Distribution of hot-water extractable material, water-soluble alginate and alkali-soluble alginate in different parts of Undaria pinnatifida.

The yields of hot-water extractable material (HWEM), water-soluble alginate (WSA) and alkali-soluble alginate (ASA) from six parts of Undaria pinnatifida were estimated. The M:G ratio of these individual alginates was determined and three kinds of uronic acid blocks were characterized. The results obtained are as follows: 1) The contents of HWEM were varied irregularly from 4.7% at the apical part of midrib to 23.4% at the sporophyll. 2) The contents of WSA were varied irregularly from 1.4% at the apical part of midrib to 7.7% at the sporophyll. 3) The contents of ASA were varied also irregularly from 11.6% at the apical part of midrib as well as blade to 19.8% at the lower part of midrib. 4) The mannuronic acid contents in the WSA were higher in general than those in the ASA. 5) The M: G ratios of alginates from midrib were estimated to be 1.45 for the basal part, 1.48 for the middle part and 0.61 for the apical part. The values of M:G ratios of alginates and the amount of MM and GG blocks suggest that the growth of midrib may be most active between lower and middle parts of the U. pinnatifida body.