hydroxyproline: a crystalline amino acid obtained from gelatin or collagen
amino acid: organic compounds containing an amino group and a carboxylic acid group
toothbrush tree: glabrous or pubescent evergreen shrub or tree of the genus Salvadora; twigs are fibrous and in some parts of the world are bound together in clusters and used as a toothbrush; shoots are used as camel fodder; plant ash provides salt