English: Astaxanthin biosynthesis starts with three molecules of isopentenyl pyrophosphate (IPP) and one molecule of dimethylallyl pyrophosphate (DMAPP) that are combined by IPP isomerase and converted to geranylgeranyl pyrophosphate (GGPP) by GGPP synthase. Two molecules of GGPP are then coupled by phytoene synthase to form phytoene. Next, phytoene desaturase creates four double bonds in the phytoene to form lycopene. Then, lycopene cyclase first forms γ-carotene then subsequently forms β-carotene. From β-carotene, hydrolases (blue) and ketolases (green) form multiple intermediate molecules until the final molecule, astaxanthin is obtained.