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Substituent effects of cis-cinnamic acid analogues as plant growh inhibitors
- Nishikawa, Keisuke, Fukuda, Hiroshi, Abe, Masato, Nakanishi, Kazunari, Taniguchi, Tomoya, Nomura, Takashi, Yamaguchi, Chihiro, Hiradate, Syuntaro, Fujii, Yoshiharu, Okuda, Katsuhiro, Shindo, Mitsuru
- Phytochemistry 2013 v.96 pp. 132-147
- Spiraea, allelochemicals, growth retardation, hydrophobicity, lettuce, phytotoxicity, root growth
- 1-O-cis-Cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure–activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA.