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|Title:||Quinoline alkaloids in honey: further analytical (HPLC-DAD-ESI-MS, multidimensional diffusion-order NMR spectroscopy), theoretical and chemometric studies.||Authors:||Beretta, G
MAFFEI FACINO, R.
|Keywords:||Honey; Pyrrolidinyl quinoline alkaloids; Kynurenic acid; Nuclear magnetic resonance; High pressure liquid chromatography; Mass spectrometry||Issue Date:||2009||Project:||None||Journal:||JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS||Abstract:||
The wound-healing properties of honey are well established and it has been suggested that, among itspharmaco-active constituents, kynurenic acid (KA) exerts antinociceptive action on injured tissue byantagonizing NMDA at peripheral GABA receptors. The aim of this study was to investigate the quantitativeprofile of KA and of two recently identified, structurally related derivatives, 3-pyrrolidinyl-kynurenicacid (3-PKA) and its -lactamic derivative (-LACT-3-PKA), by examining their mass spectrometric behavior,in honeys from different botanical sources. We used a combination of HPLC-DAD-ESI-MS and NMRtechniques (one-dimensional 1H NMR and diffusion-ordered spectroscopy NMR).Chestnut honey constantly contained KA (2114.9–23 g/kg), 3-PKA (482.8–80 mg/kg) and -LACT-3-PKA(845.8–32 mg/kg), confirming their reliability as markers of origin. A new metabolite, 4-quinolone (4-QUIN), was identified for the first time in one chestnut honey sample (743.4 mg/kg). Small amountsof KA were found in honeydew, sunflower, multifloral, almond and eucalyptus honeys, in the rangeof 23.1–143 mg/kg, suggesting contamination with chestnut honey. Total phenol content (TPC) was inthe range from 194.9 to 1636.3mgGAE/kg and total antiradical activity (TAA) from 61 to 940 mg/GAE/kg),depending on the botanical origin.Principal component analysis (PCA)was then done on these data. The three different clusters depicted:(i) antinociceptive activity from KA and/or its derivatives, typical of chestnut honey; (ii) antioxidant/radical scavenging activity by antioxidants responsible for the antiinflammatory action (darkhoneys); (iii) peroxide-dependent antibacterial activity due to H2O2 production by glucose oxidase inhoney.The PCA findings provide useful indications for the dermatologist for the treatment of topical diseases,and the profiling of KA and its derivatives may shed light on new aspects of the kynurenine pathwayinvolved in tryptophan metabolism.
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