engleski

Evaluation of extraction procedures to yield the highest pigment content, antioxidant and antityrosinase activity from green algae Ulva lactuca

Green macroalgae Ulva lactuca, also known as marine green salad has high amount of different biologically active compounds such as polysaccharides, pigments, terpenes, etc. [1]. In this study, the aim was to evaluate conventional (successive solvent extraction – hexane, chloroform, methanol) and modern (solid-phase extraction, SPE, using methanol and dichloromethane) extraction procedures, as well as an environmentally-friendly option (ethanol, further fractionated using non-toxic solvents – hexane, chloroform, ethyl acetate, and butanol) for purpose of extracting pigments such as lutein, chlorophylls, and others that could posses’ activity against tyrosinase, an enzyme that has an an important role in melanogenesis and enzymatic browning [2]. High-pressure liquid chromatography (HPLC) was used for the successful identification of lutein, chlorophyll b, and canthaxanthin. The highest content of lutein was found in SPE methanolic fraction (3.422 ± 0.007 mg/g), followed by chloroform extract (1.638 ± 0.002 mg/g). Chlorophyll b was most abundant in the ethyl acetate fraction (0.443 ± 0.001 mg/g), while the canthaxanthin content was also the highest in SPE methanol fraction (0.091 ± 0.000 mg/g). In SPE dichloromethane fraction and butanol fraction no pigments were identified. Antioxidant activity using both DPPH and ABTS methods has shown to be the highest for SPE methanol fraction. The highest monophenolase activity was observed for ethanol extract (20.39 ± 8.01 %) followed by chloroform (14.36 ± 4.31 %) and hexane extracts (7.51 ± 1.02 %), while no activity was observed for all other extracts and fractions. Samples showed better diphenolase activity. The highest activity was observed for methanol extract (57.33 ± 2.53 %), followed by chloroform extract (54.09 ± 1.05 %) and methanol fraction (51.78 ± 0.95 %). All the results suggest that not only pigments exert antityrosinase activity, but also other isolated molecules. SPE has shown to be the best-used method for lutein isolation from U. lactuca and has been shown to significantly contribute to antioxidant activity.

Green macroalgae ; bioactivity ; pigmentation ; HPLC

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