• Microbiology and Biotechnology Letters
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• v.23 no.5
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• pp.526-530
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• 1995

Phospholipase A$_{2}$ (PLA$_{2}$) is lipolytic enzyme that has known to be involved in inflammation. In the course of our screening for antiinflammatory compounds from natural products, a compound having PLA$_{2}$ inhibitory activities was isolated from the methanol extract of Umbilicaria esculenta. The compound was identified as lecanoric acid based on various NMR studies including DEPT, HETERO-COSY and HMBC experiments. Lecanoric acid inhibited human rheumatoid synovial PLA$_{2}$ activity with IC$_{50}$ of 0.17 mM and also exhibited antitumor activity (ED$_{50}$=2.7 $\mu $g/ml) against skin tumor cell line (LOX-IMVI).

• The Plant Pathology Journal
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• v.38 no.1
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• pp.25-32
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• 2022

Plant pathogens pose major threats on agriculture and horticulture, causing significant economic loss worldwide. Due to the continuous and excessive use of synthetic pesticides, emergence of pesticide resistant pathogens has become more frequent. Thus, there is a growing needs for environmentally-friendly and selective antimicrobial agents with a novel mode of action, which may be used in combination with conventional pesticides to delay development of pesticide resistance. In this study, we evaluated the potentials of lichen substances as novel biopesticides against eight bacterial and twelve fungal plant pathogens that have historically caused significant phytopathological problems in South Korea. Eight lichen substances of diverse chemical origins were extracted from axenic culture or dried specimen, and further purified for comparative analysis of their antimicrobial properties. Usnic acid and vulpinic acid exhibited strong antibacterial activities against Clavibacter michiganensis subsp. michiganensis. In addition, usnic acid and vulpinic acid were highly effective in the growth inhibition of fungal pathogens, such as Diaporthe eres, D. actinidiae, and Sclerotinia sclerotiorum. Intriguingly, the growth of Rhizoctonia solani was specifically inhibited by lecanoric acid, indicating that lichen substances exhibit some degrees of selectivity to plant pathogens. These results suggested that lichen substance can be used as a selective biopesticide for controlling plant disease of agricultural and horticultural significance, minimizing possible emergence of pesticide resistant pathogens in fields.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1524-1528
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• 2010

The antioxidant properties of 46 lichen species, collected from the highly UV-exposed alpine areas of southwestern China, were evaluated for their potential therapeutic utilization. The anti-linoleic acid peroxidation activity, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity, reducing power, and total phenolic contents were all assessed in vitro in the methanol extract of the lichens. A potent reducing power was detected in a number of the lichen extracts, when compared with butylated hydroxyanisole (BHA). In general, it was found that many of the lichens, with antioxidant properties, contained large quantities of phenolic content. Extracts of Peltigera praetextata and Sticta nylanderiana were found to exhibit the most potent activity in all of the antioxidant tests. In particular, extracts of S. nylanderiana displayed a 1.37 times greater anti-linoleic acid peroxidation activity, when compared with the ascorbic acid used as the positive control. S. nylanderiana also possessed the strongest free radical scavenging activity amongst all the tested species, with an inhibition rate of 90.4% at concentration of $330{\mu}g/ml$. Activity-guided bioautographic TLC and HPLC analyses were used to establish which compounds were responsible for the potent antioxidant activities of the S. nylanderiana extract. These analyses revealed lecanoric acid to be primarily responsible for the effective antioxidant properties of S. nylanderiana. Overall, these results have indicated that several highland lichens have the potential of being utilized as novel bioresources for naturally occurring antioxidant therapies.