Subcritical Water Extraction and Characterization of 1 Bioactive Compounds from Haematococcus Pluvialis

13 14 In this work, extraction and characterization of compounds with antioxidant and antimicrobial 15 activity from Haematococcus pluvialis microalga in red phase have been carried out. To do 16 this, subcritical water extraction (SWE) has been combined with analytical techniques such as 17 HPLC-DAD, HPLC-QqQMS and GC-MS and in-vitro assays (i.e., for antioxidant and 18 antimicrobial activity). The effect of the extraction temperature (50, 100, 150 and 200 oC) and 19 solvent polarity has been studied in terms of yield and activity of the extracts. Results 20 demonstrate that the extraction temperature has a positive influence in the extraction yield and 21 antioxidant activity. Thus, the extraction yield achieved with this process was higher than 22 30% of dry weight at 200 oC as extraction temperature. Moreover, the extract obtained at 200 23 oC presented the highest antioxidant activity by far, while temperature does not seem to 24 significatively affect the antimicrobial activity. Chemical composition was determined by 25 HPLC-DAD, HPLC-QqQMS and GC-MS. Short chain fatty acids turned out to be responsible 26 of the antimicrobial activity, whereas the antioxidant activity was correlated to vitamin E 27 (present exclusively in the 200 oC extract), together with simple phenols, caramelization 28 products and possible Maillard reaction products obtained during the extraction at high 29 temperatures. 30 31