Protective effect of glutathione S-transferase enzyme activity against aflatoxin B1 in poultry species: relationship between glutathione S-transferase enzyme kinetic parameters, and resistance to aflatoxin B1

Comparative studies designed to investigate the role of glutathione S-transferase (GST) activity on the enzyme catalyzed trapping of aflatoxin B-1-8,9-epoxide (AFBO) with glutathione, and the relationship with aflatoxin B-1 (AFB(1)) resistance have not been conducted in poultry. Hepatic cytosolic fractions of chickens, quail, turkeys and ducks were used to measure in vitro the enzymatic parameters maximal velocity (V-max), Michaelis-Menten constant (K-m) and intrinsic clearance (CLint) for GST activity. AFB(1) used ranged from 2.0 to 157.5 mu M and the AFB(1)-GSH produced was identified and quantitated by HPLC. Significant differences were found in GST V-max values, being the highest in chickens, followed by quail, ducks and turkeys. The K-m values were also significantly different, with chickens < ducks < turkeys < quail. Chickens had the higher CLmt value in contrast to ducks. Differences by sex showed that duck females had a higher CLmt value than the turkey and quail, whereas duck males had a CLmt close to that of turkey. The ratio AFBO production/AFB(1)-GSH production follows the order duck>turkey>quail>chicken, in agreement with the known poultry sensitivity. The extremely high AFB(1) epoxidation activity/GST activity ratio observed in ducks might be the explanation for the development of hepatocellular carcinoma in this species.

Automated summary

This study investigated the role of glutathione S-transferase (GST) activity in the trapping of aflatoxin B-1-8,9-epoxide (AFBO) with glutathione and its relationship with aflatoxin B-1 (AFB(1)) resistance in poultry. Significant differences were found in GST activity among chickens, quails, turkeys, and ducks, as well as differences based on sex within the same species. The results suggest that the differences in GST activity may contribute to the variation in AFB(1) metabolism and resistance among different poultry species.