Identification and Characterization of Polyphenols from Carissa spinarum Fruit and Evaluation of Their Antioxidant and Anti-quorum Sensing Activity.

Quorum sensing controls bacterial virulence through signaling molecules, which plays a vital role in managing foodborne pathogens that cause food spoilage and human infections. Though many synthetic compounds have been used to control infection, antibiotic resistance has become a global issue. Targeting the bacterial quorum sensing using the bioactive compounds could be an alternative strategy to combat their resistance. In this context, polyphenols from an unexplored unripe and ripe fruits of Carissa spinarum were evaluated for anti-quorum sensing activity. The study aimed at determining nutritional, phytochemical composition, and polyphenol profiling to evaluate their antioxidant potential of the fruit. Furthermore, the violacein inhibition, anti-biofilm, and effect on the motility of foodborne pathogens were also studied. The phytochemical content of C. spinarum fruit showed the phenolic and flavonoid content 273.20 mg GAE/100 g and 453.78 mg QE/100 g fresh weight , respectively, in ripe fruit. HPLC characterization of fruit extracts showed high content of syringic acid, resveratrol, and quercetin in ripe, whereas it showed epicatechin and gentisic acid in unripe fruit. The antioxidant activity of the ripe fruit extract exhibited a higher potential to scavenge DPPH radicals with IC50 4.69 mg/mL. Further, the anti-quorum sensing activity was higher in ripe fruit extract at 1.8 mg/mL inhibited with 78.65% violacein production in Chromobacterium violaceum, swimming motility, and biofilm formation in Pseudomonas aeruginosa and Yersinia enterocolitica (66.25% and 59.36% respectively at 1.2 mg/mL). Hence C. spinarum fruit bioactive could be a natural plant source for anti-quorum sensing activity to manage foodborne pathogens over synthetic compounds.