Tyrolobibenzyls E and F from Scorzonera humilis and distribution of caffeic acid derivatives,lignans and tyrolobibenzyls in European taxa of the subtribe Scorzonerinae (Lactuceae,Asteraceae)

A chemosystematic study of the subtribe Scorzonerinae, a subtribe of the Lactuceae tribe of the Asteraceae family was performed, using the recently discovered tyrolobibenzyls as well as lignans and caffeic acid derivatives as diagnostic characters. In addition to the known compounds two new tyrolobibenzyls (E and F) were isolated and their structures were established by mass spectrometry and 1D and 2D NMR spectroscopy. Twenty four samples from rootstocks of seventeen different Scorzonerinae taxa, comprising members of three genera (Podospermum, Scorzonera, and Tragopogon), were analyzed. Tyrolobibenzyls A (1), B (2), C (5), D (3), E (6), and F (4) were identified in crude extracts by means of HPLC retention times, on-line UV spectra and on-line MS/MS spectra. Quantification of these compounds was performed by HPLC, using 2,2-bis-(4-hydroxyphenyl)-propane as an internal standard. Tyrolobibenzyls A-F were only detected in samples from Scorzonera humilis, while chlorogenic acid and 3,5-dicaffeoylquinic acid were detected in all samples investigated. In contrast, caffeoyl tartaric acid and cichoric acid were not detectable in any member of the subtribe Scorzonerinae.     

Structure and biological activity of botulinum neurotoxin

Botulinum neurotoxin appears to undergo structural alterations after synthesis and also before it inhibits neurotransmitter release. Discussions and conjectures are presented in this context: 1. At what sites on the 150 kDa neurotoxin does posttranslational proteolytic processing occur? 2. Does neurotransmitter inhibition depend on separation of a segment of the neurotoxin from the rest of the molecule? 3. At what step in the intoxication pathway does activation of neurotoxin (enhanced lethality following limited proteolysis) manifest? 4. Can the receptor binding parameters (based on bovine brain synaptosome and lipid membrane), channel forming property (lipid bilayer membrane) and intracellular inhibitory activity (based on permeabilized chromaffin and PC 12 cells) provide clues to differences in the lethal potency between the neurotoxin serotypes? In addition, the following issues are considered: 5. The spontaneous fragmentation of isolated 50 kDa light chain, after its separation from 100 kDa heavy chain, 6. Effect of specific chemical modification of Arg, His, Lys, Trp, Tyr and Asp/Glu residues of types A, B and E neurotoxins on lethality and antigenicity, and 7. Development of second generation toxoids.     

Structure and biological activity of hagfish insulin

An isomorphously phased electron density map of hagfish (Myxine glutinosa) insulin has been calculated at a resolution of 3·1 Å spacing. The molecule crystallises with one molecule per asymmetric unit but is organised as a symmetric dimer lying on a 2-fold crystal axis. The structure of the hagfish insulin monomer is much more similar to that of pig insulin molecule 2 than molecule 1 of the dimer that constitutes one third of the 2 Zn insulin hexamer. There are different conformations however at the N and C termini of the B-chain. At the C terminus the two final residues on hagfish insulin partially obscure the A1 glycine residue, which in pig insulin is exposed. This structural difference has been shown, however, not to be responsible for the reduced activity of the hagfish insulin.     

Effects of pollen quantity and quality on reproduction and offspring vigor in the rare plant Scorzonera humilis (Asteraceae)

We studied the effects of pollinator exclusion, interparental distance, and supplementary hand pollination on reproduction and progeny vigor in Scorzonera humilis (Asteraceae), a rare plant of fragmented, nutrient-poor grasslands. Caged flowers produced no seeds and selfed flowers only very rarely, indicating that S. humilis is mainly self-incompatible. Seed production, seed mass, and seed germination following between-population crosses were consistently, but not significantly, higher than after within-population crosses. Seed set increased with local density of conspecifics, indicating that the reduced plant density in fragmented populations may reduce plant reproductive success. Seed set was pollen limited in all four populations studied. Supplementary hand-pollination strongly increased the survival of offspring, indicating that either pollinators transferred pollen from related individuals resulting in inbreeding depression in spite of the incompatibility system or that higher pollen loads increased pollen competition and the selectivity among gametes. In one of the populations, adding pollen from a different population strongly increased progeny fitness compared with both natural pollination and pollen supplementation from the same population. The results indicate that S. humilis is sensitive to inbreeding and that pollen limitation can reduce both the number and quality of offspring.     

Structure and biological activity of basement membrane proteins

Collagen type IV, laminin, heparan sulfate proteoglycans, nidogen (entactin) and BM-40 (osteonectin, SPARC) represent major structural proteins of basement membranes. They are well-characterized in their domain structures, amino acid sequences and potentials for molecular interactions. Such interactions include self-assembly processes and heterotypic binding between individual constituents, as well as binding of calcium (laminin, BM-40) and are likely to be used for basement membrane assembly. Laminin, collagen IV and nidogen also possess several cell-binding sites which interact with distinct cellular receptors. Some evidence exists that those interactions are involved in the control of cell behaviour. These observations have provided a more defined understanding of basement membrane function and the definition of new research goals in the future.     

Synthesis and biological activity of 3 beta-fluorovitamin D3: comparison of the biological activity of 3 beta-fluorovitamin D3 and 3-deoxyvitamin D3

The alteration in the biologic activity of the vitamin D3 molecule resulting from the replacement of a hydrogen atom with a fluorine atom is a subject of fundamental interest. To investigate this problem we synthesized 3 beta-fluorovitamin D3 6 and its hydrogen analog, 3-deoxyvitamin D3 7, and tested the biologic activity of each by in vitro and in vivo methods. Contrary to previous reports which showed that 3 beta-fluorovitamin D3 was as active as vitamin D3 in vivo, we found that the fluoro-analog was less active than vitamin D3. With regard to stimulation of intestinal calcium transport and bone calcium mobilization in the D-deficient hypocalcemic rat, 3 beta-fluorovitamin D3 showed significantly greater biologic activity than its hydrogen analog, 3-deoxyvitamin D3. In the organ-cultured, embryonic chick duodenum, 3 beta-fluorovitamin D3 was approx 1/1000th as active as the native hormone, 1,25-dihydroxyvitamin D3, while 3-deoxyvitamin D3 was inactive even at microM concentrations, in the induction of the vitamin D-dependent, calcium-binding protein. With regard to in vitro activity in displacing radiolabeled 25-hydroxyvitamin D3 from vitamin D binding protein and radiolabelled 1,25-dihydroxyvitamin D3 from a chick intestinal cytosol receptor, 3 beta-fluorovitamin D3 and 3 beta-deoxyvitamin D3 both showed very poor binding efficiencies when compared with vitamin D3. Our results show that the substitution of a fluorine atom for a hydrogen atom at the C-3 position of the vitamin D3 molecule results in a fluorovitamin 6 with significantly more biological activity than its hydrogen analog, 3-deoxyvitamin D3 7.     

Restoring Populations of the Endangered Plant Scorzonera humilis: Influence of Site Conditions,Seed Source,and Plant Stage

Changes in land‐use have resulted in the decline of many formerly common plants of nutrient‐poor grasslands in Europe. Recently, extensification schemes have been applied at sites in order to restore former habitat conditions. However, the establishment of rare and endangered plants is often severely limited by the lack of propagules both in the seed bank and in the surrounding landscape. For such species deliberate introductions may be necessary to overcome these limitations. In a 7‐year study, we assessed the importance of gaps created by sod cutting, of plant stage, and of plant origin for the restoration of populations of Scorzonera humilis, a threatened long‐lived plant of nutrient‐poor, wet grasslands. The effect of gaps on seedling emergence and survival varied strongly among the 12 sites. Gaps increased survival at nutrient‐rich, but reduced it at nutrient‐poor sites. Remarkably, young plants grown for only 5 weeks in the laboratory and transplanted into the same sites had much higher survival than seedlings from seeds sown and there were no differences in survival between nutrient‐rich and nutrient‐poor sites. The field performance of the plants from the various populations of origin varied depending on the site into which they were transplanted, indicating genotype by environment interactions and genetic differentiation among populations, but there was no home‐site advantage. While sowing only succeeded in producing adult plants in five sites, transplanting succeeded at 10 sites. Our results suggest that transplanting young plants could be a much more effective and faster way to establish new populations than sowing seeds.     

Synthesis and biological activity of vitamin D3-sulfate

Vitamin D3-3 beta-sulfate has been synthesized using pyridine sulfur trioxide as the sulfate donor. It has been shown to be pure by high performance liquid chromatography and spectral methods. Unlike previous reports, the product has been identified unambiguously as the 3 beta-sulfate ester of vitamin D3 by its ultraviolet, nuclear magnetic resonance, infrared, and mass spectra. The biological activity of vitamin D3-sulfate was then determined in vitamin D-deficient rats. Vitamin D3-sulfate has less than 5% of the activity of vitamin D3 to mobilize calcium from bone and approximately 1% of the ability of vitamin D3 to stimulate calcium transport, elevate serum phosphorus, or support bone calcification. These results disprove previous claims that vitamin D3-sulfate has potent biological activity, and they further do not support the contention that vitamin D-sulfate represents a potent water-soluble form of vitamin D in milk.     

Synthesis and biological activity of 1alpha-hydroxyvitamin D3

Hydroboration of cholesta-1,5-diene-3β-ol followed by alkaline-peroxide oxidation resulted in the formation of 1α- and 2α-hydroxy derivatives of cholesterol in nearly equal amounts. 1α-Hydroxycholesterol was then transformed to 1α-hydroxyvitamin D₃, via 1α-hydroxycholest-5,7-diene-3β-ol. 1α-Hydroxyvitamin D₃ was as active as 25-hydroxyvitamin D₃ in the stimulation of intestinal calcium transport and bone mineral mobilization in intact rats, and moreover was able to produce both response in anephric rats similar to 1α,25-dihydroxyvitamin D₃, the active metabolite of vitamin D₃, as reported originally by DeLuca's group.     

β-淀粉样肽前体蛋白的结构及生物活性

β－淀粉样肽前体蛋白是ＡＤ患者脑内神经炎斑的主要成分－－β－淀粉样肽的代谢前体。其基因定位于人第２１号染色体,经可变剪接可产生１０种转录物。β－淀粉样肽前体蛋折广泛表达于几乎所有的神经元和非神经元组织,具有一个较长的细胞外肽链、单一跨膜区及一个短的胞内区域。研究表明,它具有神经营养、调节细胞粘附及抑制丝氨酸蛋白酶等多种生物活性。现有资料还提示β－淀粉样肽前体蛋白可能是细胞因子（或其类似物）的受体。     

Structure and biological activity of the short-chain lipopolysaccharide from Bartonella henselae ATCC 49882T

The facultative intracellular pathogen Bartonella henselae is responsible for a broad range of clinical manifestations, including the formation of vascular tumors as a result of increased proliferation and survival of colonized endothelial cells. This remarkable interaction with endotoxin-sensitive endothelial cells and the apparent lack of septic shock are considered to be due to a reduced endotoxic activity of the B. henselae lipopolysaccharide. Here, we show that B. henselae ATCC 49882(T) produces a deep-rough-type lipopolysaccharide devoid of O-chain and report on its complete structure and Toll-like receptor-dependent biological activity. The major short-chain lipopolysaccharide was studied by chemical analyses, electrospray ionization, and matrix-assisted laser desorption/ionization mass spectrometry, as well as by NMR spectroscopy after alkaline deacylation. The carbohydrate portion of the lipopolysaccharide consists of a branched trisaccharide containing a glucose residue attached to position 5 of an alpha-(2-->4)-linked 3-deoxy-d-manno-oct-2-ulosonic acid disaccharide. Lipid A is a pentaacylated beta-(1'-->6)-linked 2,3-diamino-2,3-dideoxy-glucose disaccharide 1,4'-bisphosphate with two amide-linked residues each of 3-hydroxydodecanoic and 3-hydroxyhexadecanoic acids and one residue of either 25-hydroxyhexacosanoic or 27-hydroxyoctacosanoic acid that is O-linked to the acyl group at position 2'. The lipopolysaccharide studied activated Toll-like receptor 4 signaling only to a low extent (1,000-10,000-fold lower compared with that of Salmonella enterica sv. Friedenau) and did not activate Toll-like receptor 2. Some unusual structural features of the B. henselae lipopolysaccharide, including the presence of a long-chain fatty acid, which are shared by the lipopolysaccharides of other bacteria causing chronic intracellular infections (e.g. Legionella and Chlamydia), may provide the molecular basis for low endotoxic potency.     

Structure, biological activity, and enzymatic transformation of fucoidans from the brown seaweeds

Recent advances in the study of fucoidans, biologically active sulfated alpha-L-fucans of diverse structures and synthesized exclusively by marine organisms, are overviewed. Their structure, biological activity, the products of their enzymatic degradation and the different enzymes of degradation and modification are considered.