Policosanol distribution and accumulation in developing corn kernels
2009
Harrabi, Saoussem | Boukhchina, Sadok | Mayer, Paul M. | Kallel, Habib
Policosanol is a mixture of long-chain primary aliphatic alcohols. The policosanol composition of whole corn kernel was determined in three varieties of corn (Astro, GH2547, Local). The total policosanol content of GH2547 (20.5mg/kg of dry weight) was higher than those of Local (16.6mg/kg) and Astro (15.2mg/kg). The major policosanol components of whole corn kernel were dotriacontanol, triacontanol and tetracosanol. The distribution of policosanol in the germ, endosperm and pericarp of corn kernels was also determined. Corn pericarp had higher contents of policosanols (72.7-110.9mg/kg) than the endosperm (4.0-16.2mg/kg) and germ (19.3-37.1mg/kg) fractions. Corn pericarp policosanol was mainly triacontanol (33.63-46.29mg/kg), dotriacontanol (22.31-39.46mg/kg) and octacosanol (8.13-14.0mg/kg). In contrast, the corn germ fraction contained mostly dotriacontanol (more than 50%) and no triacontanol. The main components of corn endosperm policosanol were triacontanol and hexacosanol. The level of tetracosanol was highest in the germ fraction and lowest in the endosperm fraction. The greatest change in policosanol content (expressed as mg/100g of oil) occurred during the early stages of corn kernel development. Although the structures of the alcohol constituents of policosanol are similar, their patterns of accumulation were different. The highest levels of octacosanol and dotriacontanol were detected at 20days after pollination (DAP) followed by a rapid decrease between 20 and 30 DAP. Triacontanol levels decreased rapidly between 10 and 40 DAP, and then remained nearly constant.
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