Antibacterial potencial of 12 Lichen species

Abstract

Resistant bacterial infections are a major public health problem worldwide, which entails the need to search for new therapeutic agents. In this context, lichens stand out, provided that they are producers of structurally diverse compounds that have attractive biological properties, including antimicrobial activity. Thus, extracts of 12 lichen species were prepared and their potential to inhibit the growth of 5 bacterial strains was evaluated in this work. The chemical compositions of these extracts were examined using TLC and microcrystallization, being the identity of the active compounds in each extract attributed based on the bioautography technique. The most active extracts (and their identifi ed active compounds) were from Cladonia borealis (usnic, barbatic and 4-O-demethylbarbatic acids), Cladina confusa (usnic and perlatolic acids), Stereocaulom ramulosum (atranorin, perlatolic and anziaic acids) and Canoparmelia cryptochlorophaea (cryptochlorophaeic and caperatic acids), with MICs ranging from 7.8 to 31.25 μg/mL, including for resistant clinical strains. MIC values were also obtained for substances isolated from lichens for comparison purposes. A group of four extracts containing usnic acid was analyzed by 1 H NMR in order to correlate relative proportion of major metabolites and extracts activity. The less active extracts in this group, in fact, presented low proportion of usnic acid.

In Vitro and in Silico Studies of Lichen Compounds Atranorin and Salazinic Acid as Potential Antioxidant, Antibacterial and Anticancer Agents

“…The activity shown by the isolated compounds is lower than streptomycin but is higher than antibacterial activity reported by others. Micheletti with others were isolated atranorin and salazinic acid from different lichen species and were effective against S. aureus and E. coli ; the MIC value for both lichen compounds ranged from 125–250 μg/mL [10] . The MIC values of the extracts and compounds are given in Table 1.…”

“…Micheletti with others were isolated atranorin and salazinic acid from different lichen species and were effective against S. aureus and E. coli; the MIC value for both lichen compounds ranged from 125-250 μg/mL. [10] The MIC values of the extracts and compounds are given in Table 1.…”

“…Lichens stand out in this situation as they create structurally different compounds with desirable biological properties, such as antibacterial activity. [10] The spread of multiple drug-resistant bacteria has increased and has evolved with antibiotic-resistant factors due to the rigorous and uncontrolled use of antibiotics. [11] Breast cancer is the most frequent cancer among women worldwide.…”

“…Worldwide, resistant bacterial infections are a significant public health issue; this necessitates searching for novel treatment agents. Lichens stand out in this situation as they create structurally different compounds with desirable biological properties, such as antibacterial activity [10] . The spread of multiple drug‐resistant bacteria has increased and has evolved with antibiotic‐resistant factors due to the rigorous and uncontrolled use of antibiotics [11] …”

Lichen Depsides and Tridepsides: Progress in Pharmacological Approaches

“…Barbatic acid showed antiparasitic activity against the adult worms and larval stages of Schistosoma mansoni by causing death (IC 50 value of 99.43 μM), affecting mobility, as was reflected in movements being presented only in the extremities, and triggering tegumentary damage [ 18 , 67 ]. Moreover, this depside was active against Staphylococcus aureus and Enterococcus faecalis (both the commercial and the clinic strains), with MIC values of 7.8 to 31.3 µg/mL [ 68 ]. This compound also displayed molluscicidal activity against Biomphalaria glabrata at 20 and 25 µg/mL [ 67 ].…”