The cross section for one-proton knockout from 16C with a large neutron-proton separation energy asymmetry on a carbon target has been measured at an intermediate beam energy of around 240 MeV/nucleon. The measured cross section is compared to the predictions based on the eikonal reaction model with shell-model structure inputs. The beam-energy dependence of the reduction on the extracted spectroscopic strength for strongly bound nucleon removal is derived from combining the existing intermediate-energy data with the present measurement. The deduced reduction factor Rs, defined as the ratio of the measured and theoretical cross sections, for the strongly bound nucleon removal at around 240 MeV/nucleon is consistent with the systematics observed from knockout reactions induced by light nuclear targets at intermediate energies of around 80 MeV/nucleon.