13122
Assignment of the absolute configuration of cyclic peptides frequently yields challenges , leaving one or more stereogenic centers unassigned due to small quantities of sample and the limited utility of Marfey ' s or other methods for assigning amino or hydroxy acids .
 Chemical: amino or hydroxy acids
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: amino or hydroxy acids