Papaya

Scientific Name(s): Carica papaya L. Family: Caricaceae

Common Name(s): Papaya , pawpaw , melon tree 1

Clinical Overview

Uses of Papaya

Papaya has been used in patients with herniated discs, as a digestive aid, and in preparations to control edema and inflammation associated with surgical or accidental trauma, although very limited information is available to support these uses.

Papaya Dosing

There is no clinical evidence to support specific doses of papaya leaves. The fruit has GRAS status as a foodstuff.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Documented adverse effects. Avoid use.

Papaya Interactions

None well documented.

Papaya Adverse Reactions

Enzymes related to papaya (eg, carpaine and other related compounds) have been associated with perforation of the esophagus, severe gastritis, paralysis, decreased heart rate and CNS activity, and may inhibit some amebicidal activity.

Toxicology

An early report suggested that papain was teratogenic and embryotoxic in rats. Consumption of semi-ripe and unripened papaya should be avoided during pregnancy.

Botany

Papaya grow as small trees in the Americas and Africa. The common name pawpaw is sometimes also given to an unrelated plant Asimina triloba (L.) Dunal. 2 The papaya produces large leaves and smooth-skinned edible melons.

History

C. papaya is cultivated for its milky juice or latex (obtained from the fruit), which is the source of the proteolytic enzyme papain. The fruits are eaten fresh and are also the source of a flavoring used in candies and ice cream. Shallow cuts on the surface of fully grown but unripe fruits cause the exudation of a milky sap that is collected, dried, and termed crude papain. 3 Papain has been used widely in folk medicine for the treatment of digestive disorders, particularly those associated with the ingestion of protein-rich foods. Teas brewed from fermented papaya leaves are said to produce a richer mixture of proteolytic enzymes than teas from fresh leaves. Papain has been used as a vermifuge and as a component of facial creams to soften skin. Papain is sold commercially as a meat tenderizer. 3

Chemistry

Papain, also known as vegetable pepsin, is found not only in the fruit latex but also in the leaves. Papain is a mixture of protein-degrading enzymes. 4 Chymopapain has been fractioned into subcomponents designated “A” and “B”. 5 It is very similar to papain in the spectrum of its proteolytic activity, although it is less potent with respect to protein degradation. 6 Other components of papain degrade carbohydrates and fats. The seeds contain caricin, a glycoside. When caricin is combined with myrosin, it produces a mustard-like odor. Papaya seeds and pulp contain benzyl glucosinolate. This glucosinolate is hydrolyzed by the enzyme myrosinase to produce benzyl isothiocyanate. 7 The major cyanogenic glycoside in papaya is (2R)-prunasin; small amounts of sambunigrin are also present. 8 The alkaloid carpaine has been identified in the leaves. 9

Papaya Uses and Pharmacology

Research reveals no animal data regarding the use of papaya in herniated discs.

In the early 1980s, chymopapain 10 was approved for intradiscal injection in patients with documented herniated lumbar intervertebral discs and who had not responded to conservative therapy. This procedure is effective but remains the focus of controversy, particularly regarding the safety of the administration of the enzyme. 11 Anaphylactic shock was initially reported in about 1% of those receiving the drug; a number of fatalities also were reported. 12 More recent statistics, however, indicate that anaphylaxis occurs in less than 0.5% of patients, 10 , 13 and other adverse events, such as neurological problems, occur rarely. 10

Papain is used to control edema and inflammation associated with surgical or accidental trauma. 6

Diuretic activity is associated with the aqueous extracts of C. papaya . Adult male Sprague-Dawley rats were given an oral dose of 10 mg/kg of C. papaya root extracts. The demonstrated increased urine output ( P < 0.01) was similar to receiving 10 mg/kg of hydrochlorothiazide. 14

Papain solutions have produced therapeutic effects in patients with inflammatory disorders of the genitals, intestine, liver, and eye. 15 Papain (0.1% to 1%) solutions also have decreased the weight of burn crust in vitro and accelerated experimental burn healing in vivo. 15

Papaya also contains antioxidant components such as vitamin C, malic acid, and citric acid. 16 , 17

Papain is used in digestive aids. 6

Papain is unstable in the presence of digestive juices, which may account for its general lack of efficacy as a vermifuge. 3 One study alludes to the in vitro activity against helminths; benzyl isothiocyanate is considered to be the sole anthelmintic in papaya seed extracts. 5 Bacteriostatic activity of papaya is documented against several enteropathogens such as Bacillus subtilis , Enterobacter cloacae , Escherichia coli , Salmonella typhi , Staphylococcus aureus , Proteus vulgaris , Pseudomonas aeruginosa , and Klebsiella pneumoniae . 16

Benzyl isothiocyanate found in the pulp and seeds of papaya is a potent inducer of glutathione S-transferase, a phase II enzyme involved in the cellular detoxification of xenobiotics and reactive metabolites. 18

Dosage

There is no clinical evidence to support specific doses of papaya leaves. The fruit has GRAS status as a foodstuff. 19

Pregnancy/Lactation

Documented adverse effects. Avoid use.

Interactions

None well documented.

Adverse Reactions

The enzyme may induce severe allergic responses in sensitive persons. The latex can be a severe irritant and vesicant. Internally, it may cause severe gastritis. 10

Carpaine has been shown to cause paralysis, decreased heart rate and central nervous system activity, 10 and may have some amebicidal activity. 6

Toxicology

A 1978 report suggested that papain was teratogenic and embryotoxic in rats. 3 Several studies have investigated whether papaya consumption is safe during pregnancy. Rats given a ripe papaya blend in place of water showed no difference in the number of implantation sites and viable fetuses. 13 However, unripe or semi-ripe papaya, which contains a higher concentration of latex, could be unsafe during pregnancy. The crude papaya latex induced spasmodic contraction of the uterine muscles similar to oxytocin and prostaglandin F2α. 20 No adverse effects on prenatal development was observed in female Sprague-Dawley rats administered a low-dose crude aqueous extract of papaya seeds. 21 Some writers promote clinically unsupported data that eating unripe papaya for 3 consecutive days may induce abortion. They also believe that when consumed daily, the papain in the ripe fruit may have contraceptive-like activity. They believe that papain suppresses progesterone, which is needed for conception and pregnancy. Lastly, they believe papain also may affect a vital membrane involved in the development of the fetus. 22

Ingestion of large amounts of papain or papaya has been associated with perforation of the esophagus. 6

Papaya seed extract may exert potentially toxic effects on mammalian vascular smooth muscle. Benzyl isothiocyanate, the chief bioactive ingredient in seeds, irreversibly inhibits the contraction of dog carotid artery. 23 Papaya extract, when present in high concentration, was found to be cytotoxic by increasing the membrane permeability to calcium. 23

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