30549
Among these compounds , 6d , which possesses an ortho - nitro group at the benzene ring , exhibited potent inhibitory effect on the proliferation of HUVECs , A549 , K562 , PC - 3 , HCT116 , MDA - MB - 231 and MCF - 7 cells ( IC50 = 5 . 34 , 40 . 53 , 10 . 81 , 52 . 52 , 10 . 19 , 21 . 37 and 2 . 81 mu M , respectively ) .
 Chemical: ortho - nitro; Chemical: benzene
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: ortho - nitro; Chemical: benzene