Mucunain

The proteolytic enzyme mucunain (cysteine protease) is a protein found in the tissue of certain legumes of the genus Mucuna, especially the velvet bean(Mucuna pruriens). Mucuna pruriens is used naturopathically in Parkinson's disease.

In Mucuna pruriens (velvet bean, a tropical legume), mucunain occurs in the hairs covering the seed pods (Singh SK et al. 2018). When these come into contact with the skin, they release mucunain. Mucunain is a ligand for protease-activated receptors 2 and 4 (Reddy VB et al. 2008). It causes intense itching in the skin without accompanying erythema, as occurs, for example, with histamine.

1. Andersen H Holm et al (2015) Human Surrogate Models of Histaminergic and Non-histaminergic Itch (PDF). Acta Dermato-Venereologica. 95: 771-777
2. Reddy VB et al (2008). Cowhage-evoked itch is mediated by a novel cysteine protease: a ligand of protease-activated receptors. J Neurosci 28: 4331-4335
3. Singh SK et al (2018) Analyzing trichomes and spatio-temporal expression of a cysteine protease gene Mucunain in Mucuna pruriens L. (DC). Protoplasm 255: 575-584.