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Ursolic acid (UA), belongs to a group of pentacyclic triterpenoids and is known to possess some very interesting biological properties. Protocols have been developed in order to synthesize bioactive UA analogs which have resulted in numerous ursolic acid analogs being synthesized during the period 2012-2016. Ursolic acid and its analogues can be employed to treat various cancers, inflammatory diseases, diabetes, Parkinson's disease, Alzheimer's disease, hepatitis B, hepatitis C and AIDS to mention but a few. Areas covered: This review covers patents on therapeutic activities of ursolic acid (UA) and its synthetic derivatives published during the four year period 2012-2016. A discussion about structure-activity relationships (SAR) of these analogs is also included. Expert opinion: Ursolic acid and its synthetic derivatives demonstrated excellent anticancer, antidiabetic, antiarrhythmic, anti-hyperlipidemic, antimicrobial, anti-hypercholesterolemic, and anti-cardiovascular properties. Additionally, various ursolic acid analogues have been synthesized through modification at positions C

Introduction: Boswellic acids (BAs), a group of pentacyclic triterpenoids, have demonstrated very interesting biological properties that resulted in a number of protocols being developed for their synthesis. During the last twenty-five years (1990–2015), numerous BAs have been prepared. Both natural BAs and their synthetic derivatives can be used to treat various cancers as well as inflammatory diseases.Areas covered: This review covers patents on therapeutic activities of natural BAs and their synthetic derivatives published in last twenty-five years (1990–2015). Only BA patents to treat cancer and inflammation are available. A discussion about structure-activity relationships (SAR) of these analogs is also included.Expert opinion: BAs possess excellent anticancer and anti-inflammatory properties. A large number of BAs and their analogues have been prepared through modification at the C3-OH and C24-CO2H functional groups. Most importantly, the C-24 amide and amino derivatives demonstrated increas...

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

Lapachol (1), β-lapachone (2) and α-lapachone (3) are three well-studied natural products isolated from Tabebuia impetiginosa having most interesting chemodiversity and demonstrating diverse biological effects. Areas covered: The current review summarizes the recent and past discovery of chemotherapeutic agents based on the compounds 1-3. This review presents an overview of patents filed over the past two decades (1997 to 2016) mostly relating to the anticancer effects of these lapachol and lapachone analogues. Expert opinion: The large number of interesting patents published on the therapeutic potential of quinones 1-3 and their synthetic derivatives lends credence to the importance of these molecules. Moreover, these quinones demonstrated potent anticancer effects towards various cancer cell lines and chemical modification of these quinones have led to products displaying enhanced anticancer effects. It is noteworthy that the majority of patents published are on the anticancer effects of quinones 1-3 and their synthetic derivatives along with a limited number of additional biological effects. It is our opinion that in order to get lead compounds, there needs to be a greater focus on the elucidation of the precise mechanism of action of these compounds including SAR and in vivo studies.

The retinoids, natural or synthetic derivatives of vitamin A, exhibit a variety of biological effects that may have implications in cancer chemoprevention and therapy. The chemopreventative action of classical retinoids has been ascribed to receptor-mediated modulation of a range of biological processes, including cell differentiation and proliferation. The therapeutic interest of several synthetic retinoids (also known as retinoid-related molecules) is related to their proapoptotic activity, which appears to be independent of the receptor-transactivating activity. This review focuses on the relevant features of recently reported synthetic retinoids, with particular reference to their therapeutic potential and current understanding of the mechanism of action. These agents are structurally heterogeneous compounds, including molecules closely related to natural retinoids and molecules with a retinoid-like structure (e.g., atypical retinoids) that include retinoic acid receptor (RAR) selective compounds or R...