| Preparation | Weigh 5.0 g of chopped Usnea longiflora into a 500 mL flask, and extract with 75 mL of ethyl acetate for 2 times, 4 h each time, and combine the extracts. Suction filtration, concentrated to 1/6~1/8 of the original volume, naturally cooled, crystallized, filtered off the mother liquor, and dried at 80°C to obtain the crude usnic acid. 30 times the amount of benzene-ethanol (volume ratio 1:1) mixed solvent was added to the crude product, refluxed for 2 h, filtered while hot, the filtrate was concentrated to 1/5 of the original volume, and crystals were precipitated by cooling. Dry at 80 ℃, recrystallize twice with ethyl acetate, and the obtained relatively pure pale yellow needle crystal is the fine usnic acid. |
| Chemical Properties | Yellow crystalline powder, soluble in organic solvents such as methanol, ethanol, and DMSO, derived from Usnea diffracta Vain. |
| Uses | Usnic acid is used as fragrance; preservative in deodorants; in anti ac ne formulations; antibiotic for topical application. |
| Uses | Usnic Acid acts as an antibacterial and antifungal agent, and are often seen used in cosmetics and facial application chemicals. |
| Uses | (+)-Usnic acid has been used to study the following:
- The mechanism of its antimicrobial activity in bacterial cells.
- Its ability as an antibiofilm agent against Group A Streptococci (GAS).
- Its ability as a potent anti-virulent compound against Candida albicans.
- The mechanism of its toxic effect on hepatocytes.
- Its ability to inhibit the motility of human lung cancer cells.
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| Definition | ChEBI: (-)-usnic acid is the (-)-enantiomer of usnic acid. It has a role as an EC 1.13.11.27 (4-hydroxyphenylpyruvate dioxygenase) inhibitor. It is a conjugate acid of a (-)-usnic acid(2-). It is an enantiomer of a (+)-usnic acid. |
| General Description | (+)-Usniacin is a primary reference substance with assigned absolute purity (considering chromatographic purity, water, residual solvents, inorganic impurities). The exact value can be found on the certificate. Produced by PhytoLab GmbH & Co. KG. |
| Biological Activity | mic: 0.05 μg/62.5 μl to 3.1 μg/62.5 μlmicroorganisms can colonize a wide variety of medical devices, putting patients at risk for systemic and local infectious complications, including local-site infections, endocarditis, and catheter-related bloodstream infections. (+)-usniacin is a secondary lichen metabolite that possesses antimicrobial activity against various planktonic gram-positive bacteria. |
| Contact allergens | Usnic acid is a component of lichens, also used as atopical antibiotic. Allergic contact dermatitis fromlichens occurs mainly occupationally in forestry andhorticultural workers, and in lichen pickers. |
| in vitro | (+)-usniacin showed antimicrobial activity against the same microorganisms as that of acetone extract. among the three analogues it was the most active one having quite low mic values. furthermore, (+)-usniacin did not show any activity against a. hydrophila and b. cereus whereas (d)-usnic acid did. on the other hand, (+)-usniacin was active against y. enterocolitica whereas (d)-usnic acid was not active [1]. |
| Purification Methods | This very weak acid is the natural form which is recrystallised from Me2CO, MeOH or *C6H6. At 25o it is soluble in H2O (<0.01%), Me2CO (0.77%), EtOAc (0.88%), MeOCH2CH2OH (0.22%) and furfural (7.32%). [Curd & Robertson J Chem Soc 894 1937, Barton & Brunn J Chem Soc 603 1953, resolution: Dean et al. J Chem Soc 1250 1953, synthesis: Barton et al. J Chem Soc 538 1956, Beilstein 18/5 V 586.] |
| references | [1] tay t, türk ao, yilmaz m, türk h, kivanç m. evaluation of the antimicrobial activity of the acetone extract of the lichen ramalina farinacea and its (+)-usnic acid, norstictic acid, and protocetraric acid constituents. z naturforsch c. 2004 may-jun;59(5-6):384-8.
[2] ghione m, parrello d, grasso l. usnic acid revisited, its activity on oral flora. chemioterapia. 1988 oct;7(5):302-5. |
