engleski

Optimization of ultrasound-assisted extraction of pigments from Cystoseira compressa from the Adriatic Sea

Brown macroalgae, where Cystoseira compressa also belongs, have been receiving more attention in the scientific research due to the presence of fucoxanthin in high abundance. The presence of chlorophyll a is also characteristic for brown macroalgae and it represents the primary pigment that is responsible for the sunlight energy caption. As these pigments exhibit promising biological activites, macroalgae can play important role in food, cosmetic and pharmaceutical industries. The objective of this study was not only to determine the potential of ultrasound-assisted extraction (UAE) for fucoxanthin extraction from brown macroalgae Cystoseira compressa, but also to evaluate the influence of the most important process parameters and to optimize the extraction process.The freeze- dried samples were used for the optimization which was performed with with methanol:dichloromethane (MeOH:DCM, 1:1, v/v) as the extraction solvent. UAE was performed at different temperatures (30, 50 and 70 °C) for different extraction times (15, 30 and 45 min) with solvent:solid ratio (10, 20 and 30 mL/g). All experiments were performed in an ultrasound-bath. Design Expert® commercial software was used for statistical analysis and experimental design. The UAE parameters, temperature (X1), time (X2) and solvent:solid ratio (X3) were independent variables tested to determine the influence on the response (fucoxanthin and chlorophyll a content), as well to optimize the extraction process aimed to obtain the highest amount of fucoxanthin and chlorophyll a in the extracts. BBD proposed 17 experiments which included 5 central points at the following conditions: 50°C, 30 min and 20 mL/g that was used to check the reproducibility and stability of the results. The obtained extracts were used for the separation, identification and quantification of fucoxanthin and chlorophyll a. The analysis were performed with high performance liquid chromatography (HPLC). Fucoxanthin content in C. compressa extracts ranged from 2.25 mg/g dry extract to 4.33 mg/g dry extract, while chlorophyll a ranged from 2.70 mg/g dry extract to 20.86 mg/g dry extract. The results of analysis of variance (ANOVA) revealed that the linear terms of temperature (X1), time (X2), along with the interaction between temperature and time (X1X2) exhibited significant influence (p<0.05) on fucoxanthin content. On the other hand, the linear terms of temperature (X1), time (X2), interaction between time and solvent:solid ratio (X1X3), as well as quadratic term of temperature (X12) had significant influence (p<0.05) on chlorophyll a content. For fucoxanthin content, temperature had the highest effect as the fucoxanthin content was lowest (2.24 mg/g dry extract) at the highest temperature (70°C). Hence, as the time rose to 45 min, the fucoxanthin content was lower. These findings demonstrate the potential of UAE for the recovery of carotenoids and chlorophylls from macroalga Cystoseira compressa from the Adriatic Sea. The results revealed that this alga can be valuable source of both fucoxanthin and chlorophyll a. However, future studies must be focused on investigations of mechanisms of their activity which can results in their application in food, cosmetic and pharmaceutical industries.

Cystoseira compressa ; ultrasound-assisted extraction ; optimization ; pigments

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