Estudo químico biomonitorado de quatro espécies da família Myrtaceae

Abstract

The Atlantic Forest is one of the most biodiverse Brazilian biomes and has important domains, such as mangroves and restingas. Within the restingas, one of the most expressive families in terms of number of species is the Myrtaceae family. Some of the species have never been studied. Therefore, the objective of this work was to determine the chemical profile of the species Myrciaria tenella (DC.) O.Berg, Myrcia splendens (Sw.) DC, Myrcia neuwiedeana (O.Berg) E.Lucas & C.E.Wilson. and Myrcia neobrasiliensis A.R.Lourenço & E.Lucas and to evaluate the antioxidant capacity and inhibition of enzymes involved in the metabolism of carbohydrates. The chemical profile was determined by chromatographic and spectrometric analyses, such as GC/MS and ESI(-)FT-ICR MS. Biological activities were determined by spectrophotometric methods, where the antioxidant activity was measured against ABTS and DPPH synthetic radicals and the enzyme inhibition activity was determined against two enzymes, α-amylase and α-glucosidase. The crude methanolic extracts of the aerial parts of each species were analyzed, as well as their respective hexane, dichloromethanolic, ethyl acetate and aqueous fractions. By GC/MS it was possible to identify the presence of sesquiterpenic and triterpenic compounds in the hexane fractions. In the ethyl acetate fraction of the species M. neuwiedeana it was possible to isolate and identify two pentacyclic triterpenes, α-amyrin and β-amyrin. In the ESI(- )FT-ICR MS technique it was possible to identify several phenolic acids and flavonoids in methanol extracts and ethyl acetate fractions. The presence of methyl gallate and quinic acid was identified in all species and compounds such as quercetin, myricetin, quercitrin, myricitrin and triterpenic acids in the species of the genus Myrcia. All species showed excellent antioxidant capacities, mainly from the crude extracts and the more polar fractions. The ethyl acetate fractions of M. splendens (IC50 = 0.43 ± 0.06 µg/mL) and M. neobrasiliensis (IC50 = 0.42 ± 0.09 µg/mL) were the most active in the assay with the ABTS radical, showing antioxidant activity statistically similar to the standard for gallic acid (IC50 = 0.31 ± 0.02 µg/mL). In the enzyme inhibition analysis, all crude extracts were able to inhibit α-glucosidase, with the M. splendens extract being the most active (IC50 = 2.96 ± 0.16 µg/mL), and the polar fractions were the most active against α-amylase, where the aqueous fractions of M. splendens (IC50 = 1.61 ± 0.12 µg/mL) and M. neuwiedeana (IC50 = 5.74 ± 0.79 µg/ mL) showed the best results among them with activities close to the acarbose pattern (IC50 = 1.41 ± 0.26 µg/mL). The present work reported for the first time chemical aspects and biological activities presented by these species, with results that demonstrated a great chemical diversity and promissing biological results, which reaffirms the great importance of the species of the Myrtaceae family and directly contributes to the knowledge of the Brazilian flora.