Graveoumarins A-C: chiral resolution, absolute configuration, and anticoagulant/anti-inflammatory activities of 3'-methyl-3'-butenyl coumarins from <i>ruta graveolens</i> L.

Abstract

Context: Several coumarins have been isolated from Ruta graveolens L., but the chirality of many remains uncharacterized or their absolute configurations unresolved.Objective: This study aimed to comprehensively separate and characterize the chirality of 3'-methyl-3'-butenylcoumarins from R. graveolens extracts, determine their absolute configurations, and evaluate their anticoagulant and anti-inflammatory activities.Materials and methods: Comprehensive chromatographic separation and chiral HPLC analysis were employed on the R. graveolens extract. The structures of isolated compounds were elucidated using extensive spectroscopic data analysis (HR-ESI-MS, NMR) and by comparing experimental circular dichroism (CD) spectra with calculated electronic circular dichroism (ECD) spectra. The anticoagulant and anti-inflammatory (specifically inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages) activities of the isolated compounds were evaluated.Results: The study led to the isolation of two pairs of enantiomeric 3'-methyl-3'-butenylcoumarins, present in both equivalent and inequivalent ratios. This included two previously undescribed chiral 3'-methyl-3'-butenylcoumarins with specific absolute configurations [(+)-2'R-2 and (-)-2'S-3] and one undescribed achiral 3'-methyl-3'-butenylcoumarin (1). Among the tested compounds, only the racemic mixture (±)-3 exhibited moderate inhibition of NO production in the anti-inflammatory assay. No significant anticoagulant activity was reported for the compounds.Conclusions: This study successfully characterized the chirality and determined the absolute configurations of specific 3'-methyl-3'-butenylcoumarins from R. graveolens, including the discovery of three new compounds. While most isolated compounds lacked significant anticoagulant or anti-inflammatory activity in the tested models, racemic (±)-3 showed moderate anti-inflammatory potential by inhibiting NO production. These findings provide new insights for the future development and utilization of coumarins from R. graveolens.