Kopsirachin, ein ungewöhnliches Alkaloid aus der Apocynaceae Kopsia dasyrachis Ridl. 189. Mitteilung über organische Naturstoffe

Abstract

Kopsirachine, an Unusual Alkaloid from the Apocynaeeae Kopsia dasyrachis Ridl. SummaryFrom the leaves of Kopsiu dusyruchis Ridl. a new type of alkaloid, kopsirachine (l), built up from catechin (2) and skytanthine (3) has been isolated. The structure elucidation is based on spectral and chemical evidence. Oxidative cleavage of its derivative 4 with KMnO, afforded veratric acid which was identified as its methylester by comparison with an authentic sample. Pyrolysis of 1 yielded &skytanthine (3). The stereochemistry of the skytanthine substituents in 1 could not yet be established.Aus den Blattern von Kopsiu dasyrachis Ridl. wurden bisher drei Indolalkaloide, Kopsidasin-N-oxid, Kopsidasin und Kopsidasinin isoliert und in ihrer Struktur aufgeklart [2]. In der vorliegenden Mitteilung wird uber die Isolierung und Strukturaufklarung des Hauptalkaloides, Kopsirachin (l), berichtet. Die Verbindung ist aufgebaut aus einem Mol Catechin und zwei Molen Skytanthin.1. Chemische und spektroskopische Befunde. -Kopsirachin (1, M = 6203)) ist amorph und besitzt ein UV-Spektrum [h,,, 281 nm (log& = 3,88), h,,, 256 (3,71)], welches eine grosse Ahnlichkeit mit demjenigen von Catechin (2)4) zeigt. Auch aus dem Vergleich der 'H-und I3C-NMR-Spektren von 1 und 2 lasst sich folgern, dass sich die beiden Chromophore entsprechen; s. unten. Im IR-Spektrum von 1 sind AromatenBanden bei 1620 und 1510 cm-' erkennbar.Im Elektronenstoss-Massenspektrum (EI-MS) von 1 wird das Molekularion nicht registriert, das Ion mit hochster Masse tritt bei m / z 166 (C,,H2,N)5) auf. Es entsteht durch die offenbar bevorzugten Spaltungen der C(

Chromone and Flavonoid Alkaloids: Occurrence and Bioactivity

“…Kopsirachin [2-(3,4-dihydroxyphenyl)-3,4-dihydro-6,8-bis(octahydro-2,4,7-trimethyl-1 H -2-pyridin-1-yl)-2 H -1-benzopyran-3,5,7-triol] ( 41 , Figure 15) is a flavoalkaloid isolated from the leaves of Kopsia dasyrachis Ridl., Apocynaceae [28]. It consists of two skytanthine moieties linked to the C -6 and C -8 positions of a catechin molecule.…”

Novel Cage Indoles from a Malaysian Kopsia

“…The genus Kopsia (Apocynaceae) comprises some 30 species of shrubs and trees distributed mainly over Southeast Asia, India and China. , There are about 12 species distributed over the lowland forest of Peninsular Malaysia and another six in North Borneo. , Some medicinal uses have been reported for the cultivated species K. officinalis , which is used in China for the treatment of rheumatoid arthritis, dropsy, and tonsilitis, and in Malaysia the roots of several Kopsia species are used for poulticing ulcerated noses in tertiary syphilis . The genus has yielded a prodigious array of new natural products with novel carbon skeletons as well as useful bioactivities. − We have previously reported in preliminary form the occurrence of caged indoles from the leaf extract of Kopsia teoi L. Allorge 5,6 and would like now to furnish full details as well as the further isolation of a new member of this class of alkaloids, viz., kopsinitarine D for which we have also carried out X-ray analysis.…”

Cardiovascular Effects of Aspidofractinine-Type Alkaloids from Kopsia

“…The genus Kopsia (Apocynaceae) comprises some 30 species of shrubs and trees distributed mainly over Southeast Asia, India, and China, of which about 18 species occur in Malaysia. , The phytochemistry of this genus has received considerable attention, which has resulted in a considerable number of new natural products with novel structures and useful bioactivities. − Some medicinal uses have been reported, such as for the cultivated species K. officinalis , which is used in China for the treatment of rheumatoid arthritis, dropsy, and tonsilitis, and in Malaysia, the roots of several Kopsia species are known to be used for poulticing ulcerated noses in tertiary syphilis .…”