Sources of pigments

Usually, pigments are always being found in the animals and plants in which these pigments are known as biological pigment or biochromes. In the living organism, most of them have the biological structures which consist of pigments such as skin, hair, eyes, fur that present in animals. The most common animal pigment is refers to melanin and heme groups (haemoglobin). Melanin is naturally present in the human body especially in the skin laye while heme groups are found in the blood . Besides, leaf and flowers of plants contain their own biological pigment. Plant pigments include a variety of different kinds of molecule which includes porphyrins(chlorophyll), carotenoids, anthocyanins and betalains. Table 1 below shows the categories of plant pigment as well as their examples.

Table 1 Types of plant pigment and their examples

Plant pigments	Examples
Porphyrins/ Chlorophyll	Chlorophyll a, chlorophyll b
Carotenoids	Carotene I. Alpha carotene II. Beta carotene III. Lycopene IV. rhodopsin Xanthophylls I. canthaxanthin II. zeaxanthin III. lutein
Anthocyanin	Aurantinidin, cyaniding, luteolinidin, malvidin, peonidin, petunidin, rosinidin
Betalains	Betacyanin, betaxanthin

Both animals and plants have the pigments which can absorb and reflect sunlight at certain wavelength and hence the colours of living organism can be presented naturally as their physical appearances.

The organic and inorganic pigments are always being synthesized chemically from the reaction between organic compounds and from the reaction by using transition elements respectively. Most of them are artificially made in industry. However, some inorganic pigments occur naturally in the form of metal oxides and sulfides. For example, the natural inorganic pigment can be found in limonite, amorphous, hematite, ocher, umber, sienna and others.