Anthochlor pigments

[2] Important anthochlor pigments accumulating plants are from the genus Coreopsis, Snapdragon (Antirrhinum majus) or Bidens ferulifolia.

Hydroxychalcones are intermediates of the subsequent biosynthesis of flavonoids and quickly isomerize to flavanones either chemically or enzymatically.

Functioning as intermediates of the subsequent biosynthesis of flavonoids, hydroxyl chalcones are not chemically stable and quickly isomerize to flavanones.

In the presence of the enzyme chalcone reductase (CHR) and NADPH as a co-factor, the oxygen function of the polyketide intermediate is reduced and eliminated as water prior to cyclization, resulting in the formation of 6’-deoxychalcones.

This additional hydroxyl group causes a shift of light absorption and leads to a slightly different yellow tone when the chalcone is accumulated in plants.

Apart from providing yellow flower colouration, anthochlor pigments play an indispensable role in the floral immune system and plant health.

[citation needed] Exposing anthochlors to ammonia or alkaline vapour of cigarettes results in a colour shift from yellow to orange.