Safety evaluation of dried L-tryptophan fermentation product in Sprague-Dawley rats

• Published in: Toxicology reports 2022-01, Vol.9, p.1099-1113
• Main Authors: Ko, Soo Min, Park, Ji-Eun, Kim, Sang-Ho, Park, Myeong Kyu, Seol, Ja Kyung, Heo, In Kyung, Shin, Yong-Uk, Kim, So-Young, Kim, Yang Hee, Son, Woo-Chan
• Format: Article
• Language: English
• Subjects: Dried L-tryptophan fermentation product; Eosinophilia-myalgia syndrome; Metabolically engineered Corynebacterium glutamicum; Oral administration; Regular; Subchronic toxicity
• ISSN: 2214-7500; 2214-7500
• DOI: 10.1016/j.toxrep.2022.05.005

The subchronic toxicity of oral L-tryptophan produced by fermentation with metabolically engineered Corynebacterium glutamicum was evaluated in Sprague-Dawley rats. Doses of 0, 500, 1000, and 2000 mg/kg/day were administered to groups of 10 male and 10 female rats for 90 days. For the groups administered 0 and 2000 mg/kg/day, an additional 5 male and 5 female rats were tested as a recovery group. No adverse effects associated with the test substance were observed in all rats during the 90-day administration of the product, irrespective of dose, and at 4 weeks of recovery at dosages of 0 and 2000 mg/kg/day. Furthermore, histochemical and immunohistochemical analyses for L-tryptophan-associated eosinophilia-myalgia syndrome (EMS) did not reveal significant changes in both sexes of groups administered 0 or 2000 mg/kg/day. Based on these results, it could be concluded that there were no significant adverse effects related to the test substance in all animals; therefore, dried L-tryptophan fermentation product can be used as feed additive material. •L-tryptophan has long been used as a feed additive in livestock.•Subchronic toxicity of L-tryptophan (0–2000 mg/kg/day) was evaluated in SD rats.•L-tryptophan did not induce significant changes in all parameters.•Consumption of L-tryptophan would not have significant safety concerns in humans.