ABSTRACT
Date (Phoenix dactylifera L.) fruit phenolic-acid or flavonol fractions were examined in vitro for antioxidant and antiatherogenic properties. Two fractions of each subgroup were prepared from two date varieties, 'Amari' and 'Hallawi', by solid phase extraction on C18. The fractions were analyzed for phenolics composition by RP-HPLC and tested for ferric-reducing antioxidant power, free radical scavenging capacity, inhibition of Cu(2+)-induced LDL oxidation, and enhancement of HDL-mediated cholesterol efflux from macrophages. All four fractions exhibited variable capacities to reduce ferric ions, scavenge radicals, and inhibit LDL oxidation. Flavonol fractions were considerably better inhibitors of LDL oxidation compared to phenolic acid fractions, with IC50's of 9-31 nmol GAE mL(-1) compared to 85-116 nmol GAE mL(-1), respectively. Only the flavonol fractions stimulated cholesterol removal from macrophages. Within each subgroup, the levels of all the activities varied with fraction composition. The results demonstrated strong structure-activity relationships for date phenolics and identified date flavonols as potential antiatherogenic bioactives.
Subject(s)
Antioxidants/pharmacology , Cholinergic Antagonists/pharmacology , Flavonols/pharmacology , Hydroxybenzoates/pharmacology , Phoeniceae/chemistry , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Animals , Antioxidants/isolation & purification , Cholesterol/metabolism , Cholinergic Antagonists/isolation & purification , Flavonols/isolation & purification , Fruit/chemistry , Hydroxybenzoates/isolation & purification , Macrophages/drug effects , Macrophages/metabolism , Mice , Phoeniceae/classificationABSTRACT
Date (Phoenix dactylifera L.) fruit soluble phenolics composition and anti-atherogenic properties were examined in nine diverse Israeli grown varieties. Ethanol and acetone extracts of 'Amari', 'Barhi', 'Deglet Noor', 'Deri', 'Hadrawi', 'Hallawi', 'Hayani', 'Medjool', and 'Zahidi' fruit were analyzed for phenolics composition by RP-HPLC and tested for anti-atherogenicity by measuring their effects on LDL susceptibility to copper ion- and free radical-induced oxidation, and on serum-mediated cholesterol efflux from macrophages. The most frequently detected phenolics were hydroxybenzoates, hydroxycinnamates, and flavonols. Significant differences in phenolics composition were established between varieties as well as extraction solvents. All extracts inhibited LDL oxidation, and most extracts also stimulated cholesterol removal from macrophages. Considerable varietal differences were measured in the levels of the bioactivities. Also, acetone extracts exhibited a significantly higher anti-atherogenic potency for most varieties. The presence of soluble ingredients with anti-atherogenic capacities in dates and the possible involvement of phenolics are discussed.
Subject(s)
Antioxidants/chemistry , Arecaceae/chemistry , Arecaceae/classification , Fruit/chemistry , Phenols/chemistry , Acetone , Animals , Cell Line, Tumor , Chromatography, High Pressure Liquid , Copper/metabolism , Ethanol , Humans , Israel , Lipid Metabolism/drug effects , Lipoproteins, LDL/blood , Macrophages/chemistry , Macrophages/drug effects , Mice , Thiobarbituric Acid Reactive Substances/metabolismABSTRACT
Antioxidant activity and composition of Israeli-grown marula ( Sclerocarrya birrea subsp. caffra) fruit juice and health-promoting aspects of juice consumption on serum lipids and lipoproteins pattern in healthy volunteers were studied. Marula juice was found to contain high vitamin C and potassium levels and low sugar concentration (267 mg dL (-1), 328 mg dL (-1), and 7.3 g dL (-1), respectively). The juice contains a significant level of phenolics (56 mg of pyrogallol equiv dL (-1)) and was found to be a potent antioxidant (382 mg of vitamin C equiv dL (-1)). The antioxidant activity was resistant to pasteurization regimens and long-term freezing and slowly decreased during refrigeration, losing up to 14% of its capacity after 4 weeks. Three-week administration of the juice as a food supplement to healthy subjects significantly reduced their serum total cholesterol (by 8%), LDL-cholesterol concentration (by 17%), and triglyceride level (by 7%), increased their serum HDL-cholesterol level (by 10%), and attenuated serum oxidative stress. Upon a 4 week "washout" period, most of these parameters returned toward baseline values. Separation of the juice soluble phenolics by HPLC produced potent antioxidant fractions, tentatively containing hydrolyzable tannins, catechins, and hydroxycinnamic acid derivatives, which could be responsible for the observed protection against atherosclerosis risk factors following marula fruit juice consumption.
