1236

OJ.,,"-

HEALTH & NUTRITION

Extracts as antioxidant prophylactic agents

Inreviewing the book by St. Ange-lo (I) which had a picture of a bit-ten apple. I wrote, "At first sight.

one wonders what lipid oxidation hasgal 10 do with apples as depicted onthe cover of the book. The answerbecomes clear when it is realized thatthe reactions catalyzed by lipoxyge-nases are the major cause of off-flavorproduction in unprocessed plant foodsduring storage," Indeed the shelf lifeof manufactured foods is invariablylimited by oxidative degradation ofthe polyunsaturated fatty acids of thefood lipids and by browning reactions.Many foods of plant origin containlipids and Iauy acids that are highlyunsaturated (e.g., linoleic acid andlinolenic acid in potatoes). Plant oilsfrequently contain large amounts oflinoleic acid and sometimes linolenicacid. while some animal fats. panicu-larly those from ruminants, containmore saturated fat and oleic acid. Fishoils. which technically are animal fatsbut are usually referred to as marineoils. are highly unsaturated, however.

The oxidative degradation of thesepolyunsaturated fatty acids is the pri-mary factor in limiting the shelf life ofmost manufactured foods (2-5); thisnecessitates use of antioxidants duringthe food manufacturing process(1.3.6-8). Reactions involving freeradicals lead to deterioration in foodflavor and loss of food quality.Although the rancid flavor of fats.peanuts, and coffee; the stale flavor ofdried potato, baked goods, and beer;and warmed-over meat flavor are typi-cal examples. in some cases the prod-ucts arising from such reactions appearto be an imponant part of the flavor.Consumers may appreciate the contri-botion of volatile compounds as desir-able flavors in fresh milk, dried pota-toes. cheeses. and the "creamy" flavorof cream.

The extent to which the oxidationof fatty acids and their esters con-tributes to the formation of volatilecompounds in foods depends on manyfactors, including the chemical suuc-ture of the fatty acid, the water activi-ty. the process, and the storage tem-perature. The propensity to oxidize is

7JIir article is by DUde I. Anwma.«OICA l... mtIlloNJl, P.O. lJoJc MI 34, Micood.

Sa.., Lod4: <Utd ",. Pluumocology GrrHIp,U.... nby «LDNkHI King's Co1kge,M..,.", RDtMl,LDNkHI SW3 6llC. UniI«l Kingdom, <Utd is btu«l ..

/tis p1UIItII1liDfr Oft"" topic "PUmt Emocu <WIPUmt·o.riwId AnIi<W4turts: New a..."".",

A>tllo,;""'" Prop/fylactic Agents?" dIuing",. 1997 AOCS Annoo1 Muri"l/ .l~

equally dependent on oxygen concen-trations and the presence of minorcompounds such as antioxidants andtrace metals. Indeed. certain foodproducts containing unsaturated acylcompounds (e.g .• in cooking oil) maydegrade to fonn volatile compounds atthe high temperatures normallyachieved under frying conditions(2,5,8,9),

Processing of foods can also resultin formation of antioxidant com-pounds. For example, Maillard reac-tion products (reducrones, mel-anoidins, and heterocyclic corn-pounds). soy protein hydrolysales,microbial fermentation products (glu-cose oxidases. catalases, and superox-ide dismurase) are typical. Interesting-ly, the curing of meat yields nitrosylheme pigments that protect meat pig-ments as well as meat lipids from oxi-dation. In earlier days, the primeobjective of the use of nitrites in thecuring of meat was the developmentof the characteristic pink color thatresults from the combination of myo-globin andlor hemoglobin with nitricoxide. It is now known that the pro-cess provides microbial stability andfreedom from outgrowth ofpathogenic organisms (reviewed inRefs. 10,11). By contrast. the increas-ing awareness that there is a role forfree radicals and antioxidants in thepathogenesis of human diseases and inthe process of aging has led to thesuggestion that antioxidants, particu-larly plant diet-derived antioxidants,might have health benefits as prophy-lactic agents (7.12-19). Many tropi-

cal fruits and plants also are richsources or such diet-derived antioxi-dants.

Antioxidants indigenous to foods(3,6.7,20-22) and oil-soluble antioxi-dants in foods, such as butylatedhydroxyanisole (BHA). butylatedhydroxy toluene (BHT), tertiary butyl-hydroquinone (TBHQ). esters of 3,4.5·trihydroxybenzoic acids (propyl, cetyl,and dodecyJ esters), erhoxyquin (6·ethoxy.l.2-dihydro-2.2,4-trimethylquinoline) (used mostly in animalfeeds), and dl-a-tocopherols, continueto be used commercially (6,22.23).Plant extracts that also have been pro-posed to contain antioxidant capabili-ties include: rosemary, sage, cocoashells. oats, tea, olives, garlic, ginger,red onion skin, grapes, apple cuticle,wheat gliadin, korum rind, licorice.nutmeg. clove. oregano, thyme, mus-tard leaf seed, flaxseed, chia seed.peanut seed coat, birch bark, carobpod. tempeli. yam, mango. mango-Steen. and vanilla. Ravonoids (benzo-y-pyrone) and other phenolic com-pounds found in these extracts arewidely discussed as potential antioxi-dant prophylactic agents (14,24).Because flavonoids are widelydistributed in plant cells. they areaccessible 10 humans through diets ofplant origin (25-27). Several grams offlavonoids are consumed daily as theyare present in fruits. vegetables. grains.nuts. stems, leaves, wine, floweringtissues. and pollen. For the plant,flavonoids are important for normalgrowth development and defenseagainst infection and Injury.

INFO~M. VOl.8, no. 12 (December 1997)

1237

Flavonoids possess recognized amicar-cinogenic. antiinflammatory, andantiallergic properties and thus maybecome useful for the treatment of cer-tain human diseases. Indeed, some ofthe active constituents of many folkmedicines are flavonoids (see reviewby Anton in Ref. 27). Examplesinclude: persimmon juice. containingvarious condensed tannins, used inJapan as traditional medicine for treat-ment of hypertension and 10 preventstroke; mountain balm. gum bush fromthe leaves of Eridictyon glutinosum;used by Indians as an expectorant,blood purifier. and Ionic; arteminin.the pentamethyl ether of quercetagetinfrom the herb Artemisia abs;nlh"m,used for its bitter principle and alsoantimalarial effects; the wood and barkof Pterocarpus used for diarrhea and asan astringent and antidiabetic agent;the stembark of Acacia tanilis used bythe Somali people for formulationsagainst asthma; and kaempferol, gen-tisin sophoricoside. and crude extractsof Butea monosperma. used in Chinesemedicine in family planning. The mul-tiple biological effects of flavonoids(27) also include mutagenicity inmicrobial experimental models andacting as antiviral agents, as inhibitorsof tumor invasion. and as inhibitors ofthe oxidative modification of low-den-sity lipoproteins (LOL) which areimportant in the pathology ofatherosclerosis (28). Flavonoids areregarded as semiessential food compo-nents (26), which are. on the whole.beneficial. In the context of manufac-tured foods. flavonoids are exploitedcommercially and are often found inmilk. lard, and butler and are used incombination with synergists such ascitric acid and ascorbic or phosphoricacid (6). It remains to be seen ifflavonoids could begin to attract themagnitude of funds that have gone intoantioxidant vitamin supplementationand intervention studies. Flavonolds.although in complex fonns upon con-sumption. are nevertheless at the heanof the most widely consumed dietaryantioxidants.

The need for food manufacturers toproduce quality products that havereasonable shelf lives by use of food-grade antioxidants during food pro-cessing must be balanced by the

Free radicals

Clinical conditions:neurodegenerative diseuses, cancer. atherosclerosis.

malaria, ischemialreperfusion injury,AIDSIHIV infection.

inflammation, diabetes. etc.

Food-grade aod plant-derived antioxidants:Ilavonoids, vitamin E, Beeroreoes. catechins. etc.

I Prooxidantlantioxidant assessment I

--~ Disease models andlor clinical trials 1+---

i.1 IOxidative stress'I

Markers of oxidative damage: DNA (base products).lipids (iscprcsranes). proteins (altered amino acids).

carbohydrates, and other markersof tissue and cellular damage

Flgur.1. Proposed .tr.tegy to study In vivo sntloxld.tlon

increasing interest in the use ofantioxidants as prophylactic agents inhuman degenerative diseases. Delin-eating the in vivo contribution of plantextracts andlor plant-derived antioxi-dants (the pure active principles inplant extracts with antioxidant indica-tions) to the modulation of the patho-logical consequences of oxidativestress in the human body is not aneasy task (17). A strategy that couldfacilitate this endeavor is suggested inFigure I.

Antioxidants act at different levelsin the oxidative sequence involvinglipids. They may act by decreasing

localized oxygen concentration, scav-enging radicals. binding metal ions.decomposing peroxides, and chain-breaking to prevent continued hydro-gen abstraction. The type of chemicalsystem that the antioxidant compoundis intended to control needs to bedefined before comparisons can bemade about antioxidant efficacy. Acomment from Hall and Cuppett of theUniversity of Nebraska (29) encapsu-lates this fundamental issue in present-day antioxidant research: "Antioxidantmechanisms of natural compoundsfrom plants are not simple; often con-trol of lipid oxidation is achieved

INFORM. Vol.8. no. 12 (December 1997)

1238

HEALTH & NUTRITION

100 Ie. :Herbor 0.0009 96 vlvSpice cocktail 0.0035 96 vlv

!60

1"~ 4.~0

.~ ____ Herber

;§ - Spice Provencal

:s 20...

60

o

0.0001 0.001 0.01 0.1

Ccncentration o(Compound (% vlv)Figure 2. Inhibition 01 phospholipid lipo.ome peroxidation by Herbor and splea cocktail. Alog plot of the concentrations i. shown. (Adapted from Aruoma at al. (40)]

through more than one mechanism.Research is needed not only to definethe mechanisms of these compoundsso that they can be used effectively infood systems: data is also needed toevaluate the safety of these compoundsand 10 identify their potential healthbenefits when added 10 the food sys-tem:' In the context of Figure I, theimportant implications can be appreci-ated. in particular. when interventiontrials and supplementation studies aredesigned and carried out. It is impor-tant to support disease end points withuse of validated ill vivo markers ofoxidative stress in order to ascertainthe efficacy of the anuoxtdant. Forexample. Rapola et al. (30) reportedthe result of the randomized trial of a-tocopherol and p-carotene supple-ments on the incidence of major coro-nary events in men with previousmyocardial infarction and concludedthat "the proportion of major coronaryevents in men with previous myocar-dial infraction who smoke was notdecreased with either a-tocopherol orJH:arotene supplements." The authors

continued, 'The risk of fatal coronaryheart disease increased in the groupsthat received either p-carotene or thecombination of a-tocopherol and p-carotene although there was a non-significant trend of increased death inthe a-tocopherol group." The obviousconclusion was nevertheless reached,i.e., that "a-tocopherol or p-carotenesupplements are not recommended inthis group of patients." Clearly, knowl-edge of how markers of oxidativedamage varied in the patients wouldhave been invaluable to the final analy-sis of the data with respect to theantioxidant efficacy.

However, before a wide-scale useof plant extracts and plant-derivedantioxidants in the treatment of humandegenerative diseases can be suggest-ed, it also is necessary to establish thepropen.ies of such molecules. Assaysthat have been developed for charac-terizing the potential antioxidantandlor prooxidant actions of foodadditives, antioxidant supplements.antioxidant drug molecules. and nutri-ent components have been discussed

with examples of their application to avariety of potential dietary antioxidantcompounds (14.17,31).

Measurement of levelsof oxidative damage in humansThere are several indicators of theextent of oxidative damage inhumans: (a) Total oxidative DNAdamage can be obtained by measuringurinary levels of 8-hydroxyguanosineby HPLC. Steady-state DNA damageis the damage sustained after "repair"by DNA repair enzymes. Measuringsteady-state damage often involvesextracting the DNA from cells andusing gas Chromatography-massspectrometry to analyze the levels ofthe oxidized bases; (b) Levels ofantioxidant enzymes and levels of lowmolecular weight antioxidants andvitamins can be obtained by measur-ing levels of catalase, superoxide dis-mutase, and glutathione peroxidasesas well as the levels of uric acid. glu-tathione, Ilavoncids, and other pheno-lic compounds absorbed from plantfoods (catechins, carnoscl, carnosieacid, hydrcxytyrosot, vanillin, vanillicacid, anthocyanins, etc.), vitamins Eand C and p-carotene; (c) Oxidativedamage to lipids could be measuredin terms of levels of lsoprostenes andthiobarbituric acid-reactive materials(TBARM) after HPLC separation. Itis important to emphasize that mea-surements of TBARM are not accu-rate measures of lipid oxidation ;11\1;110. Pcroxidarton of arachidonic acidill \1;110 generates a series ofprostaglandin F2-like compounds thatappear to be useful markers. Noveladvanced mass spectrometry tech-niques are being developed to mea-sure the levels of malondialdehydc-DNA adducts (29); and (d) Steady-slate protein damage can be quanti-fied in terms of the numbers of pro-tein carbonyls and modified tyrosineresidues. Total ongoing protein dam-age can be indicated by the concen-tration of modified tyrosines and fluo-rescent bityrosines in the urine.

Antioxidant actions or 6-gingerol,carvacrol, thymol, zingerone, andhydroxylyrosolThe compounds thymol, carvacrol.zingerone, 6-gingerol, and hydroxyty-

INFORM. Vol. 8, no. 12 (December 199n

Table 1Reactions 01 "natural" antioxidants In assays Involving reactive oxygen species

Action in lipid Rate constantperoxldation or rer reaction Prooxidant actions in:

Dietary pbospholipid with CCIJ02• Deoxyribose Bloomycincomponents liposomes (M~IS-I) """Y """Y Source or components

Vanillicacid Antioxidant 3.97 x 1()6 No effect No effect Classic vanilla flavorVanillin Antioxidant 9.54 x 107 Prooxidam No effect Classic vanilla flavorThymol Antioxidant 3.82 x 1()6 n.1. No effect Essential oil of T. I'u/garisCarvacrol Amioxidam 3.92 x lOS n.1. No effect In oil of thyme6-Gingerol Antioxidant 4.67 x 1()6 n.t. No effect In ginger oilZingerone Weak antioxidant 5.63 x 1()6 n.t. No effect Isolated from ginger rootFerulic acid Antioxidant 7.5xl()6 Antioxidant Weak prooxidant From ChiaoMexican plant+ Catechin Antioxidant 6.1 x 106 Antioxidant Prooxidant Green tea± Catechin Antioxidant 6.1 x 1()6 Antioxidant Prooxidant Green tea- Epicatechin Antioxidant 7.3 x 1()6 Antioxidant Prooxidanr Green teaHydroxytyrosol Antioxidant 8.37 x 1()6 n.t. Procxidanr Olive oil and olive fruitsCamosic acid Antioxidant 2.7 x 107 Antioxidant Prooxidant Rosemary extractCamosol Antioxidant 1-3 x 1()6 Antioxidant Prooxidant Rosemary extracta-Tocopherol Antioxidant 4.89 x lOS n.t. Prooxidant Various naturally(vitamin E) occurring forms

Vitamin0' Prooxidant \.3 x lOS Prooxidant Prooxidant Synthetic. naturallyoccurring

Trolox C Antioxidant 2.23 x lOS Antioxidant Procxidam Syntheticvitamin E analogPropyl gal1ate Antioxidant 1.67x 107 Prooxidant Prooxidant Synthetic compoundQuercetin Antioxidant 3.9 x 107 No effect Prooxidant FlavonoidMorin Antioxidant 3.01 x lOS Prooxidant Prooxidant FlavonoidChrysin Antioxidant 9.86 x 107 n.t. No effect FlavonoidFisetin Antioxldam 4.09 x lOS n.t. Prooxidant Flavonoid

n.l ... IKlI1.. led. often due 10solubililY re5lriCtions: data abstracted from the: published ....ortt of the ~utbor.(J In the pho5pbolipid assays. ascorbate il Ontn used 10 initiul/: the ruction in which 10WI! the potential IUltioxidanl IOCtion.

rosol are potent inhibitors of phospho-lipid liposomes peroxidotion and effec-tive scavengers of the reactive peroxylrndicnl (trichloromethyl. CCI302-)(Table I). Ascorbate (vitamin C) iswidely acknowledged as a biologicalantioxidant under certain conditions. Inthe phospholipid liposomes peroxide-tion assays. ascorbate often is used toinitiate the reaction. hence the prooxi-dant listing in Table I. Ascorbate is apotent scavenger of peroxyl radicalsand has been suggested to act synergis-tically with vitamin E to regenerate thetoccpheryt radicals in vivo. henceincreasing the antioxidant protection ofvitamin E. This suggestion was madeback in the late I%Os by AI Tappel. Itis logical that the plant-derived antioxi-dants could act in a similar manner toenhance antioxidant efficacy. Interest-ingly. hydrcxytyroscl exerts prooxidantaction in nonlipid assays, e.g .• oxida-tive DNA damage. but this can be com-pletely abolished by the protein albu-

min, suggesting that proteins under cer-tain conditions could act as secondaryantioxidants in a food matrix and/or inan antioxidant cocktail formulation thatmay contain the prooxidant compound(17). Hydroxytyrosol is particularlyattractive given the current interest inolive oil (32). Hydroxytyrosot is bothliposoluble and hydrosoluble and couldtherefore act as useful antioxidant inemulsions or systems where both oiland water phases are present (33).Mediterranean diets rich in vegetables,grains and vegetable oil. mainly oliveoil, have been correlated with a lowerincidence of coronary heart disease.Hydroxytyrosol has been shown to pro-tect LDL against oxidation (34). Byusing human aortic endothelial cells tomediate the oxidation of LDL andmeasuring absorbance at 234 nm ofconjugated dienes, Pearson et of. (35)demonstrated the antioxidant activitiesfor thymol, carvacrol. and zingerone.The active rosemary components

carnosol and camosic acid (see below)were the most potent antioxidants inthis system. The prooxidant actionalluded to for hydroxytyrosol may notbe physiologically relevant because ofthe high concentrations required 10exert the effect ill vitro. Thus ill vivo.the beneficial antioxidant effects whichmay be manifested by the scavengingof peroxyl radicals, hypochlorous acid(HOCl). and peroxynitrite (ONOO-)would prevail.

Rosemary and sage constituentsCamosct and cernosic acid have beensuggested to account for over 90% ofthe antioxidant properties of rosemaryextract (3.30.36-38). Purified camosoland carnosic acid are powerfulinhibitors of lipid peroxidation eitherto membrane lipids or to LDL.Carnosol and carnosic acid are goodscavengers of peroxyl radicals generat-ed by pulse radiolysis (Table J).Camoslc acid reacts with HOCl in

INFORM. Vol. 8. no. 12 (December 1997)

1239

1240

HEALTH & NUTRITION

Table 2Antioxidant activity of Herbor 025 and spice cocktail [antioxidant Index(RanclmatJ110°C)]

Antioxidant index in

[xtract"Chicken

oilSunflower

oil

Herbor02.5Spice cocktailRosemarySageThymeOreganoGinger

I..8.3

12.68.45.73.42.4

So,Lard oil

3.s9.1

11.48.54.82.92.9

1.31.82.11.81.21.31.1

1.22.02.31.81.31.31.1

such a way as to protect the protein (I-

l-antiproreinase against inactivation.Both camosol and carnosic acid stimu-late ferric ion-bleomycin-dependentDNA damage (31.37), Although thephysiological relevance of this obser-vation has yet to be evaluated. it isunlikely thai this will present anyadverse effect in vivo. Catalytic metalions (copper and iron, for example)that would catalyze free radical reac-tions in vivo are safely sequestered, butthese arc present in atheroscleroticlesions. For the food matrix, proteins(as secondary antioxidants) can abol-ish these prooxidant actions, Interest-ingly, in the deoxyribose assay whichthe author has developed for evaluat-ing prooxidanr actions (17), carnosoland carnosic acid scavenge hydroxylradicals and protect the deoxy sugarfrom damage by this species (37).

Extracts of herbs and spices areincreasingly of interest in the foodindustry because they retard oxidativedegradation of lipids. Herbor 025 is anorganoleptically neutral extract (39),showing good antioxidant properties infood applications, namely. in productssuch as ham, meat dumplings, driedoats, roasted hazelnuts. dehydratedsalmon, and fried oriental noodles.Herbor 025 is a deodorized rosemaryextract in a medium-chain triglyc-erides oil as carrier.

Carnosol (0.6%. wt/vol) andcarnosic acid (4.4%. wt/vcl) are theactive principles in Herbor 025. Thespice cocktail is an extract of four dif-ferent herbs: rosemary, sage, thyme,

and oregano. The main antioxidants inthe spice cocktail are camosol (0.28%,wt/vol), carnosie acid (1.2%, wtlvol),carvacrol (0.25%, wtlvol), and thymol(0.25%, wtlvol).

Herbor 025 and the spice cocktailhave in addition been tested for theirability 10 act as antioxidants in non-food systems (40). They are indeedpotent inhibitors of phospholipid lipo-somes peroxidation (Figure 2). Theoutcome of the Rancimat test supportsthe antioxidant activities of theextracts in the nonfood system. Chain-breaking antioxidants react with per-oxyl radieals, introducing a lag periodinto the percxidation process that cor-responds with the time taken for theantioxidant to be consumed. Herbor025, at the low concentrations tested,produced good protection againstautooxidation for chicken fat and lard(Table 2). A comparison is made inTable 2 with other extracts of sage.thyme, oregano, rosemary, and ginger.Herbor 025 and the spice cocktail areuseful antioxidants relevant to themaintenance of oxidative stability ofthe food matrix and could equallycontribute to antioxidant protection invivo.

Other considerationsIt has been widely speculated that gar-lic and ginger might be beneficial tohuman health because they exertantioxidant activity (41-43). Commer-cial ginger powder tested at concentra-tions of up to 5 mgfmL inhibits the per-oxidation of phospholipid liposomes,

but a sample of one commercial prepa-ration (Kwai) was less effective. Theginger and garlic preparations are pow-erful scavengers of hydroxyl radicals(OH·) and are able to react withhypochlorous acid at a rate sufficient toprotect catalase and a-I-antiproteinaseagainst inactivation (44). This protec-tion against attack of HOCI supportsthe suggestion that food antioxidantsmight have useful functions in vivo asscavengers of HOCI. However, the gin-ger and garlic preparations also couldinteract with iron cbelates to facilitateOH· generation from H202 (44). Cate-chins are natural products that occur ingreen lea and have been claimed topossess antioxidant actions superior toBHA and di-a-tocopherol. Ferulic acidoccurs in concentrations of up to 1.1 x10-2 moles/kg in chia seeds. Chia is adesert plant found predominantly inMexico (45). Ferulic acid is also pre-sent in grains, tomatoes, spinach, cab-bage. and asparagus. Ferulic acid athigh concentrations (up to 5 mM), and(:t:) catecbtns. (+) catechins, and (-)epicatechin are good inhibitors ofphospholipid-liposome peroxidationand scavengers of CCI302· radicals(Table I). Catechins inhibit the copper-dependent oxidation of LDL in vitro.Ferullo acid and catechins are efficientscavengers of the myeloperoxidase-derived oxidant hypochlorous acid(HOCI) (17).

The work of Plumb et al. (46) isillustrative of the theme of this article.The antioxidant properties of extractsof fruits (apple, pear, peach, plum, andgrapefruit), herbs (tarragon and basil),and spice (black pepper) were investi-gated. The extracts possessed somevery potent antioxidant properties simi-lar to those with pure dietary phyto-chemicals. The interest in the health-promoting qualities of plant foods maybe ascribed to the observation that vari-ous compounds present in these foodspossess antioxidant properties in vitro.The work of Gillman et at. (47) is illus-trative, suggesting a protective effect offruits and vegetables on developmentof stroke in men. There is a congenialscientific consensus that cancers arelargely preventable and that the mosteffective means of reducing cancer riskare avoidance of tobacco use, con-sumpuon of appropriate diets-includ-

INFORM. Vol. 8, no. 12 (December 1997)

1241

ing fruits and vegetables, and limitingexposure to occupational and environ-mental carcinogens. Block et al. (48) inan excellent review of 200 studies thatexamined the relationship between fruitand vegetable intake and various can-cers suggested that "if the consumptionof fruits and vegetables could bemanipulated by public policy, clinicaladvice, and public education, this mayhave a substantial impact on a widerange of cancers." This is highly appli-cable to a wide spectrum of humandegenerative diseases. Humans sel-dom-if at all-eat isolated com-pounds, and most plant foods are com-posed of diverse constituents in a com-plex matrix. Pears contain many com-pounds-phenolics, carotenoids, andIlavones-c-thnt individually possessantioxidant properties. Nevertheless,crude pear extract showed minimalantioxidant activity (46). Many foodsare not eaten raw but are processed,e.g., by cooking and by being chopped,etc. This invariably generates a differ-ent spectrum of compounds with dif-ferent antioxidant properties.

Concluding commentsThe view that Herbor 025 and thespice cocktail Provencal may be con-sidered as new generations of plant-derived food-grade antioxidants is par-ticularly interesting. It is clear thatdespite the endogenous and dietaryantioxidants, oxidative damage stilloccurs ill vivo. Ongoing research inmany laboratories is focused on mea-surement of markers of baseline oxida-tive damage in humans and examina-tion of how they are affected bychanges in diet (from the viewpoint offruit and vegetable intake, consump-lion of saturated/unsaturated fats),chemotherapy with antioxidant phar-maceuticals or supplementation withantioxidants (e.g., pure compounds orcomplex plant extracts) with referenceto the strategy in Figure 1. The optimalintake could be determined, as couldthe biological relevance of putativeantioxidantlprooxidant effects. Thechallenge is this: what type of baselineoxidative modulation in DNA damage,in repair enzymes, in antioxidantenzymes (e.g., overexpression of theamioxidant enzyme manganese super-oxide dismuta.se has been suggested to

The importance of free radicals in healthmay be realized by the development and

validation of assays applicable to humansfor the measurement of oxidative stress.

be protective against oxidative insult),in lipids, in proteins, and in geneexpression can supplementation inhumans or animal models (such asguinea pigs which, like humans, areunable to synthesize vitamin C) with

plant extracts and plant-derived antiox-idants (including the antioxidant vita-mins E and C and ~-carotene) pro-duce? The answers, when they come,will continue to fuel research in thisarea well into the twenty-first century.From a food stability perspective, onewould be interested in the integrity ofthe food and the effects of storage onthe molecular components of the food.That a role exists for free radicals andantioxidants in the pathogenesis ofhuman diseases and in the process oraging has led to the suggestion thatantioxidants, in particular. plant-diet-derived antioxidants, might havehealth benefits as prophylactic agents.The importance of free radicals inhealth may be realized by the develop-ment and validation of assays applica-ble to humans for the measurement oroxidative stress. This would facilitateestablishment of a logical basis for thetherapeutic use of plant extracts andplant-derived antioxidants.

ReferencesI. 51. Angelo, A., lipid Oxidation in

Food. American Chemical Soci-ety, Washington, D.C .. 1992.

2. Chan, H.-W.5 .. Autoxidation ofUnsaturated Lipids, AcademicPress, London. United Kingdom,1987.

3. Loliger, J .• The use of antioxi-dants in foods. in Free Radicalsand Food Additives. edited by 0.1.Aruoma and B. Halliwell. Taylor& Francis. London. United King-dom, 1991. pp. 121-150.

4. Frankel, E.N., Lipid oxidation,Prog. lipid Res. 19: 1-22 (1980).

5. Porter, N.A., S.E. Caldwell. andK.A. Mills, Mechanism of freeradical oxidation of unsaturatedlipids, lipids 30:277-290 (1995).

6. Hudson, BJ.F., Food Antioxidants,Elsevier Applied Science. NewYork,I990.

7. Shahidi, F., Natural Antioxidants:Chemistry, Health Effects andApplications, AOCS Press, Cham-paign, 1997.

8. Allen, J.C., and R.J. Hamilton.Rancidity in Foods, Applied Sci-ence Publishers, London, UnitedKingdom, 1989.

9. Min, D.B., and T.H. Smouse,Flavor Chemistry of Fats andOils, American Oil Chemists'Society, Champaign, 1985.

10. Hudson, B.J.F., Biochemistry ofFood Proteins, Elsevier AppliedScience, London, United King.dom, 1992.

II. Bailey, A.J., Recent Advances illthe Chemistry of Meat. RoyalSociety of Chemistry, London.United Kingdom, 1984.

12. Ames, B.N., M.K. Shigenaga,and T.M. Hagen, Oxidants,antioxidants and the degenerativedisease or aging, Proc. Natl.Acad. Sci. USA 90:7815-7822(1993).

13. Ames, B.N., L.S. Gold, and w.e.Willett, The causes and preventionof cancer, Ibid. 92:5258-5265(1996).

14. Aruoma, 0.1., Characterization ofdrugs as antioxidant prophylac-tics, Free Radical Bioi. Med.20,675-705 (1996).

15. Diplock, A.T., Antioxidants anddisease prevention. Mol. AspectsMed. 15:293-376 (1994).

INFORM. Vol. 8. no. 12 (December 1997)

1242

HEALTH & NUTRITION

16. McCord, J.M., Human disease,free radicals and theoxidant/antioxidant balance, Clin.Biocltem. 26:351-367 (1993).

17. Aruoma, 0.1., Nutrition andhealth aspects of free radicals andantioxidants. FQOdCnem. Toxicot.32.-671-683 (1994).

18. Bonorden, W.R .. and M.W.Panza, Antioxidant nutrients andprotection from free radicals, inNutritional Toxicology, edited byF.H. Kotsonis, M. Mackey, and J.Hjelle. Raven Press, New York,1994, pp. 19-48.

19. Pezzuto, 1.M., Plant-derived anti-cancer agents, Biochem. Pharma-col. 53:121-133 (1997).

20. Shahidi, F.. and J.P.K.P.D. wane-sundera, Phenolic antioxidants.Crit. Rev. Food Sci. Nutr.32.-67-103 (1990).

21. Namiki, M., Antioxidantslantimu-tagens in foods. Ibid. 29:273-300(1990).

22. Pratt, D.E., Antioxidants indige-nous to foods, Toxicol. Ind.Health 9:63-75 (1993).

23. Papas, A.M., Oil-soluble antioxi-dant in foods. Ibid. 9: 123-149(1993).

24. Cook, N.C" and S. Sam man,FI a vono i d s-c hem i s try,metabolism, cardioprotectiveeffects, and dietary sources, J.Nutr Biochem. 7:66-76 (1996).

25. Hermann, K., Flavanol andflavones in food plants, J. FoodTechnol. 11:433-448 (1976).

26. Kahnu, S., The flavonoids: Aclass of semi-essential food com-ponents: their role in human nutri-tion, World Rev. Nmr. Diet24.-117-191 (1976).

27. Cody, V., E. Middleton, and L.B.Harbone. Plant Flavonoids illBiology and Medicine: Biochenu-cal, Cellular and Medicinal Prop-erties, Alan R. Liss, New York.1988.

28. Steinberg. D., S. Parthasarathy.T.E. Carew, r.c. Khco, and J.L.Witztum, Beyond cholesterol:Modifications of low-densitylipoprotein that increase itsarherogeniciry. N. E1Igl. J. Med.320:915-924 (1989).

29. Aruoma, 0.1., and S.L. Cuppett,Antioxidant Methodology: in vivo

and in vitro Concepts, AOCSPress, Champaign. 1997.

30. Rapola, J.M., J. Virtamo, S. Ripat-ti. J.K. Huttunen, D. Albanes, P.R.Taylor, and O.P. Heinonen. Ran-domized trial of a-tocopherol and~-carotene supplements on inci-dence of major coronary events inmen with previous myocardialinfarction, l..imcet349:l715-1720(1997).

31. Aruoma, 0.1 .. Assessment ofpotential prooxidant and antioxi-dant actions, J. Am. Oil Chem.Soc. 73:1617-1625 (1996).

32. Boskou, D., Olive Oil: Chemistryand Technology. AOCS Press,Champaign. 1996.

33. Aeschbach, R., J. Loliger. B.C.Scott, A. Murcia. J. Butler. B.Halliwell, and 0.1. Aruoma. Theantioxidant actions of thymol. car-vacrol, 6-gingeroJ, zingerone andhydroxytyrosol. Food Chem. Tox-icol. 32:31-36(1994).

34. Galli. c., A. Petroni. and F. Visi-olio NaturaJ antioxidants with spe-cial reference to those in olive oiland cell protection, Eur: 1. Pharm.Sci. 21:67-68 (1994).

35. Pearson, D.A .. E.N. Frankel, R.Aeschbach, and J.B. German.Inhibition of endothelial cell-mediated oxidation of low-densitylipoprotein by rosemary and plantphenolics. 1. Agric. Food Chem.45.-578-582 (1997).

36. Wu, J.w., M.H. Lee, c.r; Ho. andS.S. Chang, Elucidation of thechemical structures of naturalantioxidants isolated from rose-mary, 1. Am. Oil Ctiem, Soc.59.-339-345 (1982).

37. Aruoma, 0.1., B. Halliwell, R.Aeschbach, and J. Loliger. Antiox-idant and pro-oxidant properties ofactive rosemary constituents:camosol and camosic acid. Xeno-biotica 22:257-265 (1992).

38. Cuvelier, M.-E .• H. Richard, andC. Berset. Antioxidative activityand phenolic composition of pilotplant and commercial extracts ofsage and rosemary. J. Alii. OilChem. Soc. 73:675-705 (1996).

39. Aeschbach, R .. R. Bachler. P.Rossie, L Sandoz. and H.J. Wille,Mechanical extraction of plantantioxidants by means of oils, Fa!

Sci. Tedmol. 96:441-443 (1994).40. Aruorna, 0.1., J.P.E. Spencer, P.

Rossi, R. Aeschbach. A. Khan, N.Mahmood, A. Munoz. A. Murcia,J. Butler, and B. Halliwell, Anevaluation of the antioxidant andantiviral action of extracts of rose-mary and provencal herbs, FoodChem. Toxicoi, 34:449-456(1996).

4). Phelps, S., and W.S. Harris, Garlicsupplementation and lipoproteinoxidation susceptibility. Lipids28.-475-477 (1993).

42. Masuda, T.. and A. Jitoe, Antiox-idative and anti-inflammatorycompounds from tropical gingers.Isolation, structure determinationand activities of cassumunins A, B,and C. new complex curcurmncidsfrom Zingiber cassumuna, J.Agric. Food Chem. 44: 1850-) 856(1995).

43. Torok, B., J. Belagyi, B. Rietz,and R. Jacob. Effectiveness ofgarlic on the radical activity inradical generating systems.Arzneim. Forscll.lDrug Res. 44:608-Q11 (1994).

44. Aruoma, 0.1.. J.P.E. Spencer. D.Warren, P. Jenner, J. Butler. andB. Halliwell, Characterization offood antioxidants: Illustratedusing commercial garlic and gin-ger preparations. Food Chem,57.-149-156 (1997).

45. Taga, M.S., E.E. Miller, and D.E.Pratt, Natural antioxidants in Chiaseeds, 1. Am. Oil Chem. Soc.61.-928-931 (1984).

46. Plumb. G.W., SJ. Chambres, N.Lambert, B. Bartolome. R.K.Heaney. S. Wanigatunga, 0.1.Aruorna. B. Halliwell, and G.Williamson, Antioxidant action offruit. herb. and spice extracts, 1.Food lJpid 3:171-188 (1996).

47. Gillman, M.W., LA. Cupples, D.Gagnou. B.M. Posner. R.C. Elli-son, w.P. Castelli, and P.A. Wolf.Protective effect of fruits and veg-etables on development of strokein men, J. Am. Med. Assoc.273: 1113-1117 (1995).

48. Block. G .. B. Patterson. and A.Subar, Fruit, vegetables, and can-cer prevention: a review of theepidemiological evidence, Nutr.Cancer 18: 1-29 (1992). •

tNFORM,Vol.8. no. 12(December 1997)