Pyrrolidine, Piperazine, and Diazinane Alkaloids from the Marine Bacterium Strain Vibrio ruber ZXR-93

Four new alkaloids, vibripyrrolidine A (<b>1</b>), vibripiperazine A (<b>2</b>), and vibridiazinane A, B (<b>3</b>, <b>4</b>), comprising one pyrrolidine, one piperazine, and two diazinane alkaloids, along with two known analogs (<b>5</b>, <b>6</b>), were isolated from the marine bacterium <i>Vibrio ruber</i> ZXR-93 cultured in ISP2 medium. Their chemical structures were elucidated by analysis of their 1D and 2D NMR, mass spectra, and electronic circular dichroism (ECD) calculations. Compounds <b>1</b> and <b>3</b>-<b>6</b> showed vigorous antibacterial activity against <i>Staphylococcus aureus</i>, with MIC values ranging from 0.96 to 7.81 μg/mL. Moreover, compound <b>1</b> exhibited robust anti-inflammatory activity in vitro using the LPS-induced RAW264.7 macrophage model. All compounds also showed moderate antineoplastic activity against cervical cancer cells (HeLa) and gastric cancer cells (SGC-7901).