Azacyclo-indoles and Phenolics from the Flowers of Juglans regia

Seven new azacyclo-indoles and phenolics and four known alkaloids were isolated from the flowers of Juglans regia. Spectroscopic and chromatographic data revealed that the structures of the new compounds are 5,6,11,12-tetrahydropyrrolo­[1′,2′:1,2]­azepino­[4,5-b]­indole-3-carbaldehyde (1), (±)-5,6,7,11c-tetrahydro-1H-indolizino­[7,8-b]­indol-3­(2H)-one (2), (±)-9-hydroxy-5-oxo-2,3,4,5-tetrahydro-1H-benzo­[b]­azepine-2-carboxamide (3), 5-(ethoxymethyl)-1-(4-hydroxyphenethyl)-1H-pyrrole-2-carbaldehyde (4), (±)-5,8-dihydroxy-4-(1H-indol-3-yl)-3,4-dihydronaphthalen-1­(2H)-one (5), (±)-4-(6-amino-9H-purin-9-yl)-5,8-dihydroxy-3,4-dihydronaphthalen-1­(2H)-one (6), and (±)-4-(6-amino-9H-purin-9-yl)-5-hydroxy-3,4-dihydronaphthalen-1­(2H)-one (7). The five pairs of enantiomers were resolved, and the absolute configurations of the enantiomers were assigned via electronic circular dichroism data. Compound 1 exhibited significant in vitro growth inhibition against the HCT-116, HepG2, BGC-823, NCI-H1650, and A2780 cancer cell lines, with IC₅₀ values of 2.87, 1.87, 2.28, 2.86, and 0.96 μM, respectively, and low cytotoxicity toward normal IEC-6 cells, with a 79.6% survival rate at a 10 μM concentration.