Quantum bounds for gravitational de Sitter entropy and the Cardy-Verlinde formula

We analyze different types of quantum corrections to the Cardy-Verlinde ent ropy formula in a Friedmann-Robertson-Walker universe and in an (anti)-de S itter space. In all cases we show that quantum corrections can be represent ed by an effective cosmological constant which is then used to redefine the parameters entering the Cardy-Verlinde formula so that it becomes valid al so with quantum corrections, a fact that we interpret as a further indicati on of its universality. A proposed relation between Cardy-Verlinde formula and the ADM Hamiltonian constraint is given.