Dear Dr. Enamul Kabir

First i have to say sorry for my delay in replying to you answer, that's for some technical problems in my account,

thanks for your answer which really it was benefit for me,

some comment in resent research confirmed some mechanisms with accordance with your answer:

* Ascorbic acid probably functions as a base or nucleophile.

* Ascorbic acid seems to act as a cofactor by supporting the release of the glucose residue from myrosinase by abstracting a proton from a water molecule producing a stronger nucleophile for subsequent attack at the anomeric center

* High concentrations of ascorbic acid inhibit and low concentrations activate myrosinase activity.

* Ascorbate functions as a catalytic base, activates a water molecule for hydrolysis and increases the hydrolysis rate.

thanks again for your cooperation.