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Pseudo-alpha- and pseudo-beta-DL-glucose, the isomers of 5-hydroxymethyl-1,2,3,4-cyclohexanetetrol with alpha-gluco and beta-gluco configurations, were used as synthetic analogs of glucose anomers to study the mechanism of glucose-stimulated insulin release by pancreatic islets. Neither isomer was phosphorylated by liver glucokinase nor stimulated insulin release from islets. Incubation of islets with pseudo-alpha-DL-glucose resulted in a considerable accumulation of the glucose analog, probably the D form, in islets. The alpha-isomer, but not the beta-isomer, inhibited both glucose-stimulated insulin release (44% inhibition at 20 mM) and islet glucokinase activity (36% inhibition at 20 mM) in a concentration-dependent manner and to a comparable degree. These results strongly suggest that the inhibition of glucose-stimulated insulin release by pseudo-alpha-DL-glucose is due to the inhibition of islet glucokinase by the glucose analog, providing additional evidence for the essential role of islet glucokinase in glucose-stimulated insulin release.

Pseudo-sugar is a compound in which a ring-oxygen of a pyranoid sugar is replaced by a methylene group, and there are 32 theoretically possible stereoisomers in the pseudo-sugar family. All the predicted 16 DL-forms have been synthesized, as well as 9 enantiomers. The most accessible starting material for a synthesis of pseudo-sugars is endo-7-oxabicyclo[2.2.l]hept-5-ene-2-carboxylic acid which is obtained by the DielsAlder reaction of furan and acrylic acid. Recently, it has been found that some pseudo-sugars are almost equally sweet as their respective true sugars. INTRODUCTION In the last two decades, several biologically active branched-chain cyclitols and their erivatives have been found in Nature, such as (+)-(l,2,3/4,5)-tetrahydroxy-l-cyclohexanemethanol (1) (ref. 1), validamycin antibiotics (2) (ref. 2), glucosidase-inhibitors: acarbose (ref. 3), trestatins (ref. 4), adiposins (ref. 5) and oligostatins (refs. 6, 7). Since their common component, hydroxymethyl-cyclohexanetetrol or its amino derivative, is structurally closely related to a true sugar, this compound has been designated as a pseudosugar or a pseudo-amino sugar. Thus, the pseudo-sugar is a name of a class of compounds in which a ring-oxygen of a pyranoid sugar is replaced by a methylene group.

Hexaacetyl-streptamin (9) und Hexaacetyl-actinamin (12) wurden, ausgehend von myo-Inosit, in vier- bzw. sechsstufiger Reaktionsfolge synthetisiert.