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

A new spirotetronate glycoside tetrocarcin Q () and six known analogues tetrocarcin A (), AC6H (), tetrocarcin N (), tetrocarcin H (), arisostatin A (), and tetrocarcin F1 () were isolated from the fermentation broth of the marine-derived actinomycete 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 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 displayed moderate antibacterial activity against ATCC 63501 with minimum inhibitory concentration (MIC) value of 12.5 μM.