Microalgae-derived compounds against <i>Helicobacter pylori</i>: antibacterial, antioxidant, and anti-inflammatory evidence

Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and affects more than half of the world´s population. It is associated with gastritis, peptic ulcers, and gastric cancers. Despite antibiotics being long effective, increasing multi-resistance to key drugs has led to lower eradication rates, highlighting the need for alternative approaches. Natural bioactive compounds from microalgae have increased attention due to their antioxidant, antibacterial, and anti-inflammatory properties. Microalgae produce a wide variety of metabolites, such as photosynthetic pigments, fatty acids, peptides, and carbohydrates, many of which show promising activity against H. pylori. Antioxidants like astaxanthin and polyphenols help neutralize reactive oxygen species, protect gastric epithelial cells, and modulate inflammatory signaling. Sulfated polysaccharides and antibacterial peptides can interfere with bacterial adhesion, damage the cell membrane, and inhibit virulence factors such as cagA and vacA. Additionally, omega-3 fatty acids (EPA and DHA) and phycocyanin have strong immunomodulatory effects, reducing NF-κB activation and lowering pro-inflammatory cytokines like IL-6 and TNF-α. In contrast to previous reviews that discuss microalgal bioactivities separately, this article takes an integrated view, connecting specific microalgal compounds with H. pylori virulence mechanisms and host inflammatory responses. Using different approaches at once, microalgal metabolites can help limit bacterial growth, reduce oxidative stress, and mitigate chronic inflammation. Overall, microalgae represent a sustainable and innovative source of bioactive compounds that could complement current therapies for H. pylori infection. Incorporating these compounds into functional foods or nutraceuticals may improve treatment outcomes, protect the gastric mucosa, and reduce the use of antibiotics. Future work should focus on improving extraction methods, enhancing bioavailability, and confirming their efficacy and safety through preclinical and clinical studies. Microalgal compounds offer a promising, safe, and environmentally friendly strategy for preventing and managing H. pylori-related diseases. Keywords: H. pylori, microalgae, bioactive compounds, antibacterial activity, antioxidant activity, anti-inflammatory activity