Novel Synthesis of Keto acid Precursor Derivative for Oxidation of Lambda-Carrageenan Polysaccharide by Alkaline Permanganate

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Novel Keto-acid derivatives of lambda-carrageenan (LCAR) as sulfated polysaccharides were synthesized through LCAR oxidation by permanganate ion in alkaline media at pH`s > 12. Stoichiometric molar ratios of LCAR, MnO₄^- and NaF were mixed in alkaline solutions of pH >12. The mixture was stirred until reaction completion (~48 hr), then the formed colloidal precipitate of MnF₄ was isolated by filtrations. A rotary evaporator was used to concentrate the filtrate to about one-fifth of its original volume, and then acidified by acetic acid to pHs of ca. 5-6. Vacuum evaporation was applied to that remains filtrate until drying, and then it was kept in a desiccator for use. The hydroxyl amine and 2,4-dinitrophenyl hydrazine were used to identify the oxidation product. The formation of the corresponding 2,4-dinitrophenyl hydrazone and dioxime derivatives, respectively, indicated the formation of ketoacid-LCAR as the final oxidation product. Such oxidation products can be applied as alternative promising in pharmaceutical, medicine, biomedicine and food industry technologies.