2. ● Pigmentation is the colouring matter found in certain animals for the
production of colours
● Animal's derive pigments from plant food or synthesize themselves
● Major animal pigments are,
○ Hemes of blood
○ Bile pigments
○ Melanin
○ Carotene
○ Keratin
○ Pterins
○ Luciferin
○ Urobilin
○ Papillochrome
○ Ommochrom
3. Hemes of blood
● It is the components of RBC and responsible for carrying oxygen from
arteries, arteriole, and capillaries to tissue and also assist in carrying co2 from
tissue to lungs.
● It provide red color to the blood
● Haem is a ironporphyrin Complex
● Structure of haem is similar to chlorophyll
4. Bile pigments
● Human bile secreted by liver have golden or brownis yellow color due to the
presence of two pigments,
a. Billirubin
b. Biliverdin
● Biliverdin is a Tetrapyrole compound and not have a metallic atom, it is green in
color
● Oxidation of biliverdin yield blue green pigment, where as reduction produces
biliverdin having red color
● Bile pigments obtained from haem of aged RBC, and other haem proteins like
Myoglobin, catalase, cytochrome, Peroxidase, etc
● The bile pigments are degraded by some microorganisms, found in our intestine
yield brown pigments, called stercobilin, chief components of faeces.
5. Melanin
● It is the natural pigments found in most organisms
● It produced through Melanogenesis
● Tyrosine on oxidation following Polymerisation produces Melanin.
● It is produced by specialized group of cells called Melanocytes
● There are 5 basic type of melanin,
a. Eumelanin
b. Pheomelanin
c. Neuromelanin
d. Allomelanin
e. Pyomelanin
● Eumelanin and pheomelanin both found in human, but eumelanin is the most abundant.
● Eumelanin is of 2type,
a. Brown eumelanin
b. Black eumelanin
● A small amount of black eumelanin in the absence of other pigments causes grey hair.
● As body ages it continues to produce black eumelanin, but stop producing brown eumelanin, that's why grey hair common in elderly.
● A small amount of brown eumelanin in the absence of other pigments causes yellow hair.
● Neuromelanin found in brain, human have the largest amount of neuromelanin.
● Pheomelanin is a cysteine containing red polymer of Benzothiazine responsible for red hair.
● Decreasd synthesis of melanin leads to a condition called Albinism.
6. Carotenoids
● These are found in plant's, algae and photosynthetic bacteria
● It produces bright yellow, red, and orange color.
● It act as antioxidant for humans.
● About 600 different types of Carotenoids are there, among them some can be
converted into vitamin A, ie provitamin A Carotenoids.
7. Keratin
● It is a structural protein
● Found in hair, nail, horn, hoofs, wood, feathers, and epithelial cell's in the
outermost layers of skin
● Keratin is of two types
a. Alpha keratin found in mammals
b. Beta keratin found in bird's and reptiles
● Keratin serve important structural and protective function
● Also important role in cellular activities such as cell growth and protein
synthesis
8. Pterins
● This pigment was first discovered in the butterflies wings
● It perform many roles colouration in biological system
9. Luciferin
● It generate bioluminescence
● It is a small molecule substrate that reacts with oxygen in the presence of
luciferas to release energy in the form of light
● Fire fly luciferin responsible for characteristic yellow light emission from fire
flies
● Latia luciferin found in fresh water snail, Latia Neritoides
● Bacterial luciferin found in bioluminescent bacteria
10. Urobilin
● It is responsible for yellow color of urine
● Urine analysis for urobilin gives insight on the effectiveness of urinary tract
function
11. Papillochrome
● A group of pale yellow pigment found in Papillionidae butterflies
Ommochrom
● It is a visual pigment occur in the eyes of crustacean and insects
● Eye color is determined by ommochrom, ranging from yellow over red and
brown to Black
12. Functions
● Provide external coloration
● Important role in physiological processes,
Eg, eye pigment cells (rods, cones) adjust or regulate the entry of light
● Synthesis of vitamins and chlorophyll
● Used for signaling
● For protection
