Ling Ni

Cytotoxic indole alkaloids from Tabernaemontana officinalis.

Continued interest in cytotoxic alkaloids resulted in the isolation of 37 alkaloids including 29 known monoterpenoid indole alkaloids from the aerial parts of Tabernaemontana officinalis. Of the remaining 8 alkaloids, six were bisindole alkaloids named taberdivarines A-F (1-6) and the two were monomers named taberdivarines G and H (7-8). Alkaloids 1 and 2 are voaphylline-vobasinyl type bisindole alkaloids, a structural type previously unknown, while 3-6 exhibited cytotoxicity against three human cancer cell lines HeLa, MCF-7, and SW480 with IC50 values ranging from 1.42 to 11.35 μM.

Dimeric Erythrina Alkaloids from the Flower of Erythrina variegata

Unprecedented dimeric Erythrina alkaloids, spirocyclic (6/5/6/6) erythrivarine A (1) and spiro-fused (6/5/7/6) rings erythrivarine B (2), were isolated from the cultivated plant, E. variegata. The structures were determined on the basis of 1D and 2D NMR, FTIR, UV, and mass spectroscopic data and X-ray crystal diffraction. The biogenetic relationship of 1 and 2 is proposed.

New dimeric and trimeric Erythrina alkaloids from Erythrina variegata

HPLC-guided chromatography isolation led to five new polymeric Erythrina alkaloids, erythrivarines C–G (1–5), from the flowers of Erythrina variegata. Their structures were elucidated by intensive spectroscopic analyses. Dimeric alkaloids 1 and 2 consisted of two erythrinine units via an acetyl glucose, whereas trimers 3–5 were coupled through direct polymerization. Alkaloids 1 and 2 showed excellent insecticidal activities against aphid Rhodobium porosum.

Five New Alkaloids from Cephalotaxus lanceolata and C. fortunei var. alpina

Five new alkaloids (1–5) were isolated from the leaves and twigs of Cephalotaxus lanceolata and C. fortunei var. alpina along with 24 known alkaloids. The new structures were elucidated based on spectroscopic data including 1D and 2D NMR, FTIR, UV and MS. These new alkaloids showed no cytotoxicity to HeLa, SGC-7901 gastric cancer, and A-549 lung cancer cell lines.

Abietane diterpenoids from Cephalotaxus lanceolata

Abstract A new abietane diterpenoid, 12-O-methyl-20-deoxocarnosol-3-one (1), and eight known abietane diterpenoids including 13-abietadien-12-one (2), 5,6-dehydrosugiol (3), sugiol (4), torreyayunnin (5), taxusabietane A (6), hinokiol (7), 3-acetoxyabieta-8,11,13-trien-12-ol (8), and martiusane (9) were obtained from leaves and twigs of Cephalotaxus lanceolata. The structures of isolated compounds (1–9) were determined based on analysis of their spectroscopic data and comparison with those reported in the literature. Compounds 3, 8 and 9 were first isolated from the plants of Cephalotaxus genus. Graphical Abstract

Indole Alkaloids from Hunteria zeylanica

Six new bisindole alkaloids, hunterizeylines A-F (1-6), three new monomers, hunterizeylines G-I (7-9), and 13 known alkaloids were isolated from an aqueous MeOH extract of the twigs and leaves of Hunteria zeylanica. Hunterizeyline H, geissoschizol, and dihydrocorynantheol displayed weak insecticidal activity against the aphid Rhodobium porosum, with IC50 values of 168.2, 360.5, and 290.6 μM, respectively.

Bisindole alkaloids from Tabernaemontana corymbosa

Continued study in bioactive monoterpenoid alkaloids led to the isolation of nine undescribed alkaloids, taberyunines A-I, together with 32 known ones from the aerial parts of Tabernaemontana corymbosa Roxb. ex Wall (Apocynaceae). Among the undescribed alkaloids, taberyunines A-G and H-I were assigned to Aspidosperma-Aspidosperma and Vobasinyl-Ibogan type bisindoles, respectively. Their structures were determined by NMR spectra, MS data and X-ray diffraction. Taberyunine B showed significant cytotoxicity against three cancer cell lines.