Download Flavone and related flavonoid glycosides

Flavone and related flavonoid
glycosides
Anthocyanidins and glycosides
Naphthoquinones and glycosides
Lignans and lignin
Pharmacognosy I
Mosul University/ College of Pharmacy
L.A. Dilbreen Barzanji
Flavone and related flavonoid
glycosides
• The flavonoids occur both in the free state and as
glycosides are the largest groups of naturally occurring
phenols. More than 2000 of these compounds are now
known, with nearly 500 occurring in the free state. Most
are O-glycosides but a considerable number of C-glycosides
are known. Dimeric compounds also known as
(Biflavonoids).
• The glycosides are generally soluble in water and alcohol,
but insoluble in organic solvents.
• The genins are only sparingly soluble in water but are
soluble in ether.
• Flavonoids dissolves in alkalis, giving yellow solutions which
on the addition of acid become colourless.
• The flavones and their close relations are often yellow
(Latin flavus, yellow), they are widely distributed in
nature but are more common in higher plants and in
young tissues, where they occur in the cell sap.
• The intensity of their yellow colour increases with the
number of hydroxyl groups and with increases of pH.
• The group is known for its anti-inflammatory and antiallergic effects, for antithrombotic and vasoprotective
properties, for inhibition of tumour promotion and as
protective for the gastric mucosa.
• Some of these pharmacological properties can be
explained on the basis of antioxidant activity .
• Many flavonoids-containing plants are diuretic
(e.g. buchu and broom) or antispasmodic (e.g.
liquorice and parsley). Some flavonoids have
antitumour, antibacterial or antifungal properties.
• Flavonoids are polyphenolic compounds based on
a C15 (C6C3C6) framework. They contain
chroman ring (C-ring) with a second aromatic ring
(B-ring) at the c-2,c-3 or C-4 position.
Flavonoids types
• Six major subgroups of flavonoids:
1. Chalcones
2. Flavone
3. Flavonol
4. Flavonone
5. Anthocyanins
6. Isoflavonoids
Phyto-oestrogens
• isoflavones , along with coumestans (also
flavonoids) and lignans , belong to a class of
substances known as non-steroidal phytooestrogens.
• Both structurally and functionally they are similar
to oestradiol and related sex hormones and exert
weak oestrogenic effects.
• They are present in certain foods and herbal
remedies and are well-documented as producing
infertility in animals as, for example, clover
disease in sheep grazing on clovers containing a
high phyto-oestrogen content.
• Studies provoking much medical and general
press attention have centered on the role of
phyto-oestrogens as dietary constituents have
positives effects in the prevention of cancers,
heart disease and post-menopausal symptoms.
• Foods containing appreciable quantities of
isoflavones are soya beans, soy products and
other legumes crops; they are also present in the
herbs Red Clover Flower and broomtops.
Agnus castus fruit
• The drug consist of the whole, ripe, dried fruit
of Vitex agnus castus.
• Synonyms include : chaste tree, chaste berry
and monk’s pepper, alluding to its association
with chastity.
• The plant is a shrub or small tree found in the
medeterian regions.
• The small dark berries are collected from the
wild in autumn and dried.
• The main flavonoids are casticin (should not be
less than 0.08%) also vitexin, penduletin and
kaempferol.
• Diterpenes
including
rotundifuran
and
vitexilactone
• Various iridoids including aucubin.
• The drug has a long history in various menstrual
problems and in deficient lactation.
• In 2001 it was recommended as a therapeutic
option for premenstrual syndrome where no
cause could be identified.
Calendula flower
• Calendula flower derives from the marigold Calendula
officinalis.
• The EP/BP specify the whole or cut , dried, and fully
opened flowers detached from the receptacle and
obtained from cultivated varieties.
• Constituents : flavonoids, triterpenoids, essential oil
and polysaccharides are the principal constituents of
calendula flower.
• All groups have been shown to exhibit pharmacological
activity and serve to illustrate the difficulty of devising
an assay which represents the true therapeutic activity
of the drug.
• The BP/EP determine the flavonoids content, expressed
as hyperoside (not less than 0.4%).
• The flavonoids mixture involves quercetin and
isorahmnetin derivatives.
• Triterpenoid saponins (calendulosides A-F); the
saponins have hemolytic and anti-inflammatory
activity.
• Antitumour and phagocytosis stimulation
properties have been reported for the
polysaccharide fraction.
• Calendula is used internally for the alleviation of
gastrointestinal disorders and externally, as an
ointment or lotion, for the treatment of minor
wounds and rashes.
Olive leaves
• The olive (Olea europea) best known medicinally for its
expressed oil, is also used in continental Europe for the
antiseptic, astringent and sedative properties of the leaves.
• It can be employed both internally and externally.
• Flavonols, including rutin and oleuropein are the principal
components.
• The pentacyclic triterpenoid (maslinic acid) occurs in the
petioles and has various biological activities; it may offer
advantages in the resistance to oxidative stress in animals.
• Olive leaves are used as an infusion for their tranquilizing
effect in nervous tension and for their antiseptic, astringent
and febrifuge properties.
Passiflora
• Passiflora (Passion Flower) consists of the dried aerial
parts of Passiflora incarnata collected during the
flowering and fruiting period.
• Constituents include: flavonoids; mainly C-glycosides of
apigenin and luteolin such as vitexin, isovitexin,
orientin, iso-orientin and their glycosides.
• The BP drug is required to contain not less than 1.5%
total flavonoids calculated as vitexin .
• Passiflora has sedative actions; it is popular ingredient
of herbal preparations designed to counteract
sleeplessness, restlessness and irritability.
Buckwheat herb
• The drug consist of the dried aerial parts of
Fagopyrum esculentum , collected when the
plant is flowering and prior to fruiting.
• Rutin is the most important therapeutic
constituent of the herb and the BP/EP requires
a minimum content of 4.0% .
• Buckwheat is used in the treatment of various
circulatory disorders, including varicose veins,
chilblains and retinal bleeding.
Visnaga
• The drug consists of the dried ripe fruits of Ammi visnaga, an
annual plant about 1-1.5 m high, it grows in the Middle East and is
collected particularly in Egypt.
• Khellin, the most important active constituents, is crystalline and
has been synthesized.
• It occurs to the extent about 1%, the highest concentration being
reported in the immature fruits, and is accompanied by two other
crystalline compounds, visnagin (about 0.1%) and khellol glucoside
(less than 0.03%)
• The drug has long been used in Egypt. Khellin, which is now
commercially available in tablets and injection, is a potent coronary
vasodilator. It has been employed in the treatment of angina
pectoris and bronchial asthma, but its use appears to be limited by
undesirable side reactions.
• Khellin has smooth muscle relaxant properties and used as
adjuvant in treatment of urinary tract diseases.
Silybin and Silymarin
• A number of flavonolignans for example, silybin
and silymarin, have antihepatotoxic properties,
and extracts of plants containing them for
example Silybum marianum are widely used in
germany for the treatment of liver ailments.
• The fruits of S. marianum contain silybin,
silydianin and silychristin.
Hesperidin and Rutin
• Although flavonoids preparations such as hesperidin and rutin are
used in medicine, they do not appear to justified the high hopes
which followed the work of scientists in 1935 on the ‘citrin’
(sometimes known as vitamin P) of paprika and lemon peel.
• Citrus and other fruits have been included in the human diet and, in
addition to ascorbic acid and other compounds, provide flavonoids
which decrease capillary fragility and are therefore employed in
cases of hypertension and radiation energy.
• The substance formerly known as ‘citrin’ is now known to be a
mixture of the rahmnoglucosides
of eriodictyol (a
tetrahydroxyflavone) and methyl eriodictyl (hesperetin).
• A similar glycoside, rutin, the rahmnoglucoside of quercetin, is
found in many plants, and commercial supplies are made from
tobacco residues, Sophora and Eucalyptus spp. or buckwheat which
yields about 3-4%.
Anthocyanidins and glycosides
• Anthocyanidins are flavonoids structurally related to the
flavones. Their glycosides are known as anthocyanins.
• These names are derived from the Greek antho-, flower,
and kyanos, blue .
• They are sap pigments and the actual colour of the plant
organ is determined by the pH of the sap. For example, the
blue colour of the cornflower and the red of roses is due to
the same glycosides and both of these plants on hydrolysis
with hydrochloric acid yield cyanidin hydrochloride.
• The most common anthocyanidin, cyanidin, occurs in about
80% of permanently pigmented leaves, 69% of fruits and
50% of flowers.
• Cyanidin is followed in order of frequency by delphinidin
and pelargonidin.
• The sugar components are usually attached in the 3- or
(more rarely) 5- position.
• It may be noted that in flavone glycosides the
attachment is usually in the 7-position.
• They may be monosaccharides (glucose, galactose,
rhamnose or arabinose)
• Disaccharides (e.g. the rhamnoglucoside of
Antirrhinum spp.)
• Trisaccharides (e.g. the 5-glucoside-3-rutinoside of
certain Solanaceae)
• Despite their biological importance the anthocyanidins
are of little pharmaceutical significance as such, but as
previously considered they constitute the monomers of
the polymeric condensed tannins.
Bilberry fruit
• Bilberry (Vaccinium myrtillus) is distributed throughout
Europe, N. Asia and N. America including Canada.
• The edible sweet-tasting berries are collected from July
to Septmeber.
• Constituents: Anthocyanins, particularly glucosides and
galactosides of cyanidin, peonidin, delphinidin,
petunidin and malvidin. Anthocyanins are responsible
for the final colour of the berries.
• These pigments increase in quantity during ripening
whereas that of the polyphenols (-)-epicatechin, (+)catechin and dimeric proanthocyanidins decrease.
• For the dried fruits, the BP/EP specifies a
minimum tannin content of 1.0% expressed as
pyrogallol and for the fresh fruits a minimum
of 0.30% anthocyanins expressed as cyanidin3-glucoside chloride.
• Uses: traditionally used to treat diarrhea,
menstrual cramps, eye problems, varicose
veins and circulatory problems.
Naphthoquinones and glycosides
• The nature of these compounds was indicated
earlier; they are produced by higher plants, fungi
and actinomycetes and exhibit a broad range of
biological
actions
including
fungicidal,
antibacterial, insecticidal, phytotoxic, cytostatic
and anticarcinogenic.
• In plants they commonly occur in the reduced
and glycosidic forms as illustrated by the 4-Dgluside of α-hydrojuglone, a constituent of
walnut tree leaves.
Henna
• Henna consists of the dried leaves of Lawsonia inermis,
a shrub cultivated in north Africa, India and Ceylon.
• Henna contains a colouring matter, lawsone (a
hydroxynaphoquinone), various phenolic glycosides,
coumarins, xanthones, quinoids, β-sitosterol glucoside,
flavonoids including luteolin and its 7-O-glucoside, fats,
resin and henna-tannin.
• Henna is commonly used as a dye for hair.
• The astringent stem-bark of L. inermis is traditionally
used in India for the treatment of jaundice,
enlargement of the liver and spleen, and for various
skin diseases.
Lignans and lignin
• Lignans are dimeric compounds formed essentially by the
union of two molecules of a phenylpropene derivative.
• Some 300 lignans have been isolated and categorized into a
number of groups according to structural features.
• Important pharmaceutical examples are the lignans of
Podophyllum spp.
• The aryltetralin-type lignan and other related compounds
are the principal active constituents of Podophyllum root
and rhizome.
• Lignin is an important polymeric substance,(C6-C3)n laid
down in a matrix of cellulose microfibrils to strengthen
certain cell walls. It is an essential component of most
woody tissues and involves vessels, tracheids, fibres and
sclereids.