Med Chem Res DOI 10.1007/s00044-017-1971-1 MEDICINAL CHEMISTRY RESEARCH ORIGINAL RESEARCH Involvement of reactive oxygen species in the oleoylethanolamide effects and its pyrazonilic analogue in melanoma cells Priscila Antiqueira-Santos 1,2 ● Daiane S. dos Santos 3 ● Carolina R. L. Hack 3 ● Alex Fabiani C. Flores 4 ● Marcelo G. Montes D’Oca 3 ● Luciana A. Piovesan 3,5 ● Luiz Eduardo M. Nery 1,2 ● Ana Paula S. Votto 1,2 Received: 29 December 2016 / Accepted: 21 June 2017 © Springer Science+Business Media, LLC 2017 Abstract The search for more substances that effectively fight melanoma is extremely important, because of its aggressive nature. In this sense, the molecular hybridization is a promising strategy. The aim of this work is to evaluate whether the antiproliferative effect of the endocannabinoid oleoylethanolamide can be improved with the addition of a trifluoromethylated pyrazolinic nucleus on its structure in B16F10 cell line. The pyrazolinic analog was named oleoyl pyrazoline. We also compared the effects of oleoylethano- lamide and that of the classic endocannabinoid anandamide (AEA). The cell viability was evaluated by MTT assay, the intracellular reactive oxygen species generation by fluori- metry, and apoptosis/necrosis by fluorescent microscopy. Also, α-tocopherol antioxidant was used to evaluate the involvement of reactive oxygen species in the cellular response. Although the effects of AEA occur in smaller concentrations, the results show that the effects of AEA and oleoylethanolamide were similar. The results showed a decrease in cell viability, induction of apoptosis and necrosis, and increased generation of reactive oxygen spe- cies by the oleoylethanolamide, while the oleoyl pyrazoline increased cell proliferation and decreased reactive oxygen species. Additionally, the effects of oleoylethanolamide in cell viability were decreased by inhibiting the generation of reactive oxygen species by α-tocopherol. Therefore, it is possible to suggest the involvement of reactive oxygen species in the effect of oleoylethanolamide in the B16F10 cells. Considering the great need to find substances that can fight melanoma and the lack of greater elucidation in the action mechanisms of cannabinoids and their analogs, this work provides important new information that could serve as reference to other studies. Keywords Cell viability ● Apoptosis ● B16F10 cell line ● Oleoylpyrazoline ● Oxidative stress Introduction The search for more effective substances for treatments that prevent or reduce the proliferation of melanoma cells, even in advanced stage, is extremely important due to the aggressive nature of this pathology. It was estimated that 76,380 new cases of melanoma would be diagnosed in 2016 (American Cancer Society 2016). Even though melanoma accounts for only 1% of all skin cancer cases worldwide, it is responsible for the vast majority of skin cancer related deaths (American Cancer Society 2016). * Ana Paula S. Votto anavotto@yahoo.com.br 1 Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande–FURG, Rio Grande, RS, Brazil 2 Laboratório de Cultura Celular, Instituto de Ciências Biológicas, FURG, Rio Grande, RS, Brazil 3 Laboratório Kolbe de Síntese Orgânica, Escola de Química e Alimentos, FURG, Rio Grande, RS, Brazil 4 Escola de Química e Alimentos, FURG, Rio Grande, RS, Brazil 5 Nanobusiness Informação e Inovação Ltda, Incubadora de Projetos, Instituto Nacional de Metrologia, Qualidade e Tecnologia–INMETRO, Duque de Caxias, Rio de Janeiro, Brazil Electronic supplementary material The online version of this article (doi:10.1007/s00044-017-1971-1) contains supplementary material, which is available to authorized users.