Extensions of the standard model (SM) with gauge symmetry SU(3)c SU(4)L U(1)X (3-4-1 models), where anomaly cancellation takes place among fermion families, predict the existence of two extra neutral gauge bosons which transmit tree-level flavor changing neutral currents (FCNC). In this work, in the context of a 3-4-1 model, we study the bounds arising from experimental data related to K and B neutral meson mixing on the angles and phases that parametrize the mixing matrix in the down quark sector.