Assessment of in vitro and in vivo anti-inflammatory activity of Psidium guajava leaf extract using zebrafish as an animal model

The study experiments upon the anti-inflammatory property of guava leaf extract. The phytochemical analysis of Psidium guajava extract showed the presence of various secondary metabolites such as phenols, flavonoids, alkaloids, steroids and terpenoids. The total phenolic content of methanol and the aqueous extract was found to be 410.73±4.8 and 429.40±5.6mg GAE/g whereas the flavonoid content was found to be 341.42±5.77 and 292.83±3.99mg QE/g, respectively. The solvent system consisting of Toluene: Ethyl acetate: Formic acid in the ratio of 5:4:1 was optimized for the purification of flavonoid quercetin using column chromatography. The HPLC analysis reported the highest recoverable quercetin content to be 26.85µg/g in methanol extract. The methanol and aqueous extract showed high cell viability percentage of >80% on human lymphocyte cells. Moreover, the haemolysis was found to be <20% in the concentration of 20-100µg/ml for both methanol and aqueous extract. The methanol and aqueous extract showed significant cytoprotective activity against lymphocyte cell (P>0.05).The histopathological analysis of adult zebra fish model demonstrated that methanol extract of concentration 500µg/ml completely reduced the migration of inflammatory cells. The TNF-? gene expression was reduced by 53.17 and 78.69% at the concentration of 250 and 500µg/ml, respectively.