corynoxine and 2-oxindole

A facile and straightforward method was developed to construct the fused tetracyclic 3-spirooxindole skeleton, which exists widely in natural products. The formation of the tetracyclic 3-spirooxindole structure was achieved through a transition-metal-free intramolecular cross-dehydrogenative coupling of pyridinium, which were formed in situ by the condensation of 3-(2-bromoethyl)indolin-2-one derivatives with 3-substituted pyridines. As examples of the application of this new methodology, two potentially medicinal natural products, (±)-corynoxine and (±)-corynoxine B, were efficiently synthesized in five scalable steps.

Topics: Biological Products; Chemistry Techniques, Synthetic; Hydrogen; Indoles; Oxindoles; Pyridines; Spiro Compounds

An unusual oxindole alkaloid inner salt, macrophyllionium (1), and a pair of new tetracyclic oxindole alkaloids, macrophyllines A (2) and B (3), together with six known alkaloids, were isolated from the aerial parts of Uncaria macrophylla. Corynantheidine (8) exhibited moderate cytotoxicity against HL-60 and SW480 cells with IC(50) values of 13.96 and 23.28 μM, respectively. Dihydrocorynantheine (9) exhibited significant vasodilating activity against phenylephrine-induced contraction in rat thoracic aorta rings (IC(50) = 6.73 μg/mL). In addition, compounds 2, 6, and 9 showed weak inhibitory action on KCl-induced contraction.

Topics: Alkaloids; Animals; Aorta, Thoracic; Drug Screening Assays, Antitumor; Drugs, Chinese Herbal; HL-60 Cells; Humans; Indole Alkaloids; Indoles; Inhibitory Concentration 50; Male; Molecular Structure; Oxindoles; Phenylephrine; Potassium Chloride; Rats; Rats, Sprague-Dawley; Stereoisomerism; Uncaria; Vasodilation