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Report No.

NMR analysis of fractionated irradiated $$kappa$$-carrageenan oligomers as plant growth promoter

Abad, L.*; Saiki, Seiichi; Nagasawa, Naotsugu; Kudo, Hisaaki*; Katsumura, Yosuke*; Dela Rosa, A. M.*

The optimum molecular weight of irradiated $$kappa$$-carrageenan for the plant growth promoting effect is known to be around 10 kDa, which is obtained by irradiation at doses of 100 kGy in solid and of 2 kGy in 1% aqueous solution. In this study, isolated fraction by membrane filter of irradiated $$kappa$$-carrageenan was analyzed by NMR. The chemical shifts of $$^{13}$$C and $$^{1}$$H spectra at the range of 3-10 kDa indicated that the basic functional structure of $$kappa$$-carrageenan (alternating D-galactose-4-sulfate and 3,6-anhydro-D-galactose dimer) remains intact. No radiolytic product having carbonyl groups was detected at the range of 3-10 kDa, and moved to less than 3 kDa probably. From these results, it is assumed that the plant growth promoting effect of irradiated $$kappa$$-carrageenan depends on the molecular weight, its intact structure, and not on the radiolytic products.



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Category:Chemistry, Physical



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