PIGMENTS, PERFUMES AND POISONS

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Food from plants (conclusion) Proteins.
Vitamins Chemistry of plant foods at
Thanksgiving Quiz 6 on Tuesday after
Thanksgiving! Main topics Drugs, medicines,
foods from plants including todays class. Review
Quiz 5, study lectures, Reader, use Appendix as
back-up. Do Practice Questions!
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Major food families

• Carbohydrates highly water-soluble, many
  OH-groups. Can be simple sugars or polymers.
• Fats and Oils Largest family of lipids. They are
  triglycerides.
• Proteins Polymers of amino acids
• Minerals as metal ions
• Water structure of water molecule!
• Vitamins

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Amino Acids, Peptides and Proteins Primary
Metabolites!

• Proteins are polymers composed of thousands of
  amino acid units linked by peptide bonds
• Peptides consist of 2 to about 100 amino acid
  units linked by peptide bonds
• Amino acids Monomers of Peptides and Proteins
• (Polypeptides very large peptides, but not as
  large as proteins)

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Carbon atom with 4 different substituents
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http//www.chemie.fu-berlin.de/chemistry/bio/amino
-acids_en.html
Glycine H2NCH2COOH Not chiral!
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Alanine H2NCH(CH3)COOH
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Peptides 2 to about 100 amino acid units linked
by peptide bonds
enzyme
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A human peptide hormone
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Proteins polymers composed of amino acid units

• Primary structure amino acid sequence
• Secondary structure due to intramolecular
  hydrogen bonding alpha helix or beta pleated
  sheet

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Proteins alpha helix
Intramolecular hydrogen bonding
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Proteins Tertiary structureoften asymmetric!
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DenaturationLoss of the native or original
shape of a protein or peptide

• when heated
• when salt is added (pickling)
• when strong acid or base is added
• when interacting with heavy metal ions
• by radiation

• Hydrogen bonding is interrupted
• Loss of correct folding pattern
• Function is affected!

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Vitamins, a definition

• Organic compounds required for life that cannot
  be synthesized by mammalian organisms (in
  sufficient quantities), must be supplied by diet.
  They are needed in small quantities only.
• All are coenzymes (or cofactors)
• function in a wide variety of capacities within
  the body, as cofactors for enzymatic reactions.
• All are organic compounds
• Otherwise they are chemically unrelated

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Water-soluble Vitamins

• Vitamin C (ascorbic acid)
• All of the Vitamin B group

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Fat-soluble Vitamins

• Vitamin A (Retinol)
• Vitamin E (Tocopherol)
• Vitamin D
• Vitamin K

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Vitamin C Ascorbic Acid

• Widespread in plants
• Chiral carbons?
• Artificial versus natural
• Deficiency symptoms in humans
• Vitamin C is a potent antioxidant

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Antioxidants and Radicals

• Antioxidants are molecules which can absorb
  (react with) free radicals before vital molecules
  are damaged.

• Radicals (also called "free radicals) are atoms
  or clusters of atoms with an unpaired electron.
• They are extremely unstable and highly reactive !
  In their reactions they break bonds of other
  molecules.
• In living organisms they can damage important
  cellular components such as DNA, enzymes or the
  cell membrane.

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Examples of Radicals
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Important Antioxidants

• Vitamin C
• Vitamin E
• ?-carotene
• all phenolic compounds (tannins, anthocyanins,
  flavonoids )

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Vitamin E Tocopherol
Plant sources In seeds (nuts, corn, wheat germ,
dissolved in plant oils)
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Vitamin A Retinol
Human body can synthesize retinol from ?-carotene
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Vitamin A and the vision process
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Antioxidants At Thanksgiving
http//www.ars-grin.gov/duke/

• Cranberries
• ALPHA-TOCOPHEROL Fruit 9 - 81 ppm
• ASCORBIC-ACID Fruit 75 - 1,003 ppm
• Lots of Anthocyanins!
• Sweet potatoes or pumpkin pie
• ? - carotene
• Herbs oregano, dill, thyme and rosemary
• Spices e.g. eugenol (a phenolic!) in cinnamon,
  cloves, nutmeg

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Happy Thanksgiving!
After Thanksgiving Quiz 6 on Tuesday after
Thanksgiving! Main topics Drugs, medicines,
foods from plants including todays class. Review
Quiz 5. Study lectures, Reader. Use Appendix as
back-up. Do Practice Questions! Our remaining
topics Fibers from plants Dyes from
plants Genetically engineered plants (?)