Antibacterial and antibiofilm agents in the group of xanthone derivatives with piperazine moiety active against drug-resistant Helicobacter pylori strains

Helicobacter pylori (H. pylori) cause chronic inflammation of the gastric mucosa which can lead to epithelial atrophy and metaplasia resulting in peptic ulcer disease and gastric cancer. The increasing resistance of H. pylori to antibiotics and chemotherapeutics used to treat the infection is a serious problem. However, it has been confirmed that the introduction of effective anti-H. pylori therapy can prevent the progression to cancerous changes. This problem calls for the search for new and effective therapies. Xanthones are a group of compounds with extensive biological activities, including antibacterial activity, also against H. pylori. Addressing this issue, the aim of the study was to evaluate the potential of a group of 13 xanthone derivatives against susceptible and resistant H. pylori strains. Moreover, our objective was to conduct tests aimed at determining their ability to inhibit biofilm formation. The antimicrobial evaluation revealed that benzylpiperazine coupled at the C-2 position to xanthone (compounds C11 and C12) had good selective bacteriostatic activity against reference and clinical H. pylori strains (MBC/MIC ratio >4) but with no activity against other bacteria such as Staphylococcus aureus, Escherichia coli, and Lactobacillus paracasei. Analysis of the activity of compounds C11 and C12 against the biofilm formed by H. pylori strain ATCC 700684, and the clinical strain showed that these compounds caused a significant reduction in the amount of biofilm produced (5-20×). Moreover, cell viability analysis confirmed a 3-4× reduction in the viability of cells forming biofilm after treatment with C11 and C12. Finally,both compounds did not impair human fibroblast viability at tested concentrations and were not mutagenic in the Ames test. Therefore, they could be promising leads as antibacterial candidates for multidrug-resistant strains of H. pylori.