Abstract
The effects of heat and acid treatments on eicosanoids concentration in the red alga, Gracilaria asiatica, were investigated. Leukotriene B4 (LTB4) and prostaglandin A2 (PGA2) increased but PGE2 decreased when the alga was boiled with 4% acetic acid. Two isomers of LTB4, which appeared in the HPLC of both the authentic LTB4 and the extract of alga treated with acid, were identified as 6-trans-LTB4 and 6-trans-12-epi-LTB4. The concentration of LTB4 increased when the alga was added with 4% acetic acid after boiling and incubated at 37°C at pH2 (pH similar to gastric fluid). Furthermore, the alga extract showed similar chemotactic activity to mice polymorphonuclear leukocytes as the authentic LTB4. Mice orally administered with the algal extract containing 50μg of LTB4 showed diarrhea, but it did not result in death.
