Leaves and Associated Chemicals

  • Aromatic Nature of Leaves
    • Leaves contain chemicals that are aromatic, meaning they have qualities that make them volatile and detectable by smell, unlike the aromatic definition in organic chemistry.
    • Examples of the use of aromatherapy with these aromatic compounds.

Efficacy of Aromatherapy

  • General Use
    • Aromatherapy utilizes various plant extracts, including oils, for therapeutic purposes.
  • Clove Oil
    • Used in aromatherapy and flavoring due to its powerful analgesic properties.
    • Contains active compounds called terpenoids.

Terpenoids in Common Plants

  • Cinnamon
    • Derived from the bark of a tree, contributes to its distinctive flavor and aroma through terpenes.
  • Citrus Oil and Ginger
    • Demonstrated strong antibacterial properties attributed to terpenoids.
  • Camphor
    • Recognizable scent associated with products like Vicks VapoRub.
    • Edible forms are used as flavoring in many Indian desserts.
  • Menthol
    • Commonly used to alleviate chest congestion and as a flavoring agent.
    • Variations in mint species result in different terpene combinations leading to diverse flavors from strong peppermint to sweet mint.
  • Salvinorin A
    • An active diterpene from Salvia divinorum, known for its hallucinogenic effects, differentiated from typical alkaloid hallucinogens.
    • Historically used by Mexican curanderos in divination ceremonies.
    • In 2010, labeled as a dangerous drug in Georgia, though still able to grow in the wild.

Glycosides

  • Definition and Taste
    • Glycosides contribute to the bitter flavor in many vegetables, notably those in the Brassicaceae family (mustard family).
  • Examples:
    • Common members include kohlrabi, broccoli, cabbage, and brussels sprouts.
    • Bitter flavor generated from glucosinolates, which serve as natural pesticides for plants.
  • Health Implications
    • Low concentrations of glucosinolates have anti-cancer properties, notably present in broccoli sprouts.
    • High levels can lead to toxicity, as seen with mustard gas.

Medicinal Use and Toxicity of Glycosides

  • Foxglove (Digitalis purpurea)
    • Contains digitalins used for treating congestive heart failure but can be toxic in higher concentrations.
    • Caution advised when planting due to potential toxicity to pets and children.
    • Doctor William Withering's 1775 documentation of foxglove for heart conditions as a pioneer of herbalist medicine.
  • Prunus Species
    • Bitter almonds, apple seeds, cherries, and peaches contain amygdalin, which can lead to cyanide poisoning.
    • Almond smell associated with cyanide as a warning sign.

Conservation and Ethnobotanical Issues

  • Threats to Medicinal Plants
    • Noted decline in rainforest biodiversity, with less than 1% of plant species evaluated for medicinal properties.
    • Deforestation and wildcrafting as significant threats to species existence.
    • Overharvesting of plants like ginseng impacting availability.
  • Universal Health Care and Access
    • Approximately 80% of the global population relies on traditional plant-based medicines due to limited access to conventional healthcare.
  • Bioprospecting and Ethical Concerns
    • Researcher and pharmaceutical companies identifying plants for drug development often face criticism regarding fair benefit sharing.
    • Term "biopiracy" refers to exploitative practices of obtaining indigenous knowledge without fair compensation.
    • Merck's INBIO project in Costa Rica presents both opportunities and challenges in bioprospecting.

Recommendations for Further Research

  • Ethnobotanical Research
    • Refer to resources like James Duke's phytochemical database, Green Pharmacy, UMD Native American ethnobotany repository, and US Forest Service.
    • Distinguish traditional use from commercial recreational use in research (e.g., vision quests versus smoking marijuana).
    • Detailed exploration of plants highlighted in the presentation will require extensive research and accurate specifics.