  The general expression for the second order large scale curvature
perturbation in the form of a functional over a background solution is derived.
The explicit expressions was obtained for two special forms of the inflationary
potential. In the considered cases, it is shown that a significant level of
non-Gaussianity can be generated during the super-Hubble evolution only if
nonadiabatic perturbations are non-negligible at the end of inflation.
