Abstract
Chemical investigations were made on a new unsaturated crystalline diuronide isolated from alginase hydrolysate of alginic acid. This uronide has [α] 22D-8°(in water), E232mμ1%=143 and m.p. 135.5-136.5°C (decomp.). The presence of an α, β-unsaturated carboxylic acid formulation is supported by the following evidences:(a) an ultraviolet absorption band at 232mμ, (b) infrared absorption bands at 1648cm-1 due to double bond and at 1720cm-1 due to conjugated carboxylic group, (c) the consumption of about 1 mole of bromine per mole of the compound, (d) the production of oxalic acid on oxidation with ozone, (e) the formation of a substance that shows absorption maximum at 550mμ caused by the addition of thiobarbituric test. After hydrolysis, crystalline mannuronic lactone was obtained from the unsaturated diuronide. Occurrence of mannuronic moiety in the reducing unit was observed by paper chromatography of the hydrolysate of borohydride-reduced unsaturated compound. From these results it can be seen that the possible structure of this unsaturated diuronideis4-O-(β-D-Δ4, 5-mannoseenpyranosyluronic acid)-D-mannuronic acid.
