Total Phenolic Content, In vitro Antioxidant and Anti-inflammatory Activities of Ethanol Extract of Psidium guajava Linn. Leaves

Abstract

Oxidative stress is an imbalance between pro-oxidants and antioxidants in an organism, which is a significant factor in the pathogenesis of neurodegenerative and inflammatory diseases. The qualitative phytochemical constituents and the total phenolic concentration of ethanol extract of leaves of Psidium guajava (EEPG) were evaluated using standard methods, while its antioxidant activities were assessed via the phosphomolybdenum, 1,1-diphenyl-2-2-picrylhydrazyl (DPPH), and the ferric ion reducing (FRAP) methods. The qualitative phytochemical constituents and the total phenolic concentration of ethanol extract of Psidium guajava (EEPG) were evaluated using standard methods, while its antioxidant activities were assessed via the phosphomolybdenum, 1,1-diphenyl-2-2-picrylhydrazyl (DPPH), and the ferric ion reducing (FRAP) methods. The carrageenan-induced rat paw oedema was used to investigate the anti-inflammatory activity of EEPG (100, 200, and 400 mg/kg). Secondary metabolites such as saponins, anthraquinones, terpenoids, phenpls, flavonoids, cardiac glycosides, and alkaloids were present in EEPG. The total phenolic content of EEPG was found to be 1.292±0.093 μg/mL of garlic acid equivalent, while the total antioxidant content and ferric reducing antioxidantpower were 0.982 ± 0.01 and 2.076 ± 0.24 μg/mL of ascorbic acid equivalent, respectively. The EEPG demonstrated antioxidant activity in scavenging DPPH radicals with a maximum inhibition of 63.86% at 1000 μg/mL, while ascorbic acid had percentage inhibition of 95.6 at the lowest dose (200 μg/mL). However, the 50% inhibitory concentration (IC₅₀) of EEPG and ascorbic acid were obtained as18.68 and 580.84 μg/mL respectively. EEPG at the tested doses showed significant anti-inflammatory activity in carrageenan-induced rat paw oedema at 4 hr and 5 hr. The study revealed that EEPG exhibited both antioxidant and anti-inflammatory activities that can be further explored for drug discovery.