  It is shown that in the 70 and 700 SU(6) irreducible spaces, the SU(6)
extension of the Weinberg-Tomozawa (WT) s-wave meson-baryon interaction
incorporating vector mesons ({\it hep-ph/0505233}) scales as ${\cal O}(N_c^0)$,
instead of the well known ${\cal O}(N_c^{-1})$ behavior for its SU(3)
counterpart. However, the WT interaction behaves as order ${\cal O}(N_c^{-1})$
within the 56 and 1134 meson-baryon spaces. Explicit expressions for the WT
couplings (eigenvalues) in the irreducible SU(2$N_F$) spaces, for arbitrary
$N_F$ and $N_c$, are given. This extended interaction is used as a kernel of
the Bethe-Salpeter equation, to study the large $N_c$ scaling of masses and
widths of the lowest--lying negative parity s-wave baryon resonances.
Analytical expressions are found in the $N_c\to \infty$ limit, from which it
can be deduced that resonance widths and excitation energies $(M_R-M)$ behave
as order ${\cal O} (N^0_c)$, in agreement with model independent arguments, and
moreover they fall in the 70-plet, as expected in constituent quark models for
an orbital excitation. For the 56 and 1134 spaces, excitation energies and
widths grow ${\cal O} (N_c^{1/2})$ indicating that such resonances do not
survive in the large $N_c$ limit. The relation of this latter $N_c$ behavior
with the existence of exotic components in these resonances is discussed. The
interaction comes out repulsive in the 700.
