Synthesis, structure, and properties of α,ß-linked oligothiazoles with controlled sequence.

α,ß-Linked oligothiazoles with head-to-tail connectivity are presented as a new family of helical scaffolds. Combinations of palladium-catalyzed cross-coupling reactions at the 5- and 4-positions of 2-phenylthiazole led to the synthesis of oligo(2-phenylthiazoles) with ortho linkages with a variety of defined sequences. The secondary structures of the α,ß-linked oligo(2-phenylthiazoles) showed a clear dependence on their sequences. X-ray crystallography of the trimer, tetramer, and hexamer with head-to-tail connection revealed the formation of a helical structure, which was stabilized by a combination of intramolecular forces, including interheteroatom (S⋅⋅⋅N), CH-π, and π-π interactions. The introduction of a chiral end-group successfully led to the induction of chirality into the helical conformations. Programmable sequences for controlled geometries and photofunctions have been demonstrated through the manifold connection pathways in α,ß-linked oligothiazoles.

Identification of a gene involved in the synthesis of a dipeptidyl peptidase IV inhibitor in Aspergillus oryzae.

WYK-1 is a dipeptidyl peptidase IV inhibitor produced by Aspergillus oryzae strain AO-1. Because WYK-1 is an isoquinoline derivative consisting of three l-amino acids, we hypothesized that a nonribosomal peptide synthetase was involved in its biosynthesis. We identified 28 nonribosomal peptide synthetase genes in the sequenced genome of A. oryzae RIB40. These genes were also identified in AO-1. Among them, AO090001000009 (wykN) was specifically expressed under WYK-1-producing conditions in AO-1. Therefore, we constructed wykN gene disruptants of AO-1 after nonhomologous recombination was suppressed by RNA interference to promote homologous recombination. Our results demonstrated that the disruptants did not produce WYK-1. Furthermore, the expression patterns of 10 genes downstream of wykN were similar to the expression pattern of wykN under several conditions. Additionally, homology searches revealed that some of these genes were predicted to be involved in WYK-1 biosynthesis. Therefore, we propose that wykN and the 10 genes identified in this study constitute the WYK-1 biosynthetic gene cluster.

Identification and characterization of a novel fermented substance produced by edible Aspergillus oryzae AO-1 that inhibits DPP-IV activity.

We identified a novel fermented substance (FKA) produced by the edible Aspergillus oryzae strain AO-1 that inhibited dipeptidyl peptidase IV (DPP-IV) (IC(50) = 3.41 mg · mL(-1)). HPLC analysis of FKA showed specific one metabolite (WYK-1), which inhibited DPP-IV (IC(50) = 6.98 µM). WYK-1 was identified as a tetrahydroxyisoquinoline derivative. Interestingly, we examined 60 strains of A. oryzae, AO-1 was the only A. oryzae strain that produces WYK-1. This is the first report that an edible A. oryzae strain produces a DPP-IV inhibitor such as WYK-1. This study also suggests that FKA has applications in the development of novel antihyperglycemic therapeutics or functional foods.

HPLC determination of (+)-pseudoephedrine and (-)-ephedrine in Japanese herbal medicines containing Ephedra herb using solid-phase extraction.

We developed a rapid and simple HPLC method combined with solid-phase extraction (SPE) for quantitative analysis of (+)-pseudoephedrine (PEP) and (-)-ephedrine (EP) in Japanese herbal (Kampo) medicines such as Kakkon-to, Sho-seiryu-to, Goshaku-san and Bofu-tsusho-san. SPE was performed on TOYOPAK IC-SP M containing propylsulfonic groups. Determination of PEP and EP was carried out using ion-pair reversed-phase HPLC with sodium dodecyl sulfate. N-Benzyldiethylamine was used as an internal standard. The analytical procedure was validated with regard to specificity, linearity, accuracy, and precision. These data suggest that the analytical method developed in this study is useful for quantitative analysis of PEP and EP in various formulations of Kampo medicine containing Ephedra herb.