Thiophene-thiosemicarbazone derivative (L10) exerts antifungal activity mediated by oxidative stress and apoptosis in C. albicans.

Reactive oxygen species (ROS) cause cell damage and death. To reverse these effects, cells produce substances such as reduced glutathione (GSH) that serve as substrates for antioxidant enzymes. One way to combat microbial resistance includes nullifying the effect of glutathione in microbial cells, causing them to die from oxidative stress. The compound 2-((5-nitrothiophen-2-yl)methylene)-N-(pyridin-3-yl) hydrazine carbothioamide (L10) is a new thiophene-thiosemicarbazone derivative with promising antifungal activity. The aim of this study was to evaluate its mechanism of action against Candida albicans using assays that evaluate its effects on redox balance. Treatment with L10 promoted significant changes in the minimum inhibitory concentration (MIC) values in ascorbic acid and GSH protection tests, the latter increasing up to 64-fold of the MIC. Using nuclear magnetic resonance, we demonstrated interaction of L10 and GSH. At concentrations of 4.0 and 8.0 µg/mL, significant changes were observed in ROS production and mitochondrial membrane potential. The cell death profile showed characteristics of initial apoptosis at inhibitory concentrations (4.0 µg/mL). Transmission electron microscopy data corroborated these results and indicated signs of apoptosis, damage to plasma and nuclear membranes, and to mitochondria. Taken together, these results suggest a possible mechanism of action for L10 antifungal activity, involving changes in cellular redox balance, ROS production, and apoptosis-compatible cellular changes.

Genotoxic activity of L-asparaginase produced by Streptomyces ansochromogenes UFPEDA 3420.

L-asparaginase is an enzyme capable of hydrolyzing the substrate asparagine in aspartic acid and ammonia. Due to this mechanism of action observed, L-asparaginase is widely used in the treatment of Acute Lymphoblastic Leukemia, since these cells use asparagine for their survival. Because it is frequently used as an antineoplastic, it is necessary to evaluate its genotoxic effects. The aim of the present study was to evaluate cellular DNA damage after exposure to L-asparaginase produced by Streptomyces ansochromogenes UFPEDA 3420. NCIH-292, MCF-7 and MOLT-4 neoplastic cell lines and normal PBMC cells were used. L-Asparaginase used in this study was produced by actinobacteria S. ansochromogenes UFPEDA 3420, isolated and purified by chromatographic methods. L-Asparaginase induced micronucleus formation in PBMC cells and tumor lines when compared to the negative control. These data suggest that L-Asp appears to have a genotoxic effect very close to the positive control in normal cells (p < 0.05). The level of genomic damage measured by DNA breaks in alkaline SCGE assay was detected from the lowest concentration (12.5 µg/mL) to the highest concentration (50 µg/mL) for tumor cell lines and PBMC. In view of the above, new genotoxic studies will be carried out to better elucidate L-Asparaginase and its mutagenic potential, still unknown, enough for this drug to be safely used in conventional antineoplastic therapies.