Quercetin potentiates antiradical properties of epigallocatechin-3-gallate in periodontium of rats under systemic and local administration of lipopolisaccharide of salmonella typhi

Introduction: There has been demonstrated that pharmaceutical effect of epigallocatechin-3-gallate (EGCG), a polyphenol, which is found in green tea (Camellia sinensis), is implemented through the activation of Nrf2 (Nuclear Factor Erythroid 2-Related Factor 2).The importance of Keap1 / Nrf2 / antioxidant response element (ARE) system is determined by the fact that the state of NF-κB- and АР-1-associated pathways depends on its activity. Recent studies have demonstrated the property of quercetin to suppress ubiquitin-dependent proteolysis of complex of NF-κB and its inhibitory protein IκB. All this provides preconditions to eliminate the potentiality of NF-κB-dependent expression of the number of genes of pro-oxidant and pro-inflammatory proteins. However, co-effect produced by quercetin and EGCG on the oxidative nitrosative stress markers in the periodontal tissues is still unclear. The aim: To investigate the co-effect produced by quercetin and an inducer of the Keap1 / Nrf2 / ARE epigallocatechin-3-gallate on markers of oxidative-nitrosative stress in rats' periodontium under the systemic and local administration of Salmonella typhi lipopolysaccharide (LPS). Material and methods: The studies were conducted on 30 white rats of the Wistar line, divided into 5 groups: the 1st included intact animals, the 2nd was made up of animals after their exposure to combined systemic and local LPS administration, the 3rd and 4th groups included animals, which were given injections with water-soluble form of quercetin (corvitin) and EGCG respectively, and the 5th group involved rats, which were injected with co-administered corvitin and EGCG. The formation of superoxide anion radical (.О-2 ) was evaluated by a test with nitro blue tetrazolium using spectrophotometry of the periodontal soft tissue homogenate. The total activity of NO-synthase and concentration of peroxynitrite in the homogenate of the soft components of periodontium were evaluated spectrophotometrically. Results: Co-effect produced by corvitin and EGCG under systemic and local LPS administration is accompanied with reduced О-2 production by NADPH-dependent electron transport chains (microsomal and NOS) by 20.0 % (p <0.05) compared with values for the animals received separate corvitin during the experiment. .О-2 generation by the mitochondrial respiratory chain yielded to comparable data of the 3rd and 4th groups by 27.6 % (p <0.01) and 23.8 % (p <0.05) respectively. No differences were found between the groups exposed to combined or separate action of the above mentioned agents in the experiment when assessing О-2 generation by leukocyte NADPH-oxidase. Combined effect of corvitin and EGCG during systemic and local LSP administration showed the decrease in NOS activity and peroxynitrite concentration in periodontal tissues by 53.3 % (p <0.001) and 27.0 % (p <0.02) compared with the findings in the 3rd group, and by 42.0 % (p <0.01) and 22.3 % (p <0.01) in the 4th group. Conclusions: The co-administration of water-soluble form of quercetin and epigallocatechin-3-gallate under systemic and local introducing of lipopolysaccharide Salmonella typhi has been proven to be more effective means for preventing and correcting oxidative-nitrosative stress in the periodontal tissues than this occurs at separate administration of each of the polyphenols.

Epigallocatechin-3-gallate prevents disruption of connective tissue in periodontium and salivary glands of rats during systemic inflammation.

OBJECTIVE: Introduction: The connective tissue remodeling is essential for periodontal and salivary glands (SG) pathology. Recently there has been demonstrated the number of pharmacological effects of green tea (Camellia sinensis) such as antioxidant, anti-inflammatory, anti-aging, antibacterial, antiviral and DNA-protective effects, associated with the presence of epigallocatechin-3-gallate (EGCG) as an inducer of the Keap1 / Nrf2 / antioxidant response element signaling pathway. However, the EGCG effects on the components of soft connective tissues of periodontium and SG are still unclear. The aim: To investigate the effect of EGCG on markers of disruption of periodontal and submandibular SG connective tissues in rats during the conditions of experimental systemic inflammation (SI). PATIENTS AND METHODS: Materials and methods: The studies were conducted on 30 white rats of the Wistar line, divided into 3 groups: the 1st included intact animals, the 2nd was made up of animals after induced SI (by intraperitoneal administration of lipopolysaccharide Salmonella typhi), and the 3rd included animals, which were injected EGCG (production of Sigma-Aldrich, Inc., USA) intraperitoneally in a dose of 21.1 mg / kg 3 times a week, starting on the 30th day of SI induction. The level of collagenolysis was assessed by the content of free hydroxyproline (FHP). The process of depolymerization of proteoglycans and sialoglycoproteins was evaluated by determining their monomers, glycosaminoglycans (GAGs) and N-acetylneuraminic acid (NANA) respectively. The molar roots exposure index (MREI) was calculated. RESULTS: Results: Administering EGCG reduced the content of FHP by 33.3 % (p<0.01), the content of GAGs by 39.4% (p<0.02), and content of NANA by 34.3% (p<0.001) in the soft periodontal tissues compared with the relevant findings in the second group of the animals. In this condition the concentration of these compounds in the calcified components of periodontium (alveolar bone) lowered as well: FHP - by 41.9% (p<0.001), GAGs - by 41.0% (p<0.001), NANA - by 53.3% (p<0.001), MREI reduced to 27.1+1.6, i.e. by 27.7% (p<0.01) compared with the relevant findings in the second group of the animals. The administration of EGCG also reduced the content of FHP by 37.8% (p<0.001), the content of GAGs by 39.8% (p<0.001), and the content of NANA by 37.6% (p<0.001) in SG tissues compared with the relevant results of the second group of the animals. CONCLUSION: Conclusions: The administration of EGCG under modeled systemic inflammation is an effective means of preventing and correcting the disruption of connective tissue of periodontium and submandibular salivary glands in rats: it reduces collagenolysis and depolymerization of proteoglycans and glycoproteins.