1. by Ben Merritt

2. What are Anthocyanidins?
• From the Greek antos: flower ; kyanos: blue
• They are a class of pigments belonging to a larger group known as
flavonoids, coming from a simple C6 – C3 – C6 structure of carbon rings.
• Have been used since antiquity as dyes, contributing to the coloration of
petals, fruits, bracts and leaves.

3. Where can they be found?
• They can be found in a variety of places in plants, depending on their
specific role.
• Often they appear in quite attractive colors, so they will oftentimes exist in
flowers and berries, such as in grapes and wines, and cranberries.

4. Where can they be found?
• Yet, for the purposes of this project, I will only be considering anthocyanidins in
leaves.
• They are often found in young, developing leaves as a sort of sun screen.

5. Synthesis
• Produced in response to light, whether it be
visible, UV.
• Production results from two synthesis pathways:
acetate and shikimic acid.
• Acetate pathway produces 3 malonyl
coenzyme A (CoA).
• The shikimic acid pathway produces
phenylalanine.
• The two pathways combine to produce the base
molecule, the naringenin chalcone.

6. Structure
• Consists of three carbon rings.
• What distinguishes anthocyanidins
from anthocyanins is the presence of
sugars, generally at the C-3 position
(glycosides).
• Sugars can include glucose,
arabinose, rhamnose, and galactose.
• Degree of hydroxylation or
methoxylation on the B ring. More
OCH3 = red, more OH = blue.
• Electron deficiency - particularly
reactive towards electron-lusting
reactive oxygen species (ROS).
General structure of anthocyanins

7. Structure
• Around 12
anthocyanidins. Most
common in leaves is
cyanindin.
• Names of compounds
generally reflect species
from which they were first
obtained.
• Thus pelargonidin is from
Pelargonium, or
geranium. It often exists
in pink, scarlet, and
orange-red flowers.
• Delphinidin was named
after Delphinium, and
generally mauve or blue
flowers have this
compound.

8. How are free radicals dangerous?
• Incredibly unstable atoms or
molecules with an unpaired
electron.
• Ionizing radiation
• “Chain-reaction” problem.
• Often tear apart molecules.
Can cause various mutagenic-
related effects, esp. on DNA.
• Chain reaction ends when 2
radicals meet each other and
each contributes its unpaired
electron. This is why
anthocyanins are so
important.

9. Chemistry
• Effectively absorb UV-B light.
• UV radiation is generally
dangerous; produces free
radicals.
• Keep in mind that
anthocyanins are also very
reactive towards ROS.
• Produced in young leaves to
directly absorb UV
radiation as well as to
effectively neutralize free
radicals.
• More at higher elevations

10. Chemistry and pH
• Exists around 5-6 common
structures.
• Structures go through
de/protonation, hydration to
change structure.
• Different colors in different pH.
Name Color pH
Flavylium
Cation
Red ≤3
Carbinol
Pseudobase
Colorless 4-5
Quinoidal
Pseudobase
Purple /
Violet
6-7
Quinoidal
Pseudobase
Anion
Blue 7-8
Chalcone
Pseudobas
e
Yellowish ≥8

11. My Own Experimentation
• Rose solution
Unaltered solution: pH = ~4.1 Added 6M NaOH: pH = ~9.8
6M HCl: pH = ~0.8

12. My Own Experimentation
• Red cabbage solution
pH: ~12.5 ~7 ~5.6 ~2.5 ~11.5

13. Chemistry and pH
• As stated before, flavylium
ion undergoes various
structural changes based
on pH.
• Various tautomeric and
other insignificant
structures.

14. So what?
• Sure, these pigments are useful for plants. But why are they of importance
to humans?
• These pigments are produced exclusively in plants; thus,animals cannot
synthesize them. Therefore utilizing them has proven to be beneficial.
• Evidence that diseases like cancer, cardiovascular disease are result of
oxidative stress. So antioxidants, like anthocyanins, are thoroughly studied.
• Exhibit antimutagenic activies and even reduce the occurrence of tumors in
rats.
• Anticarcinogenic properties in cyanin-rich berries – billberry, cranberry,
lingon berry, etc.
• Lower incidence of coronary artery disease in Mediterranean thought to be
a result of diets rich in antioxidants. Studies with cyanidin show it to be an
in vivo inhibitor of LDL cholesterol oxidation.

15. So what?
Eat More Berries!!!

16. Bibliography
• Arnett, Ross H., Jr. and George F. Bazinet, Jr. Plant Biology: A Concise Introduction. Forth Ed. Saint
Louis: The C.V. Mosby Company, 1977.
• Galvano, Fabio, et al. “Anthocyanins and cyanidins: chemistry, analysis, sources and biological
properties.” IFIS Publishing, March 18, 2004. <http://www.foodsciencecentral.com/fsc/ix id12880> (February 26,
2010).
• Hopkins, William G. Introduction to Plant Physiology. Second Ed. New York: John Wiley and Sons, Inc.,
1999.
• Keusch, Peter. “Anthocyanins as pH-Indicators and Complexing Agents.” <http://www.chemie.u ni-
regensburg.de/Organische_Chemie/Didaktik/Keusch/p26_anth-e.htm> (May 28, 2010).
• Kimball, John W. “Reactive Oxygen Species (ROS).” <http://users.rcn.com/jkimball.ma.ultranet/
BiologyPages/R/ROS.html> (February 27, 2010).
• Krogh, David. Biology: A Guide to the Natural World. Third Ed. Upper Saddle River: Pearson Prentice Hall, 2005.
• Murai, Yoshinori, et al. “Altitudinal variation of UV-absorbing compounds in Plantago asiatica.”
Biochemical Systematics and Ecology. July 2009: 378-384. Print.
• Sullivan, Jack. “Anthocyanin.” Carnivorous Plant Newsletter, 1998, 27(3):86-88. Web: <http://
www.carnivorousplants.org/cpn/samples/samplemain.htm> (February 26, 2010).
• Thorsten, C. “Anthocyanins from Red Cabbage - With Experiments.” <http://www.crscientific.c
om/newsletter10-anthocyanins.html> (May 29, 2010).