ], antimycobacterial [ 31 ], cytotoxic, and anti-proliferative action [ 32 ]. Depsidone’s representatives (norstictic, connorstictic, stictic, salazinic, and lobaric acid) have proven antioxidant, antimicrobial, and antitumor properties [ 33 ]. It has been reported that major U. barbata secondary metabolites have antioxidant potential [ 34 ].…”

Protocetraric and Salazinic Acids as Potential Inhibitors of SARS-CoV-2 3CL Protease: Biochemical, Cytotoxic, and Computational Characterization of Depsidones as Slow-Binding Inactivators

“…Lichens produce a wide variety of secondary metabolites with most being synthesized by the mycobiont [27]. Approximately 1050 secondary compounds have been identified [30].…”

“…In this study, we investigated protocetraric acid and salazinic acid (Figure 1), two compounds belonging to the class of depsidones, some of the most abundant lichen secondary metabolites [30]. Depsidones are biosynthesized from depsides, which are themselves formed by the condensation of two or more hydroxybenzoic acids where the carboxyl group of one molecule is esterified with a phenolic hydroxyl group of a second molecule [29].…”

“…Depsidones are lichen secondary metabolites biosynthesized from two or more hydroxybenzoic acids [29]. This class of compounds has shown antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi, cytotoxic activity against several neoplastic cell lines, and in vitro and in vivo antioxidant properties [30][31][32]. It has also been demonstrated that some depsidones can interact with the SOS response system in human pathogenic bacteria by inhibiting bacterial recombinase RecA [30,33].…”

The Genus Cetraria s. str.—A Review of Its Botany, Phytochemistry, Traditional Uses and Pharmacology

“…crispiformis [ 89 ]. Among these metabolites, usnic, fumarprotocetraric, protocetraric, and protolichesterinic acids stand out for their potential biological applications [ 13 , 90 , 91 , 92 ].…”