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Type: Artigo de periódico
Title: Quenching of singlet molecular oxygen by natural furan diterpenes
Author: Di Mascio, P
Medeiros, MHG
Sies, H
Bertolotti, S
Braslavsky, SE
Veloso, DP
Sales, BHLN
Magalhaes, E
Braz, R
Bechara, EJH
Abstract: Singlet molecular oxygen O-2((1) Delta(g)) is a reactive oxygen species capable of damaging biological molecules and triggering oxidative stress, The quenching of this species by naturally occurring furans was measured using O-2((1) Delta(g)) from two different sources: (1) the thermal decomposition of 1,4-dimethylnaphthalene endoperoxide (1,4-DMNO2); (2) tetraphenylporphyrin sulphonate photosensitization. Four furan diterpenes were isolated from alcoholic extracts of Sucupira branca (Pterodon sp,, Leguminosae) seeds, which are used for the treatment of rheumatic diseases, suggesting anti-inflammatory activity. Using time-resolved near-IR (NIR) emission after photosensitization, the overall (physical + chemical) O-2((1) Delta(g)) quenching rate constants by these compounds were found to be of the order of 10(8) M-1 s(-1), with the exception of the conjugated furan diterpenes 3,5,6-trimethoxy-7,8-furano-3',4'-methylenedioxy-2 '',3 ''-flavane and 3,4,5,6-tetramethoxy-7,8-furano-2 '',3 ''-flavane for which 20-fold lower values were observed, These lower values are attributed to the conjugation of the furan moiety with the aromatic ring, which prevents (2 + 4) cycloaddition of O-2((1) Delta(g)) to the furan ring, Although the non-conjugated furans exhibit a low scavenging effect on lipid peroxidation in microsomes, their high O-2((1) Delta(g)) quenching constant may minimize the extent of tissue damage associated with the inflammatory process. (C) 1997 Elsevier Science S.A.
Subject: leguminosae
lipid peroxidation
near-IR (NIR) emission
time-resolved luminescence
Country: Suíça
Editor: Elsevier Science Sa Lausanne
Rights: fechado
Identifier DOI: 10.1016/S1011-1344(96)07444-1
Date Issue: 1997
Appears in Collections:Unicamp - Artigos e Outros Documentos

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