Phantolide analogues 1a–1d were newly synthesized to evaluate their odor profiles. The enantiomers of 1a and 1b were also synthesized. Both (S) enantiomers of 1a and 1b had musk odor although weakly, and but neither of the (R) enantiomers 1a and 1b had musk odor. During the investigations, we encountered the undesirable racemization in Friedel-Crafts reaction of the intermediate (S)-5.Download high-res image (133KB)Download full-size image

Serine racemase (SRR) is an enzyme that produces d-serine from l-serine. d-Serine acts as an endogenous coagonist of NMDA-type glutamate receptors (NMDARs), which regulate many physiological functions. Over-activation of NMDARs induces excitotoxicity, which is observed in many neurodegenerative disorders and epilepsy states. In our previous works on the generation of SRR gene knockout (Srr-KO) mice and its protective effects against NMDA- and Aβ peptide-induced neurodegeneration, we hypothesized that the regulation of NMDARs’ over-activation by inhibition of SRR activity is one such therapeutic strategy to combat these disease states. In the previous study, we performed in silico screening to identify four compounds with inhibitory activities against recombinant SRR. Here, we synthesized 21 derivatives of candidate 1, one of four hit compounds, and performed screening by in vitro evaluations. The derivative 13J showed a significantly lower IC50 value in vitro, and suppressed neuronal over-activation in vivo.Download high-res image (115KB)Download full-size image

The enantiodivergent synthesis of polyhydroxylated pyrrolizidines has been achieved, starting from common intermediate 1. The synthesis involved the stereoselective construction of the pyrrolizidine core unit by using intramolecular Michael cyclization reaction as the key reaction. The synthesized eight isomers were evaluated for various glycosidase inhibition effects. Compound 15 showed a moderate inhibitory activity against α-l-fucosidase and a high selectivity compared from the other glycosidases.

In order to develop new drugs for Alzheimer’s disease, we prepared 17 fatty acid derivatives with different chain lengths and different numbers and positions of double bonds by using Wittig reaction and stereospecific hydrogenation of triple bonds as key reactions. Among them, (4Z,15Z)-octadecadienoic acid (10) and (23Z,34Z)-heptatriacontadienoic acid (16) showed the most potent neurite outgrowth activities on Aβ(25–35)-treated rat cortical neurons, which activities were comparable to that of a positive control, NGF. Both fatty acids 10 and 16 possess two (Z)-double bonds at the n-3 and n-14 positions, which might be important for the neurite outgrowth activity.

Novel 4-substituted 2-pyridin-2-ylamides were developed using in-silico ligand-based drug design (LBDD) in an attempt to identify inhibitors of SH2-containing 5′-inositol phosphatase 2 (SHIP2), which is implicated in insulin-resistant type 2 diabetes. Among the compounds synthesized, N-[4-(4-chlorobenzyloxy)pyridin-2-yl]-2-(2,6-difluorophenyl)- acetamide (CPDA, 4a) was identified as a potent SHIP2 inhibitor. CPDA was found to enhance in vitro insulin signaling through the Akt pathway more efficiently than the previously reported SHIP2 inhibitor AS1949490, and ameliorated abnormal glucose metabolism in diabetic (db/db) mice.Graphical abstractHighlights► Rational design of novel SHIP2 inhibitors using in-silico LBDD was reported. ► CPDA (4a) was found to enhance in vitro insulin signaling. ► CPDA (4a) was also found to improve the abnormal glucose metabolism in db/db mice.

In this study we revealed that the addition of an N-phenylacetamide substituent to the C-1 position of 1-deoxyfuconojirimycin (DFJ) can lead to highly potent inhibitors of α-l-fucosidases. A structure–activity relationship study showed that a fluoro group on the phenyl ring greatly increased its potency and selectivity. In contrast the addition of two or three fluoro groups decreased their inhibition potency. Consequently, N-(2-fluorophenyl)-2β-DFJ acetamide (18j) was found to display very potent and selective inhibition of bovine kidney, rat epididymis, and human lysosome α-l-fucosidases, with IC50 value of 0.012, 0.044, and 0.0079 μM respectively. It is noteworthy that our designed N-phenyl-2β-DFJ acetamide derivative exhibited about 18-fold stronger effects on human lysosomal α-l-fucosidase than original DFJ and it occupied the active-site of this enzyme. We therefore expect that this compound may find applications in new therapeutic trials against genetic deficiency disorders.

New substituted (1-thioxo-1,2,3,4-tetrahydro-β-carbolin-9-yl)acetic acids were designed as the inhibitor of AKR1B1 based upon the structure of rhetsinine, a minor alkaloidal component of Evodia rutaecarpa, and twenty derivatives were synthesized and evaluated. The most active compound of the series was (2-benzyl-6-methoxy-1-thioxo-1,2,3,4-tetrahydro-β-carbolin-9-yl)acetic acid (7m), which showed comparable inhibitory activity for AKR1B1 (IC50 = 0.15 μM) with clinically used epalrestat (IC50 = 0.1 μM). In the view of activity and selectivity, the most potent compound was (2-benzyl-6-carboxy-1-thioxo-1,2,3,4-tetrahydro-β-carbolin-9-yl)acetic acid (7t), which showed strong inhibitory effect (IC50 = 0.17 μM) and very high selectivity for AKR1B1 against AKR1A1 (311:1) and AKR1B10 (253:1) compared with epalrestat.The binding conformation of the 7t (blue stick) for AKR1B1 (A) and for AKR1B10 (B), and the difference of binding pocket (C) between AKR1B1 (green solid surface) and AKR1B10 (red wireframe).