6681
Four major carotenoids of high nutritional significance , including beta - carotene , lycopene , lutein and zeaxanthin were determined in three isolates of heterocystous cyanobacteria , belonging to the genera Anabaena and Nostoc , isolated from Iranian terrestrial and aquatic ecosystems , for the first time .
 beta - carotene, lycopene, lutein, zeaxanthin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 beta - carotene, lycopene, lutein, zeaxanthin