Conjugates of the antituberculosis drug isoniazid (isonicotinyl hydrazine) and isomeric hydrazides of nicotinic and α-picolinic acid with glycoside steviolbioside from the Stevia rebaudiana plant and the product of its acid hydrolysis, diterpenoid isosteviol, were synthesized. In addition, isosteviol hydrazide and hydrazone derivatives as well as conjugates containing two isosteviol moieties joined by a dihydrazide linker were obtained. The parental compounds and their synthetic derivatives were found to inhibit the in vitro growth of Mycobacterium tuberculosis (H₃₇R_V). The measured minimal concentrations of stevio-side and steviolbioside, at which the growth of M. tuberculosis was inhibited by 100% (MIC), were 7.5 and 3.8 μg/ml, respectively. MIC values for steviolbioside and isosteviol conjugates with hydrazides of pyridine carbonic acid were within the ranges of 5–10 and 10–20 μg/ml, respectively. The maximal inhibitory effect against M. tuberculosis was shown by the isosteviol conjugates with adipic acid dihydrazide (MIC 1.7 and 3.1 μg/ml). Antituberculosis activities of the tested compounds were higher than the activity of antituberculosis drug Pyrizanamide (MIC 20 μg/ml) but lower than that of antituberculosis drug isoniazid (MIC 0.02–0.04 μg/ml).

A series of glycosides and glycoconjugates of diterpenoid isosteviol (16-oxo-ent-beyeran-19-oic acid) with various monosaccharide residues were synthesized and their cytotoxicity against some human cancer and normal cell lines was assayed. Most of the synthesized compounds demonstrated moderate to significant cytotoxicity against human cancer cell lines M-HeLa and MCF-7. Three lead compounds exhibited selective cytotoxic activities against M-HeLa (IC₅₀ = 10.0–15.1 μM) that were three times better than the cytotoxicity of the anti-cancer drug Tamoxifen (IC₅₀ = 28.0 μM). Moreover, the lead compounds were not cytotoxic with respect to the normal human cell line Chang liver (IC₅₀ > 100 μM), whereas Tamoxifen inhibited the viability of normal human Chang liver cells with an IC₅₀ value of 46.0 μM. It was determined that the cytotoxicity of the lead compounds was due to induction of apoptosis proceeding along the mitochondrial pathway. The cytotoxic activity of the synthesized compounds substantially depended on the nature of the monosaccharide residue and its position, that is, whether the monosaccharide residue was attached directly to the isosteviol skeleton or was moved away from it by means of a polymethylene linker.

The characteristic features of the manifestations of acid magmatism and metasomatic hydrothermal alteration processes in Southeastern Transbaikalia, an important mining region in Russia, are discussed. The zoned or beltlike distribution of the ores of various metals, uranium in particular, and other mineral deposits is due to the general evolutionary trends of the geodynamic regimes of the respective blocks of the territory and the subsequent magmatic differentiation trends. The highly differentiated and fluorine-rich granitoids of Southeastern Transbaikalia are located only in the zones of the consolidated crust, which are characterized by low gravity and negative quiet magnetic field values. In other zones, i.e., volcanic belts, volcanogenic troughs, and the regions dominated by the intrusive massifs of the Shakhtama complex, rare metal manifestations are absent. It was demonstrated that there is no correlation between the localization of large uranium deposits and leucocratic rare metal granite domains and that these deposits are concentrated in large volcanic calderas or volcanic troughs, controlled by long-lived fault systems. In addition to uranium, these volcanogenic structures control base metal, molybdenum, gold, fluorite, and some other mineral deposits. The results of a comparative analysis of the geochemical features of the acid volcanics that host the uranium mineralization and are classified as the last differentiation products of the contrasting latite volcanism, on the one hand, and the subvolcanic and hypabyssal derivatives of the rare metal granites, on the other, are presented. The analysis revealed the signatures of their fundamental difference from each other and that they belong to different branches of magmatic differentiation. A comparative analysis of the metasomatic aureoles of the altered wallrocks in the Late Mesozoic volcanics and the Shakhtama granitoid domains, on the one hand, and the leucocratic rare metal granite domain, on the other, is given. The data presented attest to the existence of a mixed geodynamic regime within the study area of the Central Asian mobile belt during the Jurassic and the earliest Cretaceous time: residual collisions with strong deformations in a compressional setting, accompanied by the development of late acid differentiation products of the magmatic latite series, and the incipient rifting associated with the intrusion of the leucogranites of the Kukul’bei complex in a more quiet extensional setting.