Identification of Anti-Helicobacter pylori Compounds From Usnea undulata

In this study, we evaluated 3 extracts (n-hexane, acetone, and methanol) of Usnea undulata Stirton (Usneaaceae) and 5 isolated compounds [methyl orsellinate (1), methyl beta-orsellinate (2), 7-hydroxyl-5-methoxy-6-methylphtalide (3), usnic acid (UA) (4), and salazinic acid (5)] for their inhibitory activity against Helicobacter pylori. The results showed that the n-hexane extract exhibited the strongest activity with the largest inhibition zone (d = 14 mm). For the isolated metabolites, besides UA that has been reported as a potent anti-H. pylori agent, compounds 1 and 2 showed higher inhibition compared to the reference drugs. Our results demonstrated that U. undulata could be a promising source of potential anti-H. pylori metabolites.