Synthesis and Structure-Activity Relationship of 2,6-Disubstituted Thiosemicarbazone Derivatives of Pyridine as Potential Antituberculosis Agents

Synthesis and Biological Activity of Piperidinothiosemicarbazones Derived from Aminoazinecarbonitriles

To investigate how structural modifications affect tuberculostatic potency, we synthesized seven new piperidinothiosemicrabazone derivatives 8-14, in which three of them had a pyrazine ring replacing the pyridine ring. Derivatives 8-9 and 13-14 exhibited significant activity against the standard strain (minimum inhibitory concentration (MIC) 2-4 μg/mL) and even greater activity against the resistant M. tuberculosis strain (MIC 0.5-4 μg/mL). Additionally, the effects of compounds 8-9 were entirely selective (MIC toward other microorganisms ≥ 1000 μg/mL) and non-toxic (IC50 to HaCaT cells 5.8 to >50 μg/mL). The antimycobacterial activity of pyrazine derivatives 11-12 was negligible (MIC 256 to >500 μg/mL), indicating that replacing the aromatic ring was generally not a promising line of research in this case. The zwitterionic structure of compound 11 was determined using X-ray crystallography. Absorption, distribution, metabolism, and excretion (ADME) calculations showed that all compounds, except 11, could be considered for testing as future drugs. An analysis of the structure-activity relationship was carried out, indicating that the higher basicity of the substituent located at the heteroaromatic ring might be of particular importance for the antituberculous activity of the tested groups of compounds.

The Role of NQO1 in Ovarian Cancer

Ovarian cancer is one of the most dangerous gynecologic malignancies showing a high fatality rate because of late diagnosis and relapse occurrence due to chemoresistance onset. Several researchers reported that oxidative stress plays a key role in ovarian cancer occurrence, growth and development. The NAD(P)H:quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme that, using NADH or NADPH as substrates to reduce quinones to hydroquinones, avoids the formation of the highly reactive semiquinones, then protecting cells against oxidative stress. In this review, we report evidence from the literature describing the effect of NQO1 on ovarian cancer onset and progression.