  We study a class of braneworlds where the cosmological evolution arises as
the result of the movement of a three-brane in a five-dimensional static
dilatonic bulk, with and without reflection symmetry. The resulting
four-dimensional Friedmann equation includes a term which, for a certain range
of the parameters, effectively works as a quintessence component, producing an
acceleration of the universe at late times. Using current observations and
bounds derived from big-bang nucleosynthesis we estimate the parameters that
characterize the model.
