  In [X.-W. Hou, Z.-P. Huang, S. Chen, Eur. Phys. J. D 68, 1 (2014)], Hou et
al. present, using Tsallis' entropy, possible generalizations of the quantum
discord measure, finding original results. As for the mutual informations and
discord, we show here that these two types of quantifiers can take negative
values. In the two qubits instance we further determine in which regions they
are non-negative. Additionally, we study alternative generalizations on the
basis of R\'enyi entropies.
