Densely Functionalized Macrocyclic Sesquiterpene Pyridine Alkaloids from Maytenus austroyunnanensis.

Eleven densely functionalized new dihydro-ß-agarofuran sesquiterpenoid derivatives, named maytenoids A-K (1-11), as well as one known analog, were isolated and characterized from Maytenus austroyunnanensis. Their structures were assigned based on analysis of spectroscopic data and X-ray crystallography. Compounds 1-9 are macrocyclic sesquiterpene pyridine alkaloids generated by the respective acylation of the hydroxy groups at C-3 and C-13 of dihydro-ß-agarofuran sesquiterpenoids via diverse pyridine dicarboxylic acids. Compounds 1, 2, 5-10, and 12 exhibited significant inhibitory effects on NO production at 10 µM in lipopolysaccharide (LPS)-stimulated BV2 cells.

Two New Cytotoxic Maytansinoids Targeting Tubulin from Trewia nudiflora.

Two new maytansinoids, N-methyltreflorine (1: ) and methyltrewiasine (2: ), were isolated from the dried fruits of Trewia nudiflora, together with three known congeners (3:  - 5: ). Their structures were elucidated by spectroscopic methods, and the absolute configuration of 1: and 2: was determined by X-ray crystallographic analysis. Compounds 1:  - 5: exhibited strong cytotoxicity against human tumor cell lines, including HeLa, MV-4 - 11, and MCF-7, with IC50 values ranging from 0.12 to 11 nM. Compounds 1: and 4: also showed inhibitory activity against the MCF-7/ADR cell line with IC50 values of 13 and 28 nM, respectively. Compounds 1: and 2: significantly inhibited tubulin polymerization in vitro with IC50 values of 3.6 and 3.2 µM, respectively.

Determination of maytansinoids in Trewia nudiflora using QuEChERS extraction combined with HPLC.

Three maytansinoids with strong cytotoxicities, dehydrotrewiasine, maytanbutine, and trewiasine, were isolated and identified from Trewia nudiflora, and maytanbutine was obtained from this plant for the first time. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction combined with high-performance liquid chromatography (HPLC) was established to determine the three maytansinoids in T. nudiflora. The effects of major factors on the extraction efficiency of the QuEChERS method were evaluated and the optimal conditions using acetonitrile-ethyl acetate (1:1, v/v) as the extraction solvent and PestiCarb as the clean-up sorbents were established. Compared with Soxhlet extraction (SE) and ultrasonic-assisted extraction (UAE), the QuEChERS method was easy-to-operate and afforded a cleaner extract. A phenomenex HyperClone BDS C18 column was used for HPLC analysis. Methanol-acetonitrile-water was chosen as mobile phase for gradient elution. Method validation showed that all analytes showed good linearity (r > 0.999) over the investigated ranges and satisfactory recoveries ranging from 95.0% to 105.0%. The developed QuEChERS-HPLC method was simple, efficient, and applicable to the determination of maytansinoids in T. nudiflora.