Different structural requirements of endotoxic glycolipid for tumor regression and endotoxic activity |
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Authors: | Ken-ichi Amano Edgar Ribi John L Cantrell |
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Institution: | 1. National Institutes of Health, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Montana 59840 USA.;2. Ribi ImmunoChem Research Inc., P.O. Box 1409, Hamilton, Montana 59840 USA. |
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Abstract: | Endotoxic glycolipid extracted from the heptose-less mutant of was treated with alkali and acid reagents. The glycolipid freed of all O-ester linked fatty acids by hydroxylamine had lost tumor regression activity and toxicity, whereas a partial removal of O-ester linked fatty acids by mild alkali did not impair with these activities. The glycolipid retained both activities after removal of 2-keto-3-deoxyotonate by sodium acetate (pH 4.5) but was rendered nontoxic while retaining antitumor activity when hydrolyzed by 0.1N HCl whereby 2-keto-3-deoxyoctonate and glycosidic phosphate was split off the glycolipid molecule. Nontoxic and tumor regressive fractions were separated by means of preparative thin layer chromatography of glycolipid hydrolyzed by mild acid. Thus, it was concluded that glycosidic bound phosphate and at least a portion of fatty acids of the lipid A moiety were essential for toxicity, but that this phosphate is not essential for tumor regression activity. |
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Keywords: | To whom correspondence should be addressed |
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