Structural Requirements of Cepharanthine for its radical scavenging activity

Abstract

Of the macrocyclic benzylisoquinoline alkaloids, cepharanthine and isotetrandrine show the radical scavenging activities, but tetrandrine does not. For understanding the structural requirements for radical trapping of benzylisoquinoline alkaloids, we analyzed conformational flexibilities at the global minimum structures using modified CONFLEX3 algorithm. We found that cepharanthine and isotetrandrine take the flexible cis-configuration, whereas tetrandrine takes the rigid trans-configuration. Hence, it is concluded that flexible structure is responsible for radical scavenging activity of the alkaloids.