SUBSTANCES USED FOR LOCAL EFFECTS
ASTRINGENTS (tannins)
• External usage
• Internal usage
EPITHELISANTS, GRANULANTS → DERMATOLOGICS
• External usage
TANNINS
Characteristics
• Heterogeneous organic polyphenols with relatively high molecular weight
• Amorphous compounds forming in water acidic colloid solution with astringent
taste
• After reaction with proteins produce insoluble substances → limited
therapeutical usage; leather industry – change skin to leather
• With heavy metals and alkaloids (with exception of morphine, atropine, cocaine)
fomr almost insoluble precipitates, with iron salts form inks
• The possess ability to agglutinate erythrocytes
• Oxidize, condensate and polymerize to non-active phlobaphenes
• In certain period of plant development as a defense against microorganisms
Occurence:
Dicotyledonous plants with exception of Papaveraceae and Brassicaceae
Rarely monocotyledonous plants
CLASSIFICATION ACCORDING TO THE
STRUCTURE
TANNINS
HYDROLYZABLE CONDENZED
(glycosidic)
GALLOTANINS ELLAGOTANINS CATECHINES
Gallic acid Ellagic acid Hydrogenated
+ sugar + sugar flavonols resp.
catechines
BULDING BLOCKS OF TANNINS
C
OH
OHOH
OH O
O
O
OH
OH
OH
OH
O
O
OOH
OH
OH
OH
H
OH
H
Gallic acid Ellagic acid Catechine
EXAMPLE OF DEPSIDIC BOND
ESTER BOND BETWEEN CARBOXYLIC GROUP OF ONE MOLECULE AND
HYDROXYL GROUP OF ANOTHER MOLECULE OF THE SAME COMPOUND
OH
OH OH
C
OH
O
OH
OH
O C
O
OH
OHOC
O
O
H
H
OR
H
OR
OH
H
H
OR
CH2
OR
R
R
m-trigallic acid
Tannin
= gallic acid
= m-trigallic acid
CONNECTION OF GALLIC ACID VIA C-C BOND
OH
OH
OH
COOH
OH
OH
OH
COOH
- H2
O
OH
OH
OH
OH
OH
OH
COOH
COOH
Hexahydroxydiphenic acid
(dimer of gallic acid)
ELLAGIC ACID FORMATION
OH
OH O
C
H
O OH
OH
OHO
C
H
OOH O
O
OH
OH
OH
OH
O
O
- H2O
Hexahydroxydiphenic acid Ellagic acid
CONDENSED TANNINS (CATECHINES)
Basic building block is catechine and its isomers, furthermore
hydroxyflavandiols (leucoanthocyanidins), hydroxyderivatives of
cinnamic acid.
Majority of condensed tannins is created in postmortal condensation
process without effect of enzymes.
Catechins condense in weakly acidic environment of cell liquid to true
water soluble amorphous tannins. This process is present also during
„postmortal“ wood storage. Condensation can take place also into dark
water-insoluble phlobaphenes.
Enzymatic change of catechines via polyphenoloxidases (for example red
pigmentation of cacao beans)
Some catechine tannins are in form of esters of catechine with gallic acid
(for example epicatechine-3-gallate in Theae folium).
CONDENSED TANNINS (CATECHINES)
OOH
OH
OH
OH
OH
OOH
OH
OH
OH
OH
OH
OOH
OH
OH
OH
OH
OH
OOH
OH
OH
OH
OH
Catechine (3-flavanol) Leukoanthocyanidine (3,4-flavandiol)
Dimeric condensation product as a first level
of tannin formation from
flavandiol and catechin
TANNINUM – TANNIN ČL 2005
Quercus infectoria – gall oak (Fagaceae)
Mixture of esters of glucose with gallic acid and 3galloylgallic
acid
Sources: tree widespread in Europe, Asia Minor,
Iran
Drug: Gallae – oak apples; galls produced after
laying of eggs by gall wasp (Cynips gallae
tinctoriae) into young of developing leaves.
Instead of the shoot the rounded gall is formed, in
which the larvae of wasp is living. Tannin is
accumulated inside galls.
Pharmacopeia accepts especially galls of so called
Turkish (Alepo) type. Rounded formations with
diameter 1,5 to 2 cm, hard, grey-brown,
glabrous, irregularly rough.
Usage: internal: antidiarrhoic
external: burns, frostbites, UV filter
ISOLATION OF TANNIN FROM GALLS
galls
Et2O : EtOH = 4 : 1
extract
H2O
Et2O H2O
gallotanin,
ellagotanin
gallic acid, pigments
Tannin possesses astringent taste. Storage in well closed vessels protected from light.
Solutions are prepared in time of need "ex tempore".
Hamamelidis folium – Witch hazel leaves
(ČL 2005)
Hamamelis virginiana – witch hazel (Hamamelidaceae)
Source: Shrub or tree, native in
eastern part of North America; it is
cultivated as ornamental. Flowering
in autumn, parallel with ripening of
last year fruits.
Drug: In summer harvested and dried
leaves.
CC: At least 3 % of tannins expressed
as pyrogallol in dried drugs;
(hamamelitannin, elagotannin,
flavonoids, leucoanthocyanidins).
Usage: Maceration or extract –
astringent and hemostyptic.
Component of ointments and
suppositories during hemorrhoids.
Large consumption in cosmetic
industry.
Juglandis folium – walnut leaves
Juglans regia - walnut (Juglandaceae)
Source: tree with huge crown and large
impaired-pinnated leaf. Fruit is a drupe
green, later turning black dried. In Europe
cultivated.
Drug: In June harvested, dried, integerrime
leaves without black spots.
CC: 3 % of hydrolysable ellagotannins, bitter
substances, essential oil; 5hydroxynaftochinon-1,4
= juglon, in fresh
leaves in form of glycoside.
Usage: astringent, externally for baths during
skin defects and diseases. Cosmetics –hair
pigmentation.
Internally do not use – juglon shows weak
mutagennic effect.
Quercus cortex – Oak bark ČL 2005
Quercus robur, Q. petraea – oak (Fagaceae)
Source: huge trees, rarely shrubs. Fruit is
acorn, sitting in cup-shaped cupules.
Drug: cut dried bark of fresh young
branches (mirror bark), harvested in
spring.
CC: At least 3,0 % of condensed catechine
tannins expressed as pyrogallol / dried
drug.
Usage: preferentially external – astringent
in form of digestion, for baths, to
prevent perspiration of feed,
hemorrhoids
Agrimoniae herba – agrimony herbČL 2005
Agrimonia eupatoria - agrimony (Rosaceae)
Source: perennial herb of mild climate
of northern hemisphere
Drug: dried flowering tops of herb
CC: At least 2 % of tannins prevalently
of catechine type, quercitrin, choline,
citric acid, essential oil
Usage:
Internally astringent, stomachic,
cholagogue. Support for liver
diseases therapy, during icterus.
Externally as gargle during oral
inflammations, additive to baths.
Myrtilli fructus recens – blueberry fruit fresh ČL 2005
Myrtilli fructus siccus – blueberry fruit dried ČL 2005
Vaccinium myrtillus - blueberry (Ericaceae prev. Vacciniaceae)
Source: Approx. 30 cm tall little shrub in Europe,
Asia and North America
Drug:
1. Fresh or frozen (-18 0C) fruit (berry) containing
at least 0,30 % of anthocyanins, pectin,
organic acids, sugar
Usage: vascular diseases; hemeralopia, diabetic
retinopathy
2. Dried ripen fruit containing at least 1,0 % of
tannins, expressed as pyrogallol
Usage: astringent and antidiarrhoic during catarrhs
of GIT, inflammations of oral cavity
Ratanhiae radix – Ratany root ČL 2005
Krameria triandra - ratany (Krameriaceae)
Source: xeric, approx. 1 m tall semi-shrub
native on the slopes of Cordillers in
Chile, Peru and Bolivia in attitude 1000-
2500 m.
Drug: dried, mostly broken roots with redbrown
color – „Peru-ratany“; 1/3 of
bark, 2/3 of wood
CC: at least 5,0 % of tannins, expressed as
pyrogallol / dried drug; tannins present
mainly in bark
Usage:
Digestion or powdered root internally as
antidiarrhoic
Extract: for treatment in oral cavity, against
frostbites, component of preparations
used against hemorrhoides.
Tormentillae rhizoma – potentilla rhizome ČL 2005
Potentilla erecta (P. tormentilla) - potentilla (Rosaceae)
Source: perennial herb of Europe and north
Asia
Drug: Whole or cut dried rhizome with
removed roots, red-brown color
CC: At least 7 % of tannins of catechine
type, expressed as pyrogallol / dried
drug
Usage:
Astringent, antidiarrhoic in form of
digestion or extract
Bistortae rhizoma – bistort rhizome
Polygonum bistorta - bistort (Polygonaceae)
Source: perennial herb of Europe and Asia
Drug: dried cut rhizome without roots,
inside pinkish color
CC: At least 5 % of tannins of catechine
type
Usage:
Astringent, antidiarrhoic in form of digestion
or extract.
Rubi fruticosi folium – blackberry leaves
Rubus fruticosus - blackberry (Rosaceae)
Source: thorny shrub native in Europe,
Asia, America
Drug: dried leaves of chosen forms of
species with less thorns
CC: gallotanins, inositol, organic acids
Usage: infusion as antidiarrhoic, during
oral inflammations, for baths.
Fermented leaves are tea substitute
FURTHER DRUGS WITH TANNIN CONTENT
CATECHU (Acacia catechu – mimosa catechu, Mimosaceae)
Solidified macerate from internal wood of Indian and African tree,
containing approx. 50 % of catechine tannins. Powerful astringent –
ethanol solutions used for treatment in oral cavity. Used in leather and
color industry.
KINO (Pterocarpus marsupium – indian kino tree, Fabaceae)
Solidified juice flowing from stem of tree after wounding. Native to east
India and Ceylon. Contains up to 85 % of catechine tannins.
Astringent.