Cytoprotective dihydronaphthalenones from the wood of Catalpa ovata

Three previously undescribed dihydronaphthalenones, 7-hydroxycatalponol, (4S)-3,4-dihydro-4-hydroxy-2-[(2R)-2,3-dihydroxy-3-methylbutylidene]naphthalen-1(2H)-one, and (6S)-5,6-dihydro-6-hydroxy-2,2-dimethyl-2H-benzo[h]chromen-4(3H)-one and one phthalide, (±)-3-(5-hydroxy-5-methyl-2-oxohex-3-en-1-yl)isobenzofuran-1(3H)-one, were isolated from the wood of Catalpa ovata G. Don (Bignoniaceae), together with six known compounds. The structures of the previously undescribed compounds were elucidated by interpretation of 1D and 2D NMR data. The absolute configurations of the dihydronaphthalenones were deduced by analysis of the ECD data and application of Mosher ester methodology. All isolates were investigated for their cytoprotective effects against hydrogen peroxide (H₂O₂)-induced oxidative damage in HepG2 cells. Moreover, the mRNA expression levels of antioxidant enzymes such as heme oxygenase-1 (HO-1) and NAD(P)H:quinine oxidoreductase 1 (NQO1) in HepG2 cells were examined by RT-PCR analysis. As a result, catalponol and epi-catalponol showed antioxidant activities via directly scavenging of intracellular ROS and inducing the antioxidant enzymes in vitro.

Asymmetric total synthesis of (+)-O-methylasparvenone, a rare nitrogen-free serotonin 2C receptor antagonist

The first enantioselective synthesis of the fungal metabolite (+)-O-methylasparvenone is reported.

Peptide-catalyzed kinetic resolution of planar-chiral metallocenes

Kinetic resolution of racemic planar-chiral metallocenes was performed by a resin-supported peptide catalyst, in which low-molecular-weight organocatalysts were not effective.

Desymmetrisation of meso-diols mediated by non-enzymatic acyl transfer catalysts

Complementary to enzymatic methods, catalytic enantioselective desymmetrisation of meso-diols (EDMD) by small molecule catalysts has emerged as a powerful tool that provides highly enantioenriched materials of considerable value in organic synthesis. This review traces the evolution of easily accessible catalysts used in the EDMD and compares their performance with the existing enzymatic methods.