Bisisoquinoline alkaloids

Very recently, nice recognition of free and AT-acetylated amino acids (Gly, Ala, Phe) and some structurally related guests by a dicationic cyclophane-type A/,Ar -dibenzylated chiral derivative (4) of a bisisoquinoline alkaloid S,S-(+)-tetrandine (3 DBT) has been studied by NMR titration in water [31]. In contrast to other macrocyclic hosts, DBT shows high affinity and large enan-tioselectivity (K(S)/K(R)> 10) toward the smaller N-acetylalanine and binds the larger phenylalanine more weakly and nonselectively. The binding specificity of DBT was rationalized on the basis of molecular mechanics calculations. 

The pharmacological activity of certain bisbenzylisoqui-noline alkaloids has been reviewed (Buck, 1987 Schiff, 1987). Many of these compounds have weak to moderate antimicrobial activity. Two types of bisisoquinoline alkaloids possess antitumor activity. These are bisbenzylisoqui-noline and aporphine-benzylisoquinoline alkaloids [e.g., tetrandrine (99) and thalicarpine (100), respectively]. Both have pronounced side effects (Cordell, 1978b). 

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