In vitro studies of the effects of aflatoxin B₁ and fumonisin B₁ on trypsin-like and collagenase-like activity from the hepatopancreas of white shrimp (Litopenaeus vannamei)

The in vitro effects of aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁) on the trypsin-like and collagenase-like activity from hepatopancreas (HP) of cultured white shrimp (Litopenaeus vannamei) have been studied. The presence of trypsin-like and collagenase-like enzymes in the shrimp HP was confirmed by inhibition and electrophoresis analysis. Both enzymes were strongly inhibited by phenylmethylsulfonyl fluoride (PMSF) which suggests that they belong to serine proteases. Collagenase-like protease digested native porcine type I collagen. Trypsin-like activity was inhibited by AFB₁ and FB₁. The collagenase-like activity was stimulated by FB₁. Lineweaver-Burk reciprocal plots indicated uncompetitive inhibition of trypsin-like enzyme by AFB₁. Competitive inhibition in collagenase-like enzyme, and increased K_m and V_max values of collagenase-like enzyme were observed when exposed to FB₁. These findings may suggest that AFB₁ and FB₁ toxicity to shrimp might be due to digestive deficiency and consequential histological changes in its hepatopancreas, as a result of alterations of trypsin and collagenase activity due to the presence of mycotoxins in the shrimp diet.