• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.887-896
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• 2015

To develop environment-friendly agricultural products with anti-microbial activity against Sclerotinia sclerotiorum as a pathogen of sclerotium disease, Usnea longissima was extracted by methanol and its extract was fractionated into several solvent fractions. The chloroform fraction, which showed the highest antimicrobial activity, was separated by silica gel-column chromatography and obtained into nine group subfractions. The nine group fractions were searched the antifungal activities by bioassay. The most active No. 3 subfraction was analyzed by GC-MS. Each mass spectra, corresponding to each peak of chromatogram, was compared to database of Wiley library. As a result, Usnic acid was identified as main compounds. In conclusion, Usnic acid isolated from Usnea longissima was antimicrobial chemical against Sclerotinia sclerotiorum as a pathogen of sclerotium disease.

• Journal of Microbiology
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• v.45 no.6
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• pp.578-582
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• 2007

The primary objective of this study was to assess the in vitro melanogenesis inhibitory effects of methanolic extracts of the edible and medicinal lichens, Umbilicaria (Gyrophora) esculenta and Usnea longissima. The quantities of the total phenolic compounds of methanolic extract of the two lichen extracts were determined to be 1.46% and 2.62%, respectively. In order to evaluate the antioxidative effects of the extracts, we also measured electron donating abilities (EDA) and lipid peroxidation rates. The EDA values measured by the reduction of 1.1'-diphenyl-2-picrylhydrazyl (DPPH) were 72.8% and 80.7% for the extracts, with $SC_{50}$ (median scavenging concentration) values of $1.29{\pm}0.05\;mg/ml$ and $1.03{\pm}0.06\;mg/ml$, respectively. The rates of inhibition of lipid peroxidation using linoleic acid were 92.1% and 97.3% for the extracts, with $IC_{50}$ (median inhibitory concentration) values of $0.57{\pm}0.05\;mg/ml$ and $0.53{\pm}0.06\;mg/ml$, respectively. The inhibitory rates of the extracts against tyrosinase were 67.4% and 84.8%, respectively. The extracts were shown to reduce melanin formation in human melanoma cells. Melanin contents in the samples treated with 0.01% and 0.1% U. esculenta were 47.1% and 31.2%, respectively, and those treated with 0.01% and 0.1% Usnea longissima were 51.1% and 34.9%, respectively, whereas a value of 54.0% was registered when ascorbic acid was utilized as a positive control. In addition to direct tyrosinase inhibition, it was determined that the lichen extracts affected the activity of tyrosinase via the inhibition of tyrosinase glycosylation. As a result, the methanolic extracts of U. esculenta and Usnea longissima evidenced melanogenesis inhibitory effects, which occurred via multiple routes.

• Mycobiology
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• v.42 no.1
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• pp.34-40
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• 2014

Usnea longissima has a long history of use as a traditional medicine. Several bioactive compounds, primarily belonging to the polyketide family, have been isolated from U. longissima. However, the genes for the biosynthesis of these compounds are yet to be identified. In the present study, three different types of non-reducing polyketide synthases (UlPKS2, UlPKS4, and UlPKS6) were identified from a cultured lichen-forming fungus of U. longissima. Phylogenetic analysis of product template domains showed that UlPKS2 and UlPKS4 belong to group IV, which includes the non-reducing polyketide synthases with an methyltransferase (MeT) domain that are involved in methylorcinol-based compound synthesis; UlPKS6 was found to belong to group I, which includes the non-reducing polyketide synthases that synthesize single aromatic ring polyketides, such as orsellinic acid. Reverse transcriptase-PCR analysis demonstrated that UlPKS2 and UlPKS4 were upregulated by sucrose; UlPKS6 was downregulated by asparagine, glycine, and alanine.

• Biomaterials Research
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• v.22 no.4
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• pp.328-336
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• 2018

Background: Biogenic fabrication of silver nanoparticles from naturally occurring biomaterials provides an alternative, eco-friendly and cost-effective means of obtaining nanoparticles. It is a favourite pursuit of all scientists and has gained popularity because it prevents the environment from pollution. Our main objective to take up this project is to fabricate silver nanoparticles from lichen, Usnea longissima and explore their properties. In the present study, we report a benign method of biosynthesis of silver nanoparticles from aqueous-ethanolic extract of Usnea longissima and their characterization by ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Silver nanoparticles thus obtained were tested for antimicrobial activity against gram positive bacteria and gram negative bacteria. Results: Formation of silver nanoparticles was confirmed by the appearance of an absorption band at 400 nm in the UV-vis spectrum of the colloidal solution containing both the nanoparticles and U. longissima extract. Poly(ethylene glycol) coated silver nanoparticles showed additional absorption peaks at 424 and 450 nm. FTIR spectrum showed the involvement of amines, usnic acids, phenols, aldehydes and ketones in the reduction of silver ions to silver nanoparticles. Morphological studies showed three types of nanoparticles with an abundance of spherical shaped silver nanoparticles of 9.40-11.23 nm. Their average hydrodynamic diameter is 437.1 nm. Results of in vitro antibacterial activity of silver nanoparticles against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyrogenes, Streptococcus viridans, Corynebacterium xerosis, Corynebacterium diphtheriae (gram positive bacteria) and Escherichia coli, Klebsiella pneuomoniae and Pseudomonas aeruginosa (gram negative bacteria) showed that it was effective against tested bacterial strains. However, S. mutans, C. diphtheriae and P. aeruginosa were resistant to silver nanoparticles. Conclusion: Lichens are rarely exploited for the fabrication of silver nanoparticles. In the present work the lichen acts as reducing as well as capping agent. They can therefore, be used to synthesize metal nanoparticles and their size may be controlled by monitoring the concentration of extract and metal ions. Since they are antibacterial they may be used for the treatment of bacterial infections in man and animal. They can also be used in purification of water, in soaps and medicine. Their sustained release may be achieved by coating them with a suitable polymer. Silver nanoparticles fabricated from edible U. longissima are free from toxic chemicals and therefore they can be safely used in medicine and medical devices. These silver nanoparticles were stable for weeks therefore they can be stored for longer duration of time without decomposition.