Biscoclaurine alkaloids

The bisbenzylisoquinoline or biscoclaurine alkaloids, which comprise a group of over thirty members, possess structures containing two benzyliso-quinoline nuclei joined by one, two, or three ether linkages. They occur... 

Some biscoclaurine alkaloids (bisbenzylisoqui-noline derivatives) were able to inhibit superoxide production by phorbol ester-stimulated human polymorphonuclear leucocytes (Haisong et al. 1990) and hpid peroxidation in biological membranes (Shiraishi et al. 1980). 

Akasu M, Itokawa H, Fujita M (1976) Biscoclaurine alkaloids in callus tissues of Stephania cepharantha. Phytochemistry 15 471-473... 

There are now known a eonsiderable number of alkaloids containing two distinct woquinoline nuclei, such as emetine and its congeners (p. 394), and in the morphine sub-group, -morphine, dithebainone (p. 255), disinomenine and its pseudo-isomeride (p. 268). The most important collection of such alkaloids is the bisbenzylwoquinoline or biscoclaurine section of which the following two alkaloids, berbamine and oxyacanthine, are examples, but which is typically developed in the Menispermaceas. 

The presence of alkaloids was discovered in many other Queensland plants by Dr. T.L. Bancroft, who continued the work of his father Joseph. Although the techniques and facilities available in Australia at that time were hardly adequate for the isolation, purification and structural determination of new alkaloids, or even for the identification of ones already known, the pioneering investigations by the Bancrofts, Petrie and others nevertheless formed a starting point for subsequent studies. T.L. Bancroft, for example, obtained impure samples of alkaloids from certain Daphnandra species (Monimiaceae) [11, 12], and studied their pharmacology. His work was later extended by Pyman in England 113, who isolated crystalline bases from D. micrantha that proved eventually [14] to belong to the same biscoclaurine series as berbamine (1). 

Tubocurare is used in the Amazon basin, and is kept in a container known as a tubo or tube. The poison comprises extracts of the bark of Chondodendron tomentosum and C.platyphyllum (Menispermaceae), which grow wild in Brazil. The toxic principle is the biscoclaurine-type alkaloid J-tubocurarine (d-Tc), which is described later in this section. 

Coclaurine is an important alkaloid because its demethyl analog, norco-claurine, can be regarded as the prototype building block of dimeric benzylisoquinoline alkaloid that are often referred to as biscoclaurine-type alkaloids. 

The family Menispermaceae comprises over 60 genera and about 400 species, distributed mainly in the tropical and subtropical regions in the world. Most species are lianas but some are bushes or low trees. Biscoclaurine-type alkaloids occur in many of the plants of this family. From the bark and trunks of Cocculus laurifolius, 0.13% crude base was obtained. Trilobine (0.004%) was isolated from the base together with coclaurine (90, 157). 

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