PDR for Herbal Medicines

370/GREEN TEA PDR FOR HERBAL MEDICINES

Other Names: Black Tea, Chinese Tea, Green Tea

ACTIONS AND PHARMACOLOGY

COMPOUNDS

Purine alkaloids (methyl xanthines): caffeine (previously

referred to as theine or teine; depending upon the develop-

ment stage of the leaves, 2.9-4.2%, content declining with

age), theobromine (0.15-0.2%), theophylline (0.02-0.04%)

Thterpene saponins (theafolia saponins): aglycones includ-

ing among others, barringtogenol C, Rl-barringenol

Catechins: in unfermented (green) tea 10-25%, with fermen-

tation partially changing over into oligomeric quinones with

tannin character, into theaflavine, theaflavin acid, thearubi-

gene, or into non-water soluble polymeric- flavonoids:

including, among others, quercetin, kaempferol, myrecetin

Flavonoids: including quercetin, kaempferol, myricetin

Caffeic acid derivatives: including among others, chlorogen-

ic acid, theogallin

Anorganic ions: high fluoride content (130-160 mg/kg),

potassium and aluminum ions

Volatile oil: chief components linalool, in fermented tea also

2-methyI-hept-2-en-6-on, alpha-ionon and beta-ionon, more

than 300 volatile compounds are involved in tea aroma

EFFECTS

The caffeine in the drug has a centrally stimulating and

antidepressive effect (adenosine antagonism.) Adenosine

antagonism leads to dilation of the renal vessels with a

consecutive increase of the rate of filtration (diuresis).

Caffeine is positively inotropic, promotes the secretion of

gastric juices, glycolysis and lipolysis. In animal tests,

bradykinin and prostaglandin antagonism caused a capillary

sealing and anti-inflammatory effect.

An antidiarrheal effect can be attributed to a combination of

the tannin effect and the fact that doses of 400 mg

polyphenols administered three times daily promotes the

growth of Lactobacillis and Bifidobacter species while

inhibiting the growth of Clostridium perfringens and Clos-

tridium difficile (Yamamoto, 1997).

There is clinical evidence that Green Tea has cancer

preventive effects. The types of cancer that Green Tea has

been shown to prevent as demonstrated in well controlled

clinical studies include cancers of the pancreas, colon, small

intestine, stomach, breast and the lung.

Green Tea mouthwashes have been shown to inhibit the
growth of cavity-associated bacteria such as Streptococcus
mutans, Streptococcus salivarius and Escherichia coli (Ra~
sheed 1998; Haider, 1998).

CLINICAL TRIALS

Cancer Treatment/Prevention

A large (n = 2226) case-control study was conducted in

China, where recently diagnosed cancer cases (pancreatic,

colon and rectum) among residents between the ages of 30

and 74 years were included. Controls (n = 1552) were

selected and matched to cases by age and gender and

adjustments were made for age, income, education and

cigarette smoking. As tea consumption increased, the inci-

dence of all three cancers decreased. Women with the

highest tea consumption (> or = 200 g/month) had a 33%

reduced risk for colon cancer, 43% reduced risk of rectal

cancer and 47% reduction in the risk for pancreatic cancer

(p= 0.07, 0.001 and 0.008 respectively). For men who

consumed > or = 300 g/month of Green Tea, the risk of

colon cancer was reduced by 18%, for rectal cancer there

was a 43% reduction of risk and for pancreatic cancer the

risk reduction was 47% (p= 0.38, 0.04 and 0.04 respectively)

(Ji, 1997).

A two-part case control study of 472 Japanese women with

stage I, II or III breast cancer was conducted. The first part

of the study assessed the association between consumption

of Green Tea prior to clinical cancer and the number of

axillary lymph node metastases for premenopausal women or

the increased expression of progesterone receptor and

estrogen receptor among postmenopausal women with stage

I or II cancer. The second part of the study investigated the

recurrence rate of those with stage I or II breast cancer in

relation to the amount of Green Tea consumption. There was

an inverse relationship between the amount of Green Tea

consumption and the rate of cancer recurrence. The recur-

rence rate was 16.7% for those that consumed > or = 5 cups/

day and 24.3% among those consuming < or = 4 cups/day (p

< 0.05). The authors concluded that increased consumption

of Green Tea prior to clinical cancer onset is significantly

associated with improved prognosis of stage I and II breast

cancer, and that this association may be related to a

modifying effect of Green Tea on the clinical characteristics

of the disease (Nakachi, 1998).

Dental Caries Prevention

An extract of oolong tea (semifermented tea leaves of

Camellia sinensis) containing polymerized polyphenols in

0.2% ethanol was administered to 35 volunteers between 18

and 29 years of age to test the inhibitory effect of the extract

on dental plaque deposition. The study was repeated 1 week

after the first trial using 0.2% ethanol without the tea extract.

The oolong tea cohort showed significant inhibition of

plaque deposition (Ooshima, 1994).

In another study, it was demonstrated that total inhibition of

Streptococcus mutans was possible after exposure to a 0.1%