Figure 7.

Structure–activity-relationship-based depiction of possible PCAIs interactions with potential targets. Schematic diagrams showing the possible ionic and hydrophobic interactions of the analogs with the target are based on the relative effects of the analogs against cancer cell viabilities. The most potent analogs (NSL-YHJ-2-27 and NSL-BS-056) are believed to have the most cooperative binding contacts for higher affinities and potencies. Although other factors such as the degree of cell entry may be in play, the surprising effectiveness of NSL-YHJ-3-36 suggests possible contribution of salt bridge to its effectiveness.