Proof of formation of an unstable conjugated triene on decomposition of gibberellin A3 in water
It has been shown by the methods of1H NMR and high-performance liquid chromatography with recording of UV spectra that in aqueous solutions of gibberellin A3, via gibberellenic acid, an unstable conjugated triene having λmax 326 nm is formed which is readily converted into allogibberic acid and is isolated as a mixture (1:2) with this acid. In the1H NMR spectrum of the triene, confirming its structure, spin-spin coupling both of the H-5 proton and of the protons of the methyl group with all the H-1, H-2, and the H-3 protons is observed. The precursor of allogibberic acid has been ascribed the structure of (−)-13-hydroxy-19,20-dinorgibberella-1,3,9,16-tetraen-7-oic acid with a conjugated 1,3,9-trienic system.
Micro-column liquid chromatography with multi-wave-length photometric detection : I. The OB-4 micro-column liquid chromatograph
Abstract The OB-4 micro-column liquid chromatograph is designed for high-performance liquid chromatography (HPLC) on 50–200 μl columns with typical eluent volumes of 500–2500 μl. The detector is a double-beam microspectrophotometer with two flat-window flow cells. The monochromator of the detector contains a special drive for rapid chnge of wavelength according to stepwise cyclic programmes over the range 190–360 nm. In this way multi-wavelength detection on a time-share basis is performed. The OB-4 chromatograph may be used for all types of HPLC. It consumes much smaller amounts of eluents, adsorbents and samples than other instruments. The multi-wavelength facility helps in identification and evaluation of homogeneity. Examples of applications are given.
New metabolites of gibberella fujikuroi—x : Gibberellin A10☆
Abstract The spectroscopic and chemical properties of gibberellin A15, a metabolite of Gibberella fujikuroi, are consistent with the structure VII.