Complex forming properties of cannabinoid acids in a green solvent and bioassays focused on gastric disease caused by Helicobacter pylori infection

The main objective of the present study was to determine the protolytic and coordination properties of two bioactive cannabinoid acids (cannabidiolic acid and cannabigerolic acid) in ethyl alcohol-water mixture (50/50, v/v). The complexation properties of these acids with copper(II) and zinc(II) ions were determined by potentiometric and ESI–MS methods. UV–Vis absorption spectra for the copper(II) systems confirmed the speciation models with one type of complex indicating coordination with completely deprotonated dinegative ligand molecule. The occurrence of precipitation at lower pH values limited the ability to determine complexes under these conditions. The research also aimed to identify potential biological and medicinal applications of cannabinoid acids and their complexes with zinc(II). The ability of these compounds to influence the growth of human Hs68 skin fibroblasts and AGS gastric adenocarcinoma cells was investigated. Furthermore, these structures were tested against Helicobacter pylori strains, one of the factors promoting gastric cancer development. At concentrations that were not-toxic to healthy cells (after dilution of the solutions, the composition of the ethanol/water mixture was approximately 1/99, v/v), the ligands exhibited bacterial inhibitory activity and cytotoxic properties against AGS cancer cells. Zinc(II) complexes, on the other hand, being biologically safe for all cells, had strong antibacterial properties, both inhibitory and bactericidal.