New approaches to the design of analgesic medicinal substances.

A gamma-pyrone derivative, comenic acid, activates the opioid-like receptor-mediated signaling pathway that modulates the Na1.8 channels in the primary sensory neuron membrane. These channels are responsible for the generation of the nociceptive signal; therefore, gamma-pyrones have great therapeutic potential as analgesics, and this effect deserves a deeper understanding. The novelty of our approach to the design of a medicinal substance is based on a combination of the data obtained from living neurons using very sensitive physiological methods and the results of quantum chemical calculations. This approach allows the correlation of the molecular structure of gamma-pyrones with their ability to evoke a physiological response of the neuron. Comenic acid can bind to two calcium cations. One of them is chelated by the carbonyl and hydroxyl functional groups, while the other forms a salt bond with the carboxylate anion. Calcium-bound gamma-pyrones have fundamentally different electrostatic properties from free gamma-pyrone molecules. These two calcium ions are key elements involved in ligand-receptor binding. It is very likely that ion-ionic interactions between these cations and anionic functional groups of the opioid-like receptor activate the latter. The calculated intercationic distance of 9.5 Å is a structural criterion for effective ligand-receptor binding of calcium-bound gamma-pyrones.