Isolamento e identificação de compostos fenólicos em folhas de Eugenia uniflora L.
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2013-07-19
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Universidade Federal de Goiás
Resumo
Eugenia uniflora L., known as pitangueira, is widely distrubuted in Brazil; its
leaves are used in popular medicine as a treatment for diarrhea, fever, inflamation,
hyperglycemia and hypertension. The pharmacological activities are due mainly to the
phenolic compounds present in its leaves; therefore the aim of this work was to isolate
these compounds. Powdered air-dried leaves were homogenized in 50% aqueous
acetone. The filtrate was concentrated and extracted with ethyl acetate, yielding AcOEt
fraction. The aqueous layer was lyophilized and after that dissolved in methanol to
separate the soluble and the insoluble methanolic fractions. The ethyl acetate and
methanol soluble fractions were subjected to repeated column chromatography over
Diaion HP-20 and Sephadex LH-20. Isolated compounds were analyzed by NMR H1,
C13, COSY, HSQC and HMBC (with variable temperature) and mass spectroscopy. The
applied technique of temperature variation spectroscopy has proved to be extremely
promising for identification of macrocyclic compounds, providing accurate data for not
only elucidation but correction of previously described assignments. Two galloyl esters:
2,3-di-O-galloyl-β-D-glucose (26 mg), 1,2,3,4,6-penta-O-galloyl-β-D-glucose (92 mg)
and two monomeric ellagitannins: 3-O-galloyl-4,6-HHDP-β-D-glucose (540 mg) and2-Ogalloyl-
4,6-HHDP-β-D-glucose (20 mg) were obtained. The methanol soluble fraction
furnished three dimeric ellagitannins: oenothein B (770 mg), eugeniflorinD2 (260 mg)
and camptothin A (56 mg). In addition to hydrolysable tannins, four flavonoids were also
isolated and identified: quercetin-3-O-α-L-rhamnopyranoside (114 mg), kaempferol-3-O-
α-L-rhamnopyranoside (80 mg), myricetin-3-O-α-L-rhamno-pyranoside(32 mg) and
myricetin-3-O-(2"-O-galloyl)-α-L-rhamnopyranoside (97 mg).For the first time in this
specie the following compounds were found 2,3-di-O-galloyl-β-D-glucose, 1,2,3,4,6-
penta-O-galloyl-β-D-glucose, 3-O-galloyl-4,6-HHDP-β-D-glucose, 2-O-galloyl-4,6-
HHDP-β-D-glucose, camptothin A, kaempferol-3-O-α-L-rhamnopyranoside, and
myricetin-3-O-(2"-O-galloyl)-α-L-rhamnopyranoside. The methodology applied in this
work allowed the isolation and identification of eleven phenolic compounds, in the near
future they will be tested in several biological assays.
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CARVALHO, Ariadne Gomes. Isolamento e identificação de compostos fenólicos em folhas de Eugenia uniflora L. 2013. 44 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2013.