The first structural characterization of glycyrrhizic acid, its monoammonium salt (AGA), and the complex of the salt with p-aminobenzoic acid in the solid state is reported. X-ray crystallography reveals that neutral and ionic forms of GA have similar supramolecular organization, with aglycon groups protruding from the 2D hydrogenbonded sugar platform. Interpenetration of these assemblies leads to the generation of intersecting channels where solvent and guest molecules are enclosed. It is worth noting that small solvent molecules or cations can functionally replace three water molecules which are an integral part of the sugar platform in GA. The crystal structures indicate the drug and cation binding sites and explain the similar properties of glycyrrhizic acid and its salts. The presented structures provide information about the supramolecular organization of amphiphilic GA molecule in the solid state, giving a guide into a possible aggregation mode in gels and solutions.

For the first time combretastatins were isolated from African willow tree Combretum Caffrum. Subsequent studies have shown the impact of combretastatin A4 phosphate, a water-soluble prodrug, on endothelial cells in tumor vascular system. The same effect was not observed in the vascular system. This selectivity is associated with combretastatins mechanism of action: binding to colchicine domain of microtubules, which affects the cytoskeleton functionality of immature endothelial cells. At the same time, combretastatins directly induce cell death via apoptosis and/or mitotic catastrophe pathways. The combination of both elements makes combretastatin an anticancer compound of high efficiency. The cis-configuration is crucial for its biological activity. To date, many derivatives were synthesized. The attempts to resolve spontaneous isomerization to less active trans-stilbene derivative are still in progress. This issue seems to be overcome by incorporation of the ethene bridge with heterocyclic moiety in combretastatins structure. This modification retains the cis-configuration and prevents isomerization. Nevertheless, combretastatin A4 phosphate disodium is still the most potent compound of this group. The combination therapy, which is the most effective treatment, includes combretastatin A4 phosphate (CA4P) and conventional chemotherapeutics and/or radiotherapy. CA4P is relatively well tolerated giving adverse events of moderate severity, which includes: nausea, vomiting, headache, and tumor pain. The aforementioned effects subside on the day of drug administration or on the following day.

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A novel series of methoxy-trans-stilbenes with 3,4-dimethoxy motifs was designed and synthesized. The inhibitory potency of 3,4-dimethoxystilbene derivatives against cytochrome P450 isozymes CYP1A1, CYP1B1 and CYP1A2 was evaluated. 3,4,2 0 -Trimethoxy-trans-stilbene (3,4,2 0 -TMS) exhibited extremely potent inhibitory action against CYP1B1 activity with an IC 50 of 0.004 mM. 3,4,2 0 -TMS exhibited 90-fold selectivity for CYP1B1 over CYP1A1 and 830-fold selectivity for CYP1B1 over CYP1A2. However, 3,4,2 0 ,4 0tetramethoxy-trans-stilbene appeared to be the most selective inhibitor of both CYP1B1 and CYP1A1showing very low affinity toward CYP1A2. Complementary experimental studies and computational methods were used to explain what structural determinants decide the specific affinity of stilbene derivatives to CYP1A2 and CYP1B1 binding sites.