2006 - Mônica Bordin Pessuto
MSc. Thesis
Author: Mônica Bordin Pessuto
Postgraduate Program in Pharmaceutical Sciences - State University of Maringá
Area of Knowledge: Pharmacognosy
Date of Defense: October 24, 2006
Advisor: Prof. Dr. João Carlos Palazzo de Mello
Examination Board: Profa. Dra. Selma Lucy Franco
Profa. Dra. Tomoe Nakashima
Title: Phytochemical analysis of Maytenus ilicifolia Mart ex Reiss. leaves extract and Antioxidant potential
Abstract: Maytenus ilicifolia Mart. ex Reiss.(Celastraceae) is a vegetable drug widely used in treatments by native population due to its antiulceration, antitumoural and antimicrobian activities. Popularly known as ‘espinheira-santa’, it is found in the South of Brazil, Paraguay, Uruguay and Argentina. The aim of this work was to carry out the chemical isolation and identification of condensed tannins of M. ilicifolia leaves and the evaluation of the antioxidant potential of crude, semipurified extracts and isolated substances, through tests using DPPH• as radical scavenger, with phosphomolybdenum and with thiobarbituric acid. The quality control of the vegetable raw material was accomplished following pharmacopeial and nonphamacopeial assays, thus, presenting the following results, respectively: 40.39%±1.38 (CV%=3.42) determination of water; 10.92%±0.10 (CV%=0.91) loss on drying; 31.60%±0.22 (CV%=0.72) determination of extractives; 5.04%±0.07 (CV%=1.57) total tannins content. The following compounds were isolated and identified: catechin, epicatechin, epigallocatechin, epicatechin-(4β→8)-epicatechin, epicatechin-(4β→8)-catechin. The crude, semipurified extracts (aqueous and ethyl-acetate fractions) and the isolated substances were evaluated of the antioxidant potential by using the DPPH• method (2,2-diphenyl-1-picryl hydrazyl). The obtained results, by using ascorbic acid as reference, were expressed in terms of IC50 (µg/ml), respectively, 35.34±0.35 (CV=0.98%); 47.31±0.19 (CV=0.40%); 25.39±1.04 (CV=4.07%); 7.18±0.26 ascorbic acid (CV=3.56%); catechin 2.89±0.16 (CV=8.72%); epicatechin 1.49±0.25 (CV=16.79%); epigallocatechin 2.62±0.85 (CV=32.27%); 3.05±0.09 (CV=3.01%); epicatechin-(4β→8)-epicatechin 2.24±0.29 (CV=13%); epicatechin-(4β→8)- catechin 1.90±0.72 (CV=26.79%). For the phosphomolybdenum test, the crude extract, the aqueous and ethyl-acetate fractions were tested, thus obtaining, respectively, the following results: 0.30±0.087 %F (CV=2.93%); 0.15±0.0076 %F (CV=4.95%); 0.70±0.031 %F (CV=4.40%). For the thiobarbituric acid assay the ethyl-acetate fraction, in 1; 0.8; 0.6; 0.3 and 0.1 mg/ml concentration was tested and the samples presented maximum inhibiting activity of the lipid peroxidation in concentrations even 0.8 mg/ml. In the evaluation of the antioxidant activity for reduction of DPPH• , the crude extract, aqueous and ethyl-acetate fractions presented a good antioxidant activity and, the ethyl-acetate fraction has shown better activity than the other extracts, however, it was inferior to the ascorbic acid pattern. The isolated compounds presented significant antioxidant activity and flavan-3-ols monomers presented superior antioxidant activity than dimmers compounds, and the flavan-3-ols were better as ascorbic acid pattern. The results obtained in the tests of phosphomolybdenum and thiobarbituric acid confirms the antioxidant activity of the ethyl-acetate fraction, probably due to its content in phenolic compounds.
Keywords: Maytenus ilicifolia. Condensed tannins. Antioxidant activity. DPPH• . Phosphomolybdenum method. Thiobarbituric acid.
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