Biological Activities of Toninia candida and Usnea barbata Together with Their Norstictic Acid and Usnic Acid Constituents

Abstract

The aim of this study was to investigate the chemical composition of acetone extracts of the lichens Toninia candida and Usnea barbata and in vitro antioxidant, antimicrobial, and anticancer activities of these extracts together with some of their major metabolites. The chemical composition of T. candida and U. barbata extracts was determined using HPLC-UV analysis. The major phenolic compounds in these extracts were norstictic acid (T. candida) and usnic acid (U. barbata). Antioxidant activity was evaluated by free radical scavenging, superoxide anion radical scavenging, reducing power and determination of total phenolic compounds. Results of the study proved that norstictic acid had the largest antioxidant activity. The total content of phenols in the extracts was determined as the pyrocatechol equivalent. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration using the broth microdilution method. The most active was usnic acid with minimum inhibitory concentration values ranging from 0.0008 to 0.5 mg/mL. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using the microculture tetrazolium test. Usnic acid was found to have the strongest anticancer activity towards both cell lines with IC50 values of 12.72 and 15.66 μg/mL.

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

“…The strong antimicrobial activities of evernic and norstictic acids have previously been reported [4,17]. They observed that they both exerted antibacterial activity against Gram-positive and Gram-negative bacteria, but Gram-negative bacteria were more resilient.…”

“…Also, total reactive antioxidant potential and total antioxidant reactivity analysis indicate that atranorin acts as a general antioxidant, although it appeared to enhance peroxyl radical-induced lipoperoxidation in vitro [16]. Similarly, strong antioxidant activities were found for salazinic, protocetraric, evernic and norstictic acids [4,5,17].…”

“…In searching for new therapeutic alternatives, many different lichen species were investigated, due to significant antiviral, antimicrobial, anticancer, antihyperglycemic, cardioprotective, antiparasitic, anti-inflammatory and antibiotic effects that they have exhibited so far [3][4][5].…”

Evaluation of in vitro antioxidant, antimicrobial, genotoxic and anticancer activities of lichen Cetraria islandica

“…In most lichens, phenols are important antioxidants because of their ability to scavenge free radicals such as singlet oxygen, superoxide and hydroxyl radicals (Shanab et al 2011). Numerous researches reported a significant correlation between antioxidative activities of lichens and phenolic content (Behera et al 2009;Ranković et al 2012). However, some authors believe that the antioxidant activity of extracts may not necessarily correlate with the content of polyphenolics (Odabasoglu et al 2004), suggesting that the antioxidant activity of different lichens may also depend on other, non-phenol components.…”

In vitro antimicrobial activity of the organic extract of Cladonia substellata Vainio and usnic acid against Staphylococcus spp. obtained from cats and dogs

“…This may be primarily responsible for the antimicrobial activity demonstrated in this study and others (Burkholder et al 1944, Carrazzoni 1975, Huovinen & Ahti 1986, Ahti et al 1993, Lauterwein et al 1995, Pereira et al 1997, Honda & Vilegas 1998, Yano-Melo et al 1999, Donlan 2001, Falcão et al 2004, Ribeiro et al 2006, Moura et al 2008. Ranković et al (2012) tested the antibacterial activity of usnic acid compared to streptomycin for Bacillus mycoides (ATCC 6462), B. subtilis (ATCC 6633), S. aureus (ATCC 25923), Escherichia coli (ATCC 25922), and Klebsiella pneumoniae (ATCC 13883). They observed that usnic acid obtained similar or stronger activity than the isolates tested with streptomycin.…”