Disruption in Quorum-Sensing Systems and Bacterial Biofilm Inhibition by Cembranoid Diterpenes Isolated from the Octocoral Eunicea knighti

Abstract

Three new cembranoid diterpenes, knightine (1), 11(R)-hydroxy-12(20)-en-knightal (2), and 11(R)-hydroxy-12(20)-en-knightol acetate (3), were isolated as minor constituents of the Caribbean gorgonian Eunicea knighti, along with the known cembranoids 4-8. The stereostructures of the new compounds were determined by detailed spectroscopic analyses and a combination of chemical transformations and modified Mosher's methods. All isolated cembranoids were tested against fouling using a quorum-sensing inhibition (QSI) assay and a biofilm inhibition test. Compounds 2, 3, and 6 disrupted QS systems at lower concentrations than kojic acid and Cu(2)O, and in most cases cembranoids 1-8 showed bacterial biofilm inhibition at lower concentrations than kojic acid.

Diterpenoids of Gorgonian Corals: Chemistry and Bioactivity

“…In 2012, Duque et al . re‐examined the specimens of E. knighti collected in the Colombian Caribbean Sea and isolated three new cembranoid diterpenoids , knightine ( 188 ), (11 R )‐hydroxy‐12(20)‐en‐knightal ( 189 ), and (11 R )‐hydroxy‐knight‐12(20)‐enol acetate ( 190 ). The absolute configurations of the new compounds were established by NOE experiments and the modified Mosher 's ester method.…”

Antibiofilm activity substances derived from coral symbiotic bacterial extract inhibit biofouling by the model strainPseudomonas aeruginosaPAO1

“…More recently, the culture supernatant from Antarctic marine bacterium P. haloplanktis TAC125 was shown to impair the formation of S. epidermidis biofilm (Papa et al ., 2013; Parrilli et al ., 2015). These findings demonstrate that QSI compounds are valuable antifouling agents in that they could serve as potential effective additives to environmentally friendly commercial antifouling paints due to their non‐toxicity (Tello et al ., 2012). …”

“…The marine environment is a rich storehouse of natural products possessing antibiofilm properties, and accumulating evidence has confirmed the existence of a diverse array of active compounds in coral, bryozoans, sponge and pyrosomida (Skindersoe et al ., 2008; Tello et al ., 2012). Furthermore, studies increasingly point to types of planktonic marine bacteria, such as Bacillus spp., Pseudomonas spp., Pseudoalteromonsa spp., and Vibrio spp., as frequent sources for the production of QSI compounds (Teasdale et al ., 2009; Mangwani et al ., 2015; Benneche et al ., 2016; Casillo et al ., 2017).…”

“…Compared with the planktonic environment, coral ecosystems have a much higher biodiversity and represent a potential source from which to isolate QS inhibitors. Indeed, several studies have described the QSI or antibiofilm potential of several natural compounds originating from coral, including the soft coral Antillogorgia elisabethae , the black coral Antipathes dichotoma , the octocoral Eunicea knighti and the cave coral Acropora millepora (Tello et al ., 2012; Karina et al ., 2013; Diana et al ., 2016). The wide existence of QSI bacteria in coral environments invites us to explore the feasibility of QSI‐based biofouling control methods.…”

Quorum Sensing Inhibitors from the Sea Discovered Using Bacterial N-acyl-homoserine Lactone-Based Biosensors

“…In terms of QSI compounds, four cembranoids ( 62 – 65 ) (Figure 12), were isolated from octocoral Eunicea knighti with QSI property. QSI assays were carried out using P. putida IsoF wild strain, E. coli pSB401, and C. violaceum (ATCC 31532) biosensor [45,46]. Another three cembranoid epimers at C-8 ( 66 – 68 ) (Figure 12), were isolated from the Colombian Caribbean octocoral Pseudoplexaura flagellosa based on inhibition of the production of violacein pigment of C. violaceum (ATCC 31532) biosensor [47].…”