CHARACTERIZATION OF ACIDIC HETEROGLYCANS FROM TREMELLA-FUCIFORMIS BERK WITH CYTOKINE STIMULATING ACTIVITY

Four kinds of acidic heteroglycan, T3a-T3d, were isolated from the bod y of the fungus Tremella fuciformis Berk. The molecular weights of T3a -T3d were 550, 420, 55, and 48 kDa, respectively. Glycosidic linkage a nalysis showed that they had a mannan backbone consisting of 3-linked Manp, and side chains containing glucosyl, mannosyl, fucosyl, xylosyl, and glucuronic acid residues attached through O-2, O-4, or O-6 of abo ut half of the backbone mannosyl residues. A partial acidic hydrolysat e of T3a could be divided into a low-branching region (T3a-1, 2, 3, 4) mainly branched at the 2-position of 3-linked Manp in the mannan back bone, and a high-branching region (T3a-5A) branched at the 2,4- or 2,4 ,6-positions of 3-linked Manp in the backbone. The low-branching regio n, which is predominant in the backbone, was substituted with non-redu cing terminal GlcpA, Fucp and short side chains consisting of (1 --> 6 )-linked Glcp and (1 --> 2)-linked Manp linked through C-2 of the mann an backbone. The high-branching region, which is a minor component of the backbone, was linked with long side chains of (1 --> 6)-linked Glc p and (1 --> 4)-linked GlcpA in their branching points. T3a-T3d were a ble to induce human monocytes to produce interleukin-1, interleukin-6, and tumor necrosis factor in vitro. The different fragments of the ac idic hydrolysate of T3a (T3a-1, 2, 3, 3, 5A) also induced monocytes to secret interleukin-6 with high potency, indicating that the activity may be caused by a common structure, (1 --> 3)-mannan in the four hete roglycans and their fragments. The change of molecular weight had no o bvious influence on the activity of the heteroglycans. (C) 1996 Elsevi er Science Ltd.