Toxicological assessment of minoxidil: A drug with therapeutic potential besides alopecia.

Minoxidil is regularly prescribed for alopecia, and its therapeutic potential has expanded in recent times. However, few studies have been conducted to evaluate its toxicity, and controversial findings regarding its mutagenic activities remain unsolved. This study aimed to access cytotoxic, genotoxic, and mutagenic properties of minoxidil using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, comet assay, and micronucleus test in mouse fibroblast (L929) cells and its point mutation induction potential in the Salmonella/microsome assay. Furthermore, an in vivo toxicity assessment was conducted in Caenorhabditis elegans. Minoxidil showed cytotoxicity at 2.0 mg/mL in MTT assay. Genotoxicity was observed after 3 h treatment in L929 cells using comet assay. No mutagenic effect was observed in both the micronucleus test and the Salmonella/microsome assay. The lethal dose 50 in C. elegans was determined to be 1.75 mg/mL, and a delay in body development was detected at all concentrations. In conclusion, minoxidil induces DNA damage only in early treatment, implying that this DNA damage may be repairable. This observation corroborates the absence of mutagenic activities observed in L929 cells and Salmonella typhimurium strains. However, the toxicity of minoxidil was evident in both C. elegans and L929 cells, underscoring the need for caution in its use.

Evaluation of DNA damage in spinal cord and mutagenic effect of a Phα1ß recombinant toxin with analgesic properties from the Phoneutria nigriventer spider.

Phα1ß peptide isolated from the venom of the Phoneutria nigriventer spider has shown higher analgesic action in pre-clinical studies than ω-conotoxin MVIIA peptide used to treat severe chronic pain. In view of the great potential for the development of a new Phα1ß-based drug, a Phα1ß recombinant form (CTK 01512-2) has been studied for efficacy and safety. The aim of this study was to evaluate cytotoxic, genotoxic and mutagenic effects of a Phα1ß recombinant form and compare it with native Phα1ß and ω-conotoxin MVIIA. Cytotoxicity was evaluated using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colourimetric assay in L929 mouse fibroblast cells (0.5-10.0 µmol/L). Genotoxic and mutagenic activities were analysed using the alkaline comet assay in peripheral blood and spinal cord, and the micronucleus test in bone marrow from Wistar rats treated by intrathecal injection of CTK 01512-2 (200, 500 and 1000 pmol/site), native Phα1ß (500 pmol/site) and ω-conotoxin MVIIA (200 pmol/site). CTK 01512-2 decreased the cell viability of the L929, showing IC50 of 3.3 ± 0.1 µmol/L, while the Phα1ß and ω-conotoxin MVIIA did not show cytotoxicity (IC50  > 5.0 µmol/L). Native and recombinant Phα1ß forms induced DNA damage in the spinal cord, but not in peripheral blood. CTK 01512-2 at 1000 pmol/site increased the micronucleus frequency suggesting mutagenic effects. In conclusion, the recombinant form has cytotoxic, genotoxic and mutagenic effects, evidenced in doses five times above the therapeutic dose.

Evaluation of DNA Damage in HepG2 Cells and Mutagenicity of Garcinielliptone FC, A Bioactive Benzophenone.

Garcinielliptone FC (GFC) is a polyprenylated benzophenone isolated from the hexanic extract of Platonia insignis seeds with potential pharmacological effects on the central nervous system. In a pre-clinical study, this compound showed anticonvulsant action, becoming a candidate to treat epilepsy disorders. However, genotoxicological aspects of GFC should be known to ensure its safe use. This study investigated the cytotoxic, genotoxic, and mutagenic effects of GFC. Cytotoxicity was evaluated using the colorimetric assay of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) in human hepatoma cells (HepG2) (2-100 µg/mL) for 3, 6 and 24 hr. The genotoxic and mutagenic potentials were analysed using the alkaline version of the comet assay, the cytokinesis-block micronucleus cytome assay in HepG2 cells, and the Salmonella/microsome assay with the strains TA98, TA97a, TA100, TA102 and TA1535, with and without metabolic activation. GFC concentrations above 50 µg/mL were cytotoxic at all experimental times. Viability of HepG2 cells was higher than 70% after exposure to GFC 2-30 µg/mL for 3 hr in the MTT test. No GFC concentration was mutagenic or genotoxic in the Salmonella/microsome and comet assays. Nuclear division index decreased, indicating the cytotoxic effect of the compound, while micronucleus and nuclear bud frequencies rose after treatment with the highest GFC concentration tested (30 µg/mL). Nucleoplasmatic bridges were not observed. The results indicate that GFC is cytotoxic and mutagenic to mammalian cells, pointing to the need for further studies to clarify the toxicological potentials of this benzophenone before proceeding to clinical studies.