FLAVONOIDS Plant Pigments

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.

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

Anthocyanin Flower Pigments

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

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