Bromelain is a protein extract derived from the stems of pineapples, although it exists in all parts of the fresh plant and fruit. The extract has a history of folk medicine use. As a culinary ingredient, it may be used as a meat tenderizer.

The term "bromelain" may refer to either of two protease enzymes extracted from the plants of the family Bromeliaceae, or it may refer to a combination of those enzymes along with other compounds produced in an extract.

Although tested in a variety of folk medicine and research models for its possible efficacy against diseases, the only approved clinical application for bromelain was issued in 2012 by the European Medicines Agency for a topical medication called NexoBrid used to remove dead tissue in severe skin burns. There is no other established application for bromelain as a nutraceutical or drug.

Bromelain extract is a mixture of protein-digesting (proteolytic) enzymes and several other substances in smaller quantities. The proteolytic enzymes are sulfhydryl proteases; a free sulfhydryl group of a cysteine amino acid side chain is required for function. The two main enzymes are:

Pineapples have a long tradition as a medicinal plant among the natives of South and Central America. The first isolation of bromelain was recorded by the Venezuelan chemist Vicente Marcano in 1891 by fermenting the fruit of pineapple. In 1892, Russell Henry Chittenden, assisted by Elliott P. Joslin and Frank Sherman Meara, investigated the matter more completely, and called it 'bromelin'. Later, the term 'bromelain' was introduced and originally applied to any protease from any member of the plant family Bromeliaceae.

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