Usnic acid and its derivatives for pharmaceutical use: a patent review (2000–2017)

ABSTRACT

Introduction: Usnic acid (UA) is a lichen-derived secondary metabolite with a unique dibenzofuran skeleton and is commonly found in lichenized fungi of the genera Usnea and Cladonia. Usnic acid has been incorporated for years in cosmetics, perfumery, and traditional medicines. It has a wide range of bioactivities, including antimicrobial, antiviral, anticancer, anti-inflammatory properties.

Areas covered: This review covers patents on therapeutic activities of UA and its synthetic derivatives published during the period 2000–2017.

Expert opinion: UA demonstrates excellent anticancer and antimicrobial properties. However, its application was withdrawn due to acute liver toxicity reported with chronic consumption. The broad spectrum of its biological activity indicates high the variability of UA’s binding preferences. The main idea to be addressed in the future should include the synthesis of UA derivatives because these might possess increased bioactivity, bioavailability and decreased toxicity. It is noteworthy that UA derivatives possessed better antibacterial, antitubercular, and anticancer activity than the parent compound . Most importantly, UA and its analogs (to a greater extent than UA) can be useful in cancer drug treatment. They have the potential for joint application with other anticancer drugs in order to overcome drug resistance.

KEYWORDS:

• Usnic acid
• antibacterial
• antitubercular
• anticancer

Article highlights

• Usnic acid (UA) is a naturally occurring compound that belongs to the dibenzofuran chemical class and has a broad spectrum of biological activity.

• This review describes the synthetic and biological efforts over the period 2000–2017 in the development of UA and its semisynthetic derivatives for antibacterial, antitubercular, anticancer, anti-inflammatory, and enzyme inhibiting potency.

• Chemical modification of UA results in the enhancement of biological and pharmaceutical potency of its derivatives and generates a broader pharmacological diversity.

• Usnic acid and its semisynthetic derivatives have great potential in the treatment of cancer.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper has not been funded.