Cytotoxic Activity of Pyrovalerone Derivatives, an Emerging Group of Psychostimulant Designer Cathinones

The growing popularity of novel psychoactive substances (NPS) has aroused the concerns of public health specialists. The pyrovalerone derivatives are a branch of synthetic cathinones, a very popular group of psychostimulant NPS. Despite numerous case reports of fatal intoxications, little is known about the cytotoxicity of these substances. Therefore, this study was aimed to evaluate the toxic properties of pyrovalerone, its highly prevalent derivative 3,4-methylenedioxypyrovalerone (3,4-MDPV) with its two major metabolites (catechol-MDPV and methylcatechol-MDPV) and the structural isomer 2,3-MDPV, together with newer members of the group, i.e., α-pyrrolidinovalerothiophenone (α-PVT) and α-pyrrolidinooctanophenone (PV9), using model human cell lines for neurons (SH-SY5Y), hepatocytes (Hep G2), and upper airway epithelium (RPMI 2650). We found that the first generation pyrovalerones (pyrovalerone, 3,4-MDPV, and 2,3-MDPV) produced a modest decrease of mitochondrial activity in the three examined cell lines, but were active in lower concentrations than methamphetamine used as a reference psychostimulant compound. Since catechol-MDPV displayed greater toxic potential than the parent compound, we suggest that the toxicity of 3,4-MDPV could be attributed to activity of this metabolite. Strikingly, the two new generation pyrovalerones, α-PVT and PV9, seem to be the most potent cytotoxic compounds: both induced highly pronounced mitochondrial dysfunction; the latter also demonstrated significant damage to cell membranes. The reported in vitro toxic activity of pyrovalerone cathinones against different cell types reinforces existing concerns regarding the health risks associated with the intake of these drugs.