  We present the visible spectrum of MBCs 133P/Elst-Pizarro and 176P/LINEAR, as
well as three Themis family asteroids: (62) Erato, (379), Huenna and (383)
Janina, obtained in 2007 using three telescopes at "El Roque de los Muchachos"'
Observatory, in La Palma, Spain, and the 8m Kueyen (UT2) VLT telescope at Cerro
Paranal, Chile.
  The spectra of 133P and 176P resemble best those of B-type asteroid and are
very similar to those of Themis family members and are significantly different
from the spectrum of comet 162P/Siding-Spring and most of the observed cometary
nuclei. CN gas emission is not detected in the spectrum of 133P. We determine
an upper limit for the CN production rate Q(CN) = $= 2.8 \times 10^{21}$ mol/s,
three orders of magnitude lower than the Q(CN) of Jupiter family comets
observed at similar heliocentric distances.
  The spectra of 133P/Elst-Pizarro and 176P/LINEAR confirm that they are likely
members of the Themis family of asteroids, fragments that probably retained
volatiles, and unlikely have a cometary origin in the trans-neptunian belt or
the Oort cloud.
