*Article* **Natural and Enantiopure Alkylglycerols as Antibiofilms Against Clinical Bacterial Isolates and Quorum Sensing Inhibitors of** *Chromobacterium violaceum* **ATCC 12472**

**Klauss E. Chaverra Daza 1,2, Edelberto Silva Gómez <sup>2</sup> , Bárbara D. Moreno Murillo <sup>3</sup> and Humberto Mayorga Wandurraga 3,\***


**Abstract:** Resistance mechanisms occur in almost all clinical bacterial isolates and represent one of the most worrisome health problems worldwide. Bacteria can form biofilms and communicate through quorum sensing (QS), which allow them to develop resistance against conventional antibiotics. Thus, new therapeutic candidates are sought. We focus on alkylglycerols (AKGs) because of their recently discovered quorum sensing inhibition (QSI) ability and antibiofilm potential. Fifteen natural enantiopure AKGs were tested to determine their effect on the biofilm formation of other clinical bacterial isolates, two reference strains and their QSI was determined using *Chromobacterium violaceum* ATCC 12472. The highest biofilm inhibition rates (%) and minimum QS inhibitory concentration were determined by a microtiter plate assay and ciprofloxacin was used as the standard antibiotic. At subinhibitory concentrations, each AKG reduced biofilm formation in a concentration-dependent manner against seven bacterial isolates, with values up to 97.2%. Each AKG displayed QSI at different levels of ability without affecting the growth of *C. violaceum*. AKG (2*S*)-3-*O*-(*cis*-13'-docosenyl)-1,2 propanediol was the best QS inhibitor (20 µM), while (2*S*)-3-*O*-(*cis*-9'-hexadecenyl)-1,2-propanediol was the least effective (795 µM). The results showed for the first time the QSI activity of this natural AKG series and suggest that AKGs could be promising candidates for further studies on preventing antimicrobial resistance.

**Keywords:** antimicrobial resistance; natural alkylglycerols; ether lipids; 1-*O*-alkyl-sn-glycerols; antibiofilm activity; quorum sensing inhibition
