Two new bibenzyls from Pleione grandiflora (Rolfe) Rolfe and their antioxidant activity.

Two new bibenzyls (1 and 2) were isolated from the pseudobulbs of Pleione grandiflora (Rolfe) Rolfe along with six known compounds, including isoarundinin I (3), isoarundinin II (4), bulbocodin D (5), batatasin III (6), 5,3'-dihydroxy- 4-(p-hydroxybenzyl)-3-methoxybibenzyl (7) and shancigusin F (8). Their structures were established on the basis of spectroscopic methods. These compounds showed potent DPPH free radical scavenging effects with IC50 values ranging from 49.72 ± 0.35 µM to 65.41 ± 0.49 µM.

[A new lignan from Euscaphis konishii].

The chemical constituents from the extract of the twigs of Euscaphis konishii with anti-hepatoma activity were investigated, twelve compounds by repeated chromatography with silica gel, Sephadex LH-20 and preparative-HPLC. The structures of the chemical components were elucidated by spectroscopy methods, as konilignan(1),(7R, 8S)-dihydrodehydrodico-niferylalcohol-9-O-ß-D-glucopyranoside(2),illiciumlignan B(3),threo-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-panediol(4),erythro-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-panediol(5), matairesinol(6), wikstromol(7), isolariciresinol(8),(+)-lyoniresinol(9), 4-ketopinoresinol(10), syringaresin(11), and vladinol D(12). Among them, compound 1 is a new lignan. Compounds 10 and 12 had moderate inhibitory activity on HepG2 cells, with IC_(50) values of 107.12 µmol·L~(-1) and 183.56 µmol·L~(-1), respectively.

[Changes in water state and soluble protein contents of wampee axes during inducing desiccation tolerance by sucrose preculture].

Progressively increasing sucrose concentration of culture medium could increase desiccation tolerance of wampee [Clausena lansium (Lour.) Skeels] axes. The changes in water state and soluble proteins of axes during acquirement of desiccation tolerance were measured by differential scanning calorimeter (DSC) and SDS-PAGE. The results showed that the cooling and heating thermograms of sucrose-precultured axes were similar to those of the control; but there was a stepwise change in the heating thermograms of sucrose-precultured axes, implying that vitrification might occur in axes. Unfreezable water amounts of wampee axes were measured, the results showed that amounts of unfreezable water of sucrose-precultured axes and control were 25.4% and 25.9% (by the linear regression equation method), or 24.3% and 23.7% (by the heat of ice fusion method) respectively, which were not significantly different. The soluble protein content of sucrose-precultured axes was 68% higher than the control, and SDS-PAGE showed that a 20-kD protein markedly increased in content.

[Synthesis of heat shock proteins in developing maize embryo].

Labeling of protein in developing maize embryo with (35)S-Met showed that, the protein synthesis rate in heat shock (42 degrees C) was similar to that in the control (25 degrees C). Heat shock inhibited protein synthesis at 16 DAP, whereas it stimulated protein synthesis at 22 and 34 DAP. The pattern of SDS-PAGE showed that, a new set of heat shock proteins were induced after heat shock. At 16 DAP, heat shock induced 3 kinds of HSPs with molecular weight 86.4, 80.0 and 73.2 kD. And at 22 DAP, 7 kinds HSPs were induced with molecular weight 86.4, 80.0, 73.2, 24.4, 18.2, 16.8 and 13.6 kD. After 22 DAP, except 3 kinds of protein with molecular weight 73.2, 24.4 and 18.2 kD were induced turnover synthesis, other 4 kinds were increased by heat shock. The pattern of 2D-PAGE further suggested that, heat shock induced more than 20 kinds of HSPs at 22 and 28 DAP, especially the smHSP of 20-30 kD were more than 10 kinds. Western blot indicated that, BiP (HSP70) and PDI (HSP60) kept a high expression level during the embryo development, and failed to respond to heat shock.

[Induction of chilling tolerance and heat shock protein synthesis in rice seedlings by heat shock].

Heat shock applied to germinated rice seeds increased the chilling tolerance of seedlings. Comparison with the control, brief heat shock applied before chilling at 4 degrees C for 2 days and recovery at 25 degrees C for another 2 days decreased the permeability of cellular membranes and increased the content of proline in rice seedlings. Heat shock applied before chilling also increased the activities of superoxide dismutase, catalase, and peroxidase and the content of ascorbate in rice seedlings. In contrast, the lipoxygenase activity and the malondialdehyde content in the heat-shocked rice seedlings were lower than those in the control. Germinated rice embryos synthesized heat shock proteins of Mr 78, 70, 64, 46, 38, 24, 17 and 16 kD during heat shock. The results of Western blot suggested that the binding protein (Bip) of HSP70 play an important role in protecting the rice seedling against chilling damage.

[Changes in desiccation tolerance and cell ultrastructures of wampee axes induced by progressively raising sucrose concentration of culture medium].

The desiccation tolerance of wampee [Clausena lansium (Lour.) Skeels] axes was significantly increased when they were pre-cultured with woody plant medium with progressively increasing sucrose contents (27% --> 50% --> 60%). Most of the plumular axes could survive a moisture content as low as 18.8% and could regenerate plantlets. Results of electron microscopy showed that when the moisture content of the plumular axes of the control was brought down to 36.3%, the plasmolemma and vacuole disappeared, and the chloroplasts and mitochondria collapsed. Plate I-1-4) While plumular axes had been pre-cultured by progressive raising of sucrose concentration of culture medium and then desiccated to a moisture content of 35.8%, plasmolysis occurred in most of the cells, with dense cytoplasm and big starch grains in the chloroplast (Plate I-6-8, Plate II-9). Furthermore, after they were desiccated to a moisture content of 18.8%, severe plasmolysis was observed, most of the chloroplasts and mitochondria were partly injured (Plate II-10). The desiccative injury in cells of the plumular axes desiccated to a moisture content of 18.8% could be repaired after 4 d of rehydration (Plate II-11-16).