Soybean trypsin inhibitor (STI) inhibited PAR-2 cleavage, and completely inhibited the UVB-induced pigmentation of the epidermal equivalents containing melanocytes (50). Treatment with STI resulted in significant depigmentation, and reduced pigment deposition within the swine epidermis and prevented UVB-induced pigmentation in vivo. STI reduced keratinocyte ingestion of microspheres or E. coli particles (48). STI-treated cells showed reduced number and shorter length podia.
STI-treated melanocytes within epidermal increased the number of less mature melanosome and dendrites with mature melanosomes. UV-induced tanning of Yucatan swine was prevented with topical treatments of STI-containing compositions (52).