History And Medical Uses Of Papain

Papain is a protein-cleaving enzyme derived from papaya and certain other plants. Enzymes are complex molecules produced in living organisms to catalyze (speed up) chemical reactions within the cell. A number of digestive enzyme supplements are available. The simple ones are extracted from tropical fruits: bromelain from pineapple and papain from papayas. Papain has a mild, soothing effect on the stomach and aids in protein digestion. It is most often used as a meat tenderizer.

Though the exact area of origin is unknown, the papaya is believed native to tropical America, perhaps in southern Mexico and neighboring Central America. It is recorded that seeds were taken to Panama and then the Dominican Republic before 1525 and cultivation spread to warm elevations throughout South and Central America, southern Mexico, the West Indies and Bahamas, and to Bermuda in 1616. Spaniards carried seeds to the Philippines about 1550 and the papaya traveled from there to Malacca and India. Seeds were sent from India to Naples in 1626. Now the papaya is familiar in nearly all tropical regions of the Old World and the Pacific Islands and has become naturalized in many areas. Seeds were probably brought to Florida from the Bahamas. Up to about 1959, the papaya was commonly grown in southern and central Florida in home gardens and on a small commercial scale. Thereafter, natural enemies seriously reduced the plantings.

The latex of the papaya plant and its green fruits contains two proteolytic enzymes, papain and chymopapain. The latter is most abundant but papain is twice as potent. In 1933, Ceylon (Sri Lanka) was the leading commercial source of papain but it has been surpassed by East Africa where large-scale production began in 1937.

The presence and effects of proteinases (now termed proteases) in papaya fruit (Carica papaya) latex have been well known since the 1750s (Brocklehurst et al. 1983). But it was not until the 1870's that the importance of papaya latex as a source of enzymes was recognized.

Papain by far is the most widely studied of the cysteine enzymes because of its commercial value. Besides being used as a meat tenderizer other uses of papain include:

  • defibrinating wounds in hospitals
  • clotting milk
  • shrink proofing of wool
  • used in pet food to reduce viscosity and increase palatability
  • prevents cornea scar deformation
  • used in treatments of jellyfish and insect sings
  • used to treat edemas, inflammatory processes, and in the acceleration of wound healing
  • it is used as an ingredient in cleaning solutions for soft contact lenses
  • in low doses in can be used to as an indigestion medicine.

As we can see the uses for papain are diverse and thus it makes it an extremely valuable enzyme.

Papain has been employed to treat ulcers, dissolve membranes in diphtheria, and reduce swelling, fever and adhesions after surgery. With considerable risk, it has been applied on meat impacted in the gullet. Chemopapain is sometimes injected in cases of slipped spinal discs or pinched nerves. Precautions should be taken because some individuals are allergic to papain in any form and even to meat tenderized with papain.

In tropical folk medicine, the fresh latex is smeared on boils, warts and freckles and given as a vermifuge. In India, it is applied on the uterus as an irritant to cause abortion. The unripe fruit is sometimes hazardously ingested to achieve abortion. Seeds, too, may bring on abortion. They are often taken as an emmenagogue and given as a vermifuge. The root is ground to a paste with salt, diluted with water and given as an enema to induce abortion. A root decoction is claimed to expel roundworms. Roots are also used to make salt.

Crushed leaves wrapped around tough meat will tenderize it overnight. The leaf also functions as a vermifuge and as a primitive soap substitute in laundering. Dried leaves have been smoked to relieve asthma or as a tobacco substitute. Packages of dried, pulverized leaves are sold by "health food" stores for making tea, despite the fact that the leaf decoction is administered as a purgative for horses in Ghana and in the Ivory Coast it is a treatment for genito-urinary ailments. The dried leaf infusion is taken for stomach troubles in Ghana and they say it is purgative and may cause abortion.

Studies at the University of Nigeria have revealed that extracts of ripe and unripe papaya fruits and of the seeds are active against gram-positive bacteria. Strong doses are effective against gram-negative bacteria. The substance has protein-like properties. The fresh crushed seeds yield the aglycone of glucotropaeolin benzyl isothiocyanate (BITC) which is bacteriostatic, bactericidal and fungicidal. A single effective does is 4-5 g seeds (25-30 mg BITC).

In a London hospital in 1977, a post-operative infection in a kidney-transplant patient was cured by strips of papaya which were laid on the wound and left for 48 hours, after all modern medications had failed.

Plant extracts with a high content of proteolytic enzymes have been used for a long time in traditional medicine. Besides proteolytic enzymes from plants, 'modern' enzyme therapy additionally includes pancreatic enzymes. The therapeutic use of proteolytic enzymes is partly based on scientific studies and is partly empirical. The aim of the current review is to provide an overview of clinical trials of systemic enzyme therapy in oncology, and to discuss the evidence for their possible mechanisms of action. Clinical studies of the use of proteolytic enzymes in oncology have mostly been carried out on an enzyme preparation consisting of a combination of papain, trypsin and chymotrypsin. This review of these studies showed that enzyme therapy can reduce the adverse effects caused by radiotherapy and chemotherapy. There is also evidence that, in some types of tumours, survival may be prolonged. The beneficial effect of systemic enzyme therapy seems to be based on its anti-inflammatory potential. However, the precise mechanism of action of systemic enzyme therapy remains unsolved. The ratio of proteinases to antiproteinases, which is increasingly being used as a prognostic marker in oncology, appears to be influenced by the oral administration of proteolytic enzymes, probably via an induction of the synthesis of antiproteinases. Furthermore, there are numerous alterations of cytokine composition during therapy with orally administered enzymes, which might be an indication of the efficacy of enzyme therapy.

  • Frederick A. Senese. General Chemistry Online! Why is papain an effective meat tenderizer?
  • Edgar A. Chavez. PAPAIN-PAPAYA PEPTIDASE I. The Claremont Colleges Joint Science Program
  • Morton, J. 1987. Papaya. p. 336?346. In: Fruits of warm climates. Julia F. Morton, Miami, FL.
  • Leipner J, Saller R. Systemic enzyme therapy in oncology: effect and mode of action. Drugs 2000 Apr;59(4):769-80

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