Xiao-Dong Luo

Meliaceous Limonoids: Chemistry and Biological Activities

Natural Science Foundation of China[30000213, 30370160, 30670214]; National Basic Research Program of China (973 Program)[2009CB522300]; Chinese Academy of Sciences

A cage-monoterpene indole alkaloid from Alstonia scholaris.

An unprecedented cage-like alkaloid, scholarisine A was isolated from the leaves of Alstonia scholaris and its structure determined on the basis of 1D and 2D NMR, FTIR, UV, and high-resolution mass spectroscopic data. This alkaloid might be derived from picrinine via oxygenation, rearrangement, and lactonization.

Melodinines A-G, monoterpenoid indole alkaloids from Melodinus henryi.

Nineteen monoterpenoid indole alkaloids including seven new ones, melodinines A-G (1-7), were isolated from Melodinus henryi. The structures of the new compounds were elucidated using spectroscopic methods, and the structure of compound 4 was confirmed by single-crystal X-ray diffraction analysis. The known compounds were identified by comparing their spectroscopic data with those reported in the literature. All of the compounds were evaluated for cytotoxic activity against five human cancer cell lines, and compound 11 exhibited cytotoxicity against HL-60, SMMC-7721, A-549, and SK-BR-3 cells with IC50 values of 2.0, 16.8, 25.9, and 24.7 microM, respectively.

Monoterpenoid indole alkaloids from the bark of Alstonia scholaris.

Six new monoterpenoid indole alkaloids, scholarisines B-G (1- 6), together with 15 known analogues (7- 21), were isolated from the bark of Alstonia scholaris. Their structures were determined by 1D and 2D NMR spectra and MS analyses. The structure of 1 was further supported by the single-crystal X-ray.

Melotenine A, a Cytotoxic Monoterpenoid Indole Alkaloid from Melodinus tenuicaudatus

Melotenine A (1), an unprecedented skeleton with a 6/5/5/6/7 pentacyclic rearranged ring system, was isolated from Melodinus tenuicaudatus. The structure was elucidated by means of spectroscopic methods and further confirmed by the single-crystal X-ray diffraction analysis. A possible biogenesis was also proposed. Melotenine A exhibited potential inhibition against five human cancer cell lines.

Cytotoxic indole alkaloids from Melodinus tenuicaudatus.

Four new bisindole alkaloids, melodinines H-K (1-4), a new monomer, melodinine L (5), and 11 known alkaloids were isolated from Melodinus tenuicaudatus. The structures of 1-5 were elucidated by extensive spectroscopic methods, and the known compounds were identified by comparison with data in the literature. All of the compounds were evaluated for their cytotoxicity against five human cancer cell lines. Alkaloids 1, 3, and 4 and the known compound 11-methoxytabersonine (8) exhibited inhibitory effects, with IC(50) values comparable to those of cisplatin and vinorelbine.

Monoterpenoid indole alkaloids from Alstonia yunnanensis.

Eight new monoterpenoid indole alkaloids, alstoyunines A-H (1-8), along with 17 known analogues, were isolated from Alstonia yunnanensis. The structures of the new alkaloids were established by means of extensive spectroscopic methods. Alstoyunines C (3), E (5), and F (6) showed selective inhibition of Cox-2 (>75%). Alstoyunine F (6) showed weak cytotoxicity against the human myeloid leukemia HL-60 (IC50 = 3.89 microM) and hepatocellular carcinoma SMMC-7721 (IC50 = 21.73 microM) cell lines.

Melohenines A and B, Two Unprecedented Alkaloids from Melodinus henryi

A phytochemical study on Melodinus henryi has led to the isolation of two novel alkaloids, melohenines A (1), a monoterpenoid indole alkaloid with additional skeletal carbons arranged compactly in eight rings, and melohenine B (2), an alkaloid with an unprecedented 6/9/6/6 tetracyclic ring system regarded as a key intermediate from indole to quinoline alkaloids. Their structures were elucidated by means of spectroscopic methods and further confirmed by X-ray diffraction analysis.

Limonoids and phytol derivatives from Cedrela sinensis.

Two new compounds, cedrellin (1) and 2,6,10,15-phytatetraene-14-ol (2), together with five known compounds, 7 alpha-obacunyl acetate, 6-acetoxyobacunol acetate, 7 alpha-acetoxydihydronomilin, 2,6,10-phytatriene-1,14,15-triol and phytol were isolated from leaves of Cedrela sinensis. Their structures were elucidated on the basis of combined one- and two-dimensional spectral techniques.

Melodinines M-U, Cytotoxic Alkaloids from Melodinus suaveolens

Nine new alkaloids, melodinines M-U (1-9), and 11 known alkaloids were isolated from Melodinus suaveolens. The new structures were elucidated by extensive NMR and mass spectroscopic analyses and comparison to known compounds. All compounds were evaluated for their cytotoxicity against five human cancer cell lines. Compounds 6, 11, and 16 showed significant cytotoxicity.