18272
Substituents , overall charge and charge distribution influenced the pKa - values and interaction of the porphyrins with different solvents , excipients and impurities .
 Chemical: porphyrins
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: porphyrins