Exploring the antinociceptive activity and toxicological profile of Zn(Valp)2Bipy: a promising molecule in pain research.

Background: Antiepileptic drugs have shown promise in treating acute nociceptive pain. Bioisosterism is a crucial strategy in analgesic development, enabling molecular modifications that improve therapeutic efficacy and safety. This study aims to develop and evaluate new compounds based on the concept of bioisosterism, synthesizing organocomplexes derived from compounds with established analgesic properties.

Methods: A novel prototype, Zn(Valp)₂Bipy was synthesized, characterized, and tested for antinociceptive and toxicological effects in mice. The compound was administered orally at different doses to evaluate inhibition of acetic acid-induced abdominal constrictions and both phases of the formalin test. Additional evaluation included hot plate and tail immersion assays for central antinociception, the open field test for motor coordination, and a 14-day regimen for subacute toxicity.

Results: Zn(Valp)₂Bipy (0.1, 1, and 10 mg/kg) significantly reduced abdominal constrictions and licking time in both phases of the formalin test. In the hot plate and tail immersion tests, this treatment significantly increased the latency period, indicating enhanced pain tolerance. Notably, the analgesic effect observed in the hot plate test was reversed by naloxone, suggesting an opioid-like action. Furthermore, in the open field test, the treatment did not affect the animals' motor function. When administered daily at a dose of 1 mg/kg for 14 days, the compound exhibited no observable toxicity, underscoring its safety profile.

Conclusions: Zn(Valp)₂Bipy demonstrated significant antinociceptive activity through central and peripheral mechanisms without detectable toxicity. This study provides the first evidence of analgesic potential for this complex, highlighting it as a promising drug prototype for effective pain management therapies.