Antinociceptive effect and anti-inflammatory activity of 1,4-naphthoquinones in mice

Aim: The ability of synthetic 1,4-naphthoquinones (1,4-NQs) to prevent adenosine triphosphate (ATP)-induced and purinergic P2X7 receptor (P2X7R) mediated inflammation in macrophage and neurodegeneration of neuronal cells in vitro was previously established. The aim of the present study was to investigate analgesic-like and anti-inflammatory activity of 1,4-NQs thioglucoside derivatives, compounds U-286 and U-548, in in vivo experiments. Methods: Spectrofluorimetry approach and YO-PRO-1 fluorescent dye uptake determination were applied to study the effect of 1,4-NQs upon ATP-induced P2X7R mediated macropore formation in mouse neuroblastoma Neuro-2a cells and macrophages RAW 264.7 cells. An acetic acid-induced writhing test, hot plate test, and carrageenan-induced paw edema test were used as an in vivo mouse models to study the ability of 1,4-NQs to inhibit pain and inflammation. In the in vivo experiments, compounds were administered to mice intraperitoneally at dosages of 0.1 mg/kg, 1.0 mg/kg and 10.0 mg/kg. A group of animals that received injections of sterile water was used as a control. Each dosage group and the control group consisted of 6 mice. Results: In the present work the analgesic-like and anti-inflammatory activity of 1,4-NQs, U-286 and U-548, was demonstrated. Compound U-548 showed a significant inhibitory effect in antinociceptive tests reducing the number of mouse writhings and eliminating the latent time of mouse hind paw licking, correspondingly. Selected compounds were able to almost completely reduce the size of carrageenan-induced paw edema 24 h after injection and had a potent anti-inflammatory activity. Observed effects were accompanied with aptitude of studied 1,4-NQs to inhibit the formation of purinergic P2X7R macropore associated with inflammation and nociceptive pain. Conclusions: The results obtained allow to consider compounds U-286 and U-548 and as a pharmacological basis for the development of new analgesic-like and anti-inflammatory drugs.