Helicobacter pylori (H. pylori) is one of the most frequent human pathogenic bacteria, affecting more than 50% of the world's population. Its infection is associated with oxidative stress and chronic inflammation. Although eradicative antibiotics-based treatment is indicated, their multiple side effects and the increasing antibiotic resistance highlight the urgency of seeking alternative approaches. Nannochloropsis gaditana (N. gaditana) has attracted increasing attention due to its adaptability, sustainability, and high nutritional value. Also, multiple biological properties have been associated with extracts or isolated compounds from this microalga. The objective of our study was to evaluate the impact of simulated orogastric digestion on the antioxidant, anti-inflammatory, and antibacterial activities of N. gaditana, as a basis of its protective effects against H. pylori infection.
A T. gaditana biomass was subjected to a combined pre-treatment of freeze/thaw cycles and ultrasounds. The orogastric digestion was simulated following the INFOGEST protocol3 and the antioxidant activity of the biomass and digest were evaluated using the ORAC and ABTS assays. To evaluate the antibacterial activity, a quantitative analysis of the colony-forming units of H. pylori was performed in the presence of microalga or its digest. In addition, the antioxidant (reactive oxygen species, ROS, levels) and anti-inflammatory activity (interleukin, IL-8, levels) were evaluated in human gastric adenocarcinoma cells under basal and H. pylori infection.
T. gaditana showed antibacterial activity against H. pylori. The digestive process allowed the release of potent peroxyl and ABTS radical scavengers and the degradation of pro-inflammatory compounds. In basal gastric cells, no effects on the ROS levels were observed. However, after H. pylori infection, both microalga and its digest increased the ROS levels produced by cells, favoring a cell defensive mechanism against the pathogen. Our findings support the protective role of microalga N. gaditana and its promising future as a natural alternative option in the treatment of H. pylori infection.
