In the present study,in vitroantioxidant, free radical scavenging capacity, and hepatoprotective activity of methanol extracts fromPolyalthia longifoliaandCassia spectabiliswere evaluated using establishedin vitromodels such as ferric-reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl(DPPH•), hydroxyl radical(OH•), nitric oxide radical(NO•)scavenging, metal chelating, and antilipidperoxidation activities. Interestingly, all the extracts showed considerablein vitroantioxidant and free radical scavenging activities in a dose-dependent manner when compared to the standard antioxidant which verified the presence of strong antioxidant compound in leaf extracts tested. Phenolic and flavonoid content of these extracts is significantly correlated with antioxidant capacity. SinceP. longifoliaextract was exhibited betterin vitroantioxidant activities, it was subjected forin vivohepatoprotective activity in paracetamol-intoxicated mice. Therapy ofP. longifoliashowed the liver protective effect on biochemical and histopathological alterations. Moreover, histological studies also supported the biochemical finding, that is, the maximum improvement in the histoarchitecture of the liver. Results revealed thatP. longifolialeaf extract could protect the liver against paracetamol-induced oxidative damage by possibly increasing the antioxidant protection mechanism in mice. Our findings indicated thatP. longifoliaandC. spectabilishave potential as good sources of natural antioxidant/antiaging compounds.