American pawpaw

• How It Works

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

  Asimina triloba, commonly known as pawpaw, is native to North America and has edible bean-shaped fruits. The plant extract is used in anti-lice shampoo and in pesticides.

  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 killed cancer cells resistant to commonly used chemotherapy drugs such as adriamycin. It also appeared to be more toxic to cancer cells than to normal cells. However, studies on these effects have not been conducted in humans.

• 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 or effectiveness of pawpaw for cancer treatment.
• 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.
  • Pawpaw should not be confused with graviola, also known as Brazilian pawpaw, or with papaya, another fruit with a similar texture and appearance.
• Scientific Name

  Asimina triloba

• Clinical Summary

  Asimina triloba, commonly known as pawpaw, is native to North America and has edible bean-shaped fruits.

  In vitro studies show that pawpaw extract has cytotoxic effects against cancer cell lines including those resistant to adriamycin ⁽¹⁾, as well as antiangiogenic activity ⁽⁹⁾. Compounds known as acetogenins are thought to be the active constituents ⁽²⁾. Clinical studies have not been conducted.

  Extracts of pawpaw twigs and leaves have been used in anti-lice shampoos ⁽³⁾ and as pesticides ⁽⁴⁾.

  Both the crude fruit extract and annonacin, a major constituent of pawpaw, cause neurotoxicity in vitro  ⁽¹⁰⁾.

  Asimina triloba should not be confused with graviola, also known as Brazilian pawpaw, or with papaya, another fruit with a similar texture and appearance.

• Food Sources

  Pawpaw fruit

• Purported Uses
  • Lice removal
  • Pesticide
  • Cancer treatment
• Mechanism of Action

  Acetogenins, the active constituents of pawpaw fruit, 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 multidrug-resistant cells in vitro, perhaps via inhibition of 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⁾
• References

  • 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.

  • Zhao GX, Rieser MJ, Hui YH, et al. Biologically active acetogenins from stem bark of Asimina triloba. Phytochemistry. Jul 1993;33(5):1065-1073.

  • 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.

  • 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.

  • 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.

  • Layne DR. Pawpaw. http://www.hort.purdue.edu/newcrop/cropfactsheets/pawpaw.html. Accessed July 3, 2019.

  • 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.

  • 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 July 3, 2019.

  • 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.

  • Potts LF, Luzzio FA, Smith SC, et al. Annonacin in Asimina triloba fruit: implication for neurotoxicity. Neurotoxicology. 2012 Jan;33(1):53-8.

  • 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.

  • Wood R, Peterson S. Lipids of the pawpaw fruit: Asimina triloba. Lipids.1999 Oct;34(10):1099-106.

  • 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.

  • 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.