Secondary Metabolism

• Primary Metabolism

  • compounds that are directly involved in the growth and development of a plant
  • amino acids, nucleotides, sugars, lipids
• Secondary Metabolism

  • are organic compounds that are not essential to the function of the plant but are still important
• Functions of Secondary Metabolism

  • Defense mechanism against physical factors or against herbivores and pathogens
  • Attractants of pollinators
  • Agents or plant-plant competition
• Krebs Cycle - 3-PGA

  Glycolysis - Pyruvate and Phosphoenolpyruvate

  Pentose Phosphate Pathway - Erythrose-4-phosphate
• MEP Pathway - Terpenes
• Mevalonic Acid Pathway - Terpenes
• Malonic Acid Pathway - Phenolic compounds
• Shikimic Acid Pathway - Phenolics, Nitrogen-containing secondary products
• Phenolic Compounds

  • Flavonoids
  • Anthocyanins
  • Phenolic acids
  • Caffeic acid
  • Lignans
  • Stillbenes
• Terpenoids

  • Carotenoids
  • Lycopene
  • Volatile terpenoids
  • Limonine
• Nitrogen-containing compounds

  • Alkaloids
  • caffeine
  • Isothiocyanates
• Terpenes

  • largest most diverse class of organic compounds found in plants
  • Generally lipophilic substances derived from a simple 5-carbon unit (isoprene)
• Isoprene

  • building blocks of terpene
  • hydrophobic
• Terpenes family

  • Hormones
  • Carotenoid pigments
  • Sterol and sterol derivatives
  • Latex
  • Essential oils
• Building blocks of Terpenes

  • Isopentyl pyrophosphate
  • Dimethylallyl pyrophosphate
• Geranyl Pyrophosphate (GPP)

  • Parent compound for all monoterpenes
• Carotenoid (Terpenes) - Helps protect chlorophyll
• Phytol Tail of Chlorophyll (Terpenes) - Photosynthesis
• Saponins and limonoids (Terpenes) - deters herbivores (toxins)
• Essential oils (terpenes) - insect repellants
• Phenolics

  • Family of secondary metabolites derived from aromatic amino acids
  • presence of rings
  • Includes tannins, lignins, and flavonoids
• Starting molecule of Phenolics

  • Phenylalanine
  • Tyrosine
  • Tryptophan
• Caffeic Acid, Salicylic acid, coumarin derivatives (phenolics) - exhibit allelopathic properties
• Tannins (phenolics) - feeding deterrents
• Isoflavones Phytoalexins (Phenolics) - limit the spread of bacteria and fungal pathogens
• Alkaloids

  • A large family of chemically unrelated molecules
  • Common characteristics:
  • Soluble in water
  • Presence of at least 1 Nitrogen
  • high biological activity
  • Neurotransmitters
  • Toxic in large amount; therapeutic in smaller doses
• Starting molecule of Alkaloids

  • Tryptophan
  • Tyrosine
  • Arginine
  • Lysine