Triterpene saponins from the seeds of Erythrophleum fordii and their cytotoxic activities.

Erythrosides A-G, seven undescribed oleanane-type triterpenoid saponins, were isolated from the seeds of Erythrophleum fordii. Their structures with absolute configurations were determined by extensive spectroscopic analysis including one-dimensional [1D] and two-dimensional [2D] nuclear magnetic resonance [NMR], high-resolution electrospray ionization mass spectroscopy [HR-ESI-MS] analysis, and chemical methods. Erythrosides A-G featured a diverse oligosaccharide chain containing 4-6 pentoses or hexoses at C-3 and a monoterpenic acid or a (E)-cinnamic acid unit at the C-21 position. Of particular interest, erythrosides A-C, E and F contained a rare alpha xylose in their sugar chains. The bioassay results indicated that erythrosides A-C showed moderate cytotoxic activities against human lung cancer cell line PC9 with IC50 values of 13.14, 16.67 and 17.59 µM, respectively (the positive control, Taxol, IC50 = 0.60 nM).

Cassaine diterpenoids from the seeds of Erythrophleum fordii and their cytotoxic activities.

Six new cassaine diterpenoids (1, 3-7), along with three known ones (2, 8-9) were isolated from the seeds of Erythrophleum fordii. Their structures were elucidated by extensive spectroscopic methods and acid hydrolysis. Compound 2 was tested to be the most potent one and showed more sensitive activities on MCF-7 and A549 cancer cells with IC50 values of 3.66 ±â€¯1.20 and 2.87 ±â€¯0.46 µM, respectively. Furthermore, compound 2 reduced the number of cell colonies significantly in a dose-dependent manner in the colony formation assay and triggered apoptosis of MCF-7 cell.

Isolation and identification of l/d-lactate-conjugated bufadienolides from toad eggs revealing lactate racemization in amphibians.

Three pairs of bufadienolide l/d-lactate epimers (1-6) were isolated from the eggs of the toad Bufo bufo gargarizans. The structures were elucidated by using spectroscopic methods, X-ray diffraction analysis and a modified Mosher's method. Compounds 1-6 represent the first occurrence of lactate-conjugated bufadienolides in nature, and illustrate the existence of an enzyme-controlled epimerization from l- to d-lactate in amphibians. The biosynthetic pathways, in which two key enzymes might be involved (i.e., lactate racemase and acyltransferase), were proposed. In addition, the biological assays revealed that compounds 1-4 are potent cytotoxic agents against human gastric cancer cells BGC-823 and human lung cancer cells A549 with IC50 values in a range of 8.0 to 80.0 nM.