| Herba Dendrobii, prepared from the dried stems of Dendrobium species, is a Chinese materia medica as a tonic. Many researches focus on its basic constituents as well as pharmacological activity. As well known, polysaccharides, widespread in Dendrobium species, is the main active constituent; and Dendrobium officinale Kimura et Migo is one of the most precious Dendrobium species. Its pharmacological activity on immune enhancement and hypoglycemic effects has been verified by many animal-model tests. In this dissertation, we have reported the main components as well as their distribution in different parts of the plant, and isolation, purification, properties and structure elucidation of the main ingredient from the crude polysaccharide; we have investigated the diversities of polysaccharides between from three medicinal dendrobium plants, and from Natural Dendrobium officinale and its tissue-cultured protocorm; and we have proved pharmacological activity of the polysaccharide, too. All the above-mentioned aim to conduct the production and application of dendrobiums, and to promote the research of configuration-activity relationship of dendrobium polysaccharide.1. The main components as well as its distribution in the stem of Dendrobium officinaleThe total polysaccharides (TPs) and water-soluble polysaccharides (WPs) are high in stems with a little variation of polysaccharides content between three parts from them. Polysaccharides content in the roots is quite lower, especially the water-soluble polysaccharides accounting for less than 2%, which indicates reasonable to take stems as the medicinal part. The content of alkaloid between different parts is various, upper-stem highest, root, middle-stem and the lower-stem lower in turn. The total content of alkaloid is 10% lower than that of D. nobile.2. comparative study on polysaccharides from three dendrobuim spiciesThe content of TPs from three medicinal plants, D. officinale, D. moniliforme and D. hancockii, are all quite higher. As far as WPs concerned, the latter one is 1/3 lower than the former two. Considering distribution of TPs and WPs in the plants, contents of proteins, uronic acid andneutral polysaccharide in crude polysaccharide, and anion exchange chromatographies and FT-IR, diversities exists markedly between the three dendrobuim spicies.3. Comparative study on polysaccharides from natural Dendrobium officinale and its tissue-cultured protocormCompared with natural Dendrobium officinale, content of WPs from tissue-cultured protocorm is very lower, especially the neutral polysaccharide in crude polysaccharide. While content of uronic acid is higher. DOPP-1-A1, a neutral polysaccharide composed mostly of ￡>-Glc, was quite distinct from DOPP-1-A1 which is consisted mostly of D-Man. Furthermore, DOPP-1-Alhave two ingredients: DOPP-1-Alland DOPP-1-A12, the molecular weight of which is different from that of DOP-1-A1.4. Extraction, fractionation, purification and structural determination of DOPA crude polysaccharide, obtained from aqueous extract of Dendrobium officinale Kimura et Migo, was fractionation and purified by DEAE-cellulose anion-exchange chromatography and Sephadex G-10, Sephadex S-200/ S-400 gel-permeation chromatography, giving a neutral polysaccharide DOP-1-A1 and five acidic polysaccharides DOP-2-A1, 3-A1, 4-A1, 5-A1, 6-A1. The latter five ingredients were presumed to be proteoglycans with /3-D-Manp.DOP-1-A1, its weight-average molar mass estimated to be 128 kDa by HP-GPC, has been investigated by chromatographies (TLC, GC and GC-MS), spectroscopies (UV, IR and 'H/13C NMR) and chemical techniques (periodate oxidation-Smith degradation, methylation, partial acid hydrolysis, and deacetylation). The results demonstrate that it is a 2-0-acetyl-glucomannan, composed of mannose, glucose and arabinose in the molar ratios of 40.2: 8.4: 1. It has a backbone of (1—+4)-linked (3-D-mannopyranosyl residues and P-D-glucopyranosyl residues, with branches substituted at O-6 consisting of terminal and (1—>3)-linked Man/?, (1—>3)-linked Glcp, and a small proportion of arabinofuranosyl residues at the terminal position. The acetyl groups are found to be substituted at O-2 of (1—>4)-linked Man/? and Glcp. So the main repeating units are as the following structure:p-D-Manp-(l —?3)-￡-D-lVlanp-(1 —>3)-p-D-Man/>D-Ara/-(1->3)-|3-D-Glc/>OAciOAc11I1i26264)-p-D-Manp-(l-?4)-p-D-Man/j-(l->4)-)5-D-Maiip-(l->4)-p-D-Mary>(l-*]5. Pharmacological activity on anti-oxidation and anti-inflammationDendrobium polysaccharides were verified to have a scavenging effect on O2"?-. OH, and H2O2 by anti-oxidation experiments in vitro. And the polysaccharides also showed anti-inflammatory activity by inhibition of production of plasma hemolysin, croton oil-induced dermatitis, 2ymosan-induced oedemas, and hemolytic activity of complement. Compared with other anti-inflammatory medicines, they were characteristic of moderate potenty and slowly taking effect, which indicated that the anti-inflammatory activity of polysaccharides not owing to inhibit production and distribution directly of inflammatory mediators such as PG-E2, histamine, 5-HT and bradykinin and so on, but to modulate physiological variation of inflammatory focus and inhibit production of inflammatory cytokines. As a whole, as for the anti-oxidative and anti-inflammatory activiy, natural Dendrobium officinale is better than greenhouse-cultivated plants and tissue-cultured protocorm, and each has its strong point in the pharmacological activity between the latter two; Dendrobium moniliforme is similar with Dendrobium officinale, and Dendrobium hancockii inferior. It was supposed that Dendrobium officinale can be substituted appropriately by Dendrobium moniliforme on some pharmacological activity.
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