1. FLAVONOIDS
Plant Pigments

2. PLANT PIGMENTS
Flavonoids and anthocyanins are conspicuous plant pigments in nature that
are responsible for the beauty and splendor of flowers, fruits, fruit tree blossoms
and of the autumn leaves.
Flavones are responsible for the yellow and orange colors; and the anthocyanins
are the source of red, violet and blue colors. These compounds occur mainly in
higher plants and are less common in the lower orders. You don’t find them in
algae, fungi or bacteria.
The flavonoids play a major role in attracting insects to feed and pollinate these
plants. Some of them also have a bitter taste and repel harmful insects like
caterpillars.
Flavonoids are thought to be antioxidants, and play a major role in our diet,
preventing the ravages of aging caused by free-radicals.
These compound have their biosynthetic origin in both the skimic acid pathway
and the acetogenin pathway - they are of hybrid origin.

3. NARINGENIN found in grapefruit : MIXED-ORIGIN COMPOUND shikimic acid
pathway
NARINGENIN
A different starter
than acetyl-CoA.
found in grapefruit
malonyl-CoA 3x
acetogenin
pathway :
Michael
addition
internal Claisen
and enolizations
MIXED-ORIGIN
COMPOUND
A FLAVONE
flavones are yellow
or orange pigments
naringenin

4. Anthocyanin
Flower Pigments

5. Anthocyanin Leaf Pigments
Autumn Leaves
In Spring and Summer
chlorophyll (green) masks
the anthocyanin colors.

6. ANTHOCYANIDINS AND ANTHOCYANINS
NADPH
naringenin (R=H)
[O] +
Anthocyanins are
red, violet or blue
pigments.
- 2 H2O
pelargonidin (R=H)
cyanidin (R=OH)
plant flower and
leaf pigments
cyanidin is blue
pelargonidin is pink
ANTHOCYANIDINS