Antimicrobial Spirotetronate Metabolites from Marine-Derived <i>Micromonospora harpali</i> SCSIO GJ089 GuiChun ZhangShanwen ZhuXiangcheng DingWenjuan HuangHongbo GuYu-Cheng DuanYanwen JuJianhua 2017 Two new spirotetronate aglycones, 22-de­hydroxy­methyl-kijanolide (<b>1</b>) and 8-hydroxy-22-dehydroxy­methyl-kijanolide (<b>2</b>), along with seven new spirotetronate glycosides, microsporanates A–F (<b>3</b>–<b>8</b>) and tetrocarcin P (<b>9</b>), together with three known tetrocarcins [tetrocarcins A (<b>10</b>), B (<b>11</b>), and AC6H (<b>12</b>)], were isolated from fermentation broths of the marine-derived <i>Micromonospora harpali</i> SCSIO GJ089. The structures of <b>1</b>–<b>9</b> were elucidated on the basis of 1D and 2D NMR and MS spectroscopic data. Compounds <b>3</b>–<b>8</b> feature an α,β-unsaturated carbonyl moiety within their spirotetronate skeletons. Moreover, compounds <b>3</b>–<b>12</b> displayed strong to moderate antibacterial activities against Gram positive bacteria <i>Bacillus thuringiensis</i> BT01 and <i>B. subtilis</i> BS01 with MIC values ranging from 0.016 to 8.0 μg/mL.