Bioactive Properties of Campomanesia lineatifolia: Correlation Between Anti-Helicobacter pylori Activity, Antioxidant Potential and Chemical Composition

<i>Helicobacter pylori</i> is found in the stomach of patients with chronic gastritis and peptic ulcers, infecting approximately half of the world's population. Current treatment for <i>H. pylori</i> infection involves a multi-drug therapeutic regime with various adverse effects, which leads to treatment abandonment and contributes to the emergence of resistant strains of <i>H. pylori</i>. Previously, we demonstrated that the essential oil of <i>Campomanesia lineatifolia</i> leaves exhibited an anti-<i>H. pylori</i> activity. In this study, we aimed to evaluate the phenolic content of the phenolic-rich ethanol extract (PEE) from <i>C. lineatifolia</i> and its anti-<i>H. pylori</i> and antioxidant properties. Additionally, the anti-<i>H. pylori</i> activity was assessed in polar and non-polar fractions from PEE, isolated myricitrin (MYR) and a mixture of myricitrin and quercitrin (MYR/QUER) from polar fractions, and aqueous extract (tea) to correlate the responsible fractions or compounds with the observed activity. Broth microdilution assays were performed to assess the anti-<i>H. pylori</i> activity using type cultures (ATCC 49503, NCTC 11638, both clarithromycin-sensitive) and clinical isolate strains (SSR359, clarithromycin-sensitive, and SSR366, clarithromycin-resistant). The antioxidant activity was evaluated using the DPPH assay. The total tannin and flavonoid contents were determined using the hide-powder method, the Folin-Ciocalteu reagent, and the aluminium chloride colourimetric assay, respectively. The tea (MIC 1:100), PEE, polar and non-polar fractions, MYR, and MYR/QUER inhibited the growth of <i>H. pylori</i> strains tested (MIC values ranging from 0.49 to 250 μg/mL). The antioxidant assays revealed that PEE exhibited a higher antioxidant activity (EC₅₀ = 18.47 μg/mL), which correlated to the high phenolic content (tannin and flavonoid, 22.31 and 0.15% <i>w</i>/<i>w</i>, respectively). These findings support the traditional use of <i>C. lineatifolia</i> as a multitarget medicinal plant for treating gastric ulcers and reinforce the potential use of the species as a coadjuvant in therapeutic regimes involving patients with resistant <i>H. pylori</i> infection.