Bioguided isolation of a selective compound from Calea phyllolepis leaves against breast cancer cells.

Plants of the Calea genus have been reported to contain lipophilic compounds, such as sesquiterpene lactones, with cytotoxic effect against different cancer cell lines. The aim of this manuscript was to investigate the chemical profile and cytotoxic activity of different fractions from Calea phylolepis leaves on different human cancer cell lines. The fractions were prepared using solvent extraction of increasing polarity, yielding hexane, ethyl acetate and methanolic fractions. All fractions were chemically analysed by thin layer chromatography (TLC), and their cytotoxic activity against HT-29 (colon adenocarcinoma), MCF-7 (breast cancer), U-251MG (malignant glioblastoma) and L929 (mouse fibroblast) cell lines was investigated. Among these, the hexane and ethyl acetate fractions showed higher cytotoxic effects, while the methanolic fraction did not show any cytotoxic effects. The major bioactive compound from the hexane fraction (12.15%) was isolated using chromatographic methods and was identified by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS) analysis as 6-epi-ß-verbesinol coumarate. This compound showed activity against breast cancer cells (IC50 = 5.8 ± 1.0 µg/ml), similar to etoposide. Furthermore, 6-epi-ß-verbesinol coumarate showed low cytotoxicity to normal fibroblast cells, suggesting a high selectivity index (SI = 7.39) against breast cancer cells.

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.