Analysis Of Carotenoids In Dunaliella And Enhancement Of Creatinine And Melatonin

Carotenoids,also called tetraterpenoids,are widely used in food and pharmaceutical industries owing to their good antioxidant activity.As one of the important sources of natural carotenoids,Dunaliella is a model organism to study the synthesis of carotenoids.The different types and contents of carotenoids in Dunaliella have become one of the research hotspots.Generally speaking,the focus of this paper is carotenoids of three species of Dunaliella(Dunaliella bardawil FACHB-847,Dunaliella tertiolecta FACHB-821 and Dunaliella salina CCAP 19/18).Firstly,the comparison of the antioxidative activities of five major carotenoids(Lutein,Zeaxanthin,Lycopene,?-carotene and Astaxanthin)were evaluated.To be specific,it was found that lutein showed decent antioxidant capacities in ABTS free radical scavenging and total reducing power assays;zeaxanthin exhibited favourable antioxidant activities in ABTS free radical scavenging,total reducing power and Ferric reducing antioxidant power assays.It was worth noting that the Ferric reducing antioxidant power of zeaxanthin was comparable to that of Vitamin E(VE);astaxanthin exhibited certain antioxidant abilities in the ABTS free radical scavenging and Ferric reducing antioxidant power assays;lycopene showed stronger DPPH free radical scavenging ability;?-carotene showed no obvious antioxidant effect in the four assays;.Dunaliella bardawil FACHB-847 was applied to study the effects of five compounds(Creatinine,Melatonin,Imidazole,Piperomyl butoxide and Triethylamine)on the contents of carotenoids in algal cells.It was found that creatinine could significantly increase the content of lutein in Dunaliella bardawil.The effect of creatinine on the three species of Dunaliella was verified afterwards,and results were consistent with that of the preliminary screening results.Although creatinine had no significant effect on later period cell number at later period,it increased the content of total carotenoids,lutein,?-carotene and ?-carotene,and decreased the concentration of zeaxanthin.According to the HPLC diagram,the drug effect was consistent from the fourth day to the sixteenth day.Furthermore,Dunaliella bardawil was utilized in the light optimization experiment.The light intensities were set as 4500 LUX,7500 LUX and 9500 LUX combined with different concentrations of creatinine.It was found thatthe total carotenoid content of Dunaliella bardawil was increased by more than 10% with 400?g/m L and 500 ?g/m L creatinine under 4500 LUX light intensity.Under 4500 LUX light intensity,when the concentration of creatinine was 500 ?g/m L,the content of lutein was increased by 46%,the concentration of single cell was increased by 39%;the content of?-carotene was increased by 40%,the concentration of single cell increased by 30%;the content of ?-carotene increased by nearly 77%,and the concentration of single cell increased by 67%.The total amount of zeaxanthin was increased by 84% in the group treated with a combination of 300 ?g/m L melatonin and 6000 LUX illumination intensity.Under medium light intensity of 7500 LUX,the content of lutein was increased while the concentration of zeaxanthin was decreased.When the illumination intensity reached 9500 LUX,the total carotenoid content was increased.The contents of those kinds of carotenoids,except zeaxanthin,were visibly increased when treated with melatonin,indicating that melatonin exhibited diverse effects under different light conditions.It seems that melatonin may improve the tolerance of Dunaliella bardawil to high light intensity stress,and at the same time increase carotenoid accumulation.