Anti-Helicobacter pylori Compounds of Sambucus williamsii Hance Branch

<i>Sambucus williamsii</i> Hance (Viburnaceae), the Korean elderberry, is widely used in herbal medicine and in the food industry. It is known to have various pharmacological effects, including antitumor, antioxidant, anti-inflammatory, and antimicrobial activities. During our search for anti-<i>Helicobacter pylori</i> compounds from natural resources, the methanol extract of the <i>S. williamsii</i> branch significantly inhibited the growth of <i>H. pylori</i>. Three phenolic and four lignan compounds were isolated from the methylene chloride fraction that had shown the most potent anti-<i>H. pylori</i> activity among the hexane, methylene chloride, ethyl acetate, butanol, and water fractions. The chemical structures were identified to be three phenolics of sylvopinol (<b>1</b>), dihydroconiferyl alcohol (<b>2</b>), and (7<i>S</i>,8<i>R</i>)-guaiacylglycerol (<b>3</b>) and four lignans of boehmenan (<b>4</b>), (7<i>S</i>,8<i>S</i>)-guaiacylglycerol <i>β</i>-coniferyl ether (<b>6</b>) and lawsonicin (<b>7</b>) with a new lignan, (7<i>R</i>,8<i>R</i>)-sambucanol (<b>5</b>), the structure of which was established by ¹H- and ¹³C-NMR, and HRESI-MS, as well as quantum chemical electronic circular dichroism (ECD) calculations. Among the isolates, compounds <b>3</b> and <b>4</b> exhibited significant anti-<i>H. pylori</i> activity against strains 51 and 26695. Compound <b>3</b> displayed more potent antibacterial activity with MIC values of 3.13 and 6.25 μM, and MIC₅₀ values of 28.5 and 56.8 μM against the two strains, respectively. Their inhibitory activities were higher than those of a positive control, quercetin. Furthermore, these two compounds showed moderate urease inhibitory activity. A molecular docking simulation revealed the high binding ability of <b>3</b> and <b>4</b> to the active site of <i>H. pylori</i> urease. These results will provide further insights into the design of more potent natural products for eradicating <i>H. pylori</i>.