Antimicrobial and toxicological activities of some depsides and depsidones

Abstract

Boustie & Grube, 2005). Depsides and depsidones are the most common secondary products uniquely produced in lichens by the fungal symbiont, amounting to as large as 5-10% of thallus' dry weight. The core structural motif of this acetyl polymalonylderived family of about 700 depsides and depsidones is uniform across thousands of lichen species and generally consists of two phenolic rings with various substituents, joined by ester and/or ether linkages. Depsides and depsidones have manifold properties, such as antioxidant, antiviral, antibiotic, antitumor, allergenic, plant growth inhibitory, antiherbivore and enzyme inhibitory activities. There are various reports on the antimicrobial activity of crude lichen extracts. However, studies on antimicrobial activity of lichen compounds are scarce and scattered. A correlation between phenolic constituents and antimicrobial activity has been established (Vartia, 1973; Ingolfsdottir et al., 1998; Gulluce et al., 2006; Ranković et al., 2007 a, b). The antimicrobial activity of some common depsides, namely, atranorin (1), lecanoric acid (2), erythrin (3), the meta-depside sekikaic acid (4), the depsidone lobaric acid (5) and mononuclear aromatic compounds methyl orsellinate (6) and methyl-borcinolcarboxylate (7) (Figure 1) were tested against six human and plant pathogenic bacteria and fungi in vitro to evaluate their medical efficacy as pharmacophores. In addition, toxicological studies of lichen metabolites (1)-(7) (Table 1) were carried out using brine shrimp cytotoxicity assay. METHODS AND MATERIALS General experimental: Medium pressure liquid chromatography (MPLC) was employed with accelerating

Chemical composition and bioactive properties of the lichen, <i>Pleurosticta acetabulum</i >

“…Manojlović et al [5] reported about the antimicrobial activity of salazinic and protocetraric acids. Also, strong antimicrobial activity was found for atranorin [18,19].…”

Antifungal activity of <i>Parmotrema tinctorum</i> (Delise ex Nyl.) hale and <i>Parmotrema cristiferum</i> (Taylor) hale against seed mycoflora - A comparative study

“…lecanoric acid and orsellinic acid were present in P. tinctorum while salazinic acid and con-salazinic acid were present in P. cristiferum. It is shown from earlier studies that lichen metabolites such as atranorin (Goel et al, 2011), lecanoric acid (Thadhani et al, 2012), salazinic acid (Candan et al, 2007;Goel et al, 2011) exhibit antimicrobial activity. In the present study, the observed antifungal potential of P. tinctorum and P. cristiferum to inhibit seed-borne fungi could be ascribed to the presence of these metabolites.…”

“…Among the metabolites, depsides and depsidones are most common. Studies have shown that extracts and purified metabolites from lichens exhibit diverse biological activities Molnár and Farkas, 2010;Goel et al, 2011;Thadhani et al, 2012;Shrestha and St. Clair, 2013;Babiah et al, 2014). Parmotrema A. Massal.…”

A review of studies on bioactive compounds isolated from Sri Lankan flora

“…Methanolyis of lecanoric acid isolated from Cladonia sp., H. obscurata and P. grayana, has yielded the mononuclear aromatic compound methyl orsellinate ( Figure 16), which exhibited a moderate antibacterial activity against E. coli, B. subtillus and S. typhi (Thadani et al, 2012). ( Figure 19), isolated from the stem bark of Garcinia mangostana L., has been found to be active against vancomycin resistant Enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA) with MIC values of 6.25 and 6.25 to 12.5 µg/mL, respectively.…”