Estudo químico e atividade antioxidante e antimicrobiana de Annona jahnii Saff. (Annonaceae)

Abstract

Annona jahnii Saff., belongs to the Annonaceae family. It is a small tree, native to the state of Roraima found in areas of savanna and florest. The genus Annona, covers about 150 species, being characterized by being a source of alkaloids, acetogenins, flavonoids and terpenoids that have good biological activities. Knowing that the genus is a promising source of bioactive compounds and that the species has few studies of chemical and biological character, this work has the objective of evaluating the chemical and antioxidant and antimicrobial potential of extracts of leaves and branches, as well as the essential oils of Leaves of three individuals. The collections were carried out in the rural area of Boa Vista-Roraima. Hot extracts of the leaves and branches were elaborated. A specific extraction was performed for alkaloid from pulverized vegetable materials and methanolic extracts. The essential oils were extracted by hydrodistillation in a Clevenger apparatus for 3 hours and thereafter analyzed by GC-MS and GC-DIC. For the chemical prospection of the extracts and fractions, we initially used CCD analysis and then mass spectrometry analysis, using electrospray ionization source. Finally, the extracts and oils were submitted to biological tests. The antioxidant potential was evaluated by the methods: sequestering action of the 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) and auto-oxidation of the β-carotene / linoleic acid system and antimicrobial potential by the broth microdilution method. Regarding the plant extracts, the methanols presented the highest yield, with 15.65% and 9.51% for leaves and branches, espectively. The Prospecting of extracts by CCD revealed that the most apolar are composed of terpenes. Alkaloids, flavonoids and coumarins were identified only in polar extracts. The ESI-MS analysis showed that the extracts had complex chemical profiles in the two modes of acquisition and that the alkaloid fractions had several m / z even ions, of which m / z 266, 298, 282, 328 and 330, Showed similar fragmentation profile in all the fractions and were characterized as the alkaloids: annonaine, assimilobina, norushinsunina, corituberina and reticulina. On the volatiles study, a variation in the yield of the three oils (0.25 to 0.40%) was observed. The chemical composition of OEAJ III oil presented a difference in relation to OEAJ I and OEAJ II. Germacrene B (69.85% and 62.85%) and Bicyclogermacrene (10.49% and 18.04%) were the majority in OEAJ I and OEAJ II. And Bicyclogermacrene (23.20%) as the main components. As for the antioxidant activity, the DPPH method revealed that the extract EMFAJ (IC 50 = 0.011 mg / mL); And OEAJ I and OEAJ II (IC50 = 1.67 mg / mL) showed a better antioxidant action. In the co-oxidation method of the β-carotene / linoleic acid system, the extracts with the best potential were EHFAJ (75.43%) and EHGAJ (73.68%) and OEAJ III oil (66.71% ). The results obtained in this work are of great relevance and unpublished for the species Annona jahnii, which confirm that the species is chemically typical of the Annonaceae family, besides being a promising source of biologically active substances.