Ação de Senecio brasiliensis (spreng) Less sobre a taxa de eclosão e modulação de marcadores de toxicidade em larvas de Drosophila Melanogaster

Abstract

Brazil has a high biodiversity, and many species found here are source of compounds with unique medicinal and biotechnological properties. These compounds are synthetized by plants secondary metabolism and can act as attractive or defensive to other species. Thus, studies with plant species are necessary to knowledge about their biologial properties. Senecio brasiliensis (Spreng) Less., is a native species popularly known as “maria mole” and is found in pastures of the south region of the country, its leaves serving as food to animals and are able to cause hepatotoxicity due to its secondary metabolism, responsible for the synthesis of toxic metabolites, such as pirrolizidinic alkaloids. In spite of its documented toxicity, this plant is used by Brazilian folk with medicinal purposes. In this study, we have evaluated the biological effects to hydroalcoholic extract of leaves of S. brasiliensis (HESB) exposure in Drosophila melanogaster experimental model. The fruit fly D. melanogaster is an advantageous alternative model useful for the screening of natural substances. Phytochemical constitution of HESB showed the presence of phenolic acids and flavonoids but when comparing with other species, it presented a lower in vitro antioxidant activity by ABTS, DPPH, FRAP assays. Survival and locomotor activity of adult flies was unaltered by extract. Nevertheless, we have observed a significant decreasing in eclosion rate of flies, since its embryonic period at 1 mg/mL concentration of HESB. Biochemical and molecular parameters revealed significant changes in third instar larvae of D. melanogaster exposed to 1 mg/mL of HESB such as decreased cell viability, stimulation of the activity of antioxidant enzymes SOD and GST, decreasing of CAT, and increasing in GSH/GSSG ratio. The mRNA expression of Nrf2, TrxR, CAT, Drice and Dilp6 were also significantly up-regulated. Decreasing in the phosphorylation of JNK1/2, ERK2, p38MAPK and AKT protein kinases were verified. Apoptotic cell death was inducted by extract. This fact was attested PARP cleavage, in parallel with increasing of caspases 3/7 activity. The increased expression of Nrf2, augmented activity of GST and SOD enzymes activities, and GSH/GSSG ratio in parallel with induction of ROS formation, is an indicative of a state of oxidative stress caused by the HESB and the action of the antioxidant defense of the larvae. It was also observed a decreasing in glucose, glycogen and triglycerides levels indicating a diminution in the energetic reserve required for later stages of larval development, such as for eclosion of winged individuals. Therefore, our results demonstrated of the HESB toxicity and its capacity to induce of cell stress markers and of apoptotic cell death impairing thus the development of D. melanogaster larvae and eclosion process of adult flies.