Coupling the high-resolution LC–MS characterisation of the phenolic compounds with the antimicrobial and antibiofilm properties of helencha ( Enydra fluctuans Lour.)

This study reports the polyphenol profile of helencha ( Enydra fluctuans Lour.), an underutilised, aquatic leafy vegetable, based on high resolution accurate mass analysis. The methanolic extract of helencha leaves was screened by ultra-high performance liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS). An in-house developed database of phytochemical metabolites was referred for compound identifications. Based on the detection of the pseudomolecular ion and at least one molecule-specific fragment ion (each with < 5 ppm of mass error), 25 potentially-bioactive phenolic compounds were putatively identified. These included 6 flavonols, 4 phenolic acids, 3 lignans, 3 flavones and 1 each of flavanol, flavanone, dihydroflavonol, tetramethoxyflavone, isoflavonoid and methylated flavonol. In addition, 3 unclassified compounds are also reported. The helencha extract showed antibiofilm properties with a potent bacteriostatic activity against the clinical isolates of Pseudomonas aeruginosa , a human pathogenic bacteria. The complementary molecular docking studies indicated strong binding interactions of the identified compounds with the active site of LasR protein of P. aeruginosa. The in vitro and in silico study results would be useful to develop novel neutraceutical products based on helencha-extract and design new lead compounds to control the biofilm producing pathogenic microorganisms.