Coumarinolignoid and Indole Alkaloids from the Roots of the Hybrid Plant Citrus × paradisi Macfad (Rutaceae).

A phytochemical investigation of the roots of Citrus × paradisi Macfad. (Rutaceae) led to the isolation of two new compounds, namely 1-formyl-5-hydroxy-N-methylindolin-1-ium (1) and decyloxycleomiscosin D (2), along with ten known compounds: 1,1-dimethylpyrrolidin-1-ium-2-carboxylate (3), furan-2,3-diol (4), 5-methoxyseselin (5), umbelliferone (6), scopoletin (7), citracridone I (8), citracridone II (9), citracridone III (10), limonin (11) and lupeol (12). The structures were determined through the comprehensive spectroscopic analysis of 1D and 2D NMR and EI- and ESI-MS, as well as a comparison with the published data. Notably, compounds 3 and 4 from the genus Citrus are reported here for the first time. In addition, the MeOH extract of the roots and compounds 1-7 were screened against the human adenocarcinoma alveolar basal epithelial cell line A549 and the Caucasian prostate adenocarcinoma cell line PC3 using the MTT assay. While the extract showed significant activity, with IC50 values of 35.2 and 38.1 µg/mL, respectively, compounds 1-7 showed weak activity, with IC50 values of 99.2 to 250.2 µM and 99.5 to 192.7 µM, respectively.

Chemical Constituents of the Stem Bark of the Hybrid Plant Citrus × paradisi Macfad. (Rutaceae).

The stem bark of Citrus × paradisi Macfad. (Rutaceae) gave (23S)-isolimonexic acid (1), limonin (2), citracridone II (3), citpressine II (4), citpressine I (5), grandisine (6), 2-hydroxynoracronycine (7), citracridone I (8), 5-methoxyseselin (9), umbelliferone (10), scopoletin (11), naringenin (12), apigenin (13), friedelin (14), agrostophyllinone (15) and stigmasterol-3-O-ß-D-glucopyranoside (16). The structures of the compounds were determined using NMR and MS spectroscopic data, and by comparison with published data. The relative configuration of 1 was proposed as (23S)-isolimonexic acid using NOE studies. Hydrogenation reaction of compound 3 led to the new derivative 3',4'-dihydrocitracridone II (3a). Cytotoxicity activities against the human adenocarcinoma alveolar basal epithelial cell lines A549 and the Caucasian prostate adenocarcinoma cell lines PC3, using the MTT assays showed that the methanol crude extract was significant with IC50 values of 30.1 and 31.7 µg/mL, respectively, with the positive control, doxorubicin giving an IC50 of 0.9 µM. In addition, compounds 3, 7 and 8 gave moderate cytotoxic activities with IC50 values of 33.1, 31.2 and 32.5 µM for A549 cells and 35.7, 33.8 and 34.9 µM for PC3 cells, respectively. The hydrogenated 3a was less active than 3, suggesting that the presence of the double bond in pyrans is important for structure-activity relationship.