Three new 30-norfriedelane and a new friedelane triterpenes from the trunk bark of Caloncoba welwitschii (Oliv.) Gilg (Achariaceae).

Phytochemical investigation of the methanolic extract of the trunk bark of Caloncoba welwitschii (Oliv.) Gilg (Achariaceae) led to the isolation of four new compounds, including three new 30-norfriedelane triterpenes, welwitschiilactones D-F (1-3), one new friedelane triterpene, welwitschioic acid (4) as well as ten known compounds: stigmastane-3,6-dione (7), a mixture of ß-sitosterol and stigmasterol (6a and 6b), a mixture of ß-sitosterol and stigmasterol glucoside (11a and 11b), (2S,3S,4R,5R)-N-(1,3,4,5-tetrahydroxyndecan-2-yl)tetradecanamide (10), 1-O-ß-D-glucopyranosyl-(2S,3R,8E)-2-[(2'R)-2-hydroxylpalmitoylamino]-8-octadecene-1,3-diol (12), 3ß,21ß-dihydroxy-27-oxo-30-nor-(D:A)-friedo-olean-20(29))en-27,19α-lactone (8), 21ß-hydroxy-3,27-dioxo-30-nor-(D:A)-friedo-olean-20(29)-en-27,19α-lactone (9) and 2ß,21ß-dihydroxy-27-oxo-30-nor-(D:A)-friedo-olean-20(29)-en-27,19α-lactone (5). The structures of all the isolated compounds were determined by extensive spectroscopic analyses (1D and 2D NMR as well as ESI-MS). The relative configuration of the 20-oxymethine in 1 as well as that of 19-oxymethine in 2 and 3 has been established using the NOESY spectrum. In an experiment, a sample of welwitschiilactone C (5) was chemically modified through reduction reaction to give a new hemi-synthetic derivative namely 2ß,3ß,21ß-trihydroxy-30-nor-(D:A)-friedo-olean-20(29)-en-27,19α-lactone (5a).

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.