Análise genética, composição fenólica e das capacidades antioxidantes in vitro, e embriotóxicas e melanogênica em zebrafish de extratos de Sonchus oleraceus

Abstract

Sonchus oleraceus L. is a species that has a wide genetic diversity and geographic distribution throughout the world. It is used in food and folk medicine as an antioxidant and in the treatment of skin disorders such as vitiligo. However, it is a species that does not have scientific studies about its toxicity and melanogenic activity, until now. Based on the quantification of total phenolic compounds, antioxidant activities and genetic characterization by inter simple sequence repetitions (ISSR), the objective was to evaluate the similarity between 8 accessions of S. oleraceus and to evaluate the embryotoxicity and melanogenic capacity of extracts of S. oleraceus in zebrafish (Danio rerio). Quantification of total phenols and flavonoids were performed; antioxidant tests and evaluation of the genetic polymorphism using 17 ISSR markers of the UBC series by molecular characterization and flow cytometry, in 70% hydroalcoholic extracts obtained by reflux system, from fresh leaves of 8 accessions of S. oleraceus. Chromatographic analyzes, embryotoxicity and melanogenic capacity tests were also performed in D. rerio, aqueous extracts, hydroethanolic 70% and methanol 50% of spontaneous growth plants in areas of organic and conventional vegetable cultivation. In the quantification of phenolic compounds, total phenols ranged from 94.53 to 99.66 mg EAG g-1 and flavonoids ranged from 2.40 to 7.13 mg EQ g-1. All accessions showed IC50 values in the antioxidant tests of CAT, DPPH, ABTS and reducing power. The UBC 864 and UBC 878 primers provided greater polymorphism. There was a greater similarity (77.14%) between the accessions Itumirim ZR2 and UNICENTRO PR and a greater dissimilarity in access 2 (Itumirim ZR1) with 77%. The DNA content varied from 1.59 in access 2 (Itumirim ZR1) to 1.96 in access 5 (Pouso Alegre). In the chromatography, chlorogenic acid was characterized in the leaves and roots of S. oleraceus. Chicoric acid was also quantified in the leaves, containing 1.52 to 4.11 mg g-1 of leaf, being identified as the major compound of the plant. The embryotoxicity of S. oleraceus extracts in zebrafish embryos depends on the extract concentration used, with the highest LC50 in the aqueous root extract 0.08 mg mL-1 and the lowest in the methanol extract of root 2.90 mg mL- 1. Doses above 5 mg mL-1 in any of the extracts were lethal within 24 hours of incubation and doses below 0.0025 mg mL-1 were not embryotoxic. The teratogenic effect of the extracts on the embryos occurred from the concentration of 0.005 mg mL-1 to 2.5 mg mL-1. In the tests of melanogenic capacity, extracts of leaves and roots, in the concentration of 0.625 mg mL-1, were able to stimulate the pigmentation in the zebrafish larvae and their results ranged from 0.00055 to 0.00084 μm2 pixels. It is concluded that S. oleraceus has phenolic composition, antioxidant capacity and genetic diversity among the 8 accessions of the collection and that this diversity influenced the antioxidant results. The results also demonstrated that the extracts of S. oleraceus caused toxicity in the zebrafish embryos, in a specific concentration range, however they also have pigmentation capacity in the larvae of these same animals.