Antioxidant Activity of Flavonoids in LPS-Treated IPEC-J2 Porcine Intestinal Epithelial Cells and Their Antibacterial Effect against Bacteria of Swine Origin

Abstract

Beneficial effects of flavonoids are widely known in human medicine, but less information is available about their veterinary usage. Based on their antioxidant and antibacterial activity, proanthocyanidins (PAs) and luteolin (LUT) might be used in the prevention and treatment of gastrointestinal infections in swine. In this study, in vitro beneficial effects of grape seed oligomeric proanthocyanidins (GSOPs) and LUT were investigated against bacterial endotoxin (LPS)-induced oxidative stress in IPEC-J2 porcine epithelial intestinal cells. Furthermore, antibacterial effects of GSOP and LUT were assessed against field isolates of Escherichia coli and Salmonella enterica ser. Typhimurium. Both GSOP and LUT were found to possess potent in vitro antioxidant activity in LPS-treated IPEC-J2 cells; furthermore, they showed a bacteriostatic effect against the tested bacterial strains of porcine origin. Both flavonoids seem to be effective in the protection of porcine intestinal epithelial cells against Gram-negative bacteria in vitro, but further in vivo studies are necessary to confirm these activities and to establish their optimal dosage regimen for future usage in veterinary practice.

Protective Effects of Grape Seed Oligomeric Proanthocyanidins in IPEC-J2–Escherichia coli/Salmonella Typhimurium Co-Culture

“…Suspensions of 10 8 CFU/mL in the case of both bacteria significantly decreased the ratio of viable IPEC-J2 cells in the culture. GSOPs alone did not show a cytotoxic effect on IPEC-J2 cells up to 200 μg/mL for 24 h in previous experiments [ 9 ]. Based on these results, and in accordance with the relevant literature [ 26 , 27 ], 10 6 CFU/mL bacterial suspensions were used in the further experiments.…”

“…An antiadhesive effect against uropathogenic bacteria has been reported about A-type PAs but could not be observed in the case of compounds with a B-type structure [20,46]. However, both A-and B-type PAs could show bacteriostatic and bactericidal effects against pathogens such as E. coli and S. Typhimurium [9,[50][51][52], and PAs with a B-type structure seemed to be more effective in some cases [51,52]. Monomer units from PAs can also possess antibacterial characteristics.…”

“…Escherichia coli and Salmonella enterica ser. Typhimurium are among the main Gram-negative pathogens causing gastrointestinal (GI) infections in humans and pigs [ 9 , 10 , 11 ]. Furthermore, the former is commonly associated to the latter as both bacteria are zoonotic, and foodborne transmission with pork products represents a significant proportion of human cases [ 10 , 11 , 12 , 13 ].…”

“…Proanthocyanidins (PAs) are flavonoids widely investigated for their usage in both human and veterinary medicine due to their various beneficial effects. They have been shown to exhibit antioxidant, anti-inflammatory and anticarcinogenic properties, and activity against different pathogens, including bacteria, viruses, fungi, and parasites [ 9 , 15 , 16 , 17 ]. Furthermore, PAs are well known for their ability to inhibit the adhesion of bacteria to cells and other surfaces [ 18 , 19 , 20 ].…”

“…Their protective effect on the cardiovascular [ 21 ] and GI [ 22 ] systems has also been reported. Among many other fruits, vegetables and seeds, grape seed extract is a rich source of PAs [ 9 , 15 , 17 ]. Based on their desirable effects, PAs might serve as antibiotic alternatives through the protection of the GI tract against bacterial infections.…”