[CANCER RESEARCH54, 3428-3435, July 1, 1994)

ABSTRACT

In a previous study (Z Y. Wang et ci., Cancer Res., 52: !!62—1!70,!992),wefoundthatadministrationof a waterextractof greentealeavesas the sole source of drinking fluid inhibited ultraviolet B light (UVB)Induced carcinogenesis in SKH-! mice previously Initiated with 7,12-dimethylbenz[alanthncene (DMBA). In the present study, we comparedthe effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on UVB-lnduced skin carclnogenesis In DMBA-inltiatedSKH-! mice. A 1.25% water extract of each kind of ten leaf (US g tealeaf/100 ml water) was prepared by passing 4 liters of hot water through50g of tealeavesIn a Burntteabrewingmachine.Themeanconcentradons of solids in multiple samples of 1.25% black tea, green tea, decalfeinated black tea, and decaffeinated green tea analyzed during the courseof this study were 4.23, 3.94, 3.66, and 3.53 mg/ml, respectively. Theseconcentrations of tea solids are similar to those present in tea brewsingested by humans. Female SKH-! mice were treated topically with 200nmol of DMBA, followed 3 weeks later by Irradiation with 30 mJ/cm2 ofUVB twice weekly for 3! weeks. UVB-Induced formation of skin tumorswas markedly inhibited by oral administration of0.63 or 1.25% black tea,green tea, decaffeinated black tea, or decaffeinated green tea as the solesource of drinking fluid 2 weeks prior to and during 3! weeks of UVBtreatment. Administration of each of the eight tea preparations not only

inhibited the number of tumors, but tumor size was also markedly decreased. Histopathological examination of each tumor showed that oraladministration of the eight tea preparations had a marked Inhibitoryeffect on the formation of UVB-induced keratoacanthomas and carcinomas AdmInistration of 1.25% black tea, green tea, decaffeInated blacktea, or decaffeinated green tea inhibited the number of keratoacanthomasper mouse by 79, 78, 73, or 70%, respectively, and the number of cardnomas per mouse was Inhibited by 93, 88, 77, or 72%, respectIvely. Insummary, administration of black tea was comparable to green tea as aninhibitor of UVB-induced skin carcinogenesis in DMBA-iaitiated SKH-!mice. Oral administration of decaffeinated black tea or decaffeinatedgreen tea also had a marked inhibitory effect on UVB-induced skincarcinogenesis in DMBA-lnitiated SKH-! mice, but these tea preparationswere slightly less effective than the regular teas at the high dose leveL

INTRODUCTION

It is estimated that 600,000 new cases of skin cancer occur eachyear in the United States, and the majority of these are believed toresult from heavy exposure to UV light from the sun (1, 2). Althoughmost of these skin cancers are curable squamous cell carcinomas and

Received1/28/94;accepted4/28/94.Thecostsof publicationof thisarticleweredefrayedin partby thepaymentof page

charges. This article must therefore be hereby marked advertisement in accordance with18U.S.C.Section1734solelyto indicatethisfact.

1 This study was supported in part by Grants No. CA49756 and ES05022 from the

National Institutes of Health.2 William M. and Myrle W. Garbe Professor of Cancer and Leukemia Research.

3 To whom requests for reprints should be addressed, at Department of Chemical

Biology and Pharmacognosy, College of Pharmacy, Rutgers University, P.O. Box 789,Piscataway, NJ 08855-0789.

basal cell carcinomas, deaths do occur from these cancers as well asfrom more dangerous sunlight-induced melanomas (1, 2).

In previous studies, the oral administration of a green tea polyphenol fraction (3) or an aqueous extract of green tea leaves (4) as the solesource of drinking fluid to SKH-1 mice inhibited the formation ofUVB4-induced skin tumorigenesis. In the later study, we found thatadministration of green tea as the sole source of drinking fluidinhibited UVB-induced tumor initiation as well as UVB-inducedtumorigenesis in DMBA-initiated SKH-1 mice (4). During the courseof our studies, we also found that tumors from animals treated withUVB togetherwith green tea were only 15—25%as large as tumorsfrom UVB-treated positive controls (4). In subsequent studies, wedemonstrated an inhibitory effect of green tea on the growth ofestablished skin papillomas in mice (5).

As indicated above, previous studies on the effects of tea onUVB-induced tumongenesis in mice used only green tea or a greentea polyphenol fraction. However, of the 2.5 million metric tons of tealeaves produced worldwide in 1990, about 78% was used for thepreparation of black tea, which is mainly consumed in Westernnations, and about 20% was used for the preparation of green tea,which is mainly consumed in Asian countries and in some parts ofNorth Africa (6). Green tea is made from fresh tea leaves by blanching, twisting, and drying. The dried tea leaves contain polyphenolssuch as flavanols (catechins), flavonols, flavandiols, and phenolicacids. These polyphenols account for about 25—30%of the solids inwater extracts of green tea leaves (6). The major green tea catecbinsare (—)-epigallocatechin-3-gallate, (—)-epigallocatechin, (—)-epicatechin-3-gallate, (—)-epicatechin, and (+)-catechin. In the manufacture of black tea, the polyphenols in tea leaves undergo polyphenoloxidase-catalyzed oxidative polymerization, which leads to the formation of bisfiavanols, theaflavins, thearubigens, and other oligomersin a process commonly known as “teafermentation―(6). Theaflavins(about 1—2%of the solids in water extracts ofblack tea leaves) includetheaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin3,3'-digallate, and these substances contribute to the characteristiccolor and taste of black tea. A substantial portion of the solids in waterextracts of black tea leaves represents thearubigens, which are evenmore extensively oxidized and polymerized than theaflavins. Thethearubigens have a wide range of molecular weights and are poorlycharacterized. In this paper, we report a comparative study on theeffects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice. The comparative effects of the different tea preparations on the percentage of mice with tumors, tumors per mouse,tumor size, and the number of keratoacanthomas, squamous cellcarcinomas, and basal cell carcinomas were evaluated.

4 The abbreviations used are: UVB, ultraviolet B light; DMBA, 7,12-dimethylbenz

[a]anthracene.

3428

Inhibitory Effects of Black Tea, Green Tea, Decaffeinated Black Tea,and Decaffeinated Green Tea on Ultraviolet B Light-induced SkinCarcinogenesis in 7,12-Dimethylbenz[a]anthracene-initiatedSKH-1 Mice'

Zhi Y. Wang, Mou-Tuan Huang, You-Rong Lou, Jian-Guo Xie, Kenneth R. Reuhi, Harold L. Newmark,

Chi-Tang Ho, Chung S. Yang, and Allan H.@

Lcborato,yfor Cancer Research@ Departments ofChemicalBiology and Pharmacognosy [Z. Y. W., M-T. H., Y-R. L, J-G. X., H. L. N., C. S. Y, A. H. C.] and Pharmacology andToxicology (K. R. R.J, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway, New Jersey 08855-0789, and Department of Food Science@ Cook College@Rutgers,State University ofNew Jersey,New Brunswich@NewJersey 08901 [C-i'. H.]

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

Table1 Polyphenoland caffeinecontentof typicalsamplesof blacktea,greentea, decaffeinatedblacktea, and decaffeinatedgreentea1.25% Water extracts of black tea, green tea, decaffeinated black tea, and decaffeinated green tea were prepared as described in “Materialsand Methods.―Catechins, theaflavins,

fiavonols,andfiavonolglycosidesweredeterminedbyhigh-pressureliquidchromatographyanalysis(4).TotalpolyphenolsweredeterminedasPolyclarATabsorbables(7).Undefinedpolyphenols were determined by substracting catechins, theaflavins, flavonols, and fiavonol glycosides from the total polyphenol fraction (Polyclar AT absorbables). Undefined blackteapolyphrnolsincludethearubigens,epitheaflaviCacids,bisfiavonols,andotheruncharacterizedphenoliccompounds.Undefinedgreenteapolyphenolsarepredominantlygallocatechinandgallocatechinpilate. Totalteasolids,whichweremeasuredasdescchedearlier(4),alsocontainedprotein,aminoacids,carbohydrate,simplesugars,lipids,dietaryfiberandash.Tea

(@tg/ml) Tea (% ofsolids)DecaL

DecaL Decal. DecaLTeaconstituent Black black Green green Black black Greengreen(—)-Epigallocatechin-3-

128 104 444 367 2.94 2.67 11.16 10.34gallate

(—)-Epicatechin-3-gallate 73 69 90 90 1.68 1.77 2.26 2.54(—)-Epigailocatechin 42 33 411 313 0.97 0.85 10.33 8.82(—)-Epicatechin 37 28 98 72 0.85 0.72 2.46 2.03(+)-Catechin 20 28 2! 20 0.46 0.72 0330.56Total

catechins 300 262 1064 862 6.92 5.96 26.7124.28Theaflavin

22 12 0 0 0.51 0.30 0 0Theaflavin-3-gallate 20 12 0 0 0.46 0.30 0 0Theaflavin-3'-gallate 13 7 0 0 0.30 0.18 0 0Theaflavin-3,3'-digallate 9 5 0 0 0.22 0.12 00Total

theaflavins 64 36 0 0 1.49 0.90 00Flavonols

and flavonol 95 97 101 101 2.18 2.49 234 2.85glycosidesUndefined

polyphenols 1466 1140 589 625 33.70 29.30 14.8017.61Total

polyphenols 1925 1535 1754 1588 44.94 46.27 44.0744.73Caffeine

218 <4 221 <4 5.00 <0.1 5.56<0.1Total

tea solids 4350 3890 3980 3550 100 100 100 100

BLACKTEA/GREENTEAJUVB-INDUCEDCARCINOGENESI5

tea, green tea, decaffeinated black tea, and decaffeinated green tea are shownin Table 1.The catechins in the various tea samples were relatively stable whenstored at room temperaturefor 48 h (<15% disappearance),and similar studieswith each tea preparation in water bottles that were actively used by mice during

the courseofour studiesindicatedthat therewas a 7, 3, 23, and 0% decreasein theconcentration of catechins in actively used water bottles of mice treated with

1.25% black tea, green tea, decaffeinated black tea, and decaffeinated green tea,respectively,over a 48-h interval,where each value representsthe mean of datafrom 15 separate stability determinations for each tea preparation.

Uv Light.Ultravioletlamps(FS72T12-UVB-HO)thatemitUVB(280—320 nm; 75—80%of total energy) and UVA (320—375 nm; 20—25%of total

energy) were obtained from the Voltare Co. (Fairfield, Cl'). The dose of UVBwas quantified with an UVB Spectra 305 Dosimeter obtained from the DaavlinCo. (Bryan, OH). The radiationwas further calibratedwith an 1L1700ResearchRadiometerfPhotometer from international Ught, Inc. (Newburyport, MA).

For exposure to UV (UVA + UVB), 10 mice were housed in a 25.4 cm X45.7 cm plastic box. Six boxes (without tops) were placed under 8 UV lamps

(50.8 cm X 182.9 cm), and the boxes were systematically rotated during the

course of the study to compensate for possible small differences in flux atvarious positions under the lamps. The distance between the UV lamps and the

backs of the mice or the UVB detector was about 43 cm. The amount of

exposure to UVB was controlled by a Spectra 305 Dosimeter. The exposuretime for a 30@ dose of UVB was about 25 s. Although all data areexpressed as exposure to UVB, some additional exposure to UVA also occuned as indicated above.

Thmorigenesis ProtocoL Mice were divided into 12 groups with 30 miceper group as shown in Table 2. Female SKH-l mice were treated topically with

a single applicationof 100 @.dof acetone(groupA) or 200 nmol DMBA in 100@Llof acetone (group B). In group C, mice were treated topically with acetone

followed 3 weeks laterby UVB treatment(30 mi/cm2) twice a week for 31weeks. In groups D-L, mice were initiated with 200 nmol DMBA in acetone

followed 3 weeks later by UVB treatment (30 @J/cu2)twice weekly for 31weeks. In groupsE-L at 2 weeks before UVB treatment,the mice were given25,50,and75%ofthe full-strength0.63or 1.25%teainfusions(2 daysateachconcentration), followed by the full-strength extract which was administeredfor 1 week before and throughout the UVB treatment interval until the end of

3429

MATERIALS AND METHODS

Chemicals and Tea. Purifiedwaterwas preparedby reverseosmosisand wasused for the preparationof all tea infusions.Acetone,methanol,chloroform,ethylacetate, and 10% buffered formalin phosphatewere obtained from Fisher Scientific (Springfield, NJ). DMBA was obtained from Calbiochem-Behringer (SanDiego, CA). Polyclar AT (insolubilized polyvinylpyrrolidone) was Obtained fromthe OAF. Corp. (New York, NY). Black tea, green tea, decaffeinatedblack tea,and decaffeinated green tea were prepared from commercial grade tea leaves

@dedby the U.S. Tea Association(New YorlçNY). Decaffeinatedtea leaveswere preparedby extractingtea leaveswithmpercriticalCO2.

Animals. Female SKH-1 hairless mice (6—7weeks old) were purchasedfromCharlesRiverLaboratories(Kingston,NY). The animalswere keptin ouranimal facility for at least 1 week before use. Mice were given water andPurina Laboratory Chow 5001 diet (Ralston-Purina Co., St. Louis, MO) adlibitum and kept on a 12 h light/12 h dark cycle.

Preparation and Composition ofTea. Tea infusions were prepared usinga commercialBunnautomaticbasketteabrewer.Tea leaves (50 g) wereplacedin a filter paper-lined brewing basket, and 4 liters of hot, deionized water werepassed in the brewing machine through the tea leaves to obtain a 1.25% teainfusion (1.25 g tea leaf/!00 ml water). The resulting tea brews were similar to

those consumed by humans. The 1.25% water extracts of tea leaves werediluted 1:1 with water to make 0.63% tea extracts. Fresh tea extracts (1.25%)were prepared every Monday, Wednesday, and Friday and were used immediately as the sole source of drinking fluid throughout the entire study.Catechins, caffeine, and total solids in the tea infusions were determined asdescribed elsewhere (4). The high-pressure liquid chromatography conditionsdescribed earlier (4) were also used for the determination of theaflavins,flavonols, and flavonol glycosides. Total polyphenols were determined as totalPolyclar AT absorbables (7).

Total tea solids were determined after each preparation of tea as a measureof the consistency of tea preparation. The average concentration of total teasolids (nonvolatile constituents) present in 1.25% black tea, green tea, decalfeinated black tea, and decaffeinated green tea were 4.23 ±0.03, 3.94 ±0.04,3.66 ±0.04, and 3.53 ±0.05 mg/mI, respectively, where each value representsthe mean ±SE from 92 samples thatwere analyzedduringthe courseof thestudy. The compositions of typical samples of freshly prepared 1.25% black

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

Table2 Experimentaldesignand treatmentgroupsFemaleSKH-1 mice (30/group)were Initiatedwith 200 nmol of DMBA. One weekinter,the

miceweretreatedwithone-fouith,ore-halfthree-fourths,andfull-strengthteasolutions(2days at each dose level), followedby full-strengthteas as the sole source ofdrinkingfluidforthe durationofthe study. Controlanimalsreceivedwater.At 2 weeks after the stat of tea

administration, the mice were treated with UVB (30 mJ/cm2) @,jcea week for 31weeksDMBA

UVB(200(30@,j/@2Group

Drinking fluid nmol) twiceweekly)A

Water ——BWater +—CWater —+DWater ++EBlack tea (0.63%) ++FBlacktea (1.25)% ++GGreentea (0.63%) ++HGreentea (1.25%) ++IDecafblacktea (0.63%) ++JDecafblacktea (1.25%) ++KDecaf green tea (0.63%) ++LDecalgreentea (1.25%) + +

7 11 15 19 23 27

27 31

—0--GROUPk CONTROl.-4--GROUP B:DMBAAI.ONE

- 0- - GROUP C: UVB ALONE

@ —k--GROUP0: DMBA+

BLACK TEA/GREEN TEA/UVB-INDUCED CARCINOGENESIS

embedded in Paraplast. Six-sm sections of each tumor were stained witheosin-phloxine-hematoxylin and examined by light microscopy.

RESULTS

Effect of Oral Administration of Different Kinds of Tea onBody Weight, Fluid Consumption, and Food Consumption inSKI!-! Mice. Oral administration of black tea, green tea, decaffeinated black tea, or decaffeinated green tea (groups D-L) did notinfluence body weight (Figs. 1—5),but slight increases in food andfluid consumption were observed sporadically in some tea-treatedanimals during a 5-week observation period (data not shown). Foodconsumption during the first 5 weeks of full-strength tea administration was increased an average of 5—7%in mice that received 0.63 or1.25% black tea; 9—12%in mice that received 0.63 or 1.25% greentea; 0—2%in mice that received 0.63 or 1.25% decaffeinated blacktea; and 5—7%in mice that received 0.63% or 1.25% decaffeinatedgreen tea. Fluid consumption during this 5-week interval was increased 5—18%in mice that received 0.63 or 1.25% black tea; 15—18%in mice that received 0.63 or 1.25% green tea; 8% in mice thatreceived 0.63 or 1.25% decaffeinated black tea; and 13% in mice thatreceived 0.63 or 1.25% decaffeinated green tea.

Inhibitory Effect of Oral Administration of Different Kinds ofTea on UVB-induced Carcinogenesis in DMBA-initiated SM!-!Mice. Only a small number of tumors (1—4per group of 30 mice)were observed in control mice or in mice treated only with DMBA(groups A and B; Fig. 1). Mice that were treated with UVB (30mJ/cm2) twice a week for 31 weeks without prior DMBA initiation(group C) developed about 2 tumors per mouse, and the first tumor

EEw(I)

0

wa.Lu

-I

0

the study. The gradual increase in concentration of tea (described above)prevented any irregularities in fluid intake due to temporary taste aversion.Body weights and skin tumors greater than 1 mm in diameter were recorded.

Tumor volume was determined by measuring the three-dimensional size(height, length, and width) of all tumors and by using the average of the threemeasurements as the radius. Tumor volume was calculated by:

Volume = 4irr3/3

At the end of the study, each skin was placed in 10% buffered formalinphosphate for histological examination. All tumors from each mouse weredehydrated in ascending concentrations of ethanol, cleared in xylene, and

130

I

30

30

15

10

5@

I

I

40

7 11 15 19 23 27 31

WEEKS OF UVBTREATMENT

250

200

ISO

S

4

S100

2

SO

7 11 15 19 23 27 31

WEEKS OF UVBTREATMENT WEEKSOFUVBTREATMENTFig. 1. Formation of skin tumors in female SKH-1 mice treated with DMBA alone, UVB alone, or both DMBA (initiation) and UVB (postinitiation). Group A, untreated control.

Group B, mice treated with a single dose of 200 nmol of DMBA. Group C, mice treated with UVB (30 mJ/cm2) @ceweekly for 31 weeks. Group D, mice treated with a single doseof 200 nmol DMBA (initiation) followed 3 weeks later by UVB (30 mJ/cm2) twice weekly for 31 weeks. Each value is the mean from 28—30mice; bars, SE. In group C, 1 mousewith no skin tumors died during week 28, and another with tumors died during week 30. Data from these animals were included only up until death.

3430

WEEKSOF UVBTREATMENT

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

Time of appearance PercentageTumoroffirst tumor of mice No. of Volume/tumor volume/mouse

Group Drinking fluid (%) (wks of UVB treatment) with tumors tumors/mouse (mm3)(mm3)D

Watercontrol 7 93 6.0±1.0 40±12243±72EBlacktea(0.63) 13 6&' 1.5±0.3c 8±3' 12±6c

F Black tea (1.25) 19 35b 0.9 ±0.4c fl ±7( 10 ±6cGGreentea(O.63) 13 80 1.4±0.3c 12±4c 22±9'

H Greentea(1.25) 21 53― 1.2±0.4c 14±8c 16±9cI Decaffeinated black tea (0.63) 13 69k' 2.1 ±0.4' 10 ±4@?@@ 8cJ

Decaffeinatedblacktea(1.25) 19 77 1.7±0.3c 1O±4c 17±7'K Decaffeinatedgreentea(0.63) 9 64― 1.8±0.4c@ 11 36±19cL

Decaffeinatedgreentea(1.25) 15 80 1.8±O.3c 12±4c22±9'a

Female 5301-1 mice (7-8 weeks old) were treated topically with 200 nmol DMBA. One week later, the mice were treated with gradually increasing concentrations of tea in thedrinking water for 1 week and full-strength tea (0.63 or 1.25%) for an additional week prior to and during treatment with UVB (30 mJ/cm2) @ceweekly for 31 weeks. Eachvaluerepresents

the mean or mean ±SE from 28-30 mice.b Significantly different from group D using the@ test (P <0.05).C

Significantly different from group D using Student's t test (P < 0.05).

Table 4 Inhibitory effect of oral administration of black tea, green tea, decaffeinated black tea, or decaffeinated green tea on UVB-inducedformation ofkeratoacanthomasandcarcinomasin DMBA-initiated SKH-1miceThirty

micepergroupweretreatedwith200nmolDMBA.Oneweeklater,themiceweregivenincreasingdosesofblacktea(Si), greentea((IT),decaffeinatedblacktea(DBT),ordecaffeinated green tea (DOT) as the sole source of drinking fluid for 1 week and full-strength tea for the remainder of the study. At 2 weeks after the start of tea administration,

themiceweretreatedwith30 mJ/cm2of UVBtwicea weekfor31 weeks.All tumorswereexaminedby histopathology.In additionto thetumorsdescribedhere,all groupsexceptgroupB had a small number of papillomas (1—11per group), and groups D, H, and L each had one mouse with a sebaceous adenoma.

No. ofPercentageof mice withNo.of

No.ofGroupTreatment micekeratoacanthomaskeratoacanthomas

BLACK1'EA/GREENTEA/UVB-INDUCEDCARC!NOGENE5I@

Table3 Inhibitoryeffectoforal adminirtrationofblack tea,greentea, decaffeinatedblacktea, and decaffeinatedgreentea ontwnorigenesis by (NB light in DMBA-initiated SKH-1 mice―

was observed after 25 weeks of UVB administration (group C; Fig. 1).A small number of squamous cell carcinomas (3 per group of 30 mice)were observed in these animals when they were killed after 31 weeks ofUVB administration.Mice that were initiated with DMBA followed byUVB (30 mJ/cm2) twice a week for 31 weeks (group D) developed alarge number of tumors (6 per mouse), and the first tumor was observedafter 7 weeks of UVB administration(group D; Fig. 1; Table 3). Thirtythree % of these mice had a total of 18 squamous cell carcinomas whenthey were killed after 31 weeks of UVB administration (Fable 4).

Administration of 0.63 or 1.25% black or green tea to SKH-1 miceas the sole source of drinking fluid caused a dose-dependent inhibitionin UVB-induced tumorigenesis in DMBA-initiated SKH-1 mice, andblack and green tea had similar inhibitory effects (groups D-H; Figs.2 and 3; Table 3). Administration of 1.25% black tea or green tea:(a) lengthened the time for appearance of the first tumor from 7 weeksof UVB treatment (group D) to 19 or 21 weeks, respectively;(b) inhibited the percentage of mice with tumors by 62 or 43%,respectively, (c) inhibited the number of tumors per mouse by 85 or80%, respectively; and (d) inhibited the tumor volume per mouse by96 or 93%, respectively (Table 3).

Administration of 0.63 or 1.25% decaffeinated black or green tea toSM!-! mice also had a marked inhibitory effect on UVB-inducedtumorigenesis in DMBA-initiated mice, but a dose-response relation

ship was not observed (groups I-L; Figs. 4 and 5; Table 3). Administration of 1.25% decaffeinated black or green tea (groups J and L):(a) lengthened the time for appearance of the first tumor from 7 weeksof UVB treatment (group D) to 19 or 15 weeks, respectively;(b) inhibited the percentage of mice with tumors by 17 or 14%,respectively; (c) inhibited the number of tumors per mouse by 72 or70%, respectively; and (d) inhibited the tumor volume per mouse by93 or 91%, respectively (groups J and L; Table 3). These data indicatethat oral administration of black tea, green tea, decaffeinated blacktea, and decaffeinated green tea all have a strong inhibitory effect onUVB-induced tumorigenesis in DMBA-initiated mice.

Examination of the histopathology of each tumor indicated thatDMBA initiation followed by UVB administration twice a week for31 weeks (group D, positive control) resulted in 190 keratoacanthomas (6.33 keratoacanthomas per mouse) and 18 squamous cell cardnomas (0.60 carcinomas per mouse). Administration of 0.63 or 1.25%black or green tea caused a dose-dependent inhibition in the formationof UVB-induced keratoacanthomas and carcinomas in DMBA-initiated mice (groups D-H; Table 4). Administration of 1.25% black orgreen tea inhibited the percentage of mice with keratoacanthomas by64 or 56%, respectively, and the number of keratoacanthomas permouse was inhibited by 79 or 78%, respectively. Administration of1.25% black or green tea inhibited the percentage of mice with

Percentage ofmice with

carcinomas

00

1033144

217

10171717

No.ofcarcinomas/mouse

000.110.600.140.040.210.070.140.200.210.17

keratoacanthomas No. ofper mouse carcinomas―

A Acetone 30 7 2 0.07 0B DMBA 30 3 1 0.04 0C Acetone + UVBb 28 54 54 1.93 3D DMBA+UVB 30 97 190 6.33 18E DMBA + UVB + 0.63% BT 30 57 59 2.11 4F DMBA + UVB + 1.25% B'!― 29 35 39 1.35 10 DMBA + UVB + 0.63% 01― 28 54 48 1.71 6H DMBA+ UVB+ 1.25%GT 30 43 41 1.37 2I DMBA + UVB + 0.63% DBT― 29 66 73 2.52 4J DMBA + UVB + 1.25% DBT 30 67 52 1.73 6K DMBA + UVB + 0.63% DOT1 29 55 34 1.17 6L DMBA + UVB + 1.25% DOT 30 77 57 1.90 5

a All of these tumors were squamous cell carcinomas except for 1 basal cell carcinoma in group J and another in group K.b Dee mouse died during the 29th week with no tumors and one mouse died during the 30th week with a squamous cell carcinoma.C One mouse died during the 28th week with no tumors@

(Yamo@ waslostduringthe6thweekwithnotumorsandonemousewithtumorsdiedduringthe28thweek(nohistopathologydate).a o@ mouse died during the 20th week with a lymphoma.‘Onemouse died during the 28th week with a squamous cell carcinoma.

3431

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

II—e—GROUP0DMB@@+WATERII-.0—GROUPEDMBA+BLACKTEA(0.63%)II_—•@-GROUPFOMBA+BLACKTEA(1.25%)

7 11 IS 19 30 27 31

WEEKSOFUVBTREATMENT

WEEKSOFUVBTREATMENT

Fig. 2. Inhibitory effect of oral administration of two doses of black tea on the formation of UVB-induced skin tumors in mice previously initiated with DMBA. Female SKH-1mice were initiated with 200 nmol of DMBA. One week later, the mice were given gradually escalating doses of tea in the drinking water for 1 week, followed by full-strength teafor 1 week before and during treatment with UVB (30 mJ/cm2) twice weekly for 31 weeks. Each value is the mean from 29—30mice; bars, SE. In group F, one mouse without skintumors died during week 28. Data from this animal was included only up until death.

30

30

25

30

F-@ 10

S

3

230

150

130

50

7 11 15 19 n V SI

WEEKSOFUVBTREATMENT7 II IS 19 20 V SI

WEEKSOFUVBTREATMENT

BLACKTEA/GREENTEA/UVB-INDUCEDCARCINOGENESIS

100

50

50

40

WEEKSOFUVBTREATMENT

I

5

4

S

2

16 25 V11 15 19 23 27

WEEKSOFUVBTREATMENT

100

—h--GROUP 0: DMBA+ INS + WATER

-@0—G@O(W0:DMBA+UVB+GREENTEA(053%)—•—GROUPH:DMBA+ UVB+ GREENTEA(1.25%)

@ II 15 19 25 27 31

WEEKSOFUVBTREATMENT

I50

40

_ 250ELu

Lu

Fig. 3. Inhibitory effect of oral administration of two doses of green tea on the formation of UVB-induced skin tumors in mice previously initiated with DMBA. Female SKIt-imice were initiated with 200 nmol of DMBA. One week later, the mice were given gradually escalating doses of tea in the drinking water for 1 week, followed by full-strength teafor 1weekbeforeandduringtreatmentwithUVB(30mJ/cm@)twiceweeklyfor31weeks.Eachvalueis themeanfrom28-30 mice;bars, SE.In groupG, onemousewithtumorsdied during week 28 and another during week 30. Date from these animals were included only up until death.

3432

20

WEEKSOFUVBTREATMENT

S

4

30

30

,@

@ 15

@ 105

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

7 11 IS 19 23

WEEKSOFUVBTREATMENT

—e-.@@c@tjpD:DMBA+UVB+WATER—a—GROUP K OMBA + UVB + DECAFFEINATED GREEN TEA (0.63%)

—.—GROUP L DMBA + UVB + DECAFFEINATED GREEN TEA (125%)

100

SO

BLACK TEA/GREEN TEA/UVB-INDUCED CARCINOGENESIS

100

I

I

WEEKSOFUVBTREATMENT WEEKSOFUVBTREATMENTFig.5. InhibitoryeffectoforaladministrationoftwodosesofdecaffeinatedgreenteaontheformationofUVB-inducedskintumorsinmicepreviouslyinitiatedwithDMBA.Female

SKIt-i mice were initiated with 200 nmol of DMBA. One week later, the mice were given gradually escalating doses of tea in the drinking water for 1 week, followed by full-strength

tea for 1 week before and during treatment with UVB (30 mJ/cm@)twice weekly for 31 weeks. Each value is the mean from 29-30 mice; bars@SE. In group I, one mouse with skintumors died during week 20. Date from this animal was included only up until death.

50

50

V 31

7 . 11@ th@ ‘

WEEKSOFUVBTREATMENT

250

200

ISO

100

50

V SI

WEEKSOFUVBTREATMENT

30

30

30

@ 15@ —&-GROUP@ DMBA + UVB + WATER

2 @o—0—GROUPI:OMBA+UVB+DECAFFEINATEDBLACKTEA(0.63%)—--GROUP J: DMBA + UVB + DECAFFEINATED BLACK TEA (125%)

5 __________________________________________________________

0-

Lu

pFig. 4. inhibitory effect of oral administration of two doses of decaffeinated black tea on the formation of UVE-induced skin tumors in mice previously initiated with DMBA. Female

SKH-1 mice were initiated with 200 nmol of DMBA. One week later, the mice were given gradually escalating doses oftea in the drinking water for I week, followed by full-strengthteafor 1weekbeforeandduringtreatmentwithUVB(30mJ/cm@)twiceweeklyfor31weeks.Eachvalueis themeanfrom29—30mice;bars, SE.IngroupI, onemousewithskintumors died during week 20. Date from this animal was included only up until death.

@@ ____________@ 15!. t.

>. 10

5 _________a.

I

100

a0@

e0@

7 @11 31

WEEKSOFUVBTREATMENT

250

200

150

7

S

5

3433

WEEKSOFUVBTREATMENT

WEEKSOFUVBTREATMENT

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

BLACK TEA/GREEN TEA/UVB-INDUCED CARCINOGENESIS

carcinomas by 88 or 79%, respectively, and the number of carcinomasper mouse was inhibited by 88 or 79%, respectively (Table 4).Administration of 0.63 or 1.25% decaffeinated black or decaffeinatedgreen tea also had a strong inhibitory effect on the formation ofUVB-induced keratoacanthomas and carcinomas in DMBA-initiatedmice, but a-dose response relationship was not observed (groups I-L,Table 4). Administration of 1.25% decaffeinated black or decaffeinated green tea inhibited the percentage of mice with keratoacanthomasby 31 or 21%, respectively, and the number of keratoacanthomas permouse was inhibited by 73 or 70%, respectively. Administration of1.25% decaffeinated black or decaffeinated green tea inhibited thepercentage of mice with carcinomas by 49 or 49%, respectively, andthe number of carcinomas per mouse was inhibited by 77 or 72%,respectively (Table 4). The data suggest that, at a low dose level, thedecaffeinated and regular teas are equally effective at inhthiting UVBinduced carcinoma formation, but at the higher dose level, the regular teasmay be somewhat more effective inhibitors of carcinoma formation thanthe decaffeinated teas (Fable 4).

DISCUSSION

The results of the present study indicate that oral administration of1.25% black tea, green tea, decaffeinated black tea, or decaffeinatedgreen tea (1.25 g tea leaf/100 ml; 3.53—4.23mg of tea solids/mi) asthe sole source of drinking fluid markedly inhibited the formation ofUVB-induced tumors and decreased tumor size in DMBA-initiatedSKH-1 mice (Table 3; Figs. 2—5).The concentrations of tea solids,polyphenolic compounds, and caffeine in these 1.25% tea brews weresimilar to those ingested by humans (Table 1). Oral administration of1.25% black tea, green tea, decaffeinated black tea, or decaffeinatedgreen tea inhibited UVB-induced formation of keratoacanthomas permouse by 70—90%and inhibited UVB-induced formation of carcinoman per mouse by 72—93%.Administration of 0.63% black tea, greentea, decaffeinated black tea, or decaffeinated green tea (1.77—2.22mgof tea solids/ml) as the sole source of drinking fluid inhibited thenumber of UVB-induced keratoacanthomas per mouse by 60—73%and inhibited the number of UVB-induced carcinomas per mouse by65—77%(Table 4). The potent inhibitory effects of the low dose levelof tea (0.63%) suggest that even lower concentrations may haveinhibitory effects on UVB-induced carcinogenesis. The results of ourstudy indicate that black and green tea have a similar potent inhibitoryeffect on UVB-induced carcinogenesis in DMBA-initiated mice andthat both green and black tea decreased tumor size (Table 3; Figs.2—6).Earlier studies from our laboratory indicated that administrationof green tea had a marked inhibitory effect on tumor size in DMBAinitiated mice treated with UVB (4) and on the growth of establishedskin papillomas in mice (5). The similar potent inhibitory effects ofblack and green tea on tumor size described here (Figs. 2—5;Table 3)suggests that black tea may also have an inhibitory effect on thegrowth of established skin tumors.

The mechanism(s) of the inhibitory effects of green or black tea onUVB-induced carcinogenesis is unknown but may be related to theantioxidant and free radical-scavenging activities of the teas. Ascorbicacid (8), a-tocopherol (9), a-carotene (10), selenium (11), butylatedhydroxytoluene (12), and a mixture of dietary antioxidants (ascorbicacid, a-tocopherol, reduced glutathione, and butylated hydroxytoluene; Ref. 13) have been reported to inhibit UV-induced skin carcinogenesis. Several of the polyphenolic substances in green and black teahave been shown to have antioxidant activity (14—17).Unpublishedobservations in our laboratory indicate that green tea, black tea,decaffeinated green tea, and decaffeinated black tea all had about thesame ability to scavenge superoxide anion radicals. Caffeine is acomponent of green and black tea that may contribute to the inhibitory

effects of these beverages on UV-induced tumorigenesis. Topicalapplication of caffeine has been shown to inhibit UV-induced tumorigenesis on mouse skin (18), and caffeine has also been shown toinfluence mammary tumorigenesis in rats (19—21).The data presentedhere suggest that decaffeinated teas may be somewhat less effectivethan the regular teas at inhibiting UVB-induced skin carcinogenesis inDMBA-initiated mice. Other studies in our laboratory indicate thatdecaffeinated green tea may be less effective than regular green tea atinhibiting the effects of UVB as a complete carcinogen.5 Although alarge number of studies have shown an inhibitory effect of green teaor green tea constituents on chemically induced or UV-induced tumorigenesis (3—5,22—43),there are only a few studies on the potentialinhibitory effects ofblack tea on tumongenesis. Oral administration ofblack or green tea were reported to have a similar strong inhibitoryeffect on N-nitrosomethylbenzylamine-induced esophageal tumorigenesis (26, 41), and oral administration of decaffeinated black orgreen tea was reported to have a similar strong inhibitory effect on4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis (34). In the present study, we have found that orally administered black and green tea have the same potent inhibitory effects onUVB-induced skin carcinogenesis in mice. Although some work hasbeen done on the inhibitory effects of(-)-epigallocatechin-3-gallate (amajor constituent of green tea and a less prominent constituent ofblack tea) on chemical carcinogenesis (5, 23, 25, 37), both black andgreen teas are complex mixtures (Table 1), and more research isneeded to identify the active constituents in these teas and to determine the possibility of synergistic or antagonistic effects of themultiple constituents in tea. The results ofepidemiology studies on theeffects of tea on human cancer have been reviewed, but clear-cutconclusions cannot be made (44, 45). More definitive epidemiologystudies are needed.

ACKNOWLEDGMENTS

We thankDr. Douglas Balentine(ThomasJ. LiptonCo., EnglewoodCliffs,NJ) for the high-pressure liquid chromatography analyses and dry weightdeterminations with green and black tea samples, Dr. Yukihiko Ham (FoodResearch Laboratories, Mitsui Norm Co., Ltd., Fujieda, Japan) for referencesamples of theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3,3'-digallate. We also thank DebOrah Bachorik, Flo Florek, Diana Urn,and Paul T. Hans for their excellent help in the preparation of this manuscript.

REFERENCES

1. Friedman, R. J., Rigel, D. S., Berson, D. S., and Rivers, J. Skin cancer: basal cell andsquamous cell carcinoma. In: A. I. Holleb, D. J. Fink, and G. P. Murphy (ads.),American Cancer Society Textbook of Clinical Oncology, pp. 290-305. Atlante TheAmerican Cancer Society, Inc., 1991.

2. Sinajetary, S. E., and Balch, C. Malignant melanoma. In: A. I. Holleb, D. J. Fink, andG. P. Murphy (ads.), American Cancer Society Textbook of Clinical Oncology, pp.263-270. Atlante American Cancer Society, Inc., 1991.

3. Wang, Z. Y., Agarwal, R., Bickers, D. R., and Mukhtar, H. Protection againstultraviolet B radiation-induced photocarcinogenesis in hairless mice by green teapolyphenols. Carcinogenesis (Lond.), 12: 1527—1530,1991.

4. Wan&@ Y., Huang, M-T., Ferraro, T., Won& C-Q., Lou, Y-R., Reuhi, K., latropoulos, M., Yang, C. S., and Conney, A. H. inhibitory effect of green tea in thedrinking water on tumorigenesis by ultraviolet light and 12-O-tetradecanoylphorbol13-acetate in the skin of SKH-1 mice. Cancer Res., 52: 1162—1170,1992.

5. Wang, Z. Y., Huang, M-T., Ho, C-T., Chang, R. L, Ma, W., Ferraro, T., Reuhl, K. R.,Yang, C. S., and Conney, A. H. Effects ofgreen tea on the growth ofestablished skinpapillomas in mice. Cancer Res., 52: 6657-6665, 1992.

6. Graham, H. Green tea composition, consumption, and polyphenol chemistry. Prey.Med., 21: 334—350,1992.

7. Andersen, R. A., and Sower, J. A. Optimum conditions for binding of plantphenols to insoluble polyvinylpyrrolidone. Phytochemistry (Oxf.), 7: 293—301,1968.

8. Dunham, W. B., Zuckerkandl, E., Reynolds, R., Willoughby, R., Marcuson, R., Barth,R., and PaWing, L Effects of intake of L-ascorbic acid on the incidence of dermal

S Unpublished results.

3434

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

BLACKTEA/GREENTEAJUVB-INDUCEDCARCINOGENESIS

neoplasms induced in mice by ultraviolet light. Proc. NatI. Acad. Sci. USA, 79:7532—7536,1982.

9. Gensler, H. L, and Magdaleno, M. Topical vitamin E inhibition of immunosuppression and tumorigenesis induced by ultraviolet irradiation. Nutr. Cancer, 15: 97—106,1991.

10. Mathews-Roth,M.M.,andKrinsky,N. I. Carotenoidsaffectdevelopmentof UV-Binduced skin cancer. Photochem. Photobiol., 25: 507—509,1987.

11. Overvad, K., Thorlin& E. B., Bjernng, P., and Ebbesen, P. Selenium inhibits UVlight-induced skin carcinogenesis in hairless mice. Cancer Left, 27: 163-170, 1985.

12. Black,H. S., Chan,I. T., and Brown,G. E. Effectsof dietaryconstituentsonultraviolet light-mediated carcinogenesis. Cancer Res., 38: 1384—1387, 1978.

13. Black, H. S., and Chan, J. T. Suppression ofultravioletlight-induced tumor formationby dietaryantioxidants.J. Invest.Dermatol.,65: 412—414,1975.

14. Wang,Z. Y.,Cheng,S. J., Zhou,L C.,Athar,M.,Khan,W.A., Bickers,D. R.,andMukhtar, H. Antimutagenic activity of green tea polyphenols. Mutat. Res, 223:273—285,1989.

is.s@uid,N.,Goto,A.,Oguni,I.,Mashiko,S.,andNomoto,T.Reactionrateconstantsof tea leaf catechins with superoxide: superoxide-dismutase (SOD)-like activitymeasured by Cypridina luciferin analogue chemiluminescence. Chem. Express, 6:655—658,1991.

16. Osawa, T. Phenolic antioxidants in dietary plants as antimutagens. In: M-T. Huang,C. Y. Lee, and C-T. Ho (ads.), Phenolic Compounds in Foods and their Effects onHealth H: Antioxidants and Cancer Prevention. American Chemical Society Symposium Series 507, pp. 135-149. Washington, DC: American dhemical Society, 1992.

17. Laskin,J. D., Heck,D., Laskin,D. L, Mitchell,J. M.,Huang,M-T.,Wang,L Y.,Yang, C. S., Ho, C-T., and Conney, A. H. Inhibitory effects ofa green tea polyphenolfraction on 12-O-tetradecanoylphorbol-13-acetate-inducedhydrogen peroxide formation mouse epidermis. In: M-T. Huang, C. Y. Lee, and C-T. Ho (ads.), PhenolicCompounds in Foods and their Effects on Health II: Antioxidants & Cancer Prevenlion. American Chemical Society Symposium Series 507, pp. 308-314. Washington,DC:AmericanChemicalSociety,1992.

18. Zajdela, F., and Latarjet, R. Effet inhibiteur de Ia cafeine sur l'induction de cancerscutane's par les rayons ultraviolets chez la Souris. Compt. Rend. Seances. Acad. Sci.(Paris), Ser. D., 277: 1073-1076, 1973.

19. Welsch, C. W., DeHoog, J. V., and O'Connor, D. H. Influence of caffeine and/orcoffee consumption on the initiation and promotion phases of 7,12-dimethylbenz(a)anthracene-induced rat mammary gland tumorigenesis. Cancer Rca., 48:2068—2073,1988.

20. Welsch, C. W., and DeHoog, J. V. Influence of caffeine consumption on 7,12-dimethylbenz(a)anthracene-induced mammary gland tumorigenesis in female rats feda chemically defined diet containing standard and high levels of unsaturated fat.Cancer Res., 48: 2074-2077, 1988.

21. Welsch, C. W., DeHoog, J. V., and O'Connor, D. H. influence ofcaffeine consumption on carcinomatous and normal mammary gland development in mice. CancerRes., 48:2078-2082,1988.

22. Khan,W.A.,Wang,L Y.,Athar,M.,Bickers,D. R.,andMUkIItar,H. Inhibitionofthe skin tumorigenicity of (±)7@,8cx-dihydroxy-9a,10a-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene by tannic acid, green tea polyphenols and quercetin in Sencar mice.Cancer Left., 42: 7—12,1988.

23. Yoshizawa,S., Horiuchi,T., Fujiki,H., Yoshida,T., Okuda,T., and Sugimura,T.Antitumor promoting activity of(.)-epigallocatechin gallate, the main constituent of“tannin―in green tea. Phytother. Res., 1: 44—47, 1987.

24. Wang,Z. Y., Khan,W. k, Bickers,D. R., and MUkhtar,H. Protectionagainstpolycycic aromatic hydsocathon-induced skin tumor initiation in mice by green teapolyphenols. Carcinogenesis (Load.), 10: 411—415, 1989.

25. Fujita, Y. Yamane, T., Tanaka, M., Kuwata, K., Okuzumi, J., Takahashi, T., Fujiki,H. and Okuda, T. Inhibitory effect of (-)-epigallocatechin gallate on carcinogenesiswith N-ethyl-N'-thtro-N-nitrosoguanidine in mouse duodenum. Jpn. J. Cancer Res.,80: 503—505,1989.

26. Han,C.,andXu,Y.TheeffectofChineseteaontheoccurrenceofesophagealtumorsinduced by N-nitrosomethylbenzylamine in rats. Biomed. Environ. Sci., 3: 35-42,1990.

27. Xu, Y., and Han, C. The effect of Chinese tea on the occurrence of esophageal tumors

induced by N-nitrosomethylbenzylamine formed in vivo. Biomed. Environ. Sci., 3:406-412, 1990.

28. Gao, 0. D., Thou, L F., Qi, 0., Wang,H. S., and Li, T. S. Initial study ofantitumorigenesis of green tea (animal test and flow cytometry). Tumor (Chinese),10: 42—44,1990.

29. Yamane,T.,Hagiwara,N.,Tateishi,M.,Akachi,S.,Kim,M.,Okuzumi,J., Kitao,Y.,Inagake, M., Kuwata, K., and Takahashi, T. Inhibition of azoxymethane-inducedcolon carcinogenesis in rats by green tea polyphenol fraction. Jpn. J. Cancer Rca.,82:1336—1339,1991.

30. Li,Y.Comparativestudyontheinhibitoryeffectof greentea,coffeeandlevamisoleon the hepatocarcinogenic action of diethylnitrosamine. Chung-Hua Chung-Uu TsaChih, 13: 193—195,1991.

31. Harada, N., Takabayashi, F., Oguni, I., and Hara, Y. Anti-promotion effect of greentea extracts on pancreatic cancer in golden hamster induced by N-nitroso-bis(2-oxopropyl)amine. In: T. Yamanishi (ad.), Proc. tnt. Symp. Tea Sd., pp. 200—204.Shizuoka, Japan: Kurofune Printing Co., Ltd., 1991.

32. Hirose, M., Hoshiya, T., Takahashi, S., Hara, Y., and Ito, N. Inhibition of carcinogenesis by green tea catechins in rats. In: T. Yamanishi (ed), Proc. Int. Symp. TeaSd., pp. 210—213. Shizuoka, Japan: Kurofune Printing Co., Ltd., 1991.

33. Hara, Y. Prophylactic functions of tea polyphenols. In: T. Yamanishi (ed.), Proc. Int.Symp. Tea Sd., pp. 22—26.Shizuoka, Japan: Kurofune Printing Co., Ltd., 1991.

34. Wang,Z.Y.,Hong,J-Y.,Huang,M-T.,Reuhi,K.R.,Conney,A.H.,andYang,C.S.Inhibition of N-nitrosodiethylamine-and 4-(methylnitrosamino)-1-(3-pyridyl).1-butanone-induced tumorigenesis in NJ mice by green tea and black tea. Cancer Res.,52: 1943-1947, 1992.

35. Wang, Z. Y., Agarwal, R., Khan, W. A., and Mukhtar, H. Protection againstbenzo[a]pyrene and N-nitrosodiethylamine-induced lung and forestomach tumorigenesis in NJ mice by water extracts of green tea and licorice. Carcinogenesis (Lond.),13: 1491—1494,1992.

36. Huang,M-T.,Ho, C-T.,Wang,Z. Y., Ferraro,T., Finnegan-Olive,T., Lou,Y-R.,Mitchell, J. M., Laskin, J. D., Newmark, H., Yang, C. S., and Conney, A. H.Inhibitory effect of topical application of a green tea polyphenol fraction on tumorinitiation and promotion in mouse skin. Carcinogenesis (Lond.), 13: 947—954,1992.

37. Xu, Y., Ho, C-T., Amin, S. 0., Han, C., and Chung, F-L Inhibition of tobaccospecific mtrosamine-induced lung tumorigenesis in NJ mice by green tea and itsmajor polyphenol as antioxidants. Cancer Res., 52: 3875—3879,1992.

38. Ito,N.,Hirose,M.,andShied,T. Carcinogenicityandmodificationof carcinogenicresponse by plant phenols. In: M-T. Huang, C. Y. Lee, and C-T. Ho (eds.), PhenolicCompounds in Foods and their Effects on Health II: Antioxidants & Cancer Prevention. American Chemical Society Symposium Series 507, pp. 269-281. Washington,DC:AmericanChemicalSociety,1992.

39. Katiyar,S. K., Agarwal,R., Wang,Z. Y., Bhatia,A. K., and Mukhtar,H. (-)-Epigallocatechin-3-gallate in Cameiia sinensis leaves from Himalayan region ofSikkim: inhibitory effects against biochemical events and tumor initiation in SEN.CAR mouse skin. Nutr. Cancer, 18: 73-83, 1992.

40. Oguni,I., Chen,S. J., Un, P. Z., and Hara,Y. Protectionagainstcancerrisk byJapanese green tea. Prey. Med., 21: 332, 1992.

41. Wang, Z. Y., Wang, L-D., Chen, W. F., Thou, S. 0., Huang, M-T., Ho, C-T., Conney,A. H., and Yang, C. S. Inhibition ofN-nitrosomethylbenzylamine (NMBzA)-inducedesophageal tumorigenesis in rats by decaffeinated green tea and black tea. Proc. Am.Assoc. Cancer Res., 34: 125, 1993.

42. Katiyar, S. K., Agarwal, R., and MUkhtar,H. Protection against malignant conversionof chemically induced benign skin papillomas to squamous cell carcinomas inSENCAR mice by a polyphenolic fraction isolated from green tea. Cancer Res., 53:

5409—5412,1993.43. Narisawa, T., and Fukaura, Y. A very low dose of green tea polyphenols in drinking

water prevents N-methyl-N-nitrosourea-induced colon carcinogenesis in F344 rats.Jpn. J. Cancer Res., 84: 1007-1009, 1993.

44. WHOInternationalAgencyfor Researchon Cancer.Coffee,tea,matte,methyixanthines and methylglyoxyal. [ARC Monogr. Eval. Carcinog. Risks Hum., 51: 207—271,1991.

45. Yang, C. S., and Wang, Z. Y. Tea and cancer. J. Nail. Cancer Inst., 85: 1038-1049,1993.

3435

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from

1994;54:3428-3435. Cancer Res   Zhi Y. Wang, Mou-Tuan Huang, You-Rong Lou, et al.   ]anthracene-initiated SKH-1 Mice

aSkin Carcinogenesis in 7,12-Dimethylbenz[Light-inducedTea, and Decaffeinated Green Tea on Ultraviolet B

Inhibitory Effects of Black Tea, Green Tea, Decaffeinated Black

  Updated version

  http://cancerres.aacrjournals.org/content/54/13/3428

Access the most recent version of this article at:

   

   

   

  E-mail alerts related to this article or journal.Sign up to receive free email-alerts

  Subscriptions

Reprints and

  .pubs@aacr.orgDepartment at

To order reprints of this article or to subscribe to the journal, contact the AACR Publications

  Permissions

  Rightslink site. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC)

.http://cancerres.aacrjournals.org/content/54/13/3428To request permission to re-use all or part of this article, use this link

on July 15, 2020. © 1994 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from