TANNINS AND HUMAN HEALTH: Nutraceuticals effect of Tannin and its Monomers.

MAYANK TANDON & DR. S.N. RAIAnimal Nutrition Division,

National Dairy Research Institute,Karnal, INDIA

e-mail: mayanktandon1@gmail.com

TANNINS

• Plant Tannins: distinctive group of polyphenolic polymers of relatively high molecular weight (M.W = 1000 to 20,000)

• Further categorized as: HYDROLYSABLE tannins (HTs) or CONDENSED tannins (CTs or Proanthocyandins) on the basis of their structure and reactivity.

• HTs are of low M.W (500-3000) and are polyesters of Gallic acid (gallo tannins) and hexahydroxy-diphenic acid (ellagitannins) with a central polyols such as sugars/glucose and phenolic such as catechin.

• CTs, M.W (1900-28000) have no carbohydrate core and comprise a group of polyhydroxy-flavan-3-ol oligomers and polymers linked by carbon-carbon bonds between flavanol subunits.

TANNINS (Basic structure)

Hydrolysable Tannins

oo oH

o

o

oHoH oH

oH

Glucose

o oo o

Glucose

oH oH oH oH

oHoH

Gallotannins Ellagitannins

oH o

Catechin

OH

OH

OH

oH

Condensed Tannins

• Cardiovascular disease, principally heart disease and stroke, are the leading cause of mortality in both men and women in all racial and ethnic groups.

• The risk of atherosclerosis is increased by high blood pressure, hypertension, kidney disorders, obesity, diabetes, smoking, excessive alcohol consumption, stress, thyroid and adrenal gland problems, and lipid disorders

(Crespy and Williamson 2004)

• Tea contains many compounds, especially poly-phenols and epidemiologically studies show that polyphenolic compounds present in tea reduces the risk of a variety of diseases.

• Catechins are the main compounds in green tea; they consist of (-)-epicatechin, (-)-epicatechin-3-gallate (ECg), (-)-epigallocatechin, (-)-epigallocatechin-3-gallate (EGCg) etc.

(Graham, 1992)

• Monomers (catechin, epicatechin, gallic and

ellagic acid) of Tannin present in red wine/ green

tea improve the antioxidative / immune status of

the animals/ human.

(Percival et al., 2002)

• Epidemiological studies shows that poly-phenolic

compounds present in the Tea reduce the risk of

a variety of diseases.

THERAPEUTIC VALUES OF TANNIN METABOLITES

• Mice consumed wine rich in phenolic components as catechin, epicatechin, gallic acid, ellagic acid showed increased antioxidant activity.

• Gallic acid (GA) also showed strong antioxidant activity by preventing lipid per-oxidation.

• GA is a strong antioxidant that possesses antimutagenic and anticarcinogenic activities

(Shahrzad et. al., 2001)

• Green tea contains:

(+) – gallocatechin (GC),

(-)– epicatechin (EC),

(-)– epigallocatechin (EGC),

(-)– epicatechingallate (ECG),

(-)– epigallocatechingallate (EGCG)

which shows numerous biological activities including antibacterial, antioxidant, anti-tumor and cancer preventive activities.

• Catechin serve as powerful antioxidant against lipid per oxidation when phospholipid bi-layers are exposed to aqueous oxygen radicals.

• (+)Catechin prevents cancer (liver, lung, breast and colon cancer) in at least one of three ways:

First, they can prevent the formation of carcinogens,

Second, they tone up the body's natural detoxification defenses, and

Finally, they suppress cancer promotion. • (+)Catechin has other promising qualities:

antibacterial and antiviral agent, regulating cholesterol and blood pressure, and reducing blood clotting tendencies that may cause heart attacks or strokes

NEUTRACEUTICAL EFFECTS OF CATECHIN AND EPICATECHIN

• Powerful Antioxidant effect – prevent lipid peroxidation

(Terao et al., 1994).

• Antioxidant activity Scavenge free radicals and reduce oxidative stress. • Enzyme induction and enhancing detoxification glutathione peroxidase catalase superoxide dismutase

• Catechin and epicatechin have Super Oxide Dismutase (SOD) like activity. (Kim et al., 1995)

Cont… • Prevent free radical induced RBC hemolysis. (Zhang et al., 1997)

• Prevent coronary artery disease. (Ishikawa et al., 1997) • Inhibit the oxidation of LDL cholesterol, reduced body fat and thereby decrease incidence of heart disease.

• Catechins may stimulate the secretion of Bile salts and the fecal excretion of cholesterol.

• EGCG inhibit phospholipid hydro peroxidation in plasma.

• Catechin have an anti-hyperglycemic action (Liu et al., 2005)

• Lowering blood glucose and normalizing insulin release.

• Prevent cancer (Valcic et al, 1996) – prevent formation of carcinogen, increase the body’s detoxification mechanism against tumor inducing agents.

• Inhibition of Onco-gene expression (Liu, 2004)

• Gallic acid occurs as a free molecule or as part of a tannin molecule.

• GA is a strong antioxidant that possesses antimutagenic and anticarcinogenic activities

(Shahrzad et. al., 2001)

Weight gain, food intake and liver weight of the rates on control and powered green tea (PGT) treatments.

(Zhang, et al., 2002)

Measurement Control PGT (2 % in DM)

No. of rats 10 10

Initial body weight, g 166.9 167.0

Body wt. gain, g /d 68.6 79.0

Food intake, g /d 14.78 15.69

Liver weight, g /rat 9.9 10.2

Effect of dietary powered Green tea on serum cholesterol level and Atherogenic Index (A) and on serum triglyceride and lipid peroxide level (B). (Zhang, et al., 2002)

0

1

2

3

4

5

6

1 2 3 4

seru

m c

hole

ster

ol le

vel

mm

ol /l

control

PGT

0

1

2

3

4

5

1 2

mm

ol/ l control

PGT

A1. Total cholesterol m mol / l 2. HDL - Ch3. VLDL + LDL - Ch4. Atherogenic index

B1. Serum triglyceride

2. Serum lipid peroxide

Plasma cholesterol, TG and oxidative state of plasma lipoprotein in mice fed on atherogenic diet with and without tea extract. (Miura, et al., 2001)

Particular Time Control Tea group

(3.2 mg /d)

No of mice 16 17

Body weight, g 0, wks 25.1 25.9

14 23.4 26.5

Plasma cholesterol, m mol/ l

0, wks 14.6 14.6

14 83.2 75

Plasma triglyceride,

m mol /l

0 0.89 0.86

14 0.49 0.85

Plasma lipid peroxidase,

µmol MDA /l

0 6.48 8.63

8 30.3 20.0

Atheromatous area, aortic weights and aortic lipid contents in mice fed an atherogenic diet with and without tea extract. (Miura, et al., 2001)

Particulars Control Tea group % Reduction

Atheromatous area, % 36.1 27.7 23

Aorta, mg 14.3 11.0 23

Cholesterol, µmol / aorta 0.830 0.610 27

Triglycerides , µmol / aorta 0.137 0.068 50

Composition of Phenolic Compounds in Tea extract(Miura, et al., 2001)

Catechins Mg/ g

(-)Epigallocatechin-gallate (EGCg) 584

(-) Epigallocatechin (EGC) 117

(-) Epicatechin (EC) 66

(-)Gallocatechingallate (GCg) 16

(-)Epicatechin-gallate (ECg) 5

Caffeine. 4

Varying level of Potency among Catechins.

• A in vivo experiment indicated that the components of tea catechins possess varying inhibitory effects on Cu2+ - mediated oxidation of LDL in the following order:

EGCg > ECg > EC > C > EGC

(Miura, et al., 1994 & 2001)

Catalase protein expression in rats at 16 wks of age that consumed water (control), Black tea polyphenols, Green tea polyphenols for 3 wks (Negishi, et al., 2004)

catalase

020406080

100120140160

1 2 3

Control BTP GTP

% i

nte

nsit

y o

f cata

lase

exp

ressio

n

catalase

Extract was having tea Polyphenols 5 g /l of water. And water consumption was 30 ml /d

Catechin feeding effects on plasma TAS in rats (pietta, et al., 1998)

Treatment TAS (total antioxidant status), m moles/ l

Control 1.5 ± 0.3

Catechin (2.1 g /l) 3.5 ± 0.3

Colon Cu-Zn SOD in rats given catechin (pietta, et al., 1998)

0

500

1000

1500

2000

2500

3000

1

Cu

-Zn

SO

D (

un

ite

s/ g

)

Control

Catechin

Mg/Liter Muscadine Wine

Total Phenols 834

Gallic acid 14

Ellagic acid 8

Catechin 5

Epicatechin 22

B3 procyanidin 0.3

Composition of Phenolic Compounds in Muscadine

Wine (Percival et al.,2002)

Total antioxidant capacity of plasma of mice

consuming red muscadine wine or ethanol

0

0.1

0.2

0.3

0.4

1 2

Abso

rban

ce a

t 405

nm

1 : Muscadine wine 2 : Ethanol (Percival et al.,2002)

• Catechins hypothesized to help protect against various diseases by contributing, along with antioxidant vitamins (i.e. Vit. C & E) and enzymes (i.e. SOD and Catalase)

• In vivo studies show that green tea catechins increase total plasma antioxidant activity.

• Intake of Green tea extract also increases the activity of SOD in serum and the expression of catalase in the aorta.

• Malondialdehyde, marker of oxidative stress, decreases after Green tea intake

• Catechins have a direct (antioxidant) or indirect (increase of activity or expression) effect.

• Because catechins can act as antioxidant in vitro, they might prevent the oxidation of other antioxidants, such as vitamin E.

• In some cases ingestion of green tea catechins does not modify the plasma status of vitamin E and C in vivo

• Catechins increase vitamin E concentration in LDL and in this way could protect LDL against peroxidation.

Glucose concentration affected by Tannic acid (Liu et al., 2005)

• In an oral Glucose tolerance test in rats, tea catechins decreased plasma insulin levels but did not affect plasma glucose levels.

• In type 2 diabetes, lipid metabolism is modified: Plasma and Liver triglyceride levels and plasma cholesterol levels are elevated, GTE intake reduced these values in rats fed a sucrose-rich diet.

• Catechins also reduced plasma TG levels.

• Tannic acid (TA) induces glucose transport through activation of the Insulin-mediated signaling pathways in adipocytes.

• TA inhibited the expression of key genes for adipogenesis, and has an insulin-like glucose transport stimulatory activity in adipocytes.

• Epigallocatechin gallate (EGCG) enhances oral glucose tolerance in severely diabetic mice and in moderately diabetic rats.

CONCLUSION

• Tannins & its monomers have profound effects on health.

• Not advisable to take a large quantity of tannins, as they may be toxic.

• It is important to determine the correct dosage of tannins for promoting optimal health.