Seasonal variations of total lipids, fatty acid composition, and fucoxanthin contents of Sargassum horneri (Turner) and Cystoseira hakodatensis (Yendo) from the northern seashore of Japan

The present study describes the seasonal changes in lipid components of two brown algae, Sargassum horneri (Turner) and Cystoseira hakodatensis (Yendo), with specific reference to fucoxanthin (Fx) and n-3 (omega-3) polyunsaturated fatty acids (PUFAs). Young thalli of S. horneri were collected from different places, Nesaki and Matsushima, and cultivated in the same place. Total lipids (TL) and Fx contents of S. horneri increased from October or November and reached a maximum in January and then decreased thereafter. TL and Fx of S. horneri originated from Matsushima were always higher than those originated from Nesaki, suggesting that genetic variation might be a reason for the different TL and Fx contents found in both S. horneri seeds from different origin. Similar seasonal variation in the TL and Fx content has been more clearly observed in C. hakodatensis. Maximum TL content of S. horneri and C. hakodatensis reached to more than 14 and 15 % in winter season. These values were much higher than those found in previous studies showing TL content range from 1 to 5 %. Fatty acid composition of lipids from S. horneri and C. hakodatensis also changed seasonally. Total monounsaturated fatty acids showed the lower values from January to April, while there were no big variations in total saturated fatty acids and total n-6 PUFAs. On the other hand, total n-3 PUFAs became highest in winter. Overall, S. horneri and C. hakodatensis harvested from winter to spring will be used as good n-3 PUFA source with high levels of TL and Fx.