Nature’s Defenses

• Natural toxins are diverse chemical compounds produced by living organisms
• Major Classes of Natural Toxins

  • Alkaloids
  • Glycosides
  • Terpenoids
  • Proteins and Peptides
  • Mycotoxins
• Alkaloids


  e.g. Nicotine in tobacco, Morphine in poppies
• Glycosides


  e.g. Cyanogenic glycosides in cassava and almonds
• Terpenoids


  e.g. Taxol from Pacific yew trees, toxic in high doses
• Proteins and Peptides


  e.g. Ricin from castor beans, Tetrodotoxin from pufferfish
• Mycotoxins


  e.g. Aflatoxins from Aspergillus species, common in grains and nuts
• Plants produce toxins primarily as defense mechanisms against herbivores, pathogens, and competitors
• Understanding toxin mechanisms sheds light on species' chemical defenses and offensive mechanisms

  
• Cholera toxin

  Modifies the Gs protein in intestinal cells, leads to overproduction of cAMP
• Pertussis toxin


  Increases cAMP levels in respiratory cells, contributes to persistent coughing
• Exotoxin A (Pseudomonas aeruginosa)

  Inhibits protein synthesis by ADP-ribosylating EF-2
• Tetrodotoxin


  Blocks sodium channels, found in pufferfish
• Hemotoxins


  Affect blood and vascular systems, found in snake venoms

  
• Understanding snake venoms and hemotoxins can lead to the development of antidotes and therapeutic agents

  
• Historical Use of Natural Toxins

  • Hunting and Warfare
  • Cultural Practices
  • Medicinal Treatments
• Poison-tipped Arrows and Spears

  Hunters and warriors would coat the tips of their projectiles with toxic substances
• Coating Weapons


  Blades and other sharp implements were often coated with toxins
• Booby Traps and Defensive Mechanisms

  Toxins were also used in setting traps and creating defensive measures
• Rituals and Ceremonies


  Toxic substances were often integral components of ceremonial rituals
• Spiritual and Religious Rites


  Many cultures attributed mystical or supernatural significance to certain toxic compounds
• Traditional Healing Methods


  In some indigenous healing traditions, toxins were employed as therapeutic agents
• The Scythians employed venomous snake toxins on arrowheads, potentially the earliest use of biological warfare

  
• Pain Relief and Anesthesia


  Certain toxins possess analgesic or numbing effects
• Treating Infections and Wounds

  Many toxins exhibit antimicrobial or antiseptic properties
• Managing Various Ailments and Diseases


  Toxic substances were sometimes ingested, inhaled, or applied externally as remedies
• Pacific Yew Tree and Paclitaxel


  Source of Paclitaxel, a cancer drug, shift in perception of natural toxins
• The golden lancehead pit vipers (Bothrops insularis) are endemic to Ilha da Queimada Grande (Snake Island) with an estimated population of 2,000 to 4,000 snakes

  
• Access to Ilha da Queimada Grande is strictly prohibited by the Brazilian government
• Scientific research on Ilha da Queimada Grande offers valuable insights into the evolution of venom and venom delivery mechanisms, species adaptation to isolated island environments, and conservation strategies for endangered species

  
• Poison dart frogs

  Renowned for their potent skin toxins and vibrant colors, use chemical defense mechanism (aposematism)
• Batrachotoxins


  In poison dart frog skin, can disrupt nervous system function by interfering with sodium ion channels in nerve cell membranes
• Ecological Role vs. Human Uses of Poison Dart Frogs


  • Ecological Role: Predator Deterrent, Influence on Biodiversity, Indicator Species
  • Potential Human Uses: Medical Research, Conservation Efforts

  
• Cone Snails

  Inhabit tropical and subtropical waters around the world, commonly found in coral reefs, sandy bottoms, and rocky shores
• Conotoxins


  Small peptides found in cone snail venom, target specific receptors and ion channels in the nervous system

  
• Mechanism of Action of Conotoxins

  Block the transmission of pain signals in the nervous system, disrupt pain signaling pathways
• Medical Applications of Conotoxins


  Show promise for the treatment of chronic pain conditions, offer an alternative to traditional opioid medications
• Cone snail venom contains a diverse array of bioactive compounds with potential medical applications
• Conservation efforts aim to protect cone snail habitats, regulate trade, and raise awareness about the importance of these fascinating marine creatures
• Understanding natural toxins is crucial for risk management and therapeutic use