2. Introduction
Carotenoids has two group:
1. Carotenes
2. Xanthophylls
Xanthophylls are yellow pigments that occur widely in nature.
Greek xanthos : yellow and phyllon : leaf
Named as : yellow band seen in early chromatography of leaf pigments.
Xanthophylls contain oxygen atoms
They are more polar than carotenes. Easily separated by chromatography
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
3. Oxygen present either as hydroxyl groups and/or as hydrogen atoms
substituted by oxygen atoms when acting as a bridge to form epoxides.
Occurrence
Found in highest quantity in the leaves of most green plants.
(rich sources include papaya, peaches, prunes, and squash)
Found as free or in ester form along with carotene and chlorophyll.
Available in dietary animal products (yellow color of chicken egg yolks, fat,
and skin ) example lutein
Yellow color in the retina of the human eye has presence
of lutein and zeaxanthin.
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
4. Function
These are the yellow pigment of the leaves, which absorbs the
wavelength that chlorophyll cannot absorb.
Protection of plants from photo-oxidative damage.
They are also considered antioxidants.
lutein, zeaxanthin, neoxanthin, violaxanthin, flavoxanthin,
and α- and β-cryptoxanthinkamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
5. Solubility
• Xanthophyll is not dissolve in water, but soluble in hexane.
• In chloroform solution has the maximum absorption at about 445nm.
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
6. Isolation
Crude drug dried + grounded Extracted with 80% methanol
And then with pet. ether
Extract diluted with water +
Saponified with Alc. KOH
Washed with water to
Remove alkali(Excess)
Solvent removed by distillationResidue cooled
Xanthophyll separatesColumn Chromatography
ZnCO3 as adsorbent,
Benzene as solvent
Get red colored crystals, mp 192 ◦C
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
7. •Lutein from Latin word luteus meaning "yellow" is
a xanthophyll and one of 600 known naturally occurring carotenoids.
• Lutein is synthesized only by plants,
Found in high quantities in green leafy vegetables such
as spinach, kale and yellow carrots.
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
9. Constitution of Lutein
1. MF = C40H56O2
2. Unsaturation determination:
C40H56O2 +11 H2
H2-Pt
C40H78O2
3. Xanthophyll
Five molecule of Maleic anhydride
Form crystalline adduct
Confirm presence of 5 conjugated double bonds, had structure similarity with carotene
Colorless perhydro xanthophyll
Colored
4. Xanthophyll Form diacetyl/esters
Confirm two hydroxyl group presence, further confirmed by Zerewitnoff’s method
Acetylation/Esterification
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
10. Saturated formula corresponds to CnH2n-2, that is for bicyclic compounds.
It proofs it is bicyclic compound.
5. Perhydro xanthophyll
[O]
Form diketone
Confirm secondary hydroxyl groups
6.
Alkaline KMnO4
4 molecules of acetic acid kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
11. 7. Xanthophyll
KMnO4 vigorously
Dimethyl succinic acid Dimethyl malonic acid
Not form geronic acid and isogeronic acid, this confirm it is not a carotene
May have hydroxyl groups in rings, the position may be 3, 4 and 3’,4’.
8. Perhydroxanthophyll (C40H78O2) Br2
Dibromide
If bromine removed
Form perhydrocarotene (C40H78)
Of alpha carotene
Concluded it is dihydroxy alpha carotene which has hydroxyl groups at 3 and 3’.
kamal0603@gmail.com (Kamal Shah, Institute of
Pharmaceutical Research, GLA University, Mathura (UP)
