Natural Products

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Natural Products

• a.k.a. Secondary (2?) products or 2? metabolites
• Not part of universal or essential metabolic
  pathways (1? metabolism), but uses some
  precursors from 1? metabolism
• 50,000 known
• Distribution is idiosyncratic (species- specific
  profile of compounds)

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3 Major Groups

• Terpenoids (25,000)
• e.g., taxol, pyrethrin
• Alkaloids (12,000)
• e.g., cocaine, opiates, quinine
• Phenylpropanoids ( Phenolics) (8000)
• e.g., THC, warfarin, Resveratrol

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Major Function is Ecological

• Ecological (act on other species)
• Protection (e.g., absorb UV radiation)
• Defense (discourage herbivores microbes)
• Attractants (e.g, attract pollinators and
  seed- dispersing animals)
• Allelopathy (gotta beat that competition)

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Uses by people

• 30 of prescription drugs are natural products
  (antibiotics, anti-tumor, anti- inflammatory,
  painkillers, etc.)
• Multibillion /yr supplements industry
• Insecticides Herbicides
• Fibers, oils, waxes
• Flavoring agents
• Perfumes

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Terpenoids

• Basic structure is from a 5-carbon unit, isoprene

• Synthesized as isopentenyl pyrophosphate IPP
• 2 alternative pathways to IPP
• from acetylCoA, cytosol
• from pyruvate, plastids
• IPP also precursor for essential sterols and
  carotenoids

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Taxol is an extensively decorated terpenoid,
while Phorbol is less so (hydroxylations).
(Core terpenoid of Taxol is in yellow/bold).
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Alkaloids

• Contain a Nitrogen, usually derived from an amino
  acid (e.g., Tyrosin)
• Long history of usage by people at least 3000
  years

Socrates death in 400 BC from the alkaloid of
hemlock Coniine.
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The most used and abused alkaloids,
morphine/heroin and cocaine. Morphine is
converted to heroin by acetylation of the
hydroxyls.
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Biosynthetic pathways

• Difficult to study
• enzymes at very low levels in whole plants
• 2? products themselves inactivate enzymes in
  extracts
• Callus cultures can be optimized for production
  of the compounds to study

Most of the enzymes for some products, e.g.,
morphine, have been isolated and cloned.
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• Metabolic Engineering
• Using transgenic technology to alter 2? (or 1?)
  products synthesis.

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Natural Products Research Future Discovery/Needs

• Many compounds yet to be identified or screened
  for bioactivity.
• Many plants have not been screened or studied at
  all.
• Many species of angiosperms (and other plants)
  have yet to even be discovered.
• Many species are becoming extinct before they
  are screened need conservation efforts for
  them.