Structural characterization and antitumor activity of a polysaccharide from Dendrobium wardianum.

Through hot water extraction, protein removal and chromatographic purification, DWPP-Is was found to be the major polysaccharide present in the stem of D. wardianum. The Mn and Mw of DWPP-Is were 29.0 kDa and 98.6 kDa, respectively. Furthermore, mannose and glucose were found to be the most abundant monosaccharides in DWPP-Is. Their backbones consist of (1 â†’ 4)-ß-d-Glcp and O-acetylated (1 â†’ 4)-ß-d-Manp, which are similar to the structures of other anti-tumour Dendrobium polysaccharides. The inhibition rate of DWPP-Is treatment on SPC-A-1 cells (2 mg/mL, 72 h) reached 56.0%. Intragastric administration of DWPP-Is on A549 tumour-bearing KM mice (10 mg/mL, 0.2 mL) exhibited similar inhibition ratios to that of erlotinib hydrochloride (2 mg/mL). Moreover, the highest inhibition was observed in P-CK treatment combined with DWPP-Is, reaching an inhibition rate of 23.4%. These results suggest that DWPP-Is has the potential to be a functional agent for lung cancer prevention.

[The influence of abscisic acid treatment on desiccation tolerance in Dendrobium candidum protocorm-like bodies].

Effect of ABA on desiccation tolerance in the protocorm-like bodies (PLBs) of D. candidum was studied. The best result was obtained while ABA precultured at 5 micromol/L for 24 h (Fig.2). PLBs vitality rate was 10 times of the control after 2 h desiccation (Table 1). Detection of cytoplasmic osmoticums showed that ABA preculture could not induce the accumulations of soluble sugar, proline, etc (Tables 3, 4 and 7). But the content of soluble polysaccharide rose conspicuously (Table 5). So we think that the accumulation of soluble polysaccharide may play an important role in desiccation tolerance induced by ABA preculture.