Structure and biosynthesis of novel conjugated polyene fatty acids from the marine green algaAnadyomene stellata

Abstract

Novel polyunsaturated fatty acids with four conjugated double bonds were found in extracts of the green macroalga, Anadyomene stellata. The isolation of five of these with different chain lengths and varying degrees of unsaturation--16:5, 18:4, 20:5, 20:6, and 22:7--was accomplished by organic extraction followed by a combination of vacuum and high-performance liquid chromatography. One of these that was a novel substance (22:7) was characterized as 4Z,7Z,9E,11E,13Z,16Z,19Z-do cosaheptaenoic acid and assigned the trivial name stellaheptaenoic acid. The structure of this new compound, isolated as its methyl ester derivative, was deduced from detailed nuclear magnetic resonance, gas chromatography/mass spectrometry (GC/MS), and other spectroscopic methods. Incubation of a chloroplast preparation, isolated from a crude algal homogenate by differential centrifugation, with six unsaturated fatty acids (palmitoleic, 6Z,9Z,12Z,15Z-octadecatetraenoic acid, arachidonic acid, eicosapentaenoic acid, 7Z,10Z,13Z,16Z-docosatetraenoic acid, and 4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoi c acid) resulted in substantially increased synthesis of unique tetraene compounds as detected by ultraviolet spectrophotometry and tentatively identified by GC/MS.

Enhancement of human cancer cell radiosensitivity by conjugated eicosapentaenoic acid - a mammalian DNA polymerase inhibitor

“…The enzyme activity was dose-dependently From the cell extracts, total pol activity was measured as described previously (7,8). One unit of pol activity is defined as the amount that catalyzes the incorporation of 1 nmol dexyribonucleoside triphosphate (i.e., dTTP) into synthetic template-primers [i.e., poly(dA)/oligo(dT) [12][13][14][15][16][17][18] , A/T=2/1] at 37˚C in 60 min. Values are the means ± SEM of four independent experiments.…”

“…Nucleotides and chemically synthesized DNA template primers, such as poly(dA) and oligo(dT) [12][13][14][15][16][17][18] , and radioisotope reagents, such as [ 3 H]-dTTP (2'-deoxythymidine 5'-triphosphate) (43 Ci/mmol), were purchased from GE Healthcare Bio-Science Corp. (Piscataway, NJ, USA). All other reagents were of analytical grade and purchased from Nacalai Tesque Inc. (Kyoto, Japan).…”

“…The pol activity of the cell extract was measured as described previously (7,8). Poly(dA)/oligo(dT) [12][13][14][15][16][17][18] and dTTP were used as the DNA template-primer and nucleotide substrate, respectively. One unit of pol activity was defined as the amount of enzyme that catalyzed the incorporation of 1 nmol dNTP (2'-deoxyribonucleotide 5'-triphosphate, i.e.…”

“…dTTP) into the synthetic DNA template-primers [i.e. poly(dA)/oligo(dT) [12][13][14][15][16][17][18] , A/T=2/1] in 60 min at 37˚C under normal reaction conditions for the enzyme (7,8).…”

“…Fatty acids with conjugated double bonds exist in nature; seaweeds such as red and green algae contain highly n-3 unsaturated conjugated fatty acids, i.e., conjugated eicosapentaenoic acid (cEPA; 5Z7E9E14Z17Z-20:5), bosseopentaenoic acid (5Z8Z10E12E14Z-20:5) and stellaheptaenoic acid (4Z7Z9 E11E13Z16Z19Z-22:7) (11,12). As n-3 PUFAs have been shown to have anticarcinogenic activity, conjugated fatty acids converted from n-3 PUFAs may show higher tumor-INTERNATIONAL JOURNAL OF ONCOLOGY 36: 577-584, 2010 Enhancement of human cancer cell radiosensitivity by conjugated eicosapentaenoic acid -a mammalian DNA polymerase inhibitor inhibiting activity than n-3 PUFAs themselves (13,14).…”