The antimicrobial activity of acetone, methanol and aqueous extracts of the lichens Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla is assessed. The extracts are tested on six species of bacteria and 10 species of fungi using the disk-diffusion method, and broth tube dilution is used to determine minimal inhibitory concentration (MIC). The tested bacteria were more sensitive than the tested fungi. Aqueous extracts of the investigated lichens showed no antimicrobial activity against any of the test organisms, whereas the acetone and methanol extracts showed antimicrobial activity. In general, methanol extracts had stronger activity than did acetone extracts. The strongest activity was recorded for the methanol extract of Parmelia pertusa, which had the lowest measured MIC value (0.78 mg/mL). The least active species was Parmelia caperata (highest MIC value: 50 mg/mL). Bacillus mycoides was the most sensitive of the tested bacterial species, while Candida albicans was the most sensitive fungal species.
In this study, in vitro antimicrobial activity of the physodic acid, usnic acid, atranorin and gyrophoric acid isolated from the lichens Hypogymnia physodes, Parmelia caperata, Physcia aipolia and Umbilicaria polyphylla, has been investigated. An antibiotic assessment was done against six bacteria (three Gram-positive and three Gramnegative) and eight fungi by determining the minimal inhibitory concentration (MIC) by the broth tube dilution method. The tested lichen substances inhibited growth of all the tested microorganisms. The bacteria showed a higher sensitivity against the tested fungi. The highest antimicrobial activity was found in the usnic acid of the Parmelia caperata lichen, where the lowest MIC was 0.0037 mg/ml against the Klebsiella pneumoniae (even lower than the one given by the streptomycin standard). The weakest antimicrobial activity was found in the physodic acid, which inhibited most of the microorganisms in the concentration of 1 mg/ml. Generally, all the components had relatively strong antimicrobial activity against the tested microorganisms, among which were human and animal pathogens. This could be of significance for their use for pharmaceutical purposes.
Syntheses of 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one 2c-10c are reported in this paper. These compounds 2c-10c were prepared from 3-(2-bromoacetyl)-4-hydroxy-chromene-2-one 1 and corresponding thiourea derivatives 2b-10b using Hantzsch reaction. The structures of all compounds were confirmed by IR and( 1)H-NMR spectroscopy and elemental analyses. The molecules 2c-10c were evaluated for in vitro antimicrobial activity against ten bacteria and twelve fungi. All tested compounds exhibited antibacterial and antifungal activity.
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