Abstract The control of weeds in agriculture is mainly conducted with the use of synthetic herbicides. However, environmental and human health concerns and increased resistance of weeds to existing herbicides have increased the pressure on researchers to find new active ingredients for weed control which present low toxicity to non-target organisms, are environmentally safe, and can be applied at low concentrations. It is herein described the synthesis of glycerol-fluorinated triazole derivatives and evaluation of their phytotoxic and cytogenotoxic activities. Starting from glycerol, ten fluorinated triazole derivatives were prepared in four steps. The assessment of them on Lactuca sativa revealed that they present effects on phytotoxic and cytogenotoxic parameters with different degrees of efficiency. The compounds 4a, 4b, 4d, 4e, 4i, and 4j have pre-emergent inhibition behavior, while all the investigated compounds showed post emergent effect. Mechanism of action as clastogenic, aneugenic, and epigenetic were observed in the lettuce root meristematic cells, with alterations as stick chromosome, bridge, delay, c-metaphase, and loss. It is believed that glycerol-fluorinated triazole derivatives possess a scaffold that can be explored towards the development of new chemicals for the control of weed species. However nontarget non target organisms safe concentrations glycerolfluorinated glycerol activities steps efficiency 4a 4b b 4d d 4e e 4i i j preemergent pre behavior effect clastogenic aneugenic cells chromosome bridge delay cmetaphase, cmetaphase c metaphase, metaphase c-metaphase loss species

Abstract We investigated whether essential oil and aqueous and ethanolic extracts from M. vittoriana leaves have phytotoxic effects on the germination and initial development, and cytogenotoxic effects on the cell cycle, of model plants. The essential oil and extracts of M. vittoriana were characterized and used as treatments in phytotoxicity and cytotoxicity tests. The results indicated a reduction in germinative parameters and plant growth, with the higher concentrations of extracts and essential oil having the most evident effects. The cell cycle was also affected with a reduction of the mitotic index and the presence of chromosomal and nuclear alterations. All treatments showed clastogenic and aneugenic modes of action. The results can be associated with the synergistic effects of metabolites found in the extracts and essential oil, mainly the presence of the sesquiterpene germacrene D in the essential oil and of catechins, saponins, and tannins in the extracts. These substances inhibit plant germination and growth, confirming the phytotoxic effects of M. vittoriana in plant models, which should now be tested under field conditions.

Abstract Due to rising concerns for environmental and human health, many toxic compounds, such as auxin-based herbicides, have been tested in relation their toxicity effect. Especially cyto- and phytotoxic assays have been performed on a number monocot and eudicot plant species. In these approaches the toxicity level of the auxin is compared to a positive control – usually a commercial compound with known effects and chemical similarity to the target compound. However, many target compounds still lack an indication of an adequate positive control. Here, we evaluate the phytotoxic and cytotoxic effect of the auxins 2,4-dichlorophenoxyacetic acid, dicamba, and picloram in order test their potential use as positive controls. All tested auxinic herbicides showed clastogenic and aneugenic effect mechanisms. The results indicate 2,4-dichlorophenoxyacetic acid as the most phyto- and cytotoxic in the discontinuous method in Lactuca sativa L. and Allium cepa L., and also in the continuous method in A. cepa. Thus, we suggest 2,4-dichlorophenoxyacetic acid as a positive control for future mutagenesis studies involving new auxins. For studies with L. sativa in continuous method, we recommend the auxin picloram as positive control as this one was the only one which allowed the development of roots.

Abstract Herbicides are agrochemicals applied in the control of weeds. With the frequent and repetitive use of these substances, serious problems have been reported. Compounds of natural origin and their derivatives are attractive options to obtain new compounds with herbicidal properties. By aiming to develop compounds with potentiated herbicidal activity, phenoxyacetic acids were synthesized from eugenol and guaiacol. The synthesized compounds were characterized and the herbicidal potential of phenoxyacetic acids and precursors was evaluated through bioassays regarding the germination and initial development of Lactuca sativa and Sorghum bicolor seedlings, with the induction of DNA damage. The induction of changes in the mitotic cycle of meristematic cells of roots of L. sativa was also analyzed. At the concentration of 3 mmol L-1, phenols and their respective phenoxyacetic acids presented phytotoxic and cytotoxic activities in L. sativa and S. bicolor. Eugenol and guaiacol also presented genotoxic action in L. sativa. The toxic effect of eugenoxyacetic acid was more pronounced in L. sativa than in S. bicolor, similar to the commercial 2,4-D herbicide. Molecular properties of the phenols and their derivatives phenoxyacetic acids were compared with the ones obtained for the herbicide 2,4-D, where it was found a correlation between their molecular properties and bioactivity.

Herein, the synthesis of nine novel glycerol-derived 4-alkyl-substituted 1,2,3-triazoles, using the CuI-catalyzed alkyne-azide cycloaddition reaction as the key step, is reported. The triazoles were characterized by infrared and nuclear magnetic resonance (NMR 1H and 13C) spectroscopy and mass spectrometry. The nine prepared compounds were evaluated with regard to their phytotoxic, antiproliferative, and fungicidal activities. The fungicidal activity was assessed on Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. All compounds presented high efficiency (comparable to the commercial fungicide tebuconazole) in inhibiting C. gloeosporioides sporulation. The phytotoxicity of the triazoles was assessed against Lactuca sativa. Germination was the less-affected parameter, whereas the most pronounced effects of the triazoles were on the germination speed index and root growth of the L. sativa seedlings. As indicators of antiproliferative activity, the mitotic index was evaluated along with chromosomal and nuclear alterations, all of which were influenced to different degrees by the triazoles. In addition, all derivatives demonstrated aneugenic and clastogenic actions in meristematic cells of L. sativa roots. Therefore, these 4-alkyl-substituted triazoles may represent a scaffold to be explored for the development of new fungicidal agents.

Jatropha curcas L. (Euphorbiaceae) é importante para a produção de biocombustíveis e como ingrediente de ração para animais. No entanto, a presença de ésteres de forbol no óleo e na torta tornam as sementes tóxicas. A toxicidade do óleo de J. curcas é frequentemente acessada através de testes em animais, levando-os à morte. A identificação de variedades melhoradas tóxicas e não tóxicas é importante para a utilização segura das sementes de J. curcas e subprodutos para evitar a sua toxicidade ambiental. Sendo assim, o objetivo deste estudo foi propor um bioensaio, rápido usando uma planta como um modelo para avaliar a toxicidade do óleo de J. curcas, sem a necessidade de sacrificar nenhum animal. A toxicidade do óleo de J. curcas foi evidente na germinação, no crescimento radicular e nos testes de aberrações cromossômicas em Lactuca sativa. Foi demonstrado que as sementes de J. curcas contêm compostos naturais que exercem efeitos fito-, cito e genotóxicos na alface, e que os ésteres de forbol atuam como agentes aneugênicos, levando à formação de células com cromossomos pegajosos e c-metáfase. Em conclusão, os testes aplicados demonstraram reprodutibilidade, o que é importante para verificar a extensão da desintoxicação e para determinar doses tóxicas, reduzindo assim o número de animais que seriam utilizados para os testes de toxicidade.

Jatropha curcas L. (Euphorbiaceae) is important for biofuel production and as a feed ingredient for animal. However, the presence of phorbol esters in the oil and cake renders the seeds toxic. The toxicity ofJ. curcas oil is currently assessed by testing in animals, leading to their death. The identification of toxic and nontoxic improved varieties is important for the safe use of J. curcas seeds and byproducts to avoid their environmental toxicity. Hence, the aim of this study was to propose a short-term bioassay using a plant as a model to screen the toxicity of J. curcas oil without the need to sacrifice any animals. The toxicity of J. curcas oil was evident in germination, root elongation and chromosomal aberration tests in Lactuca sativa. It was demonstrated that J. curcas seeds contain natural compounds that exert phyto-, cyto- and genotoxic effects on lettuce, and that phorbol esters act as aneugenic agents, leading to the formation of sticky chromosomes and c-metaphase cells. In conclusion, the tests applied have shown reproducibility, which is important to verify the extent of detoxification and to determine toxic doses, thus reducing the numbers of animals that would be used for toxicity tests.