Larsen L N, Høvik K, Bremer J, Holm K H, Myhren F, Børretzen B
Institute of Medical Biochemistry, University of Oslo, Blindern, Norway.
Lipids. 1997 Jul;32(7):707-14. doi: 10.1007/s11745-997-0090-4.
6,9,12,15,18-Heneicosapentaenoic acid (21:5n-3) (HPA), present in small amounts in fish oils, has been prepared by chemical elongation of eicosapentaenoic acid (EPA) and its biological properties compared with EPA and docosahexaenoic acid (DHA). All the double bonds of HPA are displaced one carbon away from the carboxyl group when compared to EPA. HPA is incorporated into phospholipids and into triacylglycerol in cell culture to a similar extent as EPA and DHA. HPA is a stronger inhibitor of the conversion of alpha-linoleic acid and dihomo-gamma-linolenic acid to arachidonic acid (AA) in hepatoma cells than are EPA, DHA, and AA. HPA is a poor substrate for prostaglandin H synthase and for 5-lipoxygenase, but it inactivates prostaglandin H synthase as rapidly as do AA, EPA, and DHA. HPA inhibits thromboxane synthesis in isolated platelets as efficiently as EPA. EPA, HPA, and DHA are all weak inducers of acyl-CoA oxidase in hepatoma cells. Therefore, since fish oils contain only small amounts of HPA, it is unlikely that this fatty acid is of particular significance for the biological effects of these oils, possibly with the exception that it is a strong inhibitor of AA synthesis.
6,9,12,15,18-二十一碳五烯酸（21:5n-3）（HPA）在鱼油中含量较少，它是通过二十碳五烯酸（EPA）的化学延长制备的，并将其生物学特性与EPA和二十二碳六烯酸（DHA）进行了比较。与EPA相比，HPA的所有双键都从羧基处位移了一个碳原子。在细胞培养中，HPA掺入磷脂和三酰甘油中的程度与EPA和DHA相似。在肝癌细胞中，HPA比EPA、DHA和花生四烯酸（AA）更能强烈抑制α-亚麻酸和二高-γ-亚麻酸向花生四烯酸的转化。HPA是前列腺素H合酶和5-脂氧合酶的不良底物，但它使前列腺素H合酶失活的速度与AA、EPA和DHA一样快。HPA在分离的血小板中抑制血栓素合成的效率与EPA相同。EPA、HPA和DHA都是肝癌细胞中酰基辅酶A氧化酶的弱诱导剂。因此，由于鱼油中仅含有少量的HPA，这种脂肪酸对这些鱼油的生物学效应不太可能具有特殊意义，可能唯一的例外是它是AA合成的强抑制剂。
