American pawpaw

Health Care Professional Information

Scientific Name
Asimina triloba
Common Name

False banana, pawpaw apple, custard banana, poor man’s banana, Hoosier banana

Clinical Summary

Asimina triloba, commonly known as Pawpaw, is native to North America and has edible bean-shaped fruits.
In vitro studies showed that Pawpaw extract has cytotoxic effects against cancer cell lines including those resistant to Adriamycin (1), and has antiangiogenic activity (9). Compounds known as acetogenins are thought to be the active constituents (2). However, clinical studies are lacking.
Extracts of twigs and leaves have been used in anti-lice shampoos (3) and as pesticides (4).

Annonacin, a major constituent of Pawpaw, and the crude fruit extract cause neurotoxicity, in vitro (10).
Asimina triloba should not be confused with graviola, also known as Brazilian Paw paw, or with papaya, another fruit with a similar texture and appearance.

Food Sources

Pawpaw fruit

Purported Uses
  • Lice removal
  • Pesticide
  • Cancer treatment
Constituents
  • Acetogenins: cis- and trans-annonacin-A-one, cis- and trans-gigantetrocinone and cis-isoannonacin, trans-isoannonacin, squamolone, asimicin, bullatacin, and bullatalicin, Asitrilobins C and D
  • Lipids
  • Phenolic Acids
  • Flavonoids
    (2) (11) (12) (13) (14)
Mechanism of Action

Acetogenins inhibit Complex I of the electron transport chain and NADH oxidase, a protein in the plasma membrane (1). With the decrease in regenerable NAD, the ATP levels drop, leading to subsequent cell death by apoptosis. In vivo experiments have demonstrated Pawpaw's cytotoxicity in mice (5). Pawpaw extract is also cytotoxic to Multi-Drug Resistant cells in vitro (1). This is thought to occur via acetogenin's inhibition of the 170 kDa plasma membrane glycoprotein (the P-170 glycoprotein), an efflux pump used by cells resistant to drugs like Adriamycin (1).
Annonacin, a major ingredient of Pawpaw fruit, and the crude fruit extract were shown to be toxic to cortical neurons (10).

Contraindications
  • Pregnancy
Adverse Reactions
  • Allergic reactions (7)
  • Neurotoxicity (10)
  • Emesis (6)
Literature Summary and Critique

Unpublished case studies indicate reports of improvement by cancer patients after consuming pawpaw extract (8). These studies were conducted without proper experimental controls and statistical analyses.
There are several Web sites that promote pawpaw as an effective treatment for cancer. However, there is very little scientific evidence to support such claims.

Dosage (Inside MSKCC Only)
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References
  1. Oberlies NH, Croy VL, Harrison ML, McLaughlin JL. The Annonaceous acetogenin bullatacin is cytotoxic against multidrug-resistant human mammary adenocarcinoma cells.Cancer Lett. May 1 1997;115(1):73-79.
  2. Zhao GX, Rieser MJ, Hui YH, et al. Biologically active acetogenins from stem bark of Asimina triloba. Phytochemistry. Jul 1993;33(5):1065-1073.
  3. McCage CM, Ward SM, Paling CA, et al. Development of a paw paw herbal shampoo for the removal of head lice. Phytomedicine. Dec 2002;9(8):743-748.
  4. Ratnayake S, Rupprecht JK, Potter WM, McLaughlin JL. Evaluation of various parts of the paw paw tree, Asimina triloba (Annonaceae), as commercial sources of the pesticidal annonaceous acetogenins. J Econ Entomol. Dec 1992;85(6):2353-2356.
  5. Ahammadsahib KI, Hollingworth RM, McGovren JP, Hui YH, McLaughlin JL.Mode of action of bullatacin: a potent antitumor and pesticidal annonaceous acetogenin. Life Sci. 1993;53(14):1113-1120.
  6. Layne DR. Pawpaw. http://www.hort.purdue.edu/newcrop/cropfactsheets/pawpaw.html. Accessed October 15, 2014.
  7. Avalos J, Rupprecht JK, McLaughlin JL, Rodriguez E. Guinea pig maximization test of the bark extract from pawpaw, Asimina triloba (Annonaceae). Contact Dermatitis. Jul 1993;29(1):33-35.
  8. McLaughlin J L, Benson GB, Forsythe JW.  A novel mechanism for the control of clinical cancer: Inhibition of the production of adenosine triphosphate (ATO) with a standardized extract of paw paw (Asiminoz triloba, Annonaceae). http://www.pawpawresearch.com/pawpaw-trials1.pdf. Accessed October 15, 2014.
  9. Coothankandaswamy V, Liu Y, Mao SC, et al. The alternative medicine pawpaw and its acetogenin constituents suppress tumor angiogenesis via the HIF-1/VEGF pathway. J Nat Prod. 2010 May 28;73(5):956-61.
  10. Potts LF, Luzzio FA, Smith SC, et al. Annonacin in Asimina triloba fruit: implication for neurotoxicity. Neurotoxicology. 2012 Jan;33(1):53-8.
  11. Pomper KW, Lowe JD, Crabtree SB, Keller W. Identification of annonaceous acetogenins in the ripe fruit of the North American pawpaw ( Asimina triloba ). J Agric Food Chem. 2009 Sep 23;57(18):8339-43.
  12. Wood R, Peterson S. Lipids of the pawpaw fruit: Asimina triloba. Lipids.1999 Oct;34(10):1099-106.
  13. Woo MH, Kim DH, McLaughlin JL. Asitrilobins A and B: cytotoxic mono-THF annonaceous acetogenins from the seeds of Asimina triloba. Phytochemistry. 1999 Mar;50(6):1033-40.
  14. Brannan RG, Peters T, Talcott ST. Phytochemical analysis of ten varieties of pawpaw (Asimina triloba [L.] Dunal) fruit pulp. Food Chem.2015 Feb 1;168:656-61.

Consumer Information

How It Works

Bottom Line: Pawpaw is toxic to some cancer cells, but such effects have not been shown in humans.

The major components of Pawpaw are compounds known as acetogenins. They prevent the cell from making ATP, an important energy source. In lab studies, the extract was shown to kill cancer cells that were resistant to commonly used chemotherapy drugs such as Adriamycin, and appear to be more toxic to cancer cells than to normal cells. However, this has not been shown in humans. The plant extract is used in anti-lice shampoo and in pesticides.

Purported Uses
  • Anti-lice treatment
    Pawpaw extract has been shown to be effective as an anti-lice shampoo.
  • Anti-parasitic treatment
    Studies have not evaluated Pawpaw's ability to kill parasites. There is laboratory-based evidence that attribute this ability to other closely related plants.
  • Cancer treatment
    Pawpaw has been shown to be effective against cancer cells in test tubes, but experiments in mice produced conflicting results. There are no published clinical studies in humans to determine the safety of Pawpaw for cancer treatment.
Research Evidence

Pawpaw has not been studied in well designed clinical trials.

Do Not Take If
  • You are pregnant.
Side Effects
  • Allergic reactions
  • Nerve toxicity
  • Vomiting
Special Point

There are several Web sites that promote pawpaw as an effective treatment for cancer. However, there is very little scientific evidence to support such claims.

E-mail your questions and comments to aboutherbs@mskcc.org.