B. Juhl Nielsen

Phytochemical interrelationships in the Cornaceae

Abstract The distribution of iridoids, ellagitannins, proanthocyanidins and other compounds in the Cornaceae and related families is discussed in relation to the various taxonomic treatments. Analysis of the chemical data indicates that: (a) Benthamia and Cynoxylon are the most primitive sub-genera in Cornus, (b) Corokia possesses a chemical pattern consistent with that of the Cornaceae, but Helwingia might better be elevated to family rank, (c) Alangiaceae, Davidiaceae, Garryaceae and Nyssaceae broadly fall into the same pattern as the Cornaceaa and can be placed in a restricted order, Cornales, which excludes Araliaceae, Umbelliferae and Rhizophoraceae, and (d) the Cornales shows affinities to the Saxifragales and the Dipsacales.

4,5,6,7-tetrahydroxydecyl isothiocyanate derived from a glucosinolate in Capparis grandis

Abstract Root material of Capparis grandis , of Indian origin, contains a free isothiocyanate, identified as 4,5,6,7-tetrahydroxydecyl isothiocyanate 1 by spectroscopical and chemical means, yet without specification as to its stereochemistry. The presence of the parent glucosinolate, and three other, unidentified glucosinolates in C. grandis has been noted. The distribution of glucosinolates within the genus Capparis is reviewed and the biosynthetic origin of the individual compounds discussed.

The genus Comus: Non-flavonoid glucosides as taxonomic markers

Previous proposals for subdivision of the genus Cornus are reviewed. Twenty-seven authenticated Cornus species have been studied for their content of non-flavonoid glucosides. Two distinct groups of taxa can be distinguished on this basis: one, containing a hydroxycyclohexadienone glucoside, along with salidroside, its reduced counterpart, and the second, characterized by containing various iridoid glucosides. The two types of glucosides are apparently mutually exclusive.

Application of 2H n.m.r. spectroscopy to a study of the biosynthesis of the iridoid glucoside cornin in Verbena officinalis

2 H N.m.r. spectroscopy has been used to demonstrate that in specifically labelled deoxyloganin, the label at C-8 is retained during its conversion into cornin in Verbena officinalis, suggesting that the 6-oxo group is produced by oxidation in an unactivated position.