Anti-inflammatory, antioxidant, and anti-apoptotic properties of Thunbergia laurifolia Lindl. aqueous leaf extract on LPS-stimulated RAW 264.7 macrophages

Thunbergia laurifolia Lindl., a Thai medicinal herb, has garnered substantial attention among researchers due to its recognized efficacy as an antidote, antioxidant, and anti-inflammatory agent. Despite its extensive investigation, the specific role of T. laurifolia in apoptotic inhibition remains unexplored. Therefore, this study aimed to explore the protective properties of T. laurifolia leaf extract against lipopolysaccharide (LPS)-induced apoptosis in RAW 264.7 macrophages and determine the extractʼs total phenolic as well as flavonoid content, and its antioxidant. Moreover, the cytotoxicity including anti-inflammatory potential on LPS-stimulated RAW 264.7 macrophages were assessed by measuring the inhibition of nitric oxide (NO). The outcomes of this investigation revealed remarkable similarity between the total phenolic and flavonoid contents and antioxidant capacity of the leaf extract under scrutiny and those documented in prior studies. In addition, the extract demonstrated negligible cytotoxicity at low concentrations. Furthermore, it effectively impeded the LPS-mediated production of NO, inflammatory mediator, in the macrophages. Moreover, pre-treatment with T. laurifolia leaf extract improved LPS-induced apoptosis by reducing rate of apoptotic cell death up to 41 % at the same concentration (1.68 μL/mL) in LPS-stimulated RAW 264.7 macrophages. Collectively, these findings provide compelling initial evidence attesting to the ability of T. laurifolia leaf extract to inhibit LPS-induced apoptosis in RAW 264.7 macrophages, thereby augmenting our understanding of its potential therapeutic applications in inflammatory conditions.