2. Introduction-
Terpenoid
• Terpenes constitute one of the most important groups of
essential oils.
• The group includes constituents such as limonene,
phellandrene, cedrene etc. and their oxygenated derivatives
such as geraniol, citral, carvone, camphor, cineol and many
others.
• These compounds arise at the geranyl pyrophosphate and
fernesyl pyrophosphate levels respectively, in the acetate
mevalonate pathway from the fundamental building block
termed as isoprene (C5H8) unit.
2-Methyl-1,3-butadiene
3. Terpenoid-Classification
SR
NO.
NO. OF
CARBON
ATOM
VALUE
n
CLASS
1 10 2 MONOTERPENOIDS (C10H16)
2 15 3 SESQUITERPENOIDS (C15H24)
3 20 4 DITERPENOIDS (C20H32)
4 25 5 SESTERPENOIDS (C25H40)
5 30 6 TRITERPENOIDS (C30H48)
6 40 8 TETRATERPENOIDS (C40H64)
7 >40 >8 POLYTERPENOIDS (C5H8)n
4. Introduction-Iridoids
Monoterpene
Cyclopenta[c]pyranoid skeleton
Iridane skeleton cis-2-oxa-bicyclo-[4,3,0]-nonane
Type: Secoiridoids by cleavage of the 7,8 bond of the
cyclopentane ring
Some authors limits the definition up to: Methyl cyclopentane
Iridoid glycosides (>300)
Secoiridoid glycoside (>100)
Non-glycoside compounds (>100)
5. Iridoids: How derived?
• Named after ants of the Iridomirmex genus, from which were
isolated compounds involved in the defence mechanism of
the insects: iridoidal, iridomyrmecin and related compounds.
• Exists in plants as well: nepetalactone from Nepeta cataria
(Lamiaceae), or teucriumlactone C from Teucrium marum
have marked properties
• Nepeta cataria: effects on cats, so termed as Catnip,
katzenmelisse, herbe-aux-chats
• Iridoid: generally 10 carbons, may even have more or multiple
structure variation up to polycyclic structures
7. Iridoids: Occurence
• Biosynthetically homogenous
• Insects: ants
• Plants: dicotyledon: Angiosperm
• Plant family: Dipsacales, Gentianales, Lamiales,
Scrophulariales
• Iridoid glycoside: glucoside- glycosidic linkage between –OH
group on anomeric carbon of D-glucose and the –OH group
in the 1-position of aglycone
• Small no. of structure: 1 sugar portion is oligosaccharide
(e.g. Rehmaniosidesa)
• Glucose is linked to: 11-hydroxylmethyl group (e.g.
ebuloside in caprifoliaceae
• Non-glycosidic iridoid: alkaloid: skytanthine
8. Iridoids: Occurrence
10 carbon atom
• Polycyclic compounds: Plumericin, Polyesters(valepotriates) or
intramolecular ethers (Rehamaglutin B)
• Non-glycosidic secoiridoids: Syringa spp., Olea spp.
• C-11: carboxymethyl group (loganin, geniposide) or part of
carboxylic acid (monotropein)
• Hydroxymethyl group: Valerianceae, Caprifoliaceae
• Aldehyde or methyl group: Lamioside
• C-11 is absent: Aucubin, Catalpol, Harpagoside
9. Iridoids: Occurrence
10 carbon atom
• Pyran ring is exceptionally open: gentiobiosides of Iridodidal &
Nepatariaside (precursor of nepetalactone)
• Methyl group at C-8: aucumbin, monotropein, epoxide
(valtrate) & rarely absent (deutzioside)
• Unsaturation at 7,8 position: Geniposide, Aucumbin
• Vinyl group at C-9: gentiopicrin
• Oleoside: ethylidene-hydroxyethylidene at C-9
• Carboxy group is esterified: Oleuropein
11. Iridoids: Extraction
• Delicate due to their great instability
• Instability darkening that takes place soon after plant
collection in many species containing iridoids
• Extraction with polar solvent alcohols of various concentration
• Initial separation, re-dissolving the extraction residue in water,
then re-extracting this with immiscible solvents of increasing
polarity
• Fractionation: chromatography on alumina on charcoal (with
risk of irreversible adsorption), on porous polymers (e.g. XAD-
2) with polar eluents & more and more by polar reverse phase
HPLC
• Purification TLC, HPLC
• Detection Trim and Hill color reagent: Dilute solution of
CuSO4 and HCl, blue color
• Detection spray: vanillin H2SO4, Hot HCl
12. Iridoids: Biological-
Pharmacological properties
• Defensive function in ants
• Anti-inflammatory: weak by oral route and stronger by topical
route
• 1 mg of aucubin, verbenalin or loganin have an activity almost
similar to that of 0.5 mg of indomethacin on the TPA induced
mouse ear edema
22. 5. Artemisia
• Syn: A.cina (Santonica, wormseed)
A. annua (Sweet annie, Qinghaosu)
• Source: dried un-expanded flower heads
of Artemisia cina, A. annua, A.brevifolia,
A.maritima & other spp. Of Artemisia.
• Family: A. cina (Compositae)
A. annua (Asteraceae)
• GS: A. cina (Pakistan, Turkestan),
A. annua (China-native, Europe, US,
Turkey, Australia, Iran, Vietname, India (GJ,
UP, JK, HP, KA)
23. Constituents & Structures
A. Cina
• Sesquiterpene
lactone:santonin
• Artemisin
• Irone
A. annua
• Artemisinin
• Deoxyartemisinin
• Artemisic acid
• Arteanniun A, B
• Cadinene type
sesquiterpene
Santonin
Artemisin
Artemisinin
24. USES
• A.cina:
Strong althelmintic against round worms and less
effect against thread worms.
• A.annua
• Artemisinin: Chloroquine resistant Plasmodium falciparum
and particularly cerebral malaria
• Derivative: Artesunate, Artemether: effective
• Artemisic acid: anti-inflammatory, cytotoxic, antibacterial
25. 6. Taxus
• Syn: Yew
• Source & GS: dried bark of
• Taxus baccata (Europe)
• Taxus brevifolia &
• T. canadensis (North america)
• Taxus cuspidata (Japan)
• Taxus wallichiana (Himalaya)
• Family: Taxaceae
27. USES
• Paclitaxel: mitotic spindle
poison
• M/a: it promotes assembly
of tubulin dimers into
microtubules which is stabilized
by inhibiting their
depolymerization
• Indication: Advanced ovarian
cancer, metastatic breast cancer
• S/e: neutropenia, peripheral
neuropathy, CVS, alopecia
• Posology: 135-175 mg/m2
• Docetaxel:
• Indication: breast
cancer
• S/e: severe
neutropenia,
hypersensitivity
reaction, water
retention, cutaneous
reaction
• Posology: 100 mg/m2
28. 7. Andrographis
• Syn: Kalmegh, King of bitter, kirayet
• Source: leaves and entire aerial part of
Andrographis paniculata
• Family: Acanthaceae
• GS: growing -India, Pakistan, Srilanka,
Indonesia
• Cultivated-China, Thailand, west indies,
Mauritius
• Use: bitter tonic, febrifuge-reduce fever,
anthelmintic, astringent, cholagoggue,
cholera, diabetes, weakness, blood
purifier, jaundice, GI disturbances,
itching
