9(Z),11(E),13(E)-Octadecatrienoic Acidethylester (α-ESA) is a conjugated polyunsaturated fatty acid commonly found in plant seed oil. This fatty acid accounts for about 60% of the total fatty acid composition of bitter gourd seed oil and about 70% in tung oil. α-ESA is metabolized and converted to conjugated linoleicacid (9Z,11E-CLA) in rats. It has shown potential as a tumor growth suppressor. In colon cancer Caco-2 cells, α-ESA induced apoptosis through up-regulation of GADD45, p53, and PPARγ. In DLD-1 cells supplemented with α-ESA, apoptosis was induced via lipid peroxidation with an EC50 of 20 μM. It also inhibits DNA polymerases and topoisomerases with IC50s ranging from ~5-20 μM for different isoforms of the enzymes. α-ESA ethylester is a neutral, more lipid soluble form of the free acid.
Heneicosapentaenoic Acid (HPA), a 21:5 ω-3 fatty acid, is found in minute quantities in green algae and fish oils, resembling eicosapentaenoic acid (EPA) but with an added carbon on the carboxyl end, positioning the initial double bond at the Δ6 location. HPA serves as a tool for examining the impact of double bond positions within n-3 fatty acids, as it is incorporated into phospholipids and triacylglycerol in vivo as efficiently as EPA and docosahexaenoic acid (DHA), while significantly inhibiting the synthesis of arachidonic acid from linoleicacid. Moreover, the ethylester variant of heneicosapentaenoic acid offers a more lipophilic and stable alternative to the free acid form.