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Research Support, Non-U.S. Gov't
- Isolation and Characterization of a Reducing Polyketide Synthase Gene from the Lichen-Forming Fungus Usnea longissima
- Yi Wang , Jung A Kim , Yong Hwa Cheong , Yogesh Joshi , Young Jin Koh , Jae-Seoun Hur
- J. Microbiol. 2011;49(3):473-480. Published online June 30, 2011
- DOI: https://doi.org/10.1007/s12275-011-0362-4
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- 15 Scopus
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Abstract
- The reducing polyketide synthases found in filamentous fungi are involved in the biosynthesis of many drugs and toxins. Lichens produce bioactive polyketides, but the roles of reducing polyketide synthases in lichens remain to be clearly elucidated. In this study, a reducing polyketide synthase gene (UlPKS3) was isolated and characterized from a cultured mycobiont of Usnea longissima. Complete sequence information regarding UlPKS3 (6,519 bp) was obtained by screening a fosmid genomic library. A UlPKS3 sequence analysis suggested that it contains features of a reducing fungal type I polyketide synthase with β-ketoacyl synthase (KS), acyltransferase (AT), dehydratase (DH), enoyl reductase (ER), ketoacyl reducatse (KR), and acyl carrier protein (ACP) domains. This domain structure was similar to the structure of ccRads1, which is known to be involved in resorcylic acid lactone biosynthesis in Chaetomium chiversii. The results of phylogenetic analysis located UlPKS3 in the clade of reducing polyketide synthases. RT-PCR analysis results demonstrated that UlPKS3 had six intervening introns and that UlPKS3 expression was upregulated by glucose, sorbitol, inositol, and mannitol.
Journal Article
- Melanogenesis Inhibitory Effects of Methanolic Extracts of Umbilicaria esculenta and Usnea longissima
- Moo-Sung Kim , Hong-Bum Cho
- J. Microbiol. 2007;45(6):578-582.
- DOI: https://doi.org/2605 [pii]
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Abstract
- 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 SC50 (median scavenging concentration) values of 1.29±0.05 mg/ml and 1.03±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 IC50 (median inhibitory concentration) values of 0.57±0.05 mg/ml and 0.53±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.
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