Figure 4: Cytotoxic effect of Calo-protein from the stem bark of C. procera assayed on human skin cells and their morphological changes observed for 24 h. (a) Calo-protein was tested against skin cell up to 1000 μg/mL concentrations for 24 h. There were no toxic effects recorded at high concentrations. (b) The protein did not produce severe cytolytic effects after 24 h exposure of the plant protein in vitro. Light microscopic images showing the morphological changes of human skin fibroblast cells were exposed to the Calo-protein obtained from the stem bark of C. procera tested at varying doses (1000–0.001 μg/mL). (c) There was no alteration in the control cells, (d) while lower dose (100 μg/mL) of protein did not affect the cell morphology (e, f), the higher dose of protein (1000 μg/mL) showed some changes on HEPK cells after 24 h. Untreated cells served as a control (ctrl).