Pharmaceutical product derived from lignin - by oxidative de- and re-polymerisation and purificn.

New water-soluble low-mol. -wt. ligniod prod. is produced by (a) contacting natural or synthetic lignin with O2 in an alkaline medium in the presence of an oxidn. catalyst and isolating the water-soluble product in the form of a supernatant soln., (b) clarifying the supernatant by filtratition and subjecting it to ultrafiltration through a membrane with a mol. wt. cutoff threshold of 5000-35,000; and (c) adjust the filtrate to pH 4.5-6.0 and isolating the prod. Alternatively (and pref.) step (c) is carried out by (i) adjusting the filtrate to pH 2.1-3.4 and centrifuging to separate an acid-sensitive gel fraction and an acid-stable supernatant; (ii) adjusting the gel fraction to pH 9 with alkali and then to pH 3.5-6.9 with a cation exchanger; (iii) subjecting the supernatant from step (i), to thermal shock, removing insolubles and adjusting to pH 3.5-6.9 with alkali and (iv) combining the solns. with steps (ii) and (iii) and isolating the prod. The product is stated to be useful for treating ...