The specificity of nuclear-chemical synthesis requires availability of unlabeled isotopic carriers. For this purpose we have synthesized different N-phenyl substituted quinolinium derivatives by known literature chemical methods.

All reagents and solvents were obtained from commercial suppliers.

Nuclear-chemical synthesis was carried out in sealed glass ampoules containing the source of the phenyl cations (tritiated benzene), the nucleophile of interest and with an inorganic salt to serve as a stabilizing anion (KBF₄, KI, KClO₄). The benzene/substrate ratio was not less than 1:10³, in order to reduce the amount of the side products. The ampule was sealed and maintained for 1 - 2 months to accumulate the nuclear-chemical synthesis products. Since the radioactive decay does not depend on the reaction conditions such as temperature and pressure, the accumulation of tritium-labeled compounds was carried out at −18˚C in order to prevent the formation of thermal decomposition products. The ampule was opened and the contents were transferred to a special flask. Benzene (0.5 ml) and acetone solution of inactive N-phenylsubstituted onium carrier (0.5 ml, 1 mg/ml) were then added. Unreacted tritiated benzene was distilled off in vacuum. Then acetone (0.5 ml) was added to the dry residue and 5-μl samples were taken for thin-layer chromatographic separation of the labeled products. Radioactivity of the sorbent layer was measured using a scintillation spectrometer RackBeta 1215 (LKB Wallac, Finland).

The synthesis of double tritium labeled benzene was carried out in a vacuum by catalytic dehalogenation of p-dibromobenzene with gaseous tritium [36] . The purity of the prepared benzene sample was at least 99%. The specific activity of double tritiated benzene was 58 Ci/mmol. A hexane solution of the tritium-labeled benzene was used without a carrier. The bulk specific activity of the hexane solution was 1 Ci/ml. Such dilution was important to prevent radiolysis and the formation of side products.

Antimicrobial and antifungal activity was studied by the double serial dilution method [37] . The opportunistic pathogenic cultures were strains of Staphylococcus aureus-906, Escherichia coli-1257 and fungus Candida albicans-264/624 from L. A. Tarasevich GOSNII for Standardization and Control of Medical and Biological Pre- parations (Moscow). Candida krusei were the hospital strains, isolated from the hospital environment. Initial dilutions of the pathogens were prepared using an optical standard from a daily agar culture. The microbe loading was 2.5×10⁵ microbes per ml. The combined microbe suspension and drug solution (diluted in DMSO) was placed in the growth medium. Results were recorded after 20 hours for bacteria or 48 hours for fungus (MIC) and 7 days (MBC) at 37˚C (thermostat). Antimicrobial bacteriostatic (MIC) and bactericidal (MBC) activities were estimated from the minimum active concentration. The maximum test concentration of a new compound was 1.000 mg/ml.