American Cancer Society has been Funding Research on Papaya Leaf Enzyme

American Cancer Society research on the enzyme papain in the papaya leaf:


From 1954

From 1962
The Carboxyl-Terminal Sequence of Papain
Journal of Biological Chemistry
Albert Light

From 1964
Proc Natl Acad Sci U S A. Nov 1964; 52(5): 1276–1283.
PMCID: PMC300436

Albert Light, Robin Frater,† J. R. Kimmel,‡ and Emil L. Smith

From 1969
“Digestion of tumor cell suspensions
with papain liberates a Sialoglycopeptide fraction from the cell surface…
Abercrombie and Ambrose (1) have proposed that alterations at the cell periphery contribute significantly to many of the manifestations of the malignant cell: invasiveness, liability to passive dissemination, and disorganization of structure…”

Isolation and Chemical Characterization of a Cell-Surface Sialoglycopeptide Fraction from Novikoff Ascites Cells
Earl F. Walborg, Jr., Roberta S. Lantz and Virginia P. Wray Cancer Research 1969;29:2034-2038.

From 1970:
January 1970, Vol.7(1):1–4, IN1–IN2, 5–6, doi:10.1016/0019-2791(70)90025-X
The papain susceptibility of IgG myeloma proteins of different heavy chain subclasses ☆
J. Gergely
H.H. Fudenberg
Erna Van Loghem

From 1985
Reversible Covalent Inhibition of Papain by a Peptide Nitrile. C NMR Evidence for a Thioimidate Ester Adduct.
Joseph B. Moon,la Robert S. Coleman,Ib and Robert P. Hanzlik*
Department of Medicinal Chemistry Received July 22, 1985

From 1989:

Papaya Leaf takes 21 Days for Red Blood Cell Count to Improve


In a Sri Lankan study, Papaya leaf extract was shown to increase the red blood cell count (erythropoiesis is blood cell manufacturing in the bones) significantly in mice in the lab in 21 days, where the platelets increased in three days time.

“…the RBC count in the test group increased from 6×106/µL to 9×106/ µL at Day 21 while it remained near constant in the control group (6×106/µL).” (See source below)

Chemotherapy has effect on the red blood cell manufacturing, according to experts at

“Routine blood count monitoring is a crucial part of chemotherapy. That’s because the drugs can harm cells in the bone marrow, where blood is produced. This can result in several problems. Red blood cells carry oxygen to tissues. Anemia occurs when your body doesn’t produce enough red blood cells, making you feel extremely fatigued.” – See more at:

Does Carica papaya leaf-extract increase the platelet count? An experimental study in a murine model
Asian Pac J Trop Biomed. Sep 2013; 3(9): 720–724.
doi: 10.1016/S2221-1691(13)60145-8
PMCID: PMC3757281

Summary of Papaya Leaf Compounds

Indian Researchers Summarize Papaya Leaf Compounds in a recent issue of
International Journal of Pharmacognosy and Phytochemical Research 2014; 6(2); 260-265

Carica Papaya Leaf Extracts – An Ethnomedicinal Boon

*International Journal of Pharmacognosy and Phytochemical Research 2014; 6(2); 260-265,
Tatyasaheb Patil, Bharati medical college, sangli, Maharashtra, India
Snehal Patil, School of dental sciences, Krishna institute of medical sciences. Karad, India.
Anuprita Patil, Practicing dentist, India
Shreedevi Tatyasaheb Pati, Practicing doctor (Gynaecology)

Table 1: These compounds are responsible for various properties and therauptic uses of carica papaya leaves.9-11
Compound Tannins Saponins
Alkaloids (carpaine, pseudocarpaine, piperideine alkaloids like , dehydrocarpaine I and II) Flavonoids
Cardiac glycosides Amino acids
astringent properties, would healing property
precipitates and coagulates red blood cells, hemolytic activity, cholesterol binding properties and expectorant action
basic natural products, analgesic, antispasmodic and anti-bacterial properties, antimalarial (contains quinine)
Antiallergic, anti inflammatory, treatment of capillary fragility, free radical scavenger, platelet aggregation, microbes, ulcers, hepatoxins, viruses and anti cancer or tumor (Okwu, 2004). Flavonoids are potent water soluble antioxidants and free radical scavengers which prevent oxidative cell damage, have strong anticancer activity and protect against the different levels of carcinogenesis
Digitalis like action on heart
Antisickling property as it protects cell from oxidative damage (a reason for sickle cell crises),Vol6,Issue2,Article20.pdf