Th. Mulder-Krieger

Anthraquinones in callus cultures of Cinchona ledgeriana

Abstract From callus cultures of Cinchona ledgeriana seven known anthraquinones, purpurin, anthragallol-1,2-dimethylether, anthragallol-1,3-dimethylether, rubiadin, 1-hydroxy-2-hydroxymethylanthraquinone, 1-hydroxy-2-methylanthraquinone and morindone-5-methylether (or 1,7-dihydroxy-8-methoxy-2-methylanthraquinone), and eight new anthraquinones, 5,6-dimethoxy-1-(or -4-)hydroxy-2-(or -3-)hydroxymethylanthraquinone, 5-methoxy-2-(or -3-)methyl-1,4,6-trihydroxyanthraquinone, 2-hydroxy-1,3,4-trimethoxyanthraquinone, 4-methoxy-1,3,5-trihydroxyanthraquinone, 1,4-dimethoxy-2,3-methylenedioxyanthraquinone, 1,3-dihydroxy-4-methoxyanthraquinone, 1,3-dihydroxy-2,5-dimethoxyanthraquinone and 2,5-(or 3,5-)dihydroxy-1,3,4-(or -1,2,4-)trimethoxyanthraquinone have been isolated.

Plant Cell and Tissue Culture of Cinchona Species

The genus Cinchona, belonging to the family Rubiaceae, is still esteemed for its anti-malaria activity. Several species, e.g. C. pubescens (syn. C succirubra) and C. ledgeriana,, have been cultured in plantations during the past 130 years for the production of Cinchona bark, the raw material for the alkaloids quinine and quinidine. Cinchona plantations are mainly found in Middle-America, Central Africa, India, Phillipines, and Indonesia. After 7–12 years of growth the bark of the trees is harvested. The alkaloid content is then about 10%–15% (Smit 1984).

Modification of Flower Colour

The pigments, present in petal cells, determine the colour of flowers. Because especially blue flowers are rare in important flowers crops (Chapter V), the development of this trait will be most promising. The anthocyanidin glycosides are responsible for most red, purple and blue colours. In higher plants only six anthocyanidins commonly occur, namely pelargonidin (most red), peonidin, cyanidin, malvidin, petunidin and delphinidin (most blue) (Fig. 1.8). Generally it has been found that most blue- and violet flowers contain 3′,4′,5′-hydroxylated anthocyanins or their methylated derivatives (Section V.2.5).

The13C-NMR spectrometry of cinchonamine and quinamine

The assignment of the13C-nmr-spectra of theCinchona indole alkaloids cinchonamine and quinamine is presented.

Methods to Change Characteristics of Plants

Throughout history man has looked for methods to change the genetic properties of plants. There are several techniques available to achieve this target. Classical breeding, mutagenesis and protoplast fusion are beyond the scope of this review and will only be discussed briefly. The recombinant DNA1 technology, on the other hand, will be treated more extensively. In the creation of new flower colours, especially a combination of classical- and molecular breeding techniques seems most promising.

Genes Controlling Flavonoid Biosynthesis

The flow of genetic information in normal cells is from deoxyribonucleic acid (DNA) via ribonucleic acid (RNA) to protein (e.g., an enzyme). Thus, the base sequence of DNA specifies ultimately the amino acid sequence of a protein, which — in turn — determines its three-dimensional configuration necessary to perform biological functions.

Biosynthesis of the Various Flavonoid Classes

Flowering plants contain a multitude of secondary compounds, including flavonoids. The formation of these compounds requires many steps and should not be expected to be present in the more primitive organisms. Smith (1972) estimated that the formation of flavonoids accounts for the consumption of one-sixth of the total carbon fixed by photosynthesis in plants.