Saccharobisindole, Neoasterric Methyl Ester, and 7-Chloro-4(1H)-quinolone: Three New Compounds Isolated from the Marine Bacterium Saccharomonospora sp.

Abstract

Analysis of the chemical components from the culture broth of the marine bacterium Saccharomonospora sp. CNQ-490 has yielded three novel compounds: saccharobisindole (1), neoasterric methyl ester (2), and 7-chloro-4(1H)-quinolone (3), in addition to acremonidine E (4), pinselin (5), penicitrinon A (6), and penicitrinon E (7). The chemical structures of the three novel compounds were elucidated by the interpretation of 1D, 2D nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS) data. Compound 2 generated weak inhibition activity against Bacillus subtilis KCTC2441 and Staphylococcus aureus KCTC1927 at concentrations of 32 μg/mL and 64 μg/mL, respectively, whereas compounds 1 and 3 did not have any observable effects. In addition, compound 2 displayed weak anti-quorum sensing (QS) effects against S. aureus KCTC1927 and Micrococcus luteus SCO560.

Marine natural products

“…yielded a new indole dimer saccharobisindole 31 , asterric acid analogue 32 and the quinolone 33 . 14 …”

Naturally Occurring Asterric Acid Analogs: Chemistry and Biology

“…Its structure was established by HR-FAB-MS, IR, and NMR, and HMBC correlation together with the orthocoupled protons (H-3′ and H-4′, J = 8.7 Hz) demonstrated two hydroxyl groups rarely anchored at C-2′ and C-5′. 50 Microbial secondary metabolites are a major source of these analogs, with few examples to be thought from botanic producers. [9][10][11]27,35 This was strongly reminiscent of the classical example swainsonine, which was ever isolated from the plant genera Astragalus and Oxytropis (family Leguminosae).…”

“…Meanwhile, neoasterric methyl ester (60) exhibited quorum sensing blocking activities against S. aureus KCTC1927 and Micrococcus luteus SCO560 at 32 and 64 μg/mL, respectively. 50 In the assessment of antibacterial activity against methicillinresistant S. aureus (MRSA), methyl dichloroasterrate (17) and methyl chloroasterrate (18) showed anti-MRSA activity with MIC values of 1.0−64.0 μg/mL, while the MIC values of methyl asterrate (3) and geodin hydrate (12) were both greater than 128.0 μg/mL. Therefore, a primary structure− activity relationship was presented: both chlorinated substitution and esterification of carboxylic group could impact the antibacterial activity of asterric acid analogs.…”

“…CNQ-490. Its structure was established by HR-FAB-MS, IR, and NMR, and HMBC correlation together with the ortho -coupled protons (H-3′ and H-4′, J = 8.7 Hz) demonstrated two hydroxyl groups rarely anchored at C-2′ and C-5′ …”

“…Meanwhile, neoasterric methyl ester ( 60 ) exhibited quorum sensing blocking activities against S. aureus KCTC1927 and Micrococcus luteus SCO560 at 32 and 64 μg/mL, respectively …”