Biosynthesis and Transfer of alpha-Elostearic Acid In Vivo in Momordica charantia L. Developing Seeds and In Vitro in Microsomal Fractions of These Seeds

The research concerned the efficiency of biosynthesis and transfer to triacylglycerols (TAG) of alpha-eleostearic acid (alpha ESA). The experiments were carried out on developing seeds of Momordica charantia L. and on microsomal fractions obtained from these seeds. The seeds from in vivo conditions were collected 20, 23, 26 and 33 days after pollination (DAP) and used for lipid extraction and further analyses. Microsomal fractions were prepared from seeds at 26 DAP. The most intensive lipid accumulation occurred between 20 and 26 DAP, but continued up to 33 DAP. The most abundant lipid fraction was TAG; up to 98% of total acyl lipids at 33 DAP. The synthesised in vivo alpha ESA was very efficiently transferred to TAG and constituted about 60% of its total fatty acids in 33 DAP. The content of alpha ESA in polar lipids (containing, among others, phosphatidylcholine-the place of alpha ESA biosynthesis) was very low. The biosynthesis of alpha ESA in vitro (assays with microsomal fractions and [C-14]-labelled substrates) in the presence of NADPH was fairly intensive (about 60% of the corresponding intensity in vivo) when linolenic acid was used as a substrate. Contrary to the in vivo condition, most of the synthesised in vitro alpha ESA remained in phosphatidylcholine.