Chemical Profiling of Gmelina philippensis Cham. Leaf Extract and Its Antioxidant and Anti-Cholinesterase Properties

Gmelina philippensis Cham. (Lamiaceae) is a traditionally valued medicinal plant with unexplored potential for the management of neurodegenerative disorders. In the present study, the phytochemical profile of its methanolic leaf extract was comprehensively characterized using untargeted liquid chromatography–tandem mass spectrometry metabolomics (LC–MS/MS) and molecular networking. In addition, the extract was evaluated for its antioxidant and cholinesterase inhibitory activities relevant to Alzheimer’s disease (AD). Metabolite profiling led to the annotation of 27 compounds, with a predominance of flavonoids and iridoid glycosides unique to the genus Gmelina, along with phenolic acids, lipids, and other minor compounds. The extract exhibited potent in vitro antioxidant activity, with an IC50 of 7.49 ± 0.002 μg/mL in the DPPH assay and 639.63 ± 0.814 μg AAE/mg in the FRAP assay. Notably, the extract showed significant inhibitory activity against acetylcholinesterase and butyrylcholinesterase, with an IC50 of 4.87 ± 0.16 and 40.99 ± 0.03 μg/mL, respectively. Molecular networking further supported the metabolite annotation and highlighted clusters of bioactive iridoids and flavonoids. Overall, these findings highlight that G. philippensis as a rich source of multi-target bioactive compounds, supporting that the extract has good anti-acetylcholinesterase activity comparable to the rivastigmine that used in neurodegenerative disease. This study provides a promising foundation for the development of novel therapeutic approaches targeting neurodegenerative diseases.