Attenuation of oxidative injury by quercetin from Psidium guajava and its therapeutic potential study against periodontitis on in vitro model system

The current research focuses on the biological potential of quercetin-rich fraction from Psidium guajava (QRF PG) leaf extract, emphasizing its role decreasing oxidative stress. Our study evaluated the antioxidant potential of an ethanolic extract derived from the leaves of Psidium guajava on a specific KB cell line. Cell viability was initially evaluated by directly observing the cells via phase contrast microscope. Following which a dose optimization of QRF PG on KB cell lines was analysed by MTT assay. Our study reported nearly 70% cell viability at 25 μg QRF PG. Cytoprotective activity of QRFPG on H2O2 induced oxidative stress was analysed by MTT assay. The oxidative state of the physiologic system in vitro was analysed by lipid peroxidation with a value of the satisfying reduction in the level of lipid peroxidation to 0.429 μg/MDA units, an increase in catalase level in cells treated with QRFPG as 0.5254 enzyme units, elevation in glutathione reductase to 0.5922 enzyme units and superoxide dismutase at 1.09 enzyme units. Our study noted a steady reduction in fluorescence intensity in oral KB cells treated with QRFPG with a value of 17526.10 +/- 2586.9 AU indicating the ability of QRFPG in scavenging reactive oxygen species. The impact of QRF on the face of the Nrf2 gene was determined in KB cells subjected to oxidative stress by free radicals. The immune modulatory potential of quercetin was checked by evaluating the inflammatory mediators like cyclooxygenase 2, tumor necrosis factor-alpha and interleukins 6. The antimicrobial activity of the plant extract against the oral pathogens Streptococcus mutans and Enterococcus faecalis was done using the agar diffusion method. The present study highlights the role of QRFPG as an antioxidant, anti-inflammatory and antibacterial bioactive compound.