Tetrocarcin Q, a New Spirotetronate with a Unique Glycosyl Group from a Marine-Derived Actinomycete Micromonospora carbonacea LS276

Abstract

A new spirotetronate glycoside tetrocarcin Q (<b>1</b>) and six known analogues tetrocarcin A (<b>2</b>), AC6H (<b>3</b>), tetrocarcin N (<b>4</b>), tetrocarcin H (<b>5</b>), arisostatin A (<b>6</b>), and tetrocarcin F1 (<b>7</b>) were isolated from the fermentation broth of the marine-derived actinomycete <i>Micromonospora carbonacea</i> LS276. Their chemical structures were established on the basis of 1D- and 2D-NMR spectroscopy, as well as HR-ESI-MS analysis. The absolute configurations of their stereogenic carbons were determined by circular dichroism (CD) analysis. Compound <b>1</b> possesses 2-deoxy-allose, which is a unique sugar type at the C-9 position. This type has not been found in the previously reported spirotetronate glycosides. Compound <b>1</b> displayed moderate antibacterial activity against <i>Bacillus subitlis</i> ATCC 63501 with minimum inhibitory concentration (MIC) value of 12.5 μM.