Lecture 7a: plants that kill and heal Flashcards
Calabar bean - scientific name
Physostigma venenosum
Calabar bean - part used
bean
Calabar bean - bioactive compound
Physostigmine
Functions of physostigmine
- causes death by paralytic asphyxia
- it is a reversible inhibitor of acetylcholinesterase
- stimulates all the parasympathetic nerves
- the ability to contract the pupil led to its use to treat glaucoma
physostigmine is a parasympatholytic/parasympathomimetic ; it is a ——- agent and a miotic/mydriatic drug
parasympathomimetic; cholinergic; miotic
Deadly night shade - scientific name
Atropa belladonna
Deadly night shade - parts used
Foliage and berries
Deadly night shade - bioactive compound
Atropine
Deadly night shade is a parasmypatholytic/parasympathomimetic; it is a —— agent and a mydriatic/miotic drug
parasympatholytic; anticholinergic; mydriatic
mechanism of action of atropine
- inhibits all the parasympathetic nerves
- it is a muscarinic cholinergic blocking agent: inhibits the effect of acetylcholine on muscarinic receptors
- its ability to dilate the pupils led to its use before eye examinations and to treat certain conditions
Castor bean - scientific name
Ricinus communis
Castor bean - parts used
bean
Castor bean - bioactive compound
ricin
Ricin - mechanism of action
inhibits protein synthesis by specifically and irreversibly inactivating ribosomes (it is a ribosome inactivating protein - RIP)
Describe the different types of RIPs
1) type 1: monomer - present in wheat and barley (not poisonous)
2) type 2: dimer - most potent cytotoxic agent. Ricin is a type 2
mechanism of action of RIP2
a. the B chain binds to terminal galactose on cell surface receptors and the whole toxin is endocytose
b. the toxin reaches the Golgi and exploits retrograde transport to translocate to the ER
c. the separation of the A and B chains in the ER by protein disulfie isomerase followed by the escape of the A chain to the cytosol through the Sec61 translocon
d. in the cytosol, the A chain depurates adenine nucleotide of alpha sarin loop in the 60S ribosomal subunit and thereby inhibits protein synthesis irreversibly.
humectant - provide an example
retain moisture by preventing water loss through the outer layer of the skin
e.g. castor oil
Rosary Pea - scientific name
Abrus precatorius
Rosary Pea - parts used
bean
Rosary Pea - bioactive compound
Abrin
Lectin - functions
CHO binding proteins that are toxic and ubiquitous in nature
- inactivated by proper processing and prep
2 major forms of lectins
1) prolamine : toxic lectins that serve as storage proteins e.g. gluten
2) agglutinin: induce the clumping of red blood cells e.g. ricin
lectins are characterized by high content of —–
proline
Gluten is partially digested into —— and —— by our ——-
gliadin, glutenin, proteases
gliadin - function
it can cross the gut barrier and activate both the innate and adaptive immune system - it signals zonulin release from enterocytes that can loosen tight junctions and lets bigger molecules to go through
agglutinin are —— and resistant to —– pH and —- enzymes
small - low - proteolytic
agglutinin can increase ——— and stimuli he —– , ——
gut permeability , innate and adaptive immune system
how do agglutinins cause increased gut permeability
they bind to 2 sugars found on cell membrane : N-acetylglucosamine and N-acetylneuraminic acid and build up in lysosomes.
It also binds to epidermal growth factor (EGF) receptors and cuases tight junctions to open
Agglutinins (WGA) and neurotoxicity
- It can cross the blood brain barrier through a process called adsorptive endocytosis.
- It then binds to N-acetylneuraminic on surfaces such as gangliosides (involved in cell-cell contact, ion conductance etc.)
- It can also bind to myelin sheath and inhibit NGF
Thus reducing the overall signal transmission
Curare - scientific name
Chondodendron tomentosum
Curare - parts sued
Bark / Woody stems
Curare - bioactive compound
Tubocurarine
Curare is used as an —— in modern medicine
anesthetic
Curare - mechanism of action
- tubocurarine blocks the nAchR at the neuromuscular junction (serves as a competitive antagonist - has a greater affinity)
antidote fore curare poisoning
acetylcholinesterase inhibitor e.g. physostigmine
Foxglove - scientific name
Digitalis purpurea
Foxglove - parts used
leaves
Foxglove - bioactive compound
Digoxin
Digitalis - toxicity
causes nausea, vomiting, weakness, seizures, tremors, collapse, drooling, abnormal heart rate, and diarrhea
Digitalis - mechanism of action
- acts as a diuretic to reduce retention, a symptom of heart disease
- by promoting a regular heartbeat, digitalis causes more blood to reach the kidneys, where excess fluids are removed rather than accumulated in the body
- digoxin inhibits the sodium potassium ATP pump in the myocardium; with directly increases calcium concentration in the heart –> decreased HR and increased stroke volume (due to increased contractility)
Wolf’s bane - scientific name
Aconitum spp.
Wolf’s bane - parts used
all parts
Wolf’s bane - bioactive compound
aconitine
Aconitine - mechanism of action in the muscles
- it interacts with the voltage gated sodium non channels
- it increases the permeability of smooth muscle membrane to sodium ions, increasing calcium ion availability; therefore, muscular contraction
Aconitine - mechanism of action in the neurons
- it depolarizes both the pre and post synaptic membranes by opening sodium ion channels
- leads to increased calcium ion concentration in the presynaptic axon terminal by opening voltage gated calcium ion channels
- both excitatory or inhibitory neurotransmitters may be release and involved in the activity of aconitine on the postsynaptic cell, in addition to its direct action o the post-synaptic voltage gated sodium ion channels
Cycloplegia
paralysis of the cilia muscle of the eye
