Structure Activity Relationship of ar-Turmerone Analogues

For the analysis of structure relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cells in vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. At meta position methoxy, methyl, trifluoromethyl, or chloro groups at ortho position mathoxy or chloro group were introduced. Against HL-60 and K-562 cells, $ED_{50}$ values of the analogues are ranged from 0.8 to $30.0\;\mu{g/ml}$. Againste L1210 cell, these are located more than $20.0\;\mu{g/ml}$. However, 5-carbone-thoxy-2-methyl-6(1-naphthyl)-2-octen-4-one (5n)possesses $ED_{50}$ valuses 0.8, 2.1, $6.5\;\mu{g/ml}$ against HL-60, L1210 cells, respectively. The electronic nature of the substituents on phenyl ring of ar-tumerone dose not affect the biological activity. Therefore the flat structure of aromatic potion of ar-tumerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at the ortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should by the one having the orthogonal arrangement between the aromatic ring and the side chain.