Detoxifying Effects of a Phenolic-Rich Thunbergia laurifolia Water Extract Against Chlorpyrifos-Induced Oxidative Stress: Evidence from an Integrated In Vitro and In Vivo Study

Thunbergia laurifolia has long been used in traditional medicine for detoxification; however, the biological basis of its detoxifying effects remains poorly understood. This study investigated the detoxifying effects of a phenolic-rich aqueous extract of T. laurifolia using integrated in vitro and in vivo approaches. Caffeic acid (CA) and rosmarinic acid (RA) were used as marker compounds for extract standardization. The aqueous extract was evaluated for antioxidant, acetylcholinesterase, and apoptosis-modulating activities in vitro, followed by evaluation in a chlorpyrifos-induced oxidative stress model in vivo. The extract exhibited antioxidant activity and maintained acetylcholinesterase (AChE) activity. In LX-2 hepatic stellate cells, the extract induced predominantly early apoptosis, whereas CA and RA induced predominantly late apoptosis. In chlorpyrifos-exposed rats, the extract restored AChE activity, reduced lipid peroxidation, and enhanced endogenous antioxidant defenses, as evidenced by decreased malondialdehyde (MDA) levels and increased glutathione (GSH) levels and superoxide dismutase (SOD) activity. Collectively, these findings suggest that attenuation of oxidative stress may represent one of the mechanisms underlying the detoxifying effects traditionally attributed to T. laurifolia.