Targeting Helicobacter pylori for antibacterial drug discovery with novel therapeutics

Discovery and evolution of berberine analogues as anti-Helicobacter pylori agents with multi-target mechanisms

Thirty protoberberine derivatives, of which twenty five were new, were synthesized and evaluated for their anti-Helicobacter pylori (HP) activities, taking 2,3,10-trimethoxy-9-p-methylbenzylaminoprotopalmatine chloride 1 as the lead. Among them, berberine (BBR) derivative 7c displayed the highest potency against six tested metronidazole (MTZ)-resistant strains and two tested MTZ-susceptible strains with the MIC values of 0.4-1.6 μg/mL with favorable druglike profiles including low toxicity and high stabilities in plasma and artificial gastric fluid. Mechanistic study revealed that 7c might target HP urease with IC50 value of 0.27 μg/mL against Jack bean urease. Furthermore, 7c might change the permeability of the bacterial membrane and direct interact with HP DNA, which also contribute to its bactericidal activity. Therefore, BBR derivatives constituted a new family of anti-HP candidates, with the advantage of good safety profile and multi-target mechanisms, and are worthy for further investigation.

Helicobacter pylori CAs inhibition

Infections from Helicobacter pylori (Hp) are endangering Public Health safety worldwide, due to the associated high risk of developing severe diseases, such as peptic ulcer, gastric cancer, diabetes, and cardiovascular diseases. Current therapies are becoming less effective due to the rise of (multi)drug-resistant phenotypes and an urgent need for new antibacterial agents with innovative mechanisms of action is pressing. Among the most promising pharmacological targets, Carbonic Anhydrases (EC: 4.2.1.1) from Hp, namely HpαCA and HpβCA, emerged for their high druggability and crucial role in the survival of the pathogen in the host. Thereby, in the last decades, the two isoenzymes were isolated and characterized offering the opportunity to profile their kinetics and test different series of inhibitors.

Novel carbonic anhydrase inhibitors for the treatment of Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori, the causative agent of peptic ulcer, gastritis, and gastric cancer encodes two carbonic anhydrases (CA, EC 4.2.1.1) belonging to the α- and β-class (HpCAα/β), which have been validated as antibacterial drug targets. Acetazolamide and ethoxzolamide were also clinically used for the management of peptic ulcer.

AREAS COVERED

Sulfonamides were the most investigated HpCAα/β compounds, with several low nanomolar inhibitors identified, some of which also crystallized as adducts with HpCAα, allowing for the rationalization of the structure-activity relationship. Few data are available for other classes of inhibitors, such as phenols, sulfamides, sulfamates, dithiocarbamates, arylboronic acids, some of which showed effective in vitro inhibition and for phenols, also inhibition of planktonic growth, biofilm formation, and outer membrane vesicles spawning.

EXPERT OPINION

Several recent drug design studies reported selenazoles incorporating seleno/telluro-ethers attached to benzenesulfonamides, hybrids incorporating the EGFR inhibitor erlotinib and benzenesulfonamides, showing KIs < 100 nM against HpCAα and MICs in the range of 8-16 µg/mL for the most active derivatives. Few drug design studies for non-sulfonamide inhibitors were performed to date, although inhibition of these enzymes may help the fight of multidrug resistance to classical antibiotics which emerged in the last decades also for this bacterium.

Antimicrobial combinations against Helicobacter pylori including benzoxadiazol-based flavodoxin inhibitors: in vitro characterization

IMPORTANCE

The antimicrobial resistance of Helicobacter pylori (Hp) currently poses a threat to available treatment regimens. Developing antimicrobial drugs targeting new bacterial targets is crucial, and one such class of drugs includes Hp-flavodoxin (Hp-fld) inhibitors that target an essential metabolic pathway in Hp. Our study demonstrated that combining these new drugs with conventional antibiotics used for Hp infection treatment prevented the regrowth observed with drugs used alone. Hp-fld inhibitors show promise as new drugs to be incorporated into the treatment of Hp infection, potentially reducing the development of resistance and shortening the treatment duration.

Involvement of Nitric Oxide in Protecting against Radical Species and Autoregulation of M1-Polarized Macrophages through Metabolic Remodeling

When the expression of NOS2 in M1-polarized macrophages is induced, huge amounts of nitric oxide (•NO) are produced from arginine and molecular oxygen as the substrates. While anti-microbial action is the primary function of M1 macrophages, excessive activation may result in inflammation being aggravated. The reaction of •NO with superoxide produces peroxynitrite, which is highly toxic to cells. Alternatively, however, this reaction eliminates radial electrons and may occasionally alleviate subsequent radical-mediated damage. Reactions of •NO with lipid radicals terminates the radical chain reaction in lipid peroxidation, which leads to the suppression of ferroptosis. •NO is involved in the metabolic remodeling of M1 macrophages. Enzymes in the tricarboxylic acid (TCA) cycle, notably aconitase 2, as well as respiratory chain enzymes, are preferential targets of •NO derivatives. Ornithine, an alternate compound produced from arginine instead of citrulline and •NO, is recruited to synthesize polyamines. Itaconate, which is produced from the remodeled TCA cycle, and polyamines function as defense systems against overresponses of M1 macrophages in a feedback manner. Herein, we overview the protective aspects of •NO against radical species and the autoregulatory systems that are enabled by metabolic remodeling in M9-polarized macrophages.