Estudo fitoquímico sobre três espécies nativas da família Myrtaceae da Mata Atlântica (RJ)

Abstract

The Atlantic Forest is one of the world hotspots, mainly in the state of Rio de Janeiro and in restingas due to the advance of urbanization. In these regions, the Myrtaceae family stands out, due to its great economic importance, different biological activities and high rate of endemism. The objective of this thesis was to identify the metabolites of native and chemically unknown species of the Myrtaceae family, from the Atlantic Forest (RJ). For this purpose, instrumental chromatographic techniques were employed such as GC-FID, GC-MS, HPLC-DAD and HPLC-DAD-MS. The first study consisted of the characterization of the essential oil of Myrciaria tenella leaves, collected in Restinga da Marambaia (RJ). Thirty-six substances were identified by GC-FID and GC-MS, with the major composition of non-oxygenated terpenes such as β- and α-pinene (21.46% and 19.43%, respectively), E-caryophyllene (10.89%) and aromadendreno (9.17%). The chemical structure of the phenylpropanoid 2’,4’,6’-trimethoxyphenyl-butane was suggested as the fifth major constituent (8.45%), through the additional analyzes by 1H and 13C NMR. Furthermore, a high yield β-pinene/α-pinene-rich essential oil was obtained with only 2 h of extraction. The second study consisted of the dereplication of methanol extracts and subsequent partitions from Eugenia copacabanensis and M. tenella leaves. By GC-MS, HPLC-DAD and HPLC-DAD-MS analysis, 104 substances were identified, being 78 and 64 substances for each species and mostly reported for the first time for each taxon. For the species E. copacabanensis, 3-O-caffeoylquinic acid – chlorogenic acid, methyl gallate, quercitrin, type B procyanidin derivatives and isomers of strictinin and tellimagrandin I were the main substances. In the extract and partitions of M. tenella, ellagic acid and its derivatives, such as 3,3'-O-dimethyl ellagic acid, and the flavonols quercetin 3-O-(6''-O-galoyl)-galactoside, quercetin 3-O-(6''-O-galoyl)-glycoside, hyperoside and isoquercitrin were mostly observed. Different classes were isolated or obtained in fractions, such as the sesquiterpene 2-methoxy-clovan-9-ol in the hexane partition of E. copacabanensis leaves, with structure elucidation by one- and two-dimensional 1H and 13C NMR experiments. The third study aimed to characterize a lyophilized product from Myrcia eriopus fruits. By HPLC-DAD and ESI-QToF-MS analysis, 5 monoglycosylated anthocyanins and 2 other phenolic substances (gallic acid and myricetin) were identified, with delphinidin 3-O-glycoside and petunidin 3-O-glycoside as the major substances. The lyophilized powder had a high content of anthocyanins and antioxidant potential when compared to other Brazilian fruits. All results have a positive impact on the preservation of these Brazilian native species, through the chemical characterization and the biological tests in collaborations research, with these results previously published in high-impact scientific journals.