Antimycobacterial activity of lichen substances

Abstract

We describe here the extraction and identification of several classes of phenolic compounds from the lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema tinctorum (Nyl.) Hale, Pseudoparmelia sphaerospora (Nyl.) Hale and Usnea subcavata (Motyka) and determined their anti-tubercular activity. The depsides (atranorin, diffractaic and lecanoric acids), depsidones (protocetraric, salazinic, hypostictic and norstictic acids), xanthones (lichexanthone and secalonic acid), and usnic acid, as well seven orsellinic acid esters, five salazinic acid 8',9'-O-alkyl derivatives and four lichexanthone derivatives, were evaluated for their activity against Mycobacterium tuberculosis. Diffractaic acid was the most active compound (MIC value 15.6mug/ml, 41.6 microM), followed by norstictic acid (MIC value 62.5 microg/ml, 168 microM) and usnic acid (MIC value 62.5 microg/ml, 182 microM). Hypostictic acid (MIC value 94.0 microg/ml, 251 microM) and protocetraric acid (MIC value 125 microg/ml, 334 microM) showed moderate inhibitory activity. The other compounds showed lower inhibitory activity on the growth of M. tuberculosis, varying from MIC values of 250 to 1370 microM.

Antioxidant and antimicrobial activity of a new generation phyto-gel

“…Thanks to the presence of different extracts, this phytogel can find a potential application in a variety of skin diseases such as acne and eczema (due to the presence of the horsetail extract) [27], skin inflammation, wounds, purulent processes (due to the presence of the yarrow extract) [47], skin burns and wound infections (due to the presence of H. perforatum extract) [19], skin regeneration [48] and a antirheumatic agent (S. officinale extract) [49]. Usnic acid and its salts have well known antioxidant and antimicrobial properties [29,30], so Na-usniate is also an important component of the investigated phytogel in terms of the antioxidant and antimicrobial activity.…”

“…The antimicrobial and antioxidant activities of these plant extracts were tested before [1,[25][26][27][28], as well as the antimicrobial and antioxidant activities of usnic acid and related compounds from lichens [29,30].…”

Bioproduction of Depsidones for Pharmaceutical Purposes

“…Ingólfsdóttir et al (1998) reported that salazinic acid develops antimycobacterial activity. Honda et al (2010) studied the antibiotic properties of several different depsidones, protocetraric, salazinic, norstictic, hypostictic acids, and five salazinic acid derivatives on Mycobacterium tuberculosis. They conclude that the activity against the microorganism depends on the physico-chemical parameters (lipophilicity and pKa) of each compound, that is a function of the substituents in each molecule evaluated and of its structural characteristics.…”

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

“…It also acts as an insecticide, moisturizer, antihistamine, and agent that offers protection from the harmful effects of lightning UV (Fournet et al 1997, Cochietto et al 2002, Ingólfsdóttir 2002, Falcão et al 2004, Ribeiro et al 2006, Honda et al 2010. In humans, a hepatotoxic effect was observed when it was used systemically (Moura et al 2008).…”