This Focus Review summarizes recent advances in the synthesis of betulinic acid derivatives with modified A‐rings. It also focuses on their application as potential therapeutic agents for the treatment of cancer and other diseases. Betulinic acid (BA) exhibits therapeutically interesting biological properties, including antitumor, anti‐HIV, antiprotozoal, and hepato‐ or nephroprotective activity; however, its clinical use has been severely limited by its higher IC50 value and worse pharmacological parameters than the currently used drugs. On the other hand, semisynthetic analogues of BA are much better suited for potential clinical use. Among these analogues, compounds that contain a modified A‐ring are the most promising. We hope that this Focus Review will serve as a guide for the synthesis of new BA derivatives with applications as drug candidates. A general audience may also find this Focus Review interesting, because it describes the structural motifs that are responsible for the observed bioactivities.
To better understand the mechanism of action of antitumor triterpenes, we are developing methods to identify their molecular targets. A promising method is based on combination of quantitative proteomics with SILAC and uses active compounds anchored to magnetic beads via biotin-streptavidin interaction. We developed a simple and fast solid-phase synthetic technique to connect terpenes to biotin through a linker. Betulinic acid was biotinylated from three different conjugation sites for use as a standard validation tool since many molecular targets of this triterpene are already known. Then, a set of four other cytotoxic triterpenoids was biotinylated. Biotinylated terpenes were similarly cytotoxic to their nonbiotinylated parents, which suggests that the target identification should not be influenced by linker or biotin. The developed solid-phase synthetic approach is the first attempt to use solid-phase synthesis to connect active triterpenes to biotin and is applicable as a general procedure for routine conjugation of triterpenes with other molecules of choice.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.