Novel indole and quinoline alkaloids from Melodinus yunnanensis

6/7-Seco rearranged spiro-indolone alkaloids,meloyunines A(1)and B(2)and a monoterpenoid quinoline alkaloid meloyunine C(3)together with its possible intermediate 14,15-dehydromelohenine B(4),and their precursorΔ14-vincamenine(5)were isolated from Melodinus yunnanensis.All structures were elucidated based on NMR,FTIR,UV,and MS spectroscopic data.The isolation of monoterpenoid indole,quinoline,and its immediate from the same plant chemically supported the biosynthesis of quinoline from indole.Compound 2 was cytotoxic against several human cancer cell lines.

Four new isoflavanones from Tadehagi triquetrum

Four new isoflavanones with isoprenoid units,named triquetrumones E-H(1-4),were isolated from the whole plants of Tadehagi triquetrum.The structures were elucidated on the basis of spectroscopic analyses,including application of MS,UV,IR,1D and 2D NMR spectroscopic techniques.

Monoterpenoid indole alkaloids from Alstonia rostrata

Four new monoterpenoid indole alkaloids,alstrostines C-F together with thirteen known alkaloids were isolated from the leaves and twigs of Alstonia rostrata.All structures of new compounds were elucidated based on NMR,FTIR,UV,and MS spectroscopic data.Alstrostines C-E might originate from keto-enol tautomerism of preakummicine during biogenetic pathway of akummicine.

Three New Indole Alkaloids from Tabernaemontana divaricata

Three new monoterpene indole alkaloids,3a-hydroxymethyl-ibogamine(1),3a-acetatemethoxyl-ibogamine(2),16a-hy-droxyl-ibogamine(3)together with six known alkaloids were isolated from the branches and leaves of Tabernaemontana divaricata(Apocynaceae).The structures of these alkaloids were determined by spectroscopic analyses.All isolated compounds showed no significant cytotoxicity against SGC-7901 gastric cancer,HeLa,and A-549 lung cancer cell lines(IC50>20μM).

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.

Artificial Erythrina Alkaloids from Three Erythrina Plants,E. variegata,E. crista-galli and E. arborescens

Fourteen unprecedented artificial Erythrina alkaloids were isolated from the Erythrina variegata,E.crista-galli and E.arborescens(Fabaceae).The structures of these alkaloids were determined by spectroscopic analyses.Their possible forma-tions were proposed.All isolated compounds showed no cytotoxicity and hypoglycemic activity at cell screening bioassay.

Enantiomeric Cephalotaxus alkaloids from seeds of Cephalotaxus oliveri

Five undescribed alkaloids were isolated from the seeds of Cephalotaxus oliveri along with 27 known ones.The new structures were elucidated based on spectroscopic data including 1D and 2D NMR,MS and calculated ECD spectra.Among them,(+)-acetylcephalofortine C was an enantiomeric Cephalotaxine alkaloids.The performed bioassay revealed that those alkaloids were not cytotoxic against cancer cells and had no neuroprotective properties in the HEI-OC-1 cells model.

A New Pregnane from Munronia delavayi Franc （Meliaceae）

To search for pharmacologically active constituents of folk medicine, a new pregnane, 2α,3α,15β-trihydroxy-20（S）-tigloyl-pregnane （compound 1）, and nine known compounds, geranylgeraniol （compound 2）, β-daucosterol （compound 3）, 6-hydroxystigmast-4oen-3-one （compound 4）, sitoindoside Ⅰ （compound 5）, sitoindoside Ⅱ （compound 6）, β-sitosterol （compound 7）, kaempferol （compound 8）, quercetin （compound 9）, and rutin （compound 10）, were isolated from the ethanol extract of whole plants of Munronia delavayi Franch using chromatographic methods. The structures of compounds 1-10 were elucidated on the basis of spectral data.

Discovery of Natural Co-occurring Enantiomers of Monoterpenoid Indole Alkaloids

Main observation and conclusion Two new pairs of monoterpenoid indole alkaloids(MIAs)enantiomers as well as their new congeners were isolated from stems of Tabernaemontana bovina Lour.(Apocynaceae).Their structures were elucidated by spectroscopic analyses and confirmed by X-ray diffractions and computational calculations.Tabovine A,tabovine B and tabovines C-D possessed unprecedented 6/5/5/6/6,6/5/5/6/5 and 6/5/6/6/6 ring systems,respectively.It is the first time to report co-occurring enantiomers of MIAs.Additionally,the explanation concerning biogenesis of MIAs was provided.The findings would open a new window where we could disclose more diverse MIAs.

Monoterpenoid Indole Alkaloids with Promoting Neurite Growth from Tabernaemontana divaricata

Phytochemical investigations on Tabernaemontana divaricata led to the isolation of seven undescribed monoterpenoid indole alkaloids,taberdicatines A-G(1-7).Taberdicatines A-C might be derived from Aspidosperma-type alkaloid,less skeletal carbons in 1-2 and an additional carbon in 3.Taberdicatines D-E(4-5)were attributed to Iboga alkaloids with enantiomeric skeleton,respectively.Alkaloid 3 could promote the neurite growth of mouse primary cortical neurons at the concentration of 5 pimol/L.