Complex sentence: The best-studied compound is curcumin, which constitutes 3.14% (on average) of powdered turmeric, however, there are big variations in curcumin content in the different lines of the species Curcuma longa (1--3189 mg/100g).
Split into simpler sentences: The best-studied compound is curcumin, which constitutes 3.14% (on average) of powdered turmeric. However, there are big variations in curcumin content in the different lines of the species Curcuma longa (1--3189 mg/100g).