Document Detail


Two new antioxidant malonated caffeoylquinic acid isomers in fruits of wild eggplant relatives.
MedLine Citation:
PMID:  21800866     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Fruits of the cultivated eggplant species <i>Solanum melongena</i> and its wild relative <i>Solanum incanum</i> have a high content of hydroxycinnamic acid conjugates, which are implicated in the human health benefits of various fruits and vegetables. Monocaffeoylquinic acid esters, in particular 5-<i>O</i>-(-<i>E</i>)-caffeoylquinic acid, are usually predominant in solanaceous fruits and tubers. Two closely related caffeoylquinic acid derivatives with longer C<sub>18</sub>-HPLC retention times than those of monocaffeoylquinic acids are minor constituents in cultivated eggplant fruit. In a prior study, the two compounds were tentatively identified as 3-<i>O</i>-acetyl- and 4-<i>O</i>-acetyl-5-<i>O</i>-(<i>E</i>)-caffeoylquinic acids, and composed ≤ 2% of the total hydroxycinnamic acid conjugates in fruit of most <i>S. melongena</i> accessions. We recently found that the pair of these caffeoylquinic acid derivatives can compose 15-25% of the total hydroxycinnamic acid conjugates in fruits of <i>S. incanum</i> and wild <i>S. melongena</i>. This facilitated C18-HPLC isolation and structural elucidation using <sup>1</sup>H- and <sup>13</sup>C-NMR techniques and HR-ToF-MS. The isomeric compounds were identified as 3-<i>O</i>-malonyl-5-<i>O</i>-(<i>E</i>)-caffeoylquinic acid (isomer 1), and 4-<i>O</i>-(<i>E</i>)-caffeoyl-5-<i>O</i>-malonylquinic acid (isomer 2). Both exhibited free radical scavenging activity, albeit about fourfold lower than that of the flavonol quercetin dihydrate. By contrast, the iron chelation activities of isomers 1 and 2, respectively, were about three- and six-fold greater than that of quercetin dihydrate. Reports of malonylhydroxycinnamoylquinic acids are rare, and only a few of these compounds have been structurally elucidated using both NMR and MS techniques. To our knowledge, these two malonylcaffeoylquinic acid isomers have not previously been reported.
Authors:
Chunhui Ma; Keyvan Dastmalchi; Bruce D Whitaker; Edward J Kennelly
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-29
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  -     ISSN:  1520-5118     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-8-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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