Biomaterial Database

Structure determination of oligomeric alkannin and shikonin derivatives. 2005

Apostolos Spyros, and Andreana N Assimopoulou, and Vassilios P Papageorgiou

NMR Laboratory, Department of Chemistry, University of Crete, 71409 Iraklion, Crete, Greece.

Monomeric alkannin and shikonin (A/S) are potent pharmaceutical substances with a wide spectrum of biological activity and comprise the active ingredients for several pharmaceutical preparations. Therefore, the determination of the impurities, degradation products or byproducts in alkannin and shikonin samples is of great importance. Oligomeric alkannin and shikonin are formed during biosynthesis of these bioactive secondary metabolites in Boraginaceaous root plants, during tissue culture production of A/S, during alkaline hydrolysis of A/S esters and also thermal treatment of A/S. In the present study, a dimeric alkannin/shikonin compound was isolated by size exclusion chromatography from alkannin and shikonin commercial samples and its structure was determined by one- and two-dimensional NMR spectroscopy. The structure of the most abundant oligomeric species in these samples, a dimeric naphthoquinone, was established for the fi rst time, indicating that coupling of the side chain of one naphthoquinone unit with the aromatic ring of a second naphthoquinone leads to dimer formation. This type of coupling allows further oligomerization by leaving one isohexenyl side chain available at the second monomer unit.

UI	MeSH Term	Description	Entries
D009285	Naphthoquinones	Naphthalene rings which contain two ketone moieties in any position. They can be substituted in any position except at the ketone groups.	Naphthalenediones,Naphthazarins,Naphthoquinone
D011108	Polymers	Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).	Polymer
D002850	Chromatography, Gel	Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.	Chromatography, Exclusion,Chromatography, Gel Permeation,Chromatography, Molecular Sieve,Gel Filtration,Gel Filtration Chromatography,Chromatography, Size Exclusion,Exclusion Chromatography,Gel Chromatography,Gel Permeation Chromatography,Molecular Sieve Chromatography,Chromatography, Gel Filtration,Exclusion Chromatography, Size,Filtration Chromatography, Gel,Filtration, Gel,Sieve Chromatography, Molecular,Size Exclusion Chromatography
D019281	Dimerization	The process by which two molecules of the same chemical composition form a condensation product or polymer.	Dimerizations
D019906	Nuclear Magnetic Resonance, Biomolecular	NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.	Biomolecular Nuclear Magnetic Resonance,Heteronuclear Nuclear Magnetic Resonance,NMR Spectroscopy, Protein,NMR, Biomolecular,NMR, Heteronuclear,NMR, Multinuclear,Nuclear Magnetic Resonance, Heteronuclear,Protein NMR Spectroscopy,Biomolecular NMR,Heteronuclear NMR,Multinuclear NMR,NMR Spectroscopies, Protein,Protein NMR Spectroscopies,Spectroscopies, Protein NMR,Spectroscopy, Protein NMR
D028082	Boraginaceae	The Borage plant family is in the class Magnoliopsida, subclass Asteridae, order Lamiales. It is characterized by hairy foliage, usually alternate and simple; flowers are funnel-shaped or tubular. Some of the species contain PYRROLIZIDINE ALKALOIDS.	Alkanna,Anchusa,Cynoglossum,Ehretia,Onosma,Tournefortia,Arnebia,Alkannas,Anchusas,Arnebias,Cynoglossums,Ehretias,Onosmas,Tournefortias