Isolation of a naphthaquinone with partly hydrogenated side chain from Corynebacterium diphtheriae

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Abstract
Corynebacterium diphtheriae contains relatively large amounts (6.6 [mu]moles/g dry wt.) of a naphthaquinone whose ultraviolet-absorption spectrum is that of a typical menaquinone (vitamin-K2), the El% value corresponding with that of MK-8, but on reversed-phase paper chromatograms it runs with MK-9. In the presence of Adams catalyst hydrogen uptake is 2 atoms/ mol. less than that calculated for MK-8. Hydrogenated samples of the Corynebacterium quinone and the hydrogenation product of authentic MK-8 ran together on reversed-phase chromatograms. Infrared-absorption spectra indicated close relationship with the menaquinone series, and nuclear-magnetic-resonance measurements show that one, non-terminal, double bond of the side chain has been saturated. The compound is thus designated MK-8 (2H), indicating a menaquinone with eight isoprene units but only seven double bonds in the side chain.