Studies on Prostaglandin Formation in Gracilaria spp.

• Main Authors: Bo-Yang Hsu, 許博揚
• Other Authors: Deng-Fwu Hwang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/59783605473473570127

博士 === 海洋大學 === 食品科學系 === 96 === Gracilaria is a kind of edible red algae (Japanese name, “ogonori). People are accustomed to take raw fish with Gracilaria spp. in Japan. However, some poisoning cases occurred due to ingesting seaweed Gracilaria spp. in Japan. Those victims ate raw fish and raw seaweed. The common symptoms in the patients are nausea, vomiting and diarrhea appearing 30-60 min after ingestion. In extreme cases, they developed to very low blood pressure, followed by shock and death. In addition, the symptoms in female were more serious than those in male. The possible reason of seaweed poison cases was supposed that raw seaweed contained plenty of prostaglandin E2 (PGE2) and cyclooxygenase (COX). The enzyme (COX) in the seaweed and/or the body tissues of the victim may be acting on the arachidonic acid (precursor of PGE2) in the raw fish or in the seaweed producing PGE2. Therefore great amount of PGE2 was accumulated at short time in the victim’s body (Sajiki and Kakimi, 1998；Noguchi et al., 1994). In this study, a HPLC method was developed for quantifying prostaglandins in the seaweed. Prostaglandins included prostaglandin A2 (PGA2), PGE2 and prostaglandin F2α (PGF2α) were detected in this study. The mobile phase was gradient acetonitrile (35%~60%) and 0.017 M phosphoric acid at flow rate of 1 mL/min and 196 nm within 30 min. The standard curves of prostaglandins (PGA2, PGE2 and PGF2α) were extremely linear (R2 > 0.999) with low correlation coefficients (less than 4.7) in the range of 5~50 μg/mL. Those data implicate the standard solutions and HPLC assay system was all quite stable. The detection limit of PGA2 and PGE2 was 0.5 μg/mL and that of PGF2α was 2.5 μg/mL. The average recoveries of PGA2, PGE2 and PGF2α were 82.2±4.7%, 91.3±9.2% and 76.5±5.2%, respectively. The next section of this study is to investigate the effects of reaction conditions on PGE2 production in the seaweed. Maximum amount of PGE2 was producted as the ratio of arachidonic acid sodium salt and seaweed (wet wt) was 0.02% (w/w). Due to oxygen affecting PGE2 production, more amount of PGE2 was produced in aerobic condition than in anaerobic condition. The optimal temperature of PGE2 production was 25oC and the optimal pH was 8.5. There were different PGE2 level in different Gracilaria species and the season variation of PGE2 level was also found. The PGE2 level was 23% comparing to control when the extract solution of the seaweed was placed in 4oC after 6 hr. Arachidonic acid was metabolized to PGE2 by COX and PGE2 synthase. Therefore this result indicated that the enzymes of related PGE2 production in the extract solution were not stable. Effects of environmental factors on PGE2 production in the seaweed were also investigated. The effects of environmental conditions caused to change the PGE2 production in the seaweed. Some special environment factors including low temperature, salinity, irradiance and Ca2+, promoted PGE2 production in the seaweed, but aspirin and nimesulide inhibited. Hence, PGE2 production in the seaweed was affected by species, season, environmental factors and reaction conditions.