Natural cembranoids have shown Quorum Sensing Inhibitory (QSI) activity, but their structure-function interactions are not well understood. Thirty-four cembranoid analogues were synthesized using six natural cembranoids (1-6) previously isolated from the Colombian Caribbean octocorals Eunicea knighti and Pseudoplexaura flagellosa as lead compounds. The analogues (7-40) obtained through the selected chemical transformations were tested in vitro against the QS systems of a Chromobacterium violaceum biosensor. Half of the cembranoid analogues assayed showed superior QSI activity to the lead compounds; three (8, 13, and 18) displayed remarkable potency up to three times higher than the natural compounds. Thereby, we have synthesized a pool of cembranoid QS inhibitors that can be used in concert with natural compounds to develop antipathogenic drugs and antifouling agents. (C) 2012 Elsevier Ltd. All rights reserved.
Cembranoid Diterpenes from the Caribbean Sea Whip <i>Eunicea knighti</i>
Three new cembranoid diterpenes, knightol (1), knightol acetate (2), and knightal (3), along with the known asperdiol (4) and asperdiol acetate (5), were isolated as major compounds from the sea whip Eunicea knighti collected from the Colombian Caribbean. The structures and absolute configurations of 1−5 were determined on the basis of spectroscopic analyses and by a combination of chemical and NMR