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Tropine was proposed as a cheap and sustainable source of plant growth regulating cation (N-alkyltropinium) and paired with herbicidal anions (3,6-dichloro-2-metoxybenzoate or 4-chloro-2-methylphenoxyacetate). The synthesised salts were obtained with 82–99% yield and exhibited high water solubility and surface-active properties, without excessive foam formation. Further experiments revealed plant growth promoting properties towards maize with simultaneous enhanced herbicidal action towards cornflower. At the same time, the obtained formulations exhibited high antimicrobial activity towards common soil bacteria Pseudomonas putida and Bacillus cereus (MIC 0.003–1.0 mmol L−1). Moreover, it was confirmed that the synthesised salts were not biodegradable due to low susceptibility of cations for biotransformation. Overall, the results suggest that quaternary tropinium salts exhibit promising plant growth promoting properties as well as inhibition of weed development. [ABSTRACT FROM AUTHOR]

Tropane alkaloids have attracted increasing scientific attention as natural compounds which display interesting biological properties. Tropine, a common constituent of tropane alkaloids, is a relatively inexpensive and commonly available compound which can be transformed into the form of quaternary salt in order to increase its uptake by plants. The aim of this study was to assess the properties of quaternary N-alkyltropinium bromides with various alkyl substituents and their impact on a model crop plant (maize) in order to evaluate their applicability as potential plant growth regulators. The products were obtained with high yield (81–96%) and their structures were confirmed using NMR. Some of the obtained salts exhibited surface active properties (CMC ranging from 5.12 × 10−2 to 2.33 × 10−3 mg L−1). The conducted experiments confirmed the positive effect of the synthesized salts on maize, such as increased seed germination (up to 60%), higher fresh/dry biomass yield (up to 20%), enhanced electron transfer rate (up to 40%) as well as improved total chlorophyll content (up to 60%). Further studies revealed that the properties of N-alkyltropinium salts depended on the structure of the substituent introduced during quaternization. The substituent can be adjusted to either ensure rapid biodegradability (100% in case of ethylacetyl substituent) or antimicrobial properties (MIC ranging from 2 to 20 mg L−1). The obtained result suggest that N-alkyltropinium bromides potentially constitute a promising group of novel plant growth promoting agents. [ABSTRACT FROM AUTHOR]

Herbicidal ionic liquids (HILs) constitute a new concept in crop protection products. Their main advantage is the potential to combine the efficiency of traditional herbicides with low vapour pressure and adjustable water solubility which leads to improved environmental safety in the agricultural sector. Among many strategies to obtain new HILs, esterquats seem to be well suited for modification since both the cation and anion may be constituents of herbicides. In the framework of this study 16 new esterquat HILs were synthetized based on standard herbicides: 2,4-D, MCPA, MCPP, 4-CPA, Clopyralid and Dicamba. Germination tests performed on agricultural soil using cornflower indicated the best two HILs. Furthermore, analysis of the toxicological effects of HILs on wheat plants revealed an additional advantage of the two selected HILs. The glutathione (GSH) content and glutathione S-transferase (GST) activity showed a lower oxidative stress level in wheat plants treated with examined HILs, respectively, in comparison to a mixture of reference compounds. Finally the Ames test was applied in order to analyse the mutagenic activity of the two selected HILs. [ABSTRACT FROM AUTHOR]