Plant Secondary Metabolism: Alkaloids

00:09:32
https://www.youtube.com/watch?v=lSCjtOREhaY

Summary

TLDRThis video explores the diverse world of alkaloids, naturally occurring compounds with a variety of roles and effects. Alkaloids are known for their defensive function as insecticides or repellents and have diverse pharmacological properties in mammals, including stimulant, depressant, or hallucinogenic effects. While some alkaloids, such as coneine and physistigmene, are deadly, others have important medical applications. The video categorizes different alkaloid types, such as tropine, pyridine, quinoline, isoquinoline, indole, imidazole, purine, and phenol alkaloids, highlighting their sources and biological impacts. For instance, tropine alkaloids like atropine are both medicinal and toxic, quinoline alkaloids such as quinine were instrumental in malaria treatment, and purine alkaloids like caffeine are popular stimulants. These compounds vary widely in their presence across plant species and are integral in both plant defense and human culture.

Takeaways

  • 🥼 Alkaloids serve diverse biological roles, from defense mechanisms to pharmacological effects on mammals.
  • 🌱 Tropine alkaloids, like atropine and cocaine, originate from plants like the deadly nightshade.
  • 💊 Alkaloids exhibit wide pharmacological properties, some beneficial and others toxic.
  • 🦠 Pyridine-pipyridine and quinoline alkaloids come from diverse sources, impacting human medicine significantly with examples like nicotine and quinine.
  • 🧪 Indole and isoquinoline alkaloids like strychnine and morphine are significant for their medicinal and toxic properties.
  • 🍫 Purine alkaloids, including caffeine and theobromine, are common stimulants found in various beverages and foods.
  • 🔍 The presence of a cyclic nitrogen atom characterizes many alkaloids, influencing their activity and effects.
  • 🍵 Caffeine, a well-known purine alkaloid, acts as a stimulant in coffee and tea.
  • 🌿 Imidazole alkaloids, such as pilocarpine, are vital for treating conditions like glaucoma.
  • 💡 Phenol alkamine alkaloids distinguish themselves by lacking a cyclic nitrogen and include known compounds like ephedrine.

Timeline

  • 00:00:00 - 00:09:32

    This section introduces alkaloids, highlighting their diverse roles in defense against insects, and their varied pharmacological effects on mammals, including stimulant, depressant, and hallucinogenic properties. Some alkaloids are noted as deadly poisons, like coniine and physostigmine. Alkaloids, which contain cyclic nitrogen, are not widespread in all plants and can also be produced by some bacteria, fungi, and animals. Tropine alkaloids, characterized by a tropine ring, include well-known compounds like atropine and cocaine, which are both medicinal and toxic. The lesson sets the stage for a deeper exploration of the pharmacological properties of these alkaloids in future lessons.

Mind Map

Video Q&A

  • What roles do alkaloids play in nature?

    Alkaloids can function as insecticides or insect repellents and affect mammals' central nervous systems, causing stimulating, depressing, or hallucinogenic effects.

  • Are all alkaloids beneficial to humans?

    Some alkaloids have beneficial medicinal properties, while others can be toxic or lethal, such as coneine and physistigmene.

  • What are some examples of tropine alkaloids?

    Tropine alkaloids include atropine and cocaine, found in plants like deadly nightshade, and they can be both medicinal and poisonous.

  • Can you give examples of isoquinoline alkaloids and their effects?

    Isoquinoline alkaloids include morphine and paclitaxel, known for their narcotic and therapeutic effects in medicine.

  • What are pyridine-pipyridine alkaloids?

    Pyridine-pipyridine alkaloids are derived from pyridine and piperidine and include compounds like nicotine from tobacco.

  • What is a well-known example of a quinoline alkaloid?

    Quinoline alkaloids include quinine, isolated from the cinchona bark, which was historically used to treat malaria.

  • What are some characteristics and examples of indole alkaloids?

    Indole alkaloids, such as strychnine, can be toxic and include compounds with medicinal uses like physostigmine for glaucoma treatment.

  • What are imidazole alkaloids used for medically?

    Imidazole alkaloids include pilocarpine, used for glaucoma treatment, found in the rutaceae family.

  • What are purine or xanthine alkaloids, and where are they found?

    Common alkaloids in this group are caffeine and theobromine, found in coffee, tea, and chocolate, used as stimulants.

  • What differentiates phenol alkamine alkaloids from other alkaloids?

    Phenol alkamine alkaloids, such as ephedrine and mescaline, lack a cyclic nitrogen atom and have stimulant or psychoactive effects.

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  • 00:00:00
    [Music]
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    although the biological purpose of many
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    alkaloids is still not clearly
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    understood scientists have determined
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    that many play a role
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    in defense as insecticides or insect
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    repellents
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    in mammals these compounds display a
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    wide range of pharmacological properties
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    including stimulant or depressant action
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    on the central nervous system
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    and some even produce hallucinogenic
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    effects
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    on the other hand some alkaloids like
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    coneine and physistigmene
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    are deadly poisons here
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    some of the different classes of
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    medically relevant alkaloids produced by
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    plants will be discussed
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    alkaloids are a group of naturally
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    occurring compounds
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    and most of them share a common feature
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    of containing a cyclic nitrogen
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    now while most contain one such nitrogen
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    there are exceptions that can contain
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    up to five such as ergotamine
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    they are produced not only by certain
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    plants but also some bacteria fungi and
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    animals can make them as well
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    overall however they are not ubiquitous
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    in all plants and have a limited
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    distribution
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    in nature tropine alkaloids are
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    characterized by a tropine ring in their
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    chemical structure
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    some prominent examples include atropine
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    scopolamine hiosamine and cocaine
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    atropa belladonna also commonly known as
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    the deadly nightshade
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    produces a racemic mixture of plus and
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    minus hyacinamine isomers
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    known as atropine this plant is named
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    after a tropos
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    the greek fate that cuts the threat of
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    life as the plant
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    and this compound are both medicinal and
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    poisonous as the name implies
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    we'll get more into the pharmacological
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    properties of atropine and other
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    alkaloids in later lessons
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    now let's discuss the pyridine
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    pipyridine alkaloids
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    following reduction the tertiary base
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    pyridine is converted into the secondary
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    base piperidine the alkaloids included
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    in this class are further divided into
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    three groups based on their source
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    piperidine derivatives such as loboline
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    nicotinic acid derivatives
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    such as and derivatives of both pyridine
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    and pipyridine
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    for example nicotine from the tobacco
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    plant shown here
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    which contains a pyrilidine ring
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    structure
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    additional examples of bioactive
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    compounds in this class
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    include piperine and conein now let's go
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    over pyralyzidine alkaloids
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    these are chemically characterized by
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    the presence of a reactive carbon
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    which contributes to their high level of
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    hepatotoxic
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    or liver toxic properties senecionine
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    and retronacine from grounsell shown
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    here
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    sinesio vulgaris in the asteraceae
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    family are good examples of this
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    these are known to cause poisoning by
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    liver injury to livestock that graze on
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    the ground sole
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    comfrey known by its scientific name of
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    symphonium officinali in the boraginessi
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    family
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    likewise contains retronisine as well as
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    symphytine
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    among other pure lizardine alkaloids
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    this alkaloid class is most commonly
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    found in certain members of the
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    following plant families
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    the asteraceae boragenaceae phabaceae
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    and orchid ac
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    let's go over quinoline alkaloids the
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    best known example of medically relevant
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    quinoline alkaloid derivatives is that
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    of
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    quinine which is r revolutionize the
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    treatment of malaria
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    until the malaria parasite eventually
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    developed resistance to the drug
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    quinine was isolated from the bark of
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    cincona species
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    native to south america and also known
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    as fever bark
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    shown here in addition to queening
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    a few other medically important
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    quenelline alkaloids are also produced
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    by the genus synchona
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    and this includes quinidine which is an
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    isomer quinine
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    synchonine and its isomer cinconidine
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    now let's discuss isoquinoline alkaloids
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    these occur in a number of plant
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    families such as the papaveracy
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    rubiaceae menispermiaceae and random
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    kilace families among others
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    this class includes several highly
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    important medicines
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    including the opiate alkaloids morphine
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    and papaverine from the opium poppy
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    that has a scientific name of papaver
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    somniferum in the papaveray ce family
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    there's also imatine from the emetic or
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    vomit inducing plant of ipac
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    scientifically known as cephalus
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    epicat guana found in the ruby ace
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    family
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    and tubocurarine from the kurari vine
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    or conadengine tomentosum in the
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    menispermiaceae family
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    other therapeutic isoquenoline alkaloids
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    include hydrastine
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    and berberine from goldenseal also known
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    as hydrastus canadensis in the
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    renuncialaceae family
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    and sanguinarine from bloodroot known as
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    sanguinaria canadensis and the papaver
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    ace family
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    isoquinoline alkaloids vary in their
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    activity from narcotic
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    anesthetic and medic and more
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    now let's go over indole alkaloids these
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    are characterized by the presence of an
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    indole ring in their structure
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    there are a number of medically
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    important alkaloids in this class
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    including several poisons for example
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    ingestion of the endo alkaloid
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    strychnine
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    found in strychnos nukes vomica of the
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    loganiace family
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    shown here leads to death caused by
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    respiratory failure
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    physostigmine from physostigma venonosum
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    in the fabaceae family has medicinal
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    uses
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    such as for the treatment of glaucoma
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    and as an antidote to poisoning
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    by certain members of the solanaceae
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    family
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    plants like jimson weed or
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    deteristramonium
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    and the deadly nightshade or atropa
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    belladona
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    however overdose of this compound will
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    result in cholinergic syndrome and can
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    lead to respiratory and cardiac failure
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    other examples of this class include vin
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    christine and vinblastine from the
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    madagascar periwinkle
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    or catharanthus rosius in the apostolacy
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    family
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    these are used in cancer treatments for
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    leukemia and
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    hodgkin's lymphoma
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    next let's cover imidazole alkaloids
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    this class is characterized by the
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    presence of an amidazole ring
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    a prominent example of this class is
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    pilocarpine
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    which is found in jabarandi or
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    pilocarpus jamborandi in the rutasi
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    or citrus family it's also found in
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    other species of the pilocarpus genus
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    pilocarpine shown here is used to treat
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    forms of glaucoma
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    and dry mouth now let's cover
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    a class of alkaloids that you're
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    probably quite familiar with
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    the purine or xanthine alkaloids these
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    are widely consumed as stimulants
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    one of the most prominent members of
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    this class is caffeine
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    which is a central nervous system
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    stimulant found in coffee
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    or cafe arabica and the rubiaceae family
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    tea or camellia sinensis found in the
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    tac family
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    and yaupon holly or ilex vomitoria found
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    in the aquafolia ac family
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    theophylline which is another purine
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    alkaloid
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    exhibits smooth muscle relaxant effects
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    and is found in both tea
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    and chocolate also known as the abrama
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    cacao in the malvaci family
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    theophylline is used in therapeutic
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    applications for the treatment of
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    respiratory diseases such as chronic
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    obstructive pulmonary disease
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    or copd and asthma
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    another purine alkaloid known as
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    theobromine
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    is likewise found in tea and chocolate
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    and in fact
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    is the most abundant alkaloid of
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    chocolate
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    this exhibits vasodilatory and diuretic
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    properties in humans
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    but can cause poisoning in dogs as they
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    metabolize the compound
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    much more slowly than humans do
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    now let's cover the phenol alkamine
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    alkaloids
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    alkaloids in this group lack a cyclic
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    nitrogen atom in their chemical
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    structure
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    but they either have a free amine group
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    or
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    an alkyl substituted amine a prominent
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    example of this group includes
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    ephedrine from the traditional chinese
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    medicinal plant
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    ma huang also known as ephedra seneca
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    and the ephedry sea family other
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    examples include mescaline from the
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    peyote cactus and colchicine from the
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    autumn crocus
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    if you are a tear coffee lover you reap
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    the benefits of xanthine alkaloids to
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    kick-start your day
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    as you reflect on the myriad forms and
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    functions of alkaloids consider for a
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    moment
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    the different ways that these natural
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    products have influenced
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    different human cultures over the span
  • 00:09:21
    of time
Tags
  • Alkaloids
  • Pharmacological Properties
  • Natural Compounds
  • Plant Defense
  • Medicinal Uses
  • Stimulants
  • Toxicology
  • Atropine
  • Quinine
  • Caffeine