Contributed by Vânia G. Zuin, Maria Fátima G. F. da Silva, João Batista Fernandes, Moacir Rossi Forim, Universidade Federal de São Carlos (SP-Brazil), Department of Chemistry
The main objective of this manuscript is to provide a modern overview of the current green approaches for insect pest control, detaching some specific cases in Brazil. As is well known, these alternatives to classical agrochemicals have been attracting the interest of a vast group of people and institutions all over the world: academic, industrial, governmental, and nongovernmental sectors, as well as the society in general. The Natural Products Research Group of Universidade Federal de São Carlos, SP-Brazil (UFSCar) was formed more than 30 years ago. The research interest of the group covered many aspects of general phytochemistry. The State of São Paulo Research Foundation (FAPESP) has been contributing systematically and substantially to these interdisciplinary investigations, allowing the development of new scientific strategies for the study of natural products, for instance, supporting two thematic projects: “Study of the potential of some plant species and natural and synthetic products for the control of leaf-cutter ants”, coordinated by Prof. Fernandes; and, "Phytochemistry and chemical ecology: Search for starter compounds for new insecticidal, fungicidal and bactericidal drugs for control of plant pests”, coordinated by Prof. Silva. In developing these studies the group had strong interactions with a number of other Brazilian research groups. The National Institutes of Science and Technology Program (INCT), launched in 2008 by the Ministry of Science, Technology & Innovation (CNPq) permitted the expansion of the main group. Thus, Profs. Silva, Fernandes, Forim and Zuin aggregate in their networks the best research groups and companies of chemical ecological and education areas from several states in Brazil, including international partners based on Europe and North America more recently, in order to make Brazil a referential country when the control of insects with low impact to the environment is aimed, through the National Institute of Science and Technology for the Biorational Control of Pest-Insect (INCT-CBIP).
The efficient control of insects and the search for biologically active compounds that are closely related to human survival are important issues to be studied. Insects are the greatest competitors of mankind with regard to food, besides being vectors of a number of diseases that affect humans, herds and plants. The objective of the INCT-CBIP was to carry out studies to control biorationally pest-insect and their associated microorganisms such as fungi, bacteria and yeasts.
The assays of pesticide activity and inhibition of fungi and bacteria have been performed with plant extracts and natural products from plants or microorganisms. The toxicity of a number of extracts and natural compounds to insects, fungi and bacteria were determined. The extracts and natural compounds showed moderate activity in comparison with commercial insecticides. Thus these compounds were assayed against other targets. Neem oil from Azadirachta indica showed significant activity as an insecticide. However, if it is assumed that it is possible to modify the chemical structure and/or complexation with metals the compounds to improve activity and selectivity, our results helped in directing the rational design of coumarins, alkaloids and flavonoid derivatives and the last as potent and effective insecticide, fungicide and bactericide.
Enzymes that degrade the polysaccharides of the vegetal (pectinases and amylases) in reducing sugars have been detected in symbiotic fungus and also have been found in the fecal liquid of the Atta sexdens rubropilosa or leaf-cutting ant. These sugars constitute the main source of energy for the ants' nest. Therefore, the ants use symbiotic fungi to promote this process of degradation, once they are not capable to degrade the pectin directly.
The enzyme acetylcholinesterase (AChE) is present in the central nervous system of insects, and hydrolyses the acetylcholine neurotransmitter in acetate and choline, thus finishing the synaptic transmission, playing a fundamental role in the transmission of the cholinergic nervous impulse. Two genes, Ace1 and Ace2, have been characterised in different classes of insects and two mutations in Ace1 have been associated with resistance in mosquitos. Enzymatic bioreactors were prepared using the enzymes acetylcholinesterase, butirilcholinesterase, and pectinase, and were used for studies of mechanism of action of substances, which presented inhibition activity against insects.
In addition to promoting the development of national competence in vanguard scientific and technological areas and creating rich environments for researchers, the INCT-CBIP is directly responsible for training students and divulging the results of its investigations at several levels.
The integration of both techno-scientific and educational aspects related to the role of sustainable agriculture in Brazil allowed Prof. Zuin to be recognised as a researcher who has been contributing significantly in analysing bioactive high-value organic substances extracted from agro-industrial residues and also studying curricula for courses in environmental and green chemistry, the latter also through the IUPAC project “Green Chemistry in Higher Education: Toward a Green Chemistry Curriculum for Latin American and African Universities”. In 2014, Prof. Zuin was awarded the IUPAC CHEMRAWN VII Prize for Atmospheric and Green Chemistry, at the 5th International IUPAC Conference on Green Chemistry, held in Durban, South Africa at the end of August. As can be seen, The INCT-CBIP has a detached role in the Brazilian scenario, developing a number of green approaches for the biorational control of insects of interest in Brazil, bringing together international researchers and companies, and also contributing to the improvement of science teaching and the scientific dissemination to the population taking into account the sustainable agriculture models in Brazil.
SEVERINO, V. G. P.; FREITAS, S. D. L.; BRAGA, P. A. C.; FORIM, M.R.; SILVA, M. F. G. F.; FERNANDES, J. B.; VIEIRA, P. C.; VENANCIO, T. New limonoids from Hortia oreadica and unexpected coumarin from H. superba using chromatography over cleaning Sephadex with sodium hypochlorite. Molecules, v. 19, n. 8, p. 12031-12047, 2014.
PERLATTI, B.; FORIM, M. R.; ZUIN, V. G. Green chemistry, sustainable agriculture and processing systems. Chemical and Biological Technologies for Agriculture, v. 1, p. 5-14, 2014.
1) Diagram of complexes of bioactive natural products with inorganic ions,
2) A. aegypti,
3) Profs. Zuin and Silva.
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