Inhibitory effects of some synthetic monoethanolamine salts ofpara-substituted benzoic acids and corresponding benzoic acids on cucumber seed germination

Abstract

Benzoates and particularly, benzoic acids are known biologically for their effects in the regulation of seed germination. A series of monoethanolamine salts of para -substituted benzoic acids (MEASPBAs), the corresponding acids (BAs) and monoethanolamine (MEA) were tested at different concentrations, on Cucumis sativus L. germination in order to assess their biological activity. The correlation between the effects of different substituents of these salts and the corresponding acids with germination rate, root and shoot length, fresh and dry biomass, soluble protein content, isocitrate lyase (ICL, EC 4.1.3.1) and catalase (CAT, EC 1.11.1.6.) activity, was evaluated. Data showed that p -OH and p -CH 3 substituents had a lower inhibitory effect compared to the halogenated substituents. Moreover, the inhibition of root and shoot lengths and the dramatic decrease of fresh biomass for halogenated (p -Cl, p -Br, p -I) MEASPBAs and BAs followed the increase of the atomic size of the substituent.

Arabidopsis thalianaseed germination and early seedling growth are inhibited by monoethanolamine salts ofpara-halogenated benzoic acids

“…The pH also has an important role in determining the toxicity of the compound, with the toxicities decreasing as the pH increases (Zhao et al 1996(Zhao et al , 1998. Regarding the phytotoxicity of halogenated benzoic compounds, the tests on C. sativus (Cris¸an et al 2007) and this study show that similar conclusions can be drawn from the data: the halogenated MEASPBAs present a more inhibitory effect in comparison with the corresponding BAs compared to the controls. The data, once again, indicate that both ionized and unionized forms of a chemical can contribute to toxicity (Barron 1990;Zhao et al 1998).…”

“…Pure crystals were washed with acetone and diethylether and then dried for several hours under vacuum. The physicochemical properties of MEASPBAs were previously reported by Cris¸an et al (2007).…”

“…Each compound was tested at the following five concentrations: 0.01, 0.05, 0.1, 0.5 and 1 mM. Concentration range was selected based on a preliminary concentrationresponse study, in accordance with the results of previous studies (Maffei et al 1999;Senaratna et al 2003;Cris¸an et al 2007). MEASPBAs were dissolved in 5 mM MES (2 [N?-morpholino] ethanesulfonic acid) buffer, while BAs were dissolved in a MES buffer Á EtOH solution with a final EtOH concentration of 0.2% (v/v) (Li et al 2004).…”

“…In a previous study, we investigated the effect of para-halogenated benzoic acids and their corresponding monoethanolamine salts on cucumber seed germination, new compounds with biological activity (Cris¸an et al 2007). The data revealed potent inhibition of primary root length of cucumber seedlings treated with halogenated compounds (especially p-Cl, p-Br, p-I) correlated with a reduction in catalase activity, at a higher concentration (1 mM).…”

Effect of benzoic acid hydroxyl- and methoxy-ring substituents on cucumber (Cucumis sativusL.) root membrane potential

“…Furthermore, BAs can alter membrane permeability by solubilizing into cellular membranes and/or adsorbing to membranes to produce either a negative surface potential or an increase in the anionic field strength of the membrane (Heipieper et al 1991, Baziramakenga et al 1995, Barron et al 1996. It has been demonstrated that the number and position of BA hydroxy and methoxy ring substituents play an important role in their inhibitory activity towards ion uptake (Yu & Matsui 1997, Yu et al 2003, Ye et al 2004) and plant growth (Crisan et al 2007). …”