Thiosemicarbazone p-Substituted Acetophenone Derivatives Promote the Loss of Mitochondrial Δψ, GSH Depletion, and Death in K562 Cells.

A series of thiosemicarbazone (TSC) p-substituted acetophenone derivatives were synthesized and chemically characterized. The p-substituents appended to the phenyl group of the TSC structures were hydrogen, fluor, chlorine, methyl, and nitro, producing compounds named TSC-H, TSC-F, TSC-Cl, TSC-Me, and TSC-NO2, respectively. The TSC compounds were evaluated for their capacity to induce mitochondrial permeability, to deplete mitochondrial thiol content, and to promote cell death in the K562 cell lineage using flow cytometry and fluorescence microscopy. TSC-H, TSC-F, and TSC-Cl exhibited a bell-shaped dose-response curve for the induction of apoptosis in K562 cells due to the change from apoptosis to necrosis as the principal mechanism of cell death at the highest tested doses. TSC-Me and TSC-NO2 exhibited a typical dose-response profile, with a half maximal effective concentration of approximately 10 µM for cell death. Cell death was also evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed lower toxicity of these compounds for peripheral blood mononuclear cells than for K562 cells. The possible mechanisms leading to cell death are discussed based on the observed effects of the new TSC compounds on the cellular thiol content and on mitochondrial bioenergetics.

Oral gabapentin treatment accentuates nerve and peripheral inflammatory responses following experimental nerve constriction in Wistar rats.

Gabapentin (GBP) is an anti-convulsive drug often used as analgesic to control neuropathic pain. This study aimed at evaluating whether oral GBP treatment could improve nerve inflammation response after sciatic nerve constriction in association with selected pain and motor spontaneous behavior assessments in Wistar rats. We evaluated nerve myeloperoxidase (MPO) and inflammatory cytokines on the 5th day post-injury, time in which nerve inflammation is ongoing. In addition, the role of GBP on carrageenan-induced paw edema and peritoneal cell migration was analyzed. GBP was given by gavage at doses of 30, 60 and 120mg/kg, 60min prior to chronic constriction of the sciatic nerve (CCSN) and during 5 days post-injury, 12/12h. CCSN animals treated with saline were used as controls and for behavioral and inflammation assessments untreated sham-operated rats were also used. On the 5th day, GBP (60 and 120mg/kg) alleviated heat-induced hyperalgesia and significantly increased delta walking scores in CCSN animals, the latter suggesting excitatory effects rather than sedation. GBP (60mg/kg) significantly increased nerve MPO, TNF-α, and IL-1ß levels, comparing with the saline group. GBP (120mg/kg) reduced the anti-inflammatory cytokine IL-10 nerve levels compared with the CCSN saline group. Furthermore, GBP (60 and 120mg/kg) increased carrageenan-induced paw edema and peritoneal macrophage migration compared with the CCSN saline group. Altogether our findings suggest that GBP accentuates nerve and peripheral inflammatory response, however confirmed its analgesic effect likely due to an independent CNS-mediated mechanism, and raise some concerns about potential GBP inflammatory side effects in widespread clinical use.

Antitumor activity of (-)-alpha-bisabolol-based thiosemicarbazones against human tumor cell lines.

A series of thiosemicarbazones deriving from the natural sesquiterpene (-)-alpha-bisabolol were synthesized and tested against a panel of eight human tumor cell lines to evaluate their anti-tumor potential. Some of the compounds exhibited inhibitory effects on the growth of a wide range of cancer cell lines, but myeloid leukemia cells (K-562) were especially sensitive to all tested thiosemicarbazones (GI(50) 0.01-4.22 microM). Among the analogues, the ketone derivative 3l was the most active, exhibiting potent antitumoral activity (GI(50) 0.01 microM) and high selectivity for K-562 cells (deltaTGI 505). It also demonstrated high cytotoxicity, with an LC(50) of 1.55 microM for the K-562 cells, but it showed only moderate selectivity (deltaLC(50) 38.5 microM). Through structure-activity relationship studies, we identified some structural requirement for the antitumoral activity exhibited by these promising compounds.