Modified vitamin B12 derivatives with a peptide backbone for biomimetic studies and medicinal application

This short review highlights the author’s group research on modified vitamin B[Formula: see text] derivatives with a peptide backbone as (1) inhibitors of B[Formula: see text]-dependent enzymes and as (2) models of cofactor B[Formula: see text]-protein complexes

Detection of glyphosate with a copper(ii)-pyrocatechol violet based GlyPKit

This paper describes the development of a test kit for the selective detection of glyphosate (GlyP). A copper(II)-pyrocatechol violet complex was selected by a screening approach from a pool of 96 combinations of metal ions and commercially available indicators and subsequently incorporated as a detection zone into a hydrophobic C18 solid support. With this kit, detection of 20 μM GlyP in tap water by the “naked eye” is possible and quantifications by smartphone analysis with a limit of detection as low as 2.66 μM (450 μg L−1) have been demonstrated in a proof-of-principle study

Quantifying cyanide in water and foodstuff using corrin-based CyanoKit technologies and a smartphone

This paper describes the detection of endogenous cyanide using corrin-based CyanoKit technologies in combination with a smartphone readout device. When applied to the detection of cyanide in water, this method demonstrates high repeatability and discriminative power with a limit of blank of 0.074 ppm and an instrument limit of detection of 0.13 ppm. Quantification of endogenous cyanide in cassava and bitter almond extracts with the smartphone readout is in excellent agreement with independent analyses using traditional spectrophotometric detection. The prototype system objectively detects levels of cyanide with a high granularity at the point-of-need and does not depend on large, heavy and expensive instrumentation. The methodology has the potential to be easily adopted in resource limited situations and low-income countries

Functionalisation of vitamin B12 derivatives with a cobalt β-phenyl ligand boosters antimetabolite activity in bacteria

This study describes the syntheses of four singly- and two doubly-modified vitamin B12 derivatives for generating antimetabolites of Lactobacillus delbrueckii (L. delbrueckii). The two most potent antagonists, a Coβ-phenyl-cobalamin-c,8-lactam and a 10-bromo-Coβ-phenylcobalamin combine a c-lactam or 10-bromo modification at the “eastern” site of the corrin ring with an artificial organometallic phenyl group instead of a cyano ligand at the β-site of the cobalt center. These two doubly-modified B12 antagonists (10 nM) inhibit fully B12-dependent (0.1 nM) growth of L. delbrueckii. In contrast to potent 10-bromo-Coβ-phenylcobalamin, single modified 10-bromo-Coβ-cyanocobalamin lacking the artificial organometallic phenyl ligand does not show any inhibitory effect. These results suggest, that the organometallic β-phenyl ligand at the Co center ultimately steers the metabolic effect of the 10-bromo-analogue

Modifizierte Peptidnucleinsäuren für die sequenzselektive DNA-Spaltung und DNA-Nachweis

Es wurden Metallkomplex-Konjugate von Peptidnucleinsäuren (PNAs) synthetisiert und in zwei Projekten angewendet: als “künstliche Restriktionsenzyme“ für die sequenzselektive Spaltung von Einzelstrang-DNA sowie als Komponenten einer DNA-templatvermittelten Metallkatalyse. Im ersten Projekt konnte durch MALDI-TOF MS und HPLC der Zr(IV)-Komplex des Tris(hydroxymethyl)-aminomethan-PNA-Konjugats (Zr(IV)-15) als aktivste Spezies zur Spaltung komplementärer DNA identifiziert werden. Die Spaltung der Ziel-DNA erfolgte sequenzselektiv zu 91% (nach 164 Stunden) in unmittelbarer Nachbarschaft des Metallkomplexes. Konjugate einer Cu(II)-Pyridylpyrazol-modifizierten PNA (Cu(II)-31) wurden für die DNA-templatvermittelte Spaltung estermodifizierter PNAs eingesetzt. Als Substrat-PNAs wurden die PNA-Ester-Konjugate 16 und 17 synthetisiert, in denen die Cu(II)-Ankergruppe (Chinolin-N) in die Alkohol-PNA-Komponente integriert ist. Es kann im Grunde mit beliebigen Carbonsäuren kombiniert werden. Die Spaltreaktionen wurden durch eine Kombination aus MALDI-TOF MS- und HPLC-Analyse untersucht. Es konnte gezeigt werden, dass die Reaktion durch das DNA-Templat etwa 100-fach beschleunigt wird. Des weiteren wurden nach 10 Stunden 12 Turnover bei einem 100-fachen Substratüberschuss erzielt

Modified biovectors for the tuneable activation of anti-platelet carbon monoxide release

This communication describes the anti-platelet effects of a new class of cis-rhenium(II)- dicarbonyl-vitamin B12 complexes (B12-ReCORMs) with tuneable CO releasing properties

Metal-Salen-based Probes for the Selective Detection of Phosphates via a Disassembly Approach

Polyoxophosphates are ubiquitous in nature and play important roles in biological systems and in the environment. Pyrophosphate (PPi), an important member of this family, is produced in over 200 biochemical reactions and is a marker in clinical diagnosis. In addition to its endogenous role, PPi alias E450 is currently used as preservative, emulsifier or taste intensifier in foodstuff. Despite this widespread occurrence and biological importance, it is rather surprising that robust chemical systems that detect selectively and sensitively PPi in challenging matrices are still lacking. This mini review focuses on metal-salen complexes as reaction-based fluorescent sensors for the selective detection of PPi and other phosphates. The mode of detection is based on a novel disassembly approach in which the metal ion is sequestered by the target analyte from the complex and the metal-free ligand hydrolyses spontaneously into its fluorescent subunits. Optimizations of the probe and applications for PPi detection in cells and foodstuff are described

Metal-Salen-based Probes for the Selective Detection of Phosphates via a Disassembly Approach

Polyoxophosphates are ubiquitous in nature and play important roles in biological systems and in the environment. Pyrophosphate (PPi), an important member of this family, is produced in over 200 biochemical reactions and is a marker in clinical diagnosis. In addition to its endogenous role, PPi alias E450 is currently used as preservative, emulsifier or taste intensifier in foodstuff. Despite this widespread occurrence and biological importance, it is rather surprising that robust chemical systems that detect selectively and sensitively PPi in challenging matrices are still lacking. This mini review focuses on metal-salen complexes as reaction-based fluorescent sensors for the selective detection of PPi and other phosphates. The mode of detection is based on a novel disassembly approach in which the metal ion is sequestered by the target analyte from the complex and the metal-free ligand hydrolyses spontaneously into its fluorescent subunits. Optimizations of the probe and applications for PPi detection in cells and foodstuff are described

Vitamin B12-basierte Chemosensoren: Effizienter Nachweis von Zyaniden

Vitamin B12-basierte Chemosensoren stellen bezüglich Selektivität, Sensitivität, Biokompatibilität und Geschwindigkeit wahrscheinlich die derzeit attraktivsten Systeme zum Nachweis von Zyaniden mit blossem Auge dar. Diese Systeme erlauben aufgrund ihrer überragenden Eigenschaften den raschen, optischen Nachweis von freiem Zyanid in Nahrungsmitteln und im Blut, zwei sehr wichtige Anwendungen in der Lebensmittelkontrolle und Notfallmedizin

Recent trends in the development of vitamin B12derivatives for medicinal applications

This Feature Article highlights recent developments in the field of vitamin B12 derivatives for medicinal applications. The following topics are emphasized: (1) the development of aquacorrinoids for cyanide detection and detoxification, (2) the use of vitamin B12 conjugates and (3) antivitamins B12 for therapy and diagnosis, and (4) the design of corrinoids as activators of soluble guanylyl cyclase (sGC)