An efficient [4+3] cycloaddition reaction of in situ generated aza-o-quinodimethanes with C,N-cyclic azomethine imines has been developed. A wide range of 1,2,4-triazepine derivatives were synthesized in high yields (81–99%).

Seven 3′,8′′-linked bioflavonoids, including one new compound, (2′′S)-2′′, 3′′-dihydroamentoflavone-4′-methyl ether (1) and six known compounds: (2S)-2,3- dihydroamentoflavone-4′-methyl ether (2), (2S,2′′S)-2,3,2′′,3′′-tetrahydroamento- flavone-4′-methyl ether (3), (2S,2′′S)-tetrahydroamentoflavone (4), (2S)-2,3-dihydro- amentoflavone (5) and (2′′S)-2′′,3′′-dihydroamentoflavone (6) and amentoflavone (7), were isolated from the 60% ethanolic extract of Selaginella uncinata (Desv.) Spring. The structures of these compounds were elucidated mainly by analysis of their 1D and 2D NMR spectroscopic data, and their absolute configurations were determined by circular-dichroism (CD) spectroscopy. All the seven compounds showed protective effect against anoxia in the anoxic PC12 cells assay, in which compound 6 displayed particularly potent activity.

An example of diastereoselective and enantioselective synthesis of thiochroman derivatives through a sulfa-Michael–Michael cascade sequence is disclosed. This is a significant complement of the quinine-thiourea catalyzed sulfa-Michael–Michael cascade reaction. The densely functionalized target thiochromans were obtained in high diastereoselectivities, and with high to excellent enantioselectivities.

Curcumin analogs were first investigated for their inhibitory effects on thioredoxin reductase (TrxR). Most of them were more potent TrxR inhibitors than natural curcumin. The structure-activity relationship was summarized, and the curcumin analog was found to inhibit TrxR irreversibly in a time-dependent manner. The action was caused by covalent modification of the redox-active residues Cys(497) and Sec(498) in TrxR.

Eleven curcumin-related compounds containing a benzyl piperidone moiety were synthesized and evaluated for their effects on cultured prostate cancer PC-3 cells, pancreas cancer BxPC-3 cells, colon cancer HT-29 cells and lung cancer H1299 cells. Inhibitory effects of these compounds on the growth of PC-3, BxPC-3, HT-29 and H1299 cells were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. Compounds benzyl piperidone 2 (P2), P4, P7, 4-bromo-2-fluoro-benzyl piperidone 2 (PFBr2), PFBr3 and PFBr4 (see syntheses and structures in Figs. 1, 2) exhibited potent inhibitory effects on the growth of cultured PC-3, BxPC-3, HT-29 and H1299 cells. The IC50 for these compounds was lower than 2 µM in all four cell lines. PFBr4 was 41-, 36-, 40- and 46-fold more active than curcumin for inhibiting the growth of PC-3, BxPC-3, HT-29 and H1299 cells, respectively. The benzyl piperidone-containing compounds studied also stimulated apoptosis in PC-3 cells. Mechanistic studies indicate that the effects of both curcumin and PFBr4 on PC-3 cells were associated with a decrease in phospho-Akt and phospho-extracellular signal-regulated kinase (Erk)1/2. The present study indicates that P2, P4, P7, PFBr2, PFBr3 and PFBr4 may have useful effects on human cancer cells.