Antimicrobial, antioxidant, and antitumor activity of epsilon-poly-L-lysine and citral, alone or in combination

Abstract

BackgroundFood safety is an important worldwide public health concern, and microbial contamination in foods not only leads to food deterioration and shelf life reduction but also results in economic losses and disease.ObjectiveThe main aim of the present study was to evaluate the effect of epsilon-poly-L-lysine (ε-PL) and citral combination against Escherichia coli O157:H7 (E. coli O157:H7) strains. The preliminary antioxidant and antitumor activities were also studied.DesignSynergism is a positive interaction created when two compounds combine and exert an inhibitory effect that is greater than the sum of their individual effects. The synergistic antimicrobial effect of ε-PL and citral was studied using the checkerboard method against E. coli O157:H7. The minimal inhibitory concentration, time-kill, and scanning electron microscope assays were used to determine the antimicrobial activity of ε-PL and citral alone or in combination; 2,2-diphenyl-1-picrylhydrazyl-scavenging assay and western blotting were used in antioxidant activity assays; cell viability assay was carried out to finish preliminary antitumor test.ResultsMinimal inhibitory concentrations of ε-PL and citral resisted to the five E. coli O157:H7 strains were 2–4 µg/mL and 0.5–1 µg/mL, and the fractional inhibitory concentration indices were 0.25–0.375. The results of time-kill assay revealed that a stronger bactericidal effect in a laboratory medium might be exerted in the combination against E. coli O157:H7 than that in a food model. The compounds alone or in combination exhibited a potential 2,2-diphenyl-1-picrylhydrazyl radical–scavenging activity, and the expression of superoxide dismutase 1 and glutathione peroxidase 1 protein increased. The preliminary antitumor activity effect of the combination was better than ε-PL or citral alone.ConclusionsThese findings indicated that the combination of ε-PL and citral could not only be used as a promising naturally sourced food preservative but also be used in the pharmaceutical industry.

Chemical Composition and Evaluation of the Biological Properties of the Essential Oil of the Dietary Phytochemical Lippia citriodora

“…The radical scavenging activity of citral has been tested before using the DPPH and ABTS assays, showing significant activity (IC 50 values ranging from 30 to 260 μg/mL), in disagreement with our results [ 17 , 18 , 19 ]. Compared to lemon verbena oil, its activity was weaker showing that the oil probably owes its radical scavenging activity to its other constituents, as this is the case for other oils as well [ 20 ].…”

Protective Effect of Bruguiera gymnorrhiza (L.) Lam. Fruit on Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice: Role of Keap1/Nrf2 Pathway and Gut Microbiota

“…In order to investigate the potential antioxidant activity of BGF, DPPH radical scavenging ability and reducing power assay were performed. DPPH assay was generally used to evaluate the free radical scavenging capacity of natural antioxidant (Shi et al, 2016). In the present study, BGF exerted powerful antioxidative effect in vitro (with IC 50 of 20.45 mg/mL for DPPH assay).…”

Effect of citral on mouse hepatic cytochrome P450 enzymes

“… 2010 ; Shi, Song, et al. 2016 , Shi, Zhao, 2016 ). It has been reported to possess carminative, diuretic, deodorizing, and central nervous system-stimulating effects (Carbajal et al.…”

“… 2008 ), antitumor (Shi, Zhao, et al. 2016 ), and antibacterial activities (Somolinos et al. 2010 ; Shi, Song, et al.…”