Preliminary phytochemical characterization and marker-based quantification of Rennellia borneensis Baill. dichloromethane root extract via LC-MS/MS and validated HPLC

This study presents the first phytochemical characterisation and validated HPLC quantification method for the dichloromethane root extract of Rennellia borneensis Baill. (Rubiaceae). LC-MS/MS dereplication and molecular networking were performed in negative ionisation mode, a condition strategically selected to optimise the detection of acidic anthraquinones and phenolic compounds. Integrating SIRIUS and GNPS tools, 17 compounds were annotated, including anthraquinones, flavonoids, isoflavonoids, and a triterpenoid. Two markers: 3-hydroxy-2-methyl-9,10-anthraquinone 1 (4.41 μg/mg) and rubiadin 2 (1.21 μg/mg) were isolated for the first time from this species and quantified using a validated HPLC method. These findings establish R. borneensis as a chemically rich species and provide a scientific foundation for future bioactivity-guided research and the development of standardised herbal products.