Chemical Components from and their Inhibition of Indoleamine 2, 3-dioxygenase.

Background: In Korea, is routinely ingested as a traditional medicine or as a component of health beverages.

Objective: To research the inhibition of indoleamine 2, 3-dioxygenase (IDO) activities of components from .

Materials And Methods: the compounds were isolated by a combination of silica gel and YMC Rp-18 column chromatography, and their structures were identified by analysis of spectroscopic data (1D, 2D-NMR, and MS). All of the isolated compounds were examined for their ability to inhibit IDO, which actively suppresses immune functions by catalyzing the rate limiting reaction in the conversion of tryptophan to kynurenine.

Results: In this phytochemical study, 18 known compounds were isolated from aqueous dissolved exudates. All of the isolated compounds were examined for their ability to inhibit IDO activities for a series of anthraquinone derivatives (1-7) isolated from the extract; the IC values of these compounds ranged from 39.41 to 53.93 µM. Enzyme kinetic studies of their modes of inhibition indicated that all of the compounds were uncompetitive inhibitors.

Conclusion: The aqueous dissolved exudate can be used as a source of novel natural IDO inhibitors and merit testing as therapeutic agents in the treatments of cancer and immunopathologic diseases, such as autoimmune, inflammatory, and allergic disorders.

Summary: In this study, 18 known compounds were isolated from aqueous dissolved Aloe exudates. All of the isolated compounds were examined for their ability to inhibit indoleamine 2, 3-dioxygenase (IDO) activities for a series of anthraquinone derivatives (1-7) isolated from the Aloe extract. IDO: inhibit indoleamine 2, 3-dioxygenase, TMS: tetramethylsilane, HMQC: heteronuclear multiple quantum correlation, HMBC: heteronuclear multiple bond correlation, COSY: 1H-1H correlation spectroscopy, ESI-MS: Electrospray ionization mass spectrometry, DMSO: dimethyl sulfoxide.