catechin : a polyphenol of health benefits

Catechin : Polyphenol Health Benefit

ByShikha singh

M.Sc Nutritional Sciences

“Leave your drugs in the chemist’s pot if you can

cure the patient with food.”

Hippocrates, 420 BCThe Father of Medicine

PHYTOCHEMICAL• Phytochemicals are non-nutritive plant chemicals.• There are more than thousand known

phytochemicals.• They are protective or disease preventive in nature

due to the free radical scavenging activity i.e. they act as antioxidants.

Antioxidant

• An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules.

• Oxidation reactions can produce free radical, which start chain reaction that damage cells.

• Antioxidants terminate these chain reactions by

removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves.

TYPES OF PHYTOCHEMICAL

• Phenolic compounds.

• Terpenes (isoprenoids).

• Betalains.

• Organosulphides.

• Indoles.

• glucosinolates.

Contd…….S.No Phytochemical

sTypes Sources

1. Phenolic compounds

Monophenols, Flavonoids, Phenolic Acid, Hydroxycinnamic Acids, Lignans, Tyrosol Esters & Stilbenoids

Parsley , rosemary, Strawberries, grapes, citrus fruits, green tea , wine , apple juice ,soy, pumpkin etc.

2. Terpenes (isoprenoids)

Carotenoids, Monoterpenes & Saponins

Carrot , guava, mango, peaches, oranges etc.

3. Betalains. Betacynins & Betaxanthins. Beets, prickly pear etc

4. Organosulphides.

Dithiolthiones &Thiosulphonates

Garlic, onions etc.

5. Indoles. Indole-3-carbinol Garlic, onions etc.

6. glucosinolates Allicin, Alliin, Allyl iothiocyanate &Piperine

broccoli, black pepper etc

Flavanols

• They have 2-phenyl-3,4-dihydro-chromen-3-ol skeleton.

• Flavanols keep arteries flexible, increase small vessel circulation, reduce blood pressure and protect against sunburns.

• It is also known as flavan-3-ol.• Example :-Catechins

Catechins • Catechins is a polyphenolic antioxidant plant

metabolite.• Catechins are the major building blocks of tannins

& also known as procyanidins.• These compounds are most common in the seeds

and skins of fruits that have not fully ripened.• As fruit mature, the phenolics on the seed surface

combine with other compounds to form the seed coat.

• Catechin on enzymatic oxidation forms theaflavin which further oxidizes to thearubigins.

Types of Catechins

• (+)Catechin• (+)Gallocatechin (GC)• (+)Catechin 3-gallate (CG)• (+) Gallocatechin 3-gallate (GCG)• (-)Epicatechin (EC)• (-) Epigallocatechin (EGC)• (-)Epicatechin 3-gallate (ECG)• (-)Epigallocatechin 3-gallate (EGCG)

Contd……

Sources:-• Green Tea• Chocolate• Apples• Apricot• Peach• Red raspberry• Blackberry• Black tea• red wine

Catechin content of some foods

S.No Food Catechins mg/serving

Catechins, mg/100g food

1. Chocolate 23-30 46-61

2. Beans 70-110 35-55

3. Apricot 20-50 10-25

4. Cherry 10-44 5-22

5. Grape 6-35 3-17.5

6. Peach 10-28 5-14

7. Apple 20-86  10-43

8. Red raspberry 2-48 2-48

9. Strawberry 2-50 2-50

10. Blackberry 9-11 9-11

11 Green tea 20-160 10-80

12. Black tea 12-100 6-50

13 Red wine 8-30 8-30

14. Cider 8 4Hollman P, Katan M: Absorption, metabolism and health effects of dietary flavonoids in man. Biomed Pharmacother 1997.

Metabolism

• Flavonoids are present in plants conjugated to sugars.

• Flavan-3-ols are always present in the diet in the non-glycosylated form.

• Consequently, unlike other dietary flavonoids , there is no initial requirement for ß-glucosidase action prior to absorption.

• EGCG oxidize rapidly.• Oxidized EGCG Dimerized

product (greater scavenging activity & Fe chelating property.

• Ascorbate increases the stability of flavanols .

• Glucuronidation (to form β-glucuronides) as well as methylation reactions occur in catechin metabolism and absorption

Health benefits of Catechin

• Antioxidant activity.• Anticarcenogenic.• Antiatherogenic.• Function as enzymes.• Antibacterial.• Antibioctic• Antidiabetic.• Others

Antioxidant activity

• The free-radical causes peroxidation of polyunsaturated fatty acids in the lipid bilayer of cell membrane .

• It causes a chain reaction of lipid peroxidation, thus damaging the cellular membrane and causing further oxidation of membrane lipids and proteins.

• Subsequently, cell contents, including DNA, are damaged. It is this free radical-induced damage which is thought to precede many disease

processes. 

Scavenging activity of catechin

Catechins

Contd……..

LIPID. LIPID

OH

O .

OH

HO

HO

OH

o O

Antiatherogenic

• Atherogenesis initiated by oxidation of the lipid in LDL termed as lipid per oxidation .

• Oxidized LDL Accumulate in extra cellular sub endothelial space.

• Catechin have been shown to inhibit the oxidation of low-density lipoprotein (LDL)

• As the oxidized form of LDL that leads to the buildup of fatty streak in arteries.

Contd……

• Endothelin Reduces.• Block the platelet aggregation.• Anticarcenogenic:-• EGCG inhibit urokinase (u-plasminogen

activator).• One of the most frequently expressed

enzymes in human cancers.• Inhibit cell proliferation & induces apoptosis.

• Modulate & inhibit the NFKB activity.

Thermogenic:-

• Catechins have been found to promote thermogenesis. • Function as enzymes :-• Catechin and epicatechin have Super Oxide Dismutase

(SOD) like activity. (Kim et al., 1995)

• Antibiotic effects:-• Green tea catechins have also been shown to

possess antibiotic  properties due to their role in disrupt during the bacterial DNA replication process.

• Others:-• Lowered the Oxidative stress in cell mitochondria.• Catechin and epicatechin are monoamine oxidase

inhibitor.

Antidiabetic

• Black tea had the highest α-Amylase & α-glucosidase inhibitory activity, followed by wine.

• Reference:-Kwon, Young-in & Shetty “Inhibitory potentional of wine & tea catechins against α-Amylase & α-glucosidase for management of hyperglycemia “Journal  of Food Biochemistry (2008)

• Increases the insulin activity but this need more investigation.

• Reference:- fumto nanjo ,tsuruoka yamagata “effect of catechin on glucose tolerance” publised in Journal  of nutritional science vitaminol vol-53 (2007)

Depigmenting Effect of Catechins

• Human skin pigmentation is caused by melanin synthesis in UV irradiated melanocytes.

• Tyrosinase is a key enzyme in melanin synthesis that can catalyze three different reactions:-

Tyrosine 3,4dihydroxyphenylalanine(DOPA)

DOPA DOPAquinone DOPAquinone Melanin

Melanocyte in epidermis

Contd……….

• EGCG, EGC, and GA have significant inhibitory activity of melanin synthesis.

• flavan-3-ols containing a gallic acid moiety at the 3 position shows storong inhibition of tyrosinase activity.

• Therefore, the depigmenting effect of catechins is due to direct inhibition of tyrosinase activity.

The doctor of the future will give no medicine,

but will instruct his patients

in the care of the human frame, in diet, and in the cause and prevention of

disease.Thomas A. Edison1902

References:-

• G, Ascherio A, Rosner B, Spiegelman D, Willett W: The effect of fruit and vegetable intake on risk of coronary heart disease. Ann Intern Med 2001, 134:1106-1114

• Hollman P, Katan M: Absorption, metabolism and health effects of dietary flavonoids in man. Biomed Pharmacother 1997.

• Vinson J, Su X, Zubik L, Bose P: Phenol antioxidant quantity and quality in foods: fruits. J Agric Food Chem 2001, 49:5315-5321.

• 14. Hertog M, Feskens E, Hollman P, Katan M, Kromhout D: Dietary antioxidant flavonols and risk of coronary heart disease: the Zutphen Elderly Study. Lancet 1993,

Contd….

• Rein D, Paglieroni TG, Wun T, Pearson DA, Schmitz HH, Gosselin R, Keen CL. Cocoa inhibits platelet activation and function. Am J Clin Nutr 2000;72.

• Murphy KJ, Chronopoulos AK, Singh I, Francis MA, Moriarty H, Poke MJ, et al. Dietary flavanols and procyanidin oligomers from cocoa (Theobroma cacao) inhibit platelet function. J Nutr 2003.

Any doubt ??