Abstract
The polysaccharides of some lichens were studied chemically in relation to their host-mediated antitumour activities against sarcoma 180 in mice. A water-insoluble polysaccharide fraction, EP-3, [α]17D +200°, from Evernia prunastri (L.) ACH. was shown to be an α-glucan containing α(1→3)(1→4) linkages in the ratio of 4 : 1. The cold water-soluble fraction, EP-4, was separated into EP-7, [α]17D +12°, and EP-6, [α]17D +164°. The former was shown to be an antitumour active glucan having β (1→3) (1→4) linkages in the ratio of 3 : 1, while the latter was revealed to be an α(1→3) (1→4) glucan (approx, ratio 3 : 2). The properties of these polysaccharides were discussed in comparing with the data of everniin reported by micovic, et al. A polysaccharide AS-3-IS, [α]14D+176°, isolated from Acroscyphyus sphaerophoroides LEV. giving an intensive blue iodine-colour reaction was shown to be a new type of α-glucan consisting of α(1→3), (1→4) and (1→6) linkages. A cold water-soluble polysaccharide, AS-3-S, was revealed to be a new glycopeptide. The polysacchrides, ASu-2 and ASa-2 isolated from Alectoria sulcata (LEV.) NYL. and A. sarmentosa (ACH.) ACH. were proved to be lichenin, and ASu-3 and ASa-3 were shown to be isolichenin. The host-mediated antitumour activities of the polysaccharide fractions isolated from the above lichen species were tested.
