Papaya

Found in tropical countries, the papaya tree is also known as the pawpaw or melon tree. The seeds, leaves, and fruit have all been used in folk medicine. The sap or latex, a milky fluid collected from the mature unripe fruit, is known as crude papain when dried.

Uses and Benefits:

Commercially available papain, a mixture of proteolytic enzymes, is the active ingredient in meat tenderizers; it softens the meat by partially digesting the proteins. Contained in contact lens cleansers, dentifrices, and cosmetics, the enzyme is also used to clarify beer. Papain is available in FDA-approved topical preparations as an enzymatic debridement for necrotic tissue in burns, ulcers, and other wounds. A specific purified fraction, chymopapain, is approved for chemonucleosis (the treatment of herniated intervertebral discs by injection), which has largely fallen out of favor due to allergic and other adverse reactions.

As an herbal dietary supplement, oral papain is most often recommended as a digestive aid (especially with proteinrich meals) and for dyspepsia. Papaya preparations have also been used traditionally for inflammatory disorders, hemorrhoids, intestinal worms, diarrhea, tumors, and respiratory infections. It is used in some cultures to induce abortion and labor, and is employed topically for psoriasis, ringworm, wounds, ulcers, and infections.

Pharmacology:

Crude papain, also called "vegetable pepsin," is an enzyme mixture from the dried latex of the fruit, and is also found in the leaves and trunk. It is composed of related prote­olytic enzymes: papain, chymopapain A and B, and papaya peptidase. The purified papain enzyme is a thiol protease, obtaining enzymatic activity from the sulfhydryl group of the cysteine It is poorly active in extreme acidic or basic media, can gsted by pepsin, and is poorly absorbed when ingested til; thus, it may have unpredictable activity when exposed to contents. Papain hydrolyzes proteins, small peptidases,

Clinical Trials:

The use of oral papain tablets has been evalutied in several older, controlled clinical trials for post-traumatic in ammation. In double-blind trials of patients undergoing oral or head and neck surgeries, abdominal surgeries, and epiotomies, papaya proteolytic enzyme tablets appeared to Induce postoperative edema, inflammation, or pain when com­pared to placebo. In a randomized, single-blind study in palients undergoing oral surgery, papaya enzyme tablets were more effective than placebo, but less effective than prednisolone 20 rng/day for postsurgical pain and trismus. In a randomized, double-blind trial of college athletes with contusions or re­lated injuries, papaya enzyme tablets produced a better therapeu­tic response and less disability than placebo tablets. The results of several of these studies are questionable, however, because the criteria for the inflammatory signs or pain were subjective, and the study methodologies or results were not well described. In ad­dition, there have been no confirmatory studies in several

Adverse Effects:

There are no significant side effects reported from the clinical studies using oral papaya enzyme tablets. Griping and "intestinal inflammation" from ingestion of the fresh latex has been reported in older accounts.

Side Effects and Interactions:

A papaya extract used as a slimming aid was reported to possibly enhance the effect of warfarin.The patient was admitted for cardiac surgery and found to have an INR of , which declined after withdrawal of both warfarin and the extract. Further details of the case are unknown.

Cautions:

Allergic reactions, including angioedema and anaphylaxis, have been reported with a variety of papain products. Positive skin tests and allergic reactions to papain can be demon­strated in 1 % of individuals with allergies to other substances. Solutions of meat tenderizer used for gastric bezoars, which may not have been sufficiently dilute, have been reported to cause gastric ulcer, esophageal perforation, and hypernatremia. Crude papain orally administered to rats has been reported to be embryotoxic and teratogenic, while no detrimental effects were observed with a purified papain enzyme. Use during pregnancy and lactation is not recommended due to the limited data.

Preparations & Doses:

A typical dose of 1-2 papaya/papain enzyme tablets administered q.i.d. for about 3-7 days was used in the clinical studies to reduce inflammation. Several of these studies used Papase, a product formerly manufactured by Warner-Chilcott Laboratories, which contained 5 mg or 10,000 Warner-Chilcott units (of milk-clotting activity) per tablet. Activity of papain is expressed in many ways, depending on the supplier. Doses of commercial papain products, often recommended as a digestive aid, vary widely between 10 and 1000 mg per day, usually given as 1-4 pills with or after meals. The fresh fruit juice or leaf infusions are also advocated.

Summary Evaluation

Papaya enzymes can hydrolyze protein and are commonly employed as meat tenderizers and wound cleansers. As a dietary supplement, papaya enzymes are used as a digestive aid or to at dyspepsia, but there are no clinical trials to substantiate effects. There is in vitro and animal data to support some of p,Jpaya's traditional indications, such as for helminthic and fungal tections; these potential properties have also not been evaluted in clinical studies. A number of controlled clinical trials sugust that orally administered papaya enzymes can help to reduce post-traumatic pain and inflammation; however, these older stud (as well as other reported uses) require validation. Papain is poorly active in the gastric contents and may not be appreciably ,absorbed