Author
Toshio Goto
Bio: Toshio Goto is an academic researcher from Nagoya University. The author has contributed to research in topics: Total synthesis & Enediyne. The author has an hindex of 15, co-authored 49 publications receiving 1530 citations.
Topics: Total synthesis, Enediyne, Ketone, Vernolepin, Nucleophile
Papers
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TL;DR: In this article, the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking.
Abstract: In 1913 Willstatter made the striking observation that the same pigment can give rise to different colors. Thus, the same pigment, cyanin, is found in the blue cornflower and in the red rose. Willstatter attributed the variety of flower colors to different pH values in solution. Indeed, anthocyanin changes its color with pH; it appears red in acidic, violet in neutral, and blue in basic aqueous solution. Willstatter's pH-theory for explaining flower color variation is still to be found in major text books of organic chemistry. Very recently, however, reinvestigation has disclosed that the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking. The stacking would be mainly brought about by intermolecular or intramolecular hydrophobic interaction between aromatic nuclei such as anthocyanidins, flavones and aromatic acids. In addition, hydrogen bonds and charge transfer interactions may also be involved. The most interesting molecular complexes of anthocyanins are the metalloanthocyanins such as commelinin and protocyanin (blue cornflower pigment). These seemingly pure blue complexes each consist of six anthocyanin and six flavone molecules and two metal ions; their molecular weight is nearly 10000. A structure is proposed for commelinin.
419 citations
01 Jan 1991
TL;DR: In this article, the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking.
Abstract: In 1913 Willstatter made the striking observation that the same pigment can give rise to different colors. Thus, the same pigment, cyanin, is found in the blue cornflower and in the red rose. Willstatter attributed the variety of flower colors to different pH values in solution. Indeed, anthocyanin changes its color with pH; it appears red in acidic, violet in neutral, and blue in basic aqueous solution. Willstatter's pH-theory for explaining flower color variation is still to be found in major text books of organic chemistry. Very recently, however, reinvestigation has disclosed that the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking. The stacking would be mainly brought about by intermolecular or intramolecular hydrophobic interaction between aromatic nuclei such as anthocyanidins, flavones and aromatic acids. In addition, hydrogen bonds and charge transfer interactions may also be involved. The most interesting molecular complexes of anthocyanins are the metalloanthocyanins such as commelinin and protocyanin (blue cornflower pigment). These seemingly pure blue complexes each consist of six anthocyanin and six flavone molecules and two metal ions; their molecular weight is nearly 10000. A structure is proposed for commelinin.
342 citations
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TL;DR: Enzymic and synthetic approaches to the glycosidation of sialic acid by new methodologies are discussed, which aim to clarify their vital functions and identify the most difficult problem remaining.
160 citations
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TL;DR: In this paper, the effects of conformation rigidity and hydrogen bonding with the emitter, coelenteramide, on the chemiluminescence efficiency have been examined with several coelentazine analogues synthesized.
Abstract: In the case of chemiluminescence of coelenterazine, effects of conformation rigidity of and hydrogen bonding with the emitter, coelenteramide, on the chemiluminescence efficiency have been examined with several coelenterazine analogues synthesized. Conformational rigidity has a light enhancing effect, whereas decreasing light yield was observed by hydrogen-bond formation with the emitter.
81 citations
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TL;DR: In this paper, a deacetoxylated oxonium ion generated by treatment with a Lewis acid was used to obtain a nucleophilic reagents with this cation, such as bis(trimethylsilyl)acetylene, allyl trimethylsilane, and furan.
79 citations
Cited by
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TL;DR: The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
1,317 citations
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TL;DR: How the lessons learned from the first-generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes are described.
Abstract: Traditional cancer chemotherapy is often accompanied by systemic toxicity to the patient. Monoclonal antibodies against antigens on cancer cells offer an alternative tumor-selective treatment approach. However, most monoclonal antibodies are not sufficiently potent to be therapeutically active on their own. Antibody-drug conjugates (ADCs) use antibodies to deliver a potent cytotoxic compound selectively to tumor cells, thus improving the therapeutic index of chemotherapeutic agents. The recent approval of two ADCs, brentuximab vedotin and ado-trastuzumab emtansine, for cancer treatment has spurred tremendous research interest in this field. This Review touches upon the early efforts in the field, and describes how the lessons learned from the first-generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes. The design of ADCs currently in clinical development, and results from mechanistic studies and preclinical and clinical evaluation are discussed. Emerging technologies that seek to further advance this exciting area of research are also discussed.
749 citations
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TL;DR: In this paper, Radish and potato extracts imparted color characteristics to model juices extremely close to those of allura red, and red potatoes stand out as potential alternatives for the use of FD&C Red No. 40 (allura red).
744 citations
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715 citations
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TL;DR: Current knowledge regarding the reaction mechanisms involved in some of these processes and the structures of the resulting products is reviewed, and their effects on organoleptic and nutritional quality are also discussed.
657 citations