This document discusses several classes of plant secondary metabolites including iridoids, naphthoquinones, gentian, artemisia, taxus, and carotenoids. Iridoids are monoterpenoids found in many plants and are derived from 8-oxogeranial. Naphthoquinones are related to naphthalene and include common isomers like 1,2-naphthoquinone and 1,4-naphthoquinone. Gentian contains iridoid glycosides like gentiopicrin which give it bitter properties. Artemisia contains essential oils and compounds like santonin. Taxus contains the potent anticancer compound taxol. Carotenoids

1. Iridoids, Other terpenoids & Naphthaquinones:
Gentian, Artemisia, Taxus, Carotenoids

2. IRIDOIDS
Iridoids are a type of monoterpenoids in the general form
of cyclopentanopyran, found in a wide variety of plants
and some animals.
They are biosynthetically derived from 8 – oxogeranial.
Iridoids are typically found in plants as glycosides, most
often bound to glucose.
The chemical structure is exemplified by iridomyrmecin, a
defensive chemical produced by the genus Iridomyrmex,
for which iridoids are named.
The iridoids produced by plants act primarily as a defense
against herbivores or against infection by microorganisms.

3. NAPHTHOQUINONES
Naphthoquinone is a class of organic compounds structurally
related to naphthalene.
Two isomers are common for the parent naphthoquinones :
1,2 – Naphthoquinone
1,4 – Naphthoquinone
Naphthoquinones usually do not occur as glycosides in higher
plants.
Naphtoquinones represent the group of plant secondary
metabolites with cytotoxic properties based on their ability to
generate reactive oxygen species and interfere with the
processes of cell respiration.
The most important naphthoquinones containing plants belong
to the group of phylogenetically heterogenous plant families.

4. GENTIAN
Synonym : Gentian root, Gentiana, Radix
Gentianae.
Biological source : Gentian is the dried partially
fermented rhizome and root of yellow gentian i.e.
Gentiana lutea.
Family : Gentianaceae
Collection & Preparation: Large fleshy roots, erect
rhizomes of 2-5 yr old plants are dug out.
Collection: autumn, by cutting longitudinal into
slices.
Pieces of roots, rhizomes- white color, no odor.
During slow drying or keeping them in heaps &
fermenting by slow heating, they get dark or yellow
colored & develop characteristic odor.

5. Macroscopy:
The rhizome is yellowish – brown and has transverse
annulations and shows conical buds at the top.
The root is narrower but continuous with rhizome.
It is longitudinally wrinkled and has circular scars of
rootlets.
The drug has a peculiar odour.
The drug first gives a sweet taste, followed by an
intensely bitter taste.
Fracture- short, smooth in dried drug, tough and flexible
in moist drug.

6. Gentian
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7. Microscopy :
The transverse section of rhizome shows bark, cambium,
wood and pith.
The root shows these parts but no pith, in place of which
a triarch primary xylem is present.
The cork cells are thin walled.
Cortex has parenchyma with oil globules and calcium
oxalate.
Phloem is present in small groups and phloem fibres are
absent.
The xylem contains spiral and annular vessels and also
shows presence of interxylary phloem.

8. Chemical Constituents –
The drug contains bitter glycosides mainly gentiopicrin, which is
also called gentiopicroside.
It is a water soluble, crystalline compound with a bitter value of
12,000. During fermentation and drying, it breaks down to
gentiogenin and glucose.
Chemical Test:
Under UV radiation gentian extract shows light blue
fluorescence.
Uses :
It is used as a bitter tonic to stimulate the gastric secretion
and hence improving the appetite.

9. Bitter glycosides- mainly gentiopicrin, also called
gentiopicroside., water soluble, crystalline compound with
bitter value 12,000.
Gentiopicrin Gentiogenin + Glucose
Also contains amarogentin, amaroswerin, gentioside &
mixture of gentiopicrin & gentisin called gentinin.
Amarogentin considered bittermost substance & gives
bitter taste in even 5.8 lakh times dilution. Most of
constituents are bitter, the taste mainly due to amarogentin.
Glycosides contain monoterpene irridoids.
Contains flavonoid alkaloid - gentianine or gentisin.
Gentisin gives yellow color to drug.
Fermentation, drying
Breaks

10. Other constituents - gentisic acid, gentianose (a
trisaccharide consisting 2 glucose & 1 fructose
units), gentiobiose (disaccharide) & sucrose.
Drug should yield not less than 33% water soluble
extractive value, due to sugars.
It is decreased due to excessive fermentation

11. ARTEMISIA
Synonym : Santonica; Worm seeds
Biological source : These are the
unexpanded flower – heads of Artemisia cina
Berg, Artemisia brevifolia Wall, Artemisia
maritime Linn. and other species of Artemisia.
Family : Compositae
Macroscopy :
Color – Flowers are yellow in color, while other
parts are whitish grey. Odour – Aromatic and
sweet.
Taste – Bitter and camphoraceous
The drug consists of yellowish or brownish
flower – heads, which are oval in shape.
Flowers are fertile with tubular corolla and
cylindrical tube and narrow limb.
Calyx is absent.

12. Chemical Constituents –
Santonica contains essential oil and two crystalline substances
i.e. santonin and artemisin.
The volatile oil content varies from 1.0 to 2%, while the
percentage of santonin is about 2.0%.
The volatile oil contains cineole, pinene and resin.
Identification :
Boil 1g finely powdered drug with 10 ml alcohol and filter.
To the filtrate, add sodium hydroxide and heat again.
The liquid develops red color.
Uses :
Santonica is used as a strong anthelminthic, especially for round
worms.
Antimalarial.
It has less or no effect on hook worms and tape worms.

13. Artimisia annua
• Qninghao, Sweet-annie, Worm weed.
• B S: Chinese traditional herb Artemisia annua
Asteraceae, should contain not less than 0.8%
of artemisinin on dried basis.
• G S: Endemic to China, grows wild –Europe,
America.
• Cultivated- Vietnam, China, Iran, Turkey,
Australia.
• Also cultivated on experimental basis in
Gujarat, JK, U P, H P & Karnataka.
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14. Artimisia annua
• Cultivation Collection : CIMAP Lucknow
developed uniform, high yielding genetically
improve variety, cultivated for Aretemisinin.
Gives about 29 quintals/hectare of dry leaves &
flowering tops containing 0.11% Artemiesinin.
• Yield/ hectare 3.19 kg Artemisinin
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15. Artimisia annua
• C C: Out of 7 species only A. annua- has Artemisinin,
deoxyartemisinin 1%
• It is sesquiterpene lactone with internal peroxide linkage.
• Artemisinic acid, arteannuin A & B, Amyrin, luteolin, β-
sitosterol, stigmasterol.
• Artemisinin- does not have heterocyclic ring with N, like
other antimalarials.
• It is new type of structure
• Sparingly soluble in water while it shows decomposition
in other solvents.
• Volatile oil 0.3 to 0.4% with artemisia alcohol, artemisia
ketone, camphor, Caryophyllene & myrcene
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16. Artimisia annua
• Uses: Artemisinin- antimalarial by rapid blood
schizonticidal activity.
• Trophozite development is arrested & pathological
consequences not observed.
• Acts both against Chloroquine sensitive & resistant P.
falciparum & P. vivax malarial parasites.
• Artemisinin - most potent drug for cerebral malaria.
• Artesunate & artemether, derivatives of artemisinin
highly effective.
• Artemether-developed by C.D.R.I., Lucknow.
• Artemisic acid- antibacterial, cytotoxic, anti-
inflammatory actions
• Artemisinin- anti-HIV activity
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17. TAXUS
Synonym : Yew, Talispatra, Himalayan Yew
Biological source : This consists of dried leaves, bark
and roots of various species of Taxus.
The four important species with parts used are as under.
Taxus baccata (English or European yew) mainly leaves
Taxus brevifolia (Pacific yew) mainly stem bark.
Taxus Canadensis (Canadian or American yew) leaves and
roots.
Taxus cuspidate (Japanese yew) leaves.
Family : Taxaceae

18. Chemical Constituents –
The main constituent taxol is present in all parts of the plant
especially in leaves, roots and bark of the plant.
A derivative of taxol , called taxotere has been reported to have
better bio-availibility and pharmacological properties and has been
claimed as a promising anticancer agent.
Uses :
Taxol brings out the polymerization to microtubule
Due to this, microtubule formation is much enhanced which
causes effects on dividing cells which leads to blockade of cell
cycle.
Taxol also inhibits cell migration thus, preventing spread of
metastatic cancer cells.
Taxol has been approved by USFDA for treatment of refractory
ovarian cancer.

19. USES
• Anticancer, analgesic, anti-inflammatory, antipyretic &
anti-convulgant.
• Biological target of Taxol- microtubules produced from
α & β-tubulin.
• Microtubules - responsible for formation of mitotic
spindle imp. for cell division.
• α & β-tubulin polymerise - give microtubules & for this
microtubule associated proteins (MAP) & guanosine
triphosphate (GTP) are imp.
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20. USES
• Taxol brings polymerisation in microtubules in absence of
MAP & GTP.
• Due to this, microtubule formation increases causing
destructive effects on dividing cells leading to blockade of
cell cycle.
• And multiple abnormal esters are formed from microtubules
& get distributed in cytoplasm, these structures are non-
functional.
• Taxol -inhibits cell migration, prevents spread of metastatic
cancer cells.
• Taxol-approved USFDA - treatment of refractory ovarian
cancer.
• Against non-small cell lung carcinoma, gastric, cervical
cancers, carcinomas of head, neck, prostate, colon.
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21. TETRATERPENOIDS AND CAROTENOIDS
They are C40 compounds of terpenoid groups and
biosynthetically prepared by tail-to-tail
condensation of geranyl geraniol.
They contain long sequence of conjugated double
bonds.
Carotenoids are a prominent group of natural
coloring matters exhibiting purple, red, yellow or
orange colors.
They are present both in plants and animals.
In plants, they act as photosynthetic accessory
pigments and in animals as a source of vitamin A
and also as antioxidants.

22. Carotenoids (TETRATERPENOIDS)
• Called as tetra-terpenoids- are organic
pigments – produced by plants & algae, fungi,
bacteria
• Animals- aphids, spider mites
• Composed of 8 isoprene units(C40)
• Various colors- mostly yellow to red pigments
• Absorb light in 400-500nm region of Visible
spectrum
• Synthesized from Mevalonate precursors
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23. Carotenoids
• Hydroxylated, oxidized, hydrogenated, ring
containing derivatives exist
• Hydrocarbon carotenoids classified as
carotenes.
• Those with oxygen- xanthophylls
• Classification: 2 general classes
• 1. Carotene: have only C & H, ex. β-carotene,
• 2. Xanthophyll: have 1 or more O atoms, ex:
lutein
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24. Carotenoids
• Chemistry: Belong to category of
tetraterpenoids, i.e. contains 40 C atoms, made
up of 4 terpene units each with 10 C atoms
• Carotenoids take form of polyene HC chain ,
may be terminated by rings, may or may not
have additional O atom.
• General structure: polyene chain 9-11 double
bonds, possibly terminating rings
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25. Carotenoids
• They absorb light energy fro photosynthesis,
protect chlorophyll from photo damage
• Carotenoids with unsubstituted β -ionone rings
(β-carotene, α-carotene, β-cryptoxanthin, γ-
carotene)- have Vitamin A activity
• i.e. They can be converted to retinol
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26. α, β, Carotenoids, Vitamin A
• About 600-700 different carotenoids known
• Prominent ones: α, β, Carotene, lycopene,
lutein, zeaxanthin
• β-Carotene: provitamin A , metabolized to vit
A. Vit. A retinol can be transformed to retinal
important for vision, or retinoate – for cell
proliferation, cell differentiation
• Is an antioxidant
• Appears in red, orange, yellow fruits, veges,
• Lutein, zeaxanthin- green leaves veges
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27. Naphthaquinones
• Quinones- widely distributed aromatic compd.
• Found in many families of plants, isolated from
fungi, algae, bacteria
• Classified into benzoquinones, anthraquinones,
and naphthaquinones.
• Naphthaquinones STRUCTURALLY similar to
naphthalene, characterized by 2 carbonyl
groups in 1,4 position named as 1,4
naphthaquinones
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28. Naphthaquinones
• They are natural phenolic compounds
• Ex. Alkannin, Juglone, Lawsone, Plumbagin,
Vitamin K etc.
• Synthetic: Menadione, Atovaquone,
Buparvaquone
• They are yellow-orange colored pigments found in
families like: Plumbaginaceae, Juglandaceae,
Ebenaceae, Boraginaceae, Dioncophyllaceae,
Ancistrocladaceae, Iridaceae, Verbenaceae,
Scrophulariaceae, Avicenniaceae, Balsaminceae,
Bignoniaceae, Gentianaceae, Droseraceae,
Nepenthaceae, Lythraceae and Euphorbiaceae
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