August 19, 2022
Keio University Faculty of Pharmacy
A research group led by Keio University and Meiji Holdings Co., Ltd. has discovered that D-tryptophan (D-Trp), a type of D-amino acid, suppresses the growth of pathogenic bacteria and pathogenic commensal bacteria in the gut, thereby preventing enteritis. This research is the work of a research group led by Professor Yun-gi Kim of the Keio University Faculty of Pharmacy and Meiji Holdings Co., Ltd.
L-amino acids are essential for all life, as they function as the building blocks of proteins. In contrast, the function of D-amino acids, the enantiomers of L-amino acids, remained unknown for a long time. However, it has become clear that D-amino acids are also present in living organisms and play important roles in the physiological functions of mammals and microorganisms. D-amino acids are mainly produced by bacteria, and those generated by gut bacteria are known to function as potent bactericidal molecules. We therefore hypothesized that D-amino acids may play a role in maintaining a healthy gut environment by directly acting on harmful bacteria in the intestine.
This study revealed that D-Trp suppresses the growth of intestinal pathogenic bacteria and prevents enteritis. We also found that D-Trp inhibits the growth of intestinal pathogenic bacteria by altering tryptophan metabolism within the bacterial cells. These results suggest that D-Trp functions as a modulator for improving the gut environment.
Although it has long been known that D-amino acids are essential components of bacteria, it is becoming clear that they also have various physiological functions in mammals, including the regulation of neurotransmission, improvement of renal function, and influencing protein function. The results of this study revealed a new function of D-amino acids, in which D-Trp directly acts on pathogenic bacteria and pathogenic commensal bacteria in the gut to suppress their growth.
D-Trp holds promise for development not only as a new functional material for improving the gut environment but also for its application in the prevention and treatment of enteritis, such as infections by intestinal pathogenic bacteria and inflammatory bowel diseases.
These research findings were published in the online edition of the international scientific journal "iScience" on August 2, 2022 (US Eastern Standard Time).
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