concentration kinetics of secoisolariciresinol diglucoside and its biosynthetic precursor coniferin in developing flaxseed introduction in the plant kingdom flaxseed linum usitatissimum l is the richest source of secoisolariciresinol diglucoside sdg which is of great interest because of its potential health benefits for human beings the information about the kinetics of sdg formation during flaxseed development is rare and incompleteobjective in this study a reversedphase highperformance liquid chromatographydiode array detection hplcdad method was developed to quantify sdg and coniferin a key biosynthetic precursor of sdg in flaxseedmethodology seeds from different developmental stages which were scaled by days after flowering daf were harvested after alkaline hydrolysis the validated hplc method was applied to determine sdg and coniferin concentrations of flaxseed from different developing stagesresults coniferin was found in the entire capsule as soon as flowering started and became undetectable20 daf sdg was detected 6 daf and the concentration increased until maturity on the other hand the sdg amount in a single flaxseed approached the maximum around 25 daf before desiccation started concentration increase between 25 daf and 35 daf can be attributed to corresponding seed weight decreaseconclusion the biosynthesis of coniferin is not synchronous with that of sdg hence the concentrations of sdg and coniferin change during flaxseed development