The Role of Phenolic Hydroxy Groups in the Free Radical Scavenging Activity of Betalains

• Published in: Journal of natural products (Washington, D.C.) Vol. 72; no. 6; pp. 1142 - 1146
• Main Authors: Gandía-Herrero, Fernando, Escribano, Josefa, García-Carmona, Francisco
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society and American Society of Pharmacognosy 26.06.2009; Amer Chemical Soc; American Society of Pharmacognosy
• Subjects: antioxidant activity; Antioxidants; Antioxidants - chemistry; Antioxidants - isolation & purification; Antioxidants - pharmacology; betalains; Betalains - chemistry; Betalains - isolation & purification; Betalains - pharmacology; betaxanthins; Biological and medical sciences; Caryophyllaceae; Caryophyllaceae - chemistry; Caryophyllales; chemical structure; chemistry; Chemistry, Medicinal; chromatography; Flowers; Flowers - chemistry; free radical scavengers; Free Radical Scavengers - chemistry; Free Radical Scavengers - isolation & purification; Free Radical Scavengers - pharmacology; General and cellular metabolism. Vitamins; Hydrogen-Ion Concentration; isolation & purification; Life Sciences & Biomedicine; mass spectrometry; Medical sciences; Molecular Structure; pharmacology; Pharmacology & Pharmacy; Pharmacology. Drug treatments; phenolic compounds; Phenols; Phenols - chemistry; Phenols - pharmacology; physiology; Pigments, Biological; Pigments, Biological - physiology; plant pigments; Plant Sciences; Plants, Medicinal; Plants, Medicinal - chemistry; Science & Technology; spectroscopy; Structure-Activity Relationship; structure-activity relationships; PERFORMANCE LIQUID-CHROMATOGRAPHY; ANTIOXIDANT ACTIVITY; PEAR; FLUORESCENCE; ANTIRADICAL ACTIVITY; BIOSYNTHESIS; RED BEET; BETAXANTHIN; BETANIN; IONIZATION MASS-SPECTROMETRY; Nitrogen heterocycle; Benzene derivatives; Imine; Antioxidant; Diphenols; In vitro; Radical scavenger; Free radical; Aldimine; Organic pigment; Betalain; Structure activity relation; Medium effect; Six membered ring; Phenols; pH; Betaxanthine; Chemical synthesis; Hemisynthesis
• ISSN: 0163-3864; 1520-6025; 1520-6025
• DOI: 10.1021/np900131r

Free radical scavenging compounds play important roles as health-protecting factors. Betalains are natural water-soluble pigments present in most plant families belonging to the order Caryophyllales. They are the subject of increasing attention following the discovery of their antiradical capacity, but a systematic analysis of the structural features involved in the activity is necessary. In this paper, both natural and previously unconsidered betaxanthins were obtained in order to study the role of phenolic hydroxy groups in the high free radical scavenging activity of betalains. Pigments were characterized spectrophotometrically, chromatographically, and by ESI-MS, and their antiradical and antioxidant properties were studied under the ABTS•+ radical and FRAP assays. A high intrinsic activity is described that is not linked to the presence of hydroxy groups or aromaticity in the pigment structure. In addition, the presence of phenolic hydroxy groups implies an enhancement of the antiradical activity, reaching a TEAC value in the ABTS•+ assay of 5.8 ± 0.2 for the pure compound with two hydroxy groups.