Evaluation of antibiofilm activities of Quercetin, extracted from petals of blue butterfly pea flower against a dental plaque isolated bacterial strain of Alcaligenes faecalis DMR 19
摘要
The development of bacterial microcolonies on dental surfaces is a complex, multi-phase dynamic process that includes initial adherence to a protein layer with distinct molecular interactions, modification of oral pH by metabolic activities, bacterial growth, coaggregation, and matrix production to form a biofilm. As a natural therapeutic agent against dental biofilm, the floral extract of blue Clitorea ternatea was selected, Quercetin [2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one] was found to be its major phytocomponent, as revealed by the HPLC analysis. The in-silico analysis of docking energy (ΔG = − 5.96 kcal/mol) reflected the high binding affinity between Quercetin and the biofilm-forming proteins of dental plaque isolated MDR bacterial strain of Alcaligenes faecalis DMR 19. Statistical optimization by RSM shows that the highest Quercetin can be extracted from the phytoextract at pH 6, from a 1000 mg/ml extract after 19.5 min. Phyto-extracted Quercetin showed similar antibiofilm efficacy to that of pure Quercetin (92%) having MBEC 92 µg/mL and a more pronounced effect than amoxicillin (67%) with MBEC 60 µg/mL. Unlike antibiotic-treated bacterial cells, a very negligible tendency of revival was shown by the Quercetin-treated bacterial cells. Quercetin challenge has brought about a remarkable reduction in carbohydrate (80%), protein (52%) and nucleic acid content (80%) of the EPS, also confirmed by the change in FTIR spectra indicating quercetin-induced disruption of EPS hydrogen bonding (3400–3200 cm−1), lipids (2920–2850 cm−1), proteins (~ 1650 cm−1), and polysaccharide/eDNA components (1200–900 cm−1). Similarly, the quercetin-treated cells showed higher quorum quenching activities and greater bactericidal effect than the antibiotic, as evident from different biochemical tests and image analyses of SEM, CLSM, and FACS. Quercetin could generate a little intracellular ROS, revealing that it acts through precise antibiofilm mechanisms beyond non-specific oxidative stress (ROS generation).