21605
Since the finding that salvinorin A exerts its potent psychotropic actions through the activation of opioid receptors , the site of action of morphine and related analogues , there has been much interest in elucidating the underlying mechanisms behind its effects .
 Chemical: salvinorin A; Chemical: morphine
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: salvinorin A; Chemical: morphine