Birch-bark triterpenoids and their semi-synthetic derivatives possess a wide range
of biological activities including cytotoxic effects on various tumor cell lines. However, due
to the low solubility and bioavailability, their medicinal applications are rather limited. The
use of various nanotechnology-based drug delivery systems is a rapidly developing approach
to the solubilization of insufficiently bioavailable pharmaceuticals. Herein, the drug delivery
systems deemed to be applicable for birch-bark triterpenoid structures are reviewed. The
aforementioned disadvantages of birch-bark triterpenoids and their semi-synthetic derivatives
can be overcome through their incorporation into organic nanoparticles, which include various
dendrimeric systems, as well as embedding the active compounds into polymer matrices
or complexation with carbohydrate nanoparticles without covalent bonding. Some of the
known triterpenoid delivery systems consist of nanoparticles featuring inorganic cores covered
with carbohydrates or other polymers. Methods for delivering the title compounds
through encapsulation and emulsification into lipophilic media are also suitable. Besides, the
birch-bark triterpenoids can form self-assembling systems with increased bio-availability.
Even more, the self-assembling systems are used as carriers for delivering other chemotherapeutic
agents. Another advantage besides increased bioavailability and anticancer activity is
the reduced overall systemic toxicity in most of the cases, when triterpenoids are delivered
with any of the carriers.
Keywords: Betulin, betulinic acid, oleanolic acid, lupeol, semi-synthetic derivatives, drug delivery systems.
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