Strychnos monoindole

Fig.(7). Structure of Strychnos monoindole alkaloids evaluated for their anticancer and/or antiprotozoal acrtivites. Structure of cryptolepine and ellipticine are given for comparison purpose.

Twelve alkaloids, seven of which are new, have been isolated from the root bark of Strychnos panganensis collected in Tanzania. The novel monoindole alkaloid are A-desacetylspermostrychnine (17), 12-hydroxy-11-methoxy-nor-c-fluorocurarine (18), 12-hydroxy-l l-methoxy-/V-acetyl-nor-C-fluorocurarimine (19) [33]. 

Lastly, beside monoindole, four dimeric indole alkaloids of the reticuline-diaboline type have been isolated from the root bark of Strychnos panganensis two couple of stereoisomers on C-19 or C-19 named panganensine R (30) and S (31), and panganensine X (32) and Y (33) respectively [33]. It has not been possible to assign the C-19 configuration for 32 and 33. 

Two types of Strychnos alkaloids have been evaluated for their potential as anticancer drugs. These include the monoindole alkaloids whose structure comprises a harmane skeleton 34, Fig. (7) and the bisindole alkaloids of S. usambarensis, Fig. (8). 

Seven monoindole Strychnos alkaloids, namely matadine (35), serpentine (36), alstonine (39), melinonine F (40), normelinonine F (41), 5,6-dihydroflavopereirine (42) and strychnoxanthine (43) as well as the hemisynthetic Nb-methyharmalane, together with cryptolepine (37) as reference compound, were tested for their in vitro antiplasmodial activity... 

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