This document discusses purine alkaloids found in tea leaves. It provides details on: 1) Tea leaves contain various purine alkaloids like caffeine, theophylline, and theobromine. These compounds are responsible for tea's stimulant effects on the central nervous system. 2) Black tea leaves contain high amounts of beneficial polyphenol compounds like catechins, theaflavins, kaempferol, quercetin, and gallic acid which have antioxidant and other health promoting properties. 3) The main purine alkaloids and polyphenols in tea - caffeine, catechins, theaflavins, kaempferol and quercetin -

1. Purine
alkaloids
Dr Rajani Srivastava
Tea

4. Introduction
•Purines alkaloids are derivatives of xanthine and secondary plant
metabolic products.
•Various plants like tea, coffee, cola, guavana and mate contain
derivatives of xanthine., generally called purine alkaloids.
•They occur in various parts of the world and are popular for stimulant
beverages because of presence of CNS stimulant principle called
caffeine.

6. •They are heterocyclic compounds formed by annellation of a
pyrimidine and imidazole nucleus.
•These are considered as non alkaloids or pseudo alkaloids because
of non involvement of intact amino acids in their biosynthesis and
because of amphoteric character.
•Purine nucleus is not very common in higher plants except
constituents of nucleic acids.
•They are alkaloids but do not respond to common alkaloidal
reagent but they give murexide reaction.

7. Tea
•Synonyms: Camellia thea
•Biological source: leaves of Camellia sinensis or Thea sinensis.
Family: Theaceae.
•Geographical source: China, Myanmar, Thailand, Vietnam, India.
•Indigenous to rainy Asian forest.
•World 60% need fulfilled by three countries: India, China, Sri Lanka.
•The tea plant is a small wild tree 5-10 meters in height, branchy with
indeciduous leaves.

8. Finest quality teas are collected by picking of unopened
apical bud and young leaves.
Commercial grade of tea depends upon botanical verities,
age and possible treatment.
Varieties of tea:
green tea
Black tea
Oolong tea

9. •Green tea made by leaves of Camellia sinensis and its cultivated
varieties made by fermentation, rapid desiccation with heat and dried
(caffeine less than 2%).
•Black tea: unfermented rest is same process for preparation.
•Oolong tea: partially fermented.
•Fermentation process allows poly phenol oxidase activity which
modifies composition, appearance, odour and taste of tea.
•Fermentation process does not alter concentration of caffeine in tea.

10. Chemical constituents:
Protein ( 15-20)
Amino acids (3%)
Sugars (5%)
Ascorbic acid
Vit B complex
Purine base (caffeine ,Theophylline, Theobromine)
Phenolics (20%)
Gallo tannins
flavonoids

11. • Black tea is a rich supply of a variety of polyphenols including flavones,
flavanols, and phenolic acids.
• Catechins,
• Theaflavins,
• Kaempferol,
•Quercetin
•and gallic acid are present in plenty amount in black tea

12. Theaflavin
•It is Chemical compound
•Theaflavin and its derivatives, known collectively as theaflavins, are antioxidant
polyphenols that are formed from the condensation of flavan-3-ols in tea leaves
during the enzymatic oxidation.
•It has been reported that theaflavins have various biological activities, such as
antioxidant and anticancer activities.
•Thearubigins comprise 10–20 % of the dry weight of black tea.
•Theaflavins are one of several beneficial compounds found in black tea leaves
that support arterial health and cholesterol levels already within the normal
range.

13. Catechins
•Catechins are a group of flavonoids that are abundant in the fresh leaves of the
tea plant.
•Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant
roles in plants. It belongs to the subgroup of polyphenols called flavonoids.
•They are bioactive chemicals that have beneficial effects on health.
• The most abundant catechin in tea is epigallocatechin gallate (EGCG).
•Catechins can also be found in other food plants, such as apples, berries and
cocoa, but in lower concentration than tea.
• Green tea delivers the greatest range of catechins, cocoa products also
contain a modest amount of these antioxidant-rich polyphenols.
•Green tea contains the highest levels of catechins.

14. Kaempferol
•Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavanol, a type of
flavonoid, found in a variety of plants and plant-derived foods including
• kale,
• beans,
• tea,
• spinach, and broccoli.

15. Quercetin
•It is Plant flavanol.
•Quercetin is a plant flavanol from the flavonoid group of
polyphenols.
• It is found in many fruits, vegetables, leaves, seeds, and grains;
capers, red onions, and kale.

16. Theaflavin
Catechins
Kaempferol
Quercetin

17. Pharmacological activity
•Stimulant
•Diuretic
•Antioxidant
•Hypolipidemic
•Traditional Uses:
•Treatment of mild diarrhoea
•Other uses: used in beverages as CNS stimulant and diuretic.

18. uses:
•In humans, caffeine, 1,3,7-trimethylxanthine, is demethylated into three
primary metabolites: theophylline, theobromine, and paraxanthine.
•Since the early part of the 20th century, theophylline has been used in
therapeutics for bronchodilation, for acute ventricular failure, and for long-
term control of bronchial asthma.
•At 100 mg/kg theophylline is fetotoxic to rats, but no teratogenic
abnormalities were noted

19. •In therapeutics, theobromine has been used as a diuretic, as a cardiac
stimulant, and for dilation of arteries.
• But at 100 mg, theobromine is fetotoxic and teratogen (Collins, FDA By-
lines No. 2, April 1981). Leung (1980) reports a fatal dose in man at 10,000
mg, with 1,000 mg or more capable of inducing headache, nausea,
insomnia, restlessness, excitement, mild delirium, muscle tremor,
tachycardia, and extrasystoles.