The biological activities [15] of the phenylpropanoids and their role as antimicrobial agents [16,17] is well recognised, as well as their properties as antiallergic and anti-inflammatory agents through lipoxygenase inhibition [18] and their antimutagenic actions [19,20].In this study we have examined the antioxidant properties of the hydroxycinnamic acids in terms of their abilities to increase the resistance of low density lipoproteins (LDL) to cholesterol oxidation, lipid peroxidation and oxidative modification of the apoprotein B,j 0. The results show that the sequence of the effectiveness against lipid peroxyl radicals generated in the lipophilic phase of LDL and in protecting LDL cholesterol from oxidation is: chlorogenic = caffeic > ferulic > p-coumaric acid.

The antioxidant properties of theaflavins and theirprotein to oxidation and to prolong the efficacy of c~-tocogallate esters were studied by investigating their abilities to pherol within the LDL [6] is in the sequence scavenge free radicals in the aqueous and lipophilic phases. The EGCG = ECG ~ EC = C>EGC>GA total relative antioxidant activities in the aqueous phase were assessed by measuring their direct ABTS "+ radical scavenging and this is consistent with their partition coefficients. abilities, and by their efficacies in inhibiting the degradation of deoxyribose induced by iron. The propensities for enhancing the Theaflavins are formed during the manufacture of black resistance of LDL to oxidation mediated by Cu 2+ were also and oolong teas from the enzymic oxidation of the flavanols, measured. The results show that the hierarchy of reactivity of catechin and gallocatechins, etc. by polyphenol oxidase. The these compounds as antioxidants is: theaflavin digallate > 3'-reaction involves the oxidation of the B rings to the quinones, monogallate=3-monogallate > tbeaflavin. Spectroscopic studies followed by a Michael addition of the gallocatechin quinone show that all the compounds chelate iron and copper; enhanced absorbance in the visible region is observed in the case of the to the catechin quinone, prior to carbonyl addition across the iron-digallate complex, but not with copper, ring and subsequent decarboxylation [8]. In this study the antioxidant properties of theaflavins and their gallate esters Key words." Theaflavin; Black tea; Metal chelator; Hydroxyl ( Fig. 1) are studied by investigating their abilities to scavenge radical scavenger; Total antioxidant activity; Oxidized LDL free radicals in the aqueous and lipophilic phases. Materials and methods IntroductionTheaflavin, theaflavin 3-monogallate, theaflavin 3'-monogallate and A number of studies in vivo and in vitro have investigated theaflavin digallate were gifts of Unilever Research. The purities of the compounds were theaflavin 98%, theaflavin 3-monogallate 96%, the effects of green and black teas and their polyphenolic theaflavin Y-monogallate 90% (of the other 10%, 90% is theaflavin 3-constituents as antioxidants and in in vivo models of risk of monogallate) and theaflavin digallate 87%, the sample also containing cardiovascular diseases and cancers or markers of lipid metab-13% theaflavin 3'-monogallate. The compounds are reported to be olism. Green tea consumption has been associated with lowstable in the solid state. In most organic solvents, they are stable for up to 24 h in the dark; in low pH aqueous solution (pH<4) ered cardiovascular risk through decreased serum cholesterol they are stable for several days, but at higher pH (> 6) they will and triglyceride, increased HDL and a decreased atherogenic degrade rapidly. The compounds were stored at 4°C in the dark until index [1]. In vivo animal studies demonstrate that green tea use; stock solutions were prepared by dissolution in ultrapure (18 stimulates hepatic UDP-glucuronyl tr...

The hydroxycinnamates, intermediates in the phenylpropanoid synthetic pathway, are effective in enhancing the resistance of low-density lipoprotein (LDL) to oxidation in the order caffeic acid > ferulic acid > p-coumaric acid. It is unclear whether the mode of action of ferulic acid as an antioxidant is based on its activities in the aqueous or the lipophilic phase. Partitioning of 14C-labelled ferulic acid into plasma and its components, LDL and the albumin-rich fractions, has been studied under conditions of maximum aqueous solubility. The majority of ferulic acid associates with the albumin-rich fraction of the plasma, although a proportion is also found to partition between the LDL and aqueous phases; however, ferulic acid does not associate with the lipid portion of the LDL particle, suggesting that it exerts its antioxidant properties from the aqueous phase. This is of particular interest since the results demonstrate that ferulic acid is a more effective antioxidant against LDL oxidation than the hydrophilic antioxidant ascorbic acid.

The saturation kinetics of NADH and succinate oxidation for Cocnzyme Q (CoQ) has been rc-invest&ted in pcntanccatmckd lyophilizcd beef heart mitochondria rcconstitutcd with cxo~cnous CoQ,,. The apparent '&,,:,' for CoQ,, was one order of mawitude lower in succinatc cytochrome c reductnse than in NADH cytocbromc L' rcductase. The K,,, value in NADH oxidation approaches the natural CoQ content of beef heart mitochondria, whereas that in succinatc oxidation is close to the content of respiratory chain enzymes.

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We have investigated the respiratory activities and the concentrations of respiratory chain components of mitochondria isolated from the livers and hearts of two groups of rats aged 6 and 24 months respectively. In comparison with the adult controls (6 months), in aged rats there was a decline in total aerobic NADH oxidation in both tissues; only minor (non-significant) changes, however, were found in NADH:coenzyme Q reductase and cytochrome oxidase activities, and there was no change in ubiquinol-cytochrome c reductase activity. The coenzyme Q levels were slightly decreased in mitochondria from both organs of aged rats. The lowered NADH oxidase activity is not due to the slight decrease observed in the coenzyme Q levels, but is the result of decreased Complex I activity. Since the assay of NADH:coenzyme Q reductase requires quinone analogues, none of which can evoke its maximal turnover [Estornell, Fato, Pallotti and Lenaz (1993) FEBS Lett. 332, 127-131], its activity has been calculated indirectly by taking advantage of the relationship that exists between NADH oxidation and ubiquinol oxidation through the coenzyme Q pool. The results, expressed in this way, show a drastic loss of activity of Complex I in both the heart and the liver of aged animals in comparison with adult controls.

Plasma coenzyme Q (CoQ) was measured in 20 hyperlipidaemic patients treated with diet and simvastatin (an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase); 22 hyperlipidaemic patients treated with diet with alone; and 20 normal controls. MethodsThree groups of subjects were studied: (A) 20 patients (12 men, eight women, aged 55 (SD 8 9) years; five smokers, five with hypertension, and 11 with coronary heart disease) treated with simvastatin and a fat modified diet; (B) 22 patients (nine men, 13 women, aged 53-7 (11 4) years; five smokers, eight with hypertension, and five with coronary heart disease) treated with a fat modified diet alone; (C) 20 healthy, control subjects (10 men, 10 women, aged 48-2 (9 5) years; two smokers) receiving an unrestricted diet. In group A, 14 patients had type IIa hyperlipidaemia (four with familial hypercholesterolaemia) and six type IIb; median dose of simvastatin was 20 mg at night (range 10-80 mg), with mean duration of treatment 15 + 8 months. In group B, 18 patients had type Ila hyperlipidaemia (two with familial hypercholesterolaemia) and four type IIb. Patients were selected consecutively from attenders at our lipid clinic. Those receiving anti-lipaemic medication besides simvastatin or with secondary hyperlipidaemia were excluded. Adherence to diet was confirmed from dietetic records, and exercise patterns were similar for groups A and B. Normal subjects were volunteer university staff in excellent health.Venous blood was collected into tubes containing Na, EDTA (1 mg/ml), with minimal stasis and with subjects having fasted (12 hours) and in the semi-recumbent position.

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