The major drawback of using Fluo-4 AM is that it requires an organic anion transporter inhibitor, such as probenecid, to prevent leakage. This can hinder the studies that require extended monitoring time and longer cellular retention. To address the issue, a novel Ca indicator, Calbryte 520 AM, was developed.
View Article and Find Full Text PDFMagnesium ion (Mg) plays an important role in various biological processes. All the commercial indicators available share a common drawback, i.e.
View Article and Find Full Text PDFThe convergent synthesis of the complete ABCDEF-ring system within nogalamycin, an anthracycline natural product, was studied. The pivotal Hauser annulation for the anthraquinone core construction was achieved by the fusion of two highly functionalized segments: a cyanophthalide (the AB-ring segment) and a tricyclic quinone monoketal (the DEF-ring segment). Key transformations toward the AB-ring segment include an enantioselective enolate α-hydroxylation, a diastereoselective hydroboration-oxidation, and a directed aromatic lithiation-formylation.
View Article and Find Full Text PDFConstruction of the DEF-ring system of nogalamycin and menogaril has been achieved with a novel reductive Heck cyclization approach. Our strategy exploited the stereoelectronic preferences dictated by the anomeric effect for introduction of an O-glycosidic bond in order to direct the introduction of a bridging C-glycosidic bond with the desired stereochemistry. Our strategy relied upon a stereoselective O-aryl glycosylation reaction and a highly efficient selenoxide elimination to provide the key substrate for study of the reductive Heck cyclization reaction.
View Article and Find Full Text PDFPeroxynitrite (ONOO), a strong oxidant species, is produced by the reaction of nitric oxide (NO) and superoxide (O) radicals. It plays an important role as a biological regulator in numbers of physiological and pathological processes. In this study, we developed fluorescence-based real-time quantitative measurements to detect intracellular ONOO.
View Article and Find Full Text PDFA novel reductive Heck cyclization approach was developed in order to construct a model DEF-benzoxocin ring system that is present in nogalamycin, menogaril, and related anthracycline antitumor antibiotics.
View Article and Find Full Text PDFA series of dendritic 8-hydroxyquinoline (8-HQ) and 5-dialkyl(aryl)aminomethyl-8-HQ derivatives were synthesized and their fluoroionophoric properties toward representative alkali, alkaline earth, group IIIA and transition metal ions were investigated. Among the selected ions, Zn(II) enhanced the fluorescence of N-di-(methoxycarbonylethyl)aminoethyl-3-[4-(8-hydroxyquinolin-5-ylmethyl)piperazin-1-yl]-propanoic amide] (7) by 31-fold, while Al(III) caused enhancement to some extent. The absence of any significant fluorescence enhancement by the other ions examined renders 7a highly useful Zn(II)-selective fluorescent sensor.
View Article and Find Full Text PDFA series of 5-dialkyl(aryl)aminomethyl-8-hydroxyquinoline dansylates were synthesized and their fluoroionophoric properties toward representative alkali ions, alkaline earth ions and transition metal ions were investigated. Among the selected ions, Fe3+ caused considerable quenching of the fluorescence, while Cr3+ caused quenching to some extent. The absence of any significant fluorescence quenching effects of the other ions examined, especially Fe2+, renders these compounds highly useful Fe3+-selective fluorescent sensors.
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