anthocyanin

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 C
6
– C
3
– C
6
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
OCH
3
= 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).