# Chemical Compositional Changes in Over-Oxidized Fish Oils
## 3 Results
### Isoprostanoids and Isofuranoids  
In Figure 5A,B, the temporal changes of a range of phytoprostanes, isoprostanes, and neuroprostanes are shown. Chemical structures of the measured isoprostanoids are shown in Figure S2B,C.  
In hoki liver oil, the concentrations of several isoprostanoids had markedly increased at 30 days, after remaining relatively stable from baseline to day 15. This was the case for ALA-derived ent-16-F\({}_{1t}\)-PhytoP, ent-16-epi-16-F\({}_{1t}\)-PhytoP, 9-F\({}_{1t}\)-PhytoP, 9-epi-9-F\({}_{1t}\)-PhytoP, 16(RS)-16-A\({}_{1t}\)-PhytoP, as well as for the furunic derivative ent-16(RS)-9-epi-ST-\(\Delta^{14}\)-10-PhytoF (Figure 5A); the arachidonic acid (AA)-derived 15- and 15-epi-isomers of F\({}_{2t}\)-IsoP, the 5(RS)-5-F\({}_{2t}\)-IsoP and the all-cis isomer 5(RS)-5-F\({}_{2c}\)-IsoP (Figure 5A); the EPA-derived 5-F\({}_{3t}\)-IsoP and 5-epi-5-F\({}_{3t}\)-IsoP, the 8-F\({}_{3t}\)-IsoP and 8-epi-F\({}_{3t}\)-IsoP (Figure 5B); the DHA-derived 4-F\({}_{3t}\)-NeuroP, 4(RS)-4-F\({}_{4t}\)-NeuroP, the 10-F\({}_{4t}\)-NeuroP and 10-epi-F\({}_{4t}\)-NeuroP, 14(RS)-14-F\({}_{4t}\)-NeuroP and 20-epi-20-F\({}_{4t}\)-NeuroP (Figure 5B); and the adren acid (AdA, C22:4 n-6)-derived ent-7(RS)-7-F\({}_{2t}\)-dihomo-IsoP (Figure 5B), the DPA n-6-derived 4-F\({}_{3t}\)-NeuroP\({}_{DPA n-6}\), and the DPA n-3-derived 14(RS)-14-F\({}_{3t}\)-NeuroP\({}_{DPA n-3}\) (Figure 5B). In anchovy oil, the levels of most isoprostanes and neuroprostanes remained stable, while the levels of some of the phytoprostanes decreased within the first few days of the incubation or gradually over the course of the incubation (Figure 5A,B).  
5-epi-5-F\({}_{3t}\)-isoprostane (\(\approx\)180 ng/g oil) and 4(RS)-4-F\({}_{4t}\)-neuroprostane (\(\approx\)50 ng/g oil) were the most abundant isoprostanoids in both hoki liver oil and in anchovy oil. After 30 days, the levels had increased to \(\approx\)320 ng/g and \(\approx\)200 ng/g in the hoki liver oil, respectively, while no marked changes had occurred in the anchovy oil. The ALA-derived phytoprostanes ent-9-L\({}_{1t}\)-PhytoP and ent-16-B\({}_{1t}\)-PhytoP were hardly detectable in hoki liver oil but were distinctly present in anchovy oil at baseline (Figure 5A). During the first days of the incubation, the levels of these phytoprostanes decreased \(\approx\)75% and thereafter remained at lower levels. The AdA-derived furan 7(RS)-SC-\(\Delta^{8}\)-11-dihomo-IsoF was also unique to anchovy oil, but its level did not change during the incubation (Figure 5B). The ALA-derived phytoprostanes (except 16(RS)-16-A\({}_{1t}\)-PhytoP), AA-derived 15-F\({}_{2t}\)-IsoP, AdA-derived ent-7(RS)-7-F\({}_{2t}\)-dihomo-IsoP and 7(RS)-SC- \(\Delta^{8}\)-11-dihomo-IsoF, and the DPA n-3-derived 14(RS)-14-F\({}_{3t}\)-NeuroP\({}_{DPA n-3}\) were found in both oil types at relatively low concentrations compared to the products derived from EPA and DHA.  
Figure 4: Total concentration of the five volatiles combined in (**a**) hoki liver oil and in (**b**) anchovy oil over a 30-day period under oxidation condition A (black bars) and condition B (gray bars). Results are means \(\pm\) S.D. of three technical replicates for three parallel incubations.  
Figure 5: _Cont._  
Figure 5: (**A**) Temporal changes of phytoprostanes and arachidonic acid-derived isoprostanes in hoki  
liver oil (black bars) and anchovy oil (gray bars) during a 30-day incubation under oxidation Condition A. Results are means \(\pm\) S.D. of three technical replicates for one incubation. (**B**) Temporal changes of EPA-derived isoprostanes, DHA-derived neuroprostanes, adrenic acid (AdA)-derived dihomo-isoprostanes and furans, and DPA n-6- and DPA n-3-derived neuroprostanes in hoki liver oil (black bars) and anchovy oil (gray bars) during a 30-day incubation under oxidation Condition A (oxygen and light exposure at room temperature). Results are means \(\pm\) S.D. of three technical replicates for one incubation (n.d; not detectable).