Total syntheses of (-)-scabronines†G and A, and (-)-episcabronine†A.

Making scab(ronine)s: The total synthesis of (-)-scabronine G features a highly stereoselective oxidative dearomatization/intramolecular inverse-electron-demand Diels-Alder reaction cascade, and the first total synthesis of (-)-scabronine A comprises a highly stereoselective oxa-Michael/protonation/acetalization cascade. The first total synthesis of (-)-episcabronine A includes another highly stereoselective cascade.

A novel convergent method for the synthesis of α-acyl-γ-hydroxylactams and its application in the total synthesis of PI-090 and 091.

A novel convergent method for the synthesis of α-acyl-γ-hydroxylactams utilizing the aldol reaction of N-Boc-protected γ-methoxylactams was developed. As the first application of this method for the synthesis of biologically active natural products, the total synthesis of platelet aggregation inhibitors PI-090 and PI-091 were also investigated and successfully achieved.

Scabronine G Methyl Ester Improves Memory-Related Behavior and Enhances Hippocampal Cell Proliferation and Long-Term Potentiation via the BDNF-CREB Pathway in Olfactory Bulbectomized Mice.

A previous study reported that scabronine G methyl ester (SG-ME) potentially enhances the in vitro secretion of neurotrophic factors such as nerve growth factor via the protein kinase C (PKC)-ζ pathway. However, it remains unknown whether SG-ME can improve cognitive dysfunctions in olfactory bulbectomized (OBX) mice. To address this question, we evaluated SG-ME-treated and untreated OBX mice in a passive avoidance test. We also investigated potential effects of SG-ME on several parameters: cell proliferation and cAMP response element-binding protein (CREB) phosphorylation in the hippocampal dentate gyrus by immunohistochemistry, brain-derived neurotrophic factor (BDNF) levels in the hippocampus by Western blotting, p-CREB levels in the hippocampus by MapAnalyzer, and long-term potentiation (LTP) by electrophysiology. On the 14th day after surgery OBX mice showed altered passive avoidance and decreases in both cell proliferation and long-term potentiation in the hippocampus, while these changes were reversed by SG-ME (20 µg/mouse) 24 h after the treatment. The improvement in memory deficits was prevented when SG-ME was co-administeredwith either zeta inhibitory peptide (PKC-ζ inhibitor), anti-BDNF antibody, ANA-12 (TrkB antagonist), U0126 (MEK inhibitor), H-89 (PKA inhibitor), LY294002 (PI3K inhibitor) or KN-93 (CaMKII inhibitor). We found that SG-ME enhanced brain-derived neurotrophic factor and p-CREB levels in the hippocampus while p-CREB was localized in neurons, but not in astrocytes nor microglial cells. These findings revealed the potential of SG-ME in improving memory impairments by enhancing cell proliferation and LTP via activation of the BDNF/CREB signaling pathway in neurons.

Asymmetric and highly stereoselective synthesis of the DEF-ring moiety of (-)-FR182877 and its derivative inducing mitotic arrest.

The asymmetric and highly stereoselective synthesis of compound 1, which corresponds exactly to the DEF-ring moiety of (-)-FR182877, and the biological activities of its derivatives are described. All derivatives of 1 showed no activity in the tubulin polymerization assay, but one derivative was shown to have the ability to induce mitotic arrest by interfering with microtubule dynamics, and the cellular effects are similar to those of paclitaxel.

Total synthesis of hirsutellone B via Ullmann-type direct 13-membered macrocyclization.

Total synthesis of Hirsutellone B has been achieved by a convergent synthetic strategy. This synthesis features direct construction of the highly strained 13-membered macrocycle of Hirsutellone B utilizing the Ullmann-type reaction. To the best of our knowledge, this is the first application of macrocyclization utilizing an intramolecular Ullmann-type reaction between an aliphatic alcohol and aryl halide.