Screening of small molecular microbial products modulating immune responses and bestatin.

Microorganisms are the treasury of organic compounds which have various structures and various biologic and medicinal activities. The study of inhibitors of enzymes on the cellular surface has led to the findings of immunomodulators; bestatin, amastatin, forphenicine, and esterastin. Bestatin enhances delayed-type hypersensitivity to SRBC and oxazolone and inhibits Gardner lymphosarcoma and IMC-carcinoma in mice. It also suppressed Ps. aeruginosa infection in mice treated with an immunosuppressive agent. Bestatin has extremely low toxicity and has been studied clinically. These studies on bestatin were reviewed.