How Toxic are Pawpaw Seeds?

(I posted this question on the other pawpaw thread, then thought I'd better make a separate thread.)

A friend (who is also a member here) brought me a pawpaw to try a little bit ago, because I'd never had one before.  She asked me to save the seeds so she could plant them, so I put all eight seeds in a bowl and left it on the counter.  When I went back through the kitchen, two of the seeds were gone, and I am pretty sure my mentally handicapped adult daughter ate them (she's eaten several things over the last few months that should not have been eaten).  I don't know if she chewed them up, or if she ate them whole, and asking her won't get any information.  Should I be worried about two seeds?  She weighs about 115 lbs..  She also has several auto-immune diseases, including lupus.

Kathleen

ETA:  I moved the seeds to where she can't see them.

Pawpaw seeds taken in high doses can be toxic, the seeds and bark of the plant reportedly have medicinal properties that make a powerful anti-cancer drug, as well as a natural pesticide.
The seeds of the pawpaw (Asimina triloba) contain several biologically active compounds called acetogenins.
Rather than killing a cell by scrambling its DNA, they starve the rapidly dividing cells of the ATP that fuels them.
Two acetogenins with anticancer prospects have been isolated by Jerry L. McLaughlin, A pharmacognosist at Purdue University in West Lafayette, Ind.
In tests conducted by a major pharmaceutical company, one of those acetogenins -- bullatacin -- proved 1 million times more potent than the common anticancer drug cisplatin in inhibiting the growth of human ovarian tumors transplanted into mice.

currently several pawpaw derived acetogenins are under study at The National Cancer Institute since they are showing they are effective against cancers.

Since the seeds were apparently from a ripe fruit, there is less probability of them being dangerous enough to poison her, but you will want to watch her closely, if she starts vomiting, time to call an ambulance and tell them what she ate.  Do Mention Acetogenins as the probable poison

Given the patient's condition, I would lock those seeds up so there is no doubt that she can't get to them again.

Redhawk

Thank you, Bryant.  The seeds are in a safe spot now.  I'm trying to decide if I still want to plant pawpaws here....apple seeds are also toxic in large quantities, but we eat those once in a while with no ill effects (although I don't chew them up; not sure about her).  Don't eat them on purpose, mind you, but it does happen once in a while.

Kathleen

Hau Kathleen, something to remember is that all homeopathic or at least most homeopathic substances are toxins when too much is used.
Just some examples are hen's bane, fox glove, pawpaw bark and skin of the fruit (we already talked about the seeds), just about any remedy that works well will have a therapy dose and a lethal dose, the trick is to know which is which and when and how to use them.

Just about every thing should be eaten thinking of the adage "all things in moderation", this keeps you out of trouble most of the time (mushrooms are one of the big exceptions where you absolutely need to know for certain prior to eating).

Apple seed toxin is a cyanide compound, the quantity is small per seed but you can  grind them and concentrate the cyanide from a pint of seeds and have many lethal doses (this is where chemistry knowledge is a big help).

Any time you are not sure, if you do a "toxicity of ______" search, you will find several good, reliable sources of information about what you are searching for.

Redhawk

Thank you again -- that's all good information.  

I was probably worried for nothing, as my daughter is doing great this evening.  But I didn't want to take chances with her health.  Also, maybe someday someone else will need the information.

Kathleen

Since there are a few reported cases of death by ingestion of pawpaw parts (not the ripe fruit) on record, I think you were pertinent to ask quickly.  
With many people now trying new things and the fact that many plants do have toxic components, I feel that one should know all they can about a plant before they decide to grow it.
Knowledge is so important when it comes to plants.  When I was 5 we had a neighbor that had Hemlock bushes in their front yard and their daughter ate one or two leaves from one of those bushes.
She survived after the ambulance trip to the hospital and the parents removed the hemlocks the next day.
If they had known what bushes they were, they could have warned their daughter to not touch them and that probably would have worked.

Over the years I've seen people with pets not know that the plant the animal was chewing on was poisonous to the animal, until their pet died.
Things like that are sad and preventable.

Redhawk

Daughter is still doing fine.

Were those hemlock 'bushes' poison hemlock?  Or were they in the tsuga genus (hemlock trees)?  Because the latter aren't poisonous.

I do think I'm going to plant a couple of pawpaws here, but we are going to be very careful with them.  This is a new area to us, and we can grow things here I've never before been able to grow, but you are right -- we do need to learn as much as we can about them.

Kathleen

Greetings.

I was into some of the paw paw (asima triloba ?) literature, and got diverted by the toxicology information.

There are compounds which Bryant Redhawk pointed out, and at least some of them have interest in an antic-cancer sense.

However, at least one of the compounds is also a neurotoxin.  In particular, it kills/damage cortical neurons.  Pubmed references a few articles that are relatively recent.

In some pages on the Internet, these compounds get mentioned in the context of Parkinson's.  A few point out, the relationship (or probably better described as a correlation, as causality doesn't seem to be demonstrated) is with atypical Parkinson's.  Parkinson's responds to L-DOPA; and atypical doesn't (if I remember correctly).

Best of luck and continued good health.

Medicines in fruit, and fruit trees are so interesting to me. I mean, why are they there in the first place? What are the chances that trees just happen to contain medicine that can be utilized by human kind? It’s really crazy, when you really think about it, really...
: )

I wonder if eating the fruit itself has any unrealized benefits? Only time will tell.

I’m currently growing four varieties of paw paws. They are slow growing, but very nice looking leaves. No fruit yet, though; but, they will come in time.
I read that paw paws are the largest native North American fruit that we know about.

=M=

ScienceDirect had something else of interest.

Many people talk/write about there being components in a food which can affect the action of components such as toxins.

It seems that the ability of acetogenins in some foods to cause DA cell death (presumably by inhibiting mitochondrial complex I) can be influenced by sugars.

Annonacin caused the death of DA neurons in mesencephalic cultures via a mechanism that mostly resulted from impairment of energy metabolism. Indeed, annonacin-induced DA cell death was prevented by two hexoses, glucose and its glycolyzable isomer mannose, which both operated by partially restoring intracellular ATP levels which were decreased as a consequence of mitochondrial complex I inhibition (Lannuzel et al., 2003). Deoxyglucose, a non-metabolizable glucose/mannose analog, reversed these neuroprotective effects probably by competition, at the glucose transporter sites. Other hexoses such as galactose and fructose were not protective because they were poorly taken up by DA neurons (Lannuzel et al., 2003). Attempts to restore oxidative phosphorylation with substrates of the citric acid cycle, lactate or pyruvate, failed to provide protection to DA neurons whereas idoacetate, an inhibitor of glycolysis, inhibited survival promotion by glucose and mannose indicating that both hexoses acted upstream of the mitochondria by stimulating the glycolytic flux in these neurons (Lannuzel et al., 2003).

https://www.sciencedirect.com/topics/neuroscience/acetogenin

Peterson gives the (ripe?) composition of paw paw fruit as:

Sugars in  ripe pawpaw
Fructose 1.3-2.8
Glucose 1.8-4.0
Sucrose 6.0-13.3

I am not finding any information about deoxyglucose in fruits (or pawpaw fruit in particular), but I did run across a research paper where deoxyglucose was used as an internal standard in a fruit extraction.  If that extract was then used in a toxicology study, the results could be biased.

Kathleen,
As many of us have on this forum have, I like to grow pawpaw trees. Be aware they are sensitive to direct sunlight for the first 2-3 years depending on where on the Earth you are located. These are usually an understory tree in nature, but can be grown orchard style very nicely. I kept mine shaded for the first two years. I had a few growing out in direct sunlight and they simply shriveled up and died in the first summer. I'm a big fan of pawpaw fruit. The University of Kentucky has done extensive research on this lovely tree/fruit.  http://www.pawpaw.kysu.edu/

It makes spectacular ice cream, great smoothies, or just plain fresh! Enjoy.

Thanks for the "like" Bryant Redhawk!

Having spent years with pharmaceutical chemists, a little rubbed off.  I can manage to read and understand some of the biological literature.  But mostly I am a materials science person.