Structure-activity relationship of brassinosteroids

The plant growth-promoting activities of brassinolide and brassinosteroids with different side chains were investigated by means of the Raphanus an     

Historical background and clinical treatment of dialysis-related amyloidosis

Dialysis-related amyloidosis (DRA) is a frequent and serious complication in patients on long-term dialysis. The amyloid has a marked affinity for joint tissues, and carpal tunnel syndrome, polyarthralgia, destructive spondyloarthropathy, and bone cysts are the major clinical manifestations of DRA. beta(2)-Microglobulin (beta(2)-m) was identified as the major protein constituent of the amyloid fibrils. Risk factors for the development of DRA include age, duration of dialysis treatment, use of low-flux dialysis membrane, use of low purity dialysate, monocyte chemoattractant protein-1 GG genotype, and apolipoprotein E4 allele, although the retention of beta(2)-m in the plasma appears to be prerequisite. Clinical therapeutic strategies for DRA include dialysis, medical or surgical therapy, and renal transplantation. Preventive measures have attempted to remove beta(2)-m from the serum by using high-flux membranes and a beta(2)-m adsorption column in hemodialysis. Renal transplantation is a radical approach to treating the arthralgias attributed to the amyloid deposits while the regression of dialysi-related amyloid deposits is not identified after successful renal transplantation in many studies. It is necessary to elucidate the pathogenesis of DRA and to establish more effective prevention and therapy in the future.     

Structure-activity relationships of alkaloids from mesquite (<Emphasis Type="Italic">Prosopis juliflora</Emphasis> (Sw.) DC.)

The structure–activity relationships of alkaloids (1–5) from mesquite were subjected to assessment of growth inhibition against the shoot and root growth of monocotyledonous plants, barnyard grass, rice and timothy, and dicotyledonous ones, amaranth, lettuce and cress. All alkaloids tested generally showed growth inhibitory against both monocotyledonous and dicotyledonous plants. Furthermore, these alkaloids exhibited higher activity against the growth of root than that of shoot of all plant species used, except that juliprosopine (5) showed higher activity against the shoot growth than the root growth of rice seedling. Among these alkaloids, the highest active compound appeared to be juliprosine (4), followed by a (1:1) mixture of 3-oxo- and 3-oxo-juliprosine (3a and 3b), and juliprosopine (5). The activity of juliprosine (4) containing 2-methyl piperidine bearing hydroxyl groups at C-3 and C-3 was higher than that of 3-oxo- and 3-oxo-juliprosine (3a and 3b) containing 3-oxo- and 3-oxo-2-methylpiperidine. Compound 3 and 4 containing dihydroindolizinium ring showed higher activity than compound 5 containing tetrahydroindolizine ring, whereas compound 1 containing tetrahydroindolizinone ring showed weaker activity. The activity of secojuliprosopinal (2) without indolizine ring was very weak. It was thus clarified that the active sites in the chemical structure of alkaloids from mesquite are the functional group at C-3 and C-3 of piperidine and indolizine skeleton.     

Molecular characterization of maize acetylcholinesterase: a novel enzyme family in the plant kingdom

Acetylcholinesterase (AChE) has been increasingly recognized in plants by indirect evidence of its activity. Here, we report purification and cloning of AChE from maize (Zea mays), thus providing to our knowledge the first direct evidence of the AChE molecule in plants. AChE was identified as a mixture of disulfide- and noncovalently linked 88-kD homodimers consisting of 42- to 44-kD polypeptides. The AChE hydrolyzed acetylthiocholine and propyonylthiocholine, but not S-butyrylthiocholine, and the AChE-specific inhibitor neostigmine bromide competitively inhibited its activity, implying that maize AChE functions in a similar manner as the animal enzyme. However, kinetic analyses indicated that maize AChE showed a lower affinity to substrates and inhibitors than animal AChE. The full-length cDNA of maize AChE gene is 1,471 nucleotides, which encode a protein having 394 residues, including a signal peptide. The deduced amino acid sequence exhibited no apparent similarity with that of the animal enzyme, although the catalytic triad was the same as in the animal AChE. In silico screening indicated that maize AChE homologs are widely distributed in plants but not in animals. These findings lead us to propose that the AChE family, as found here, comprises a novel family of the enzymes that is specifically distributed in the plant kingdom.     

Elevation of anα(1,3) fucosyltransferase activity correlated with apoptosis in the human colon adenocarcinoma cell line,HT-29

We studied changes in the carbohydrate expression following apoptotic cell death induced by treatment with interferon (IFN)- and anti-Fas antibody using human colon adenocarcinoma HT-29 cells. An apoptotic cell death of HT-29 accompanied with typical DNA fragmentation was observed when the cells were cultured sequentially with IFN- and anti-Fas antibody. In flow cytometric analyses, the expression of Le^x and Le^y antigen was strongly and slightly enhanced, respectively, on the cell surface in accordance with the apoptosis. When the fucosyltransferase (Fuc-T) activities of the lysates from the treated cells were examined relative to those from untreated cells, a 2.5-fold increase of (1,3)-Fuc-T activities and a slight increase of (1,2)-Fuc-T activities were observed, but little or no increase of (1,4)-Fuc-T activity was detected. In Northern blot analyses using probes for Fuc-T III, IV, V, VI and VII genes, strong RNA messages for Fuc-T III, V and/or VI and a weak RNA message for Fuc-T IV were detected in the untreated HT-29 cells. On the other hand, in the treated cells, the messages for Fuc-T III, V and/or VI were found to almost disappear and the 2.3 kb message for Fuc-T IV was observed to elevate 2.8-fold. Therefore, we suggest that the strongly increased expression of Le^x antigen found on the HT-29 cell surface might be involved in the process of apoptosis, and that the enhancement of the antigen expression seems to result from the increased activity of (1,3)-Fuc-T encoded mainly by the Fuc-T IV gene.Abbreviations Bn Benzyl - EDTA ethylenediaminetetraacetic acid (sodium salt) - SDS sodium dodecyl sulfate - D-PBS Dulbecco's phosphate buffered saline (metal free) - FITC fluorescein isothiocyanate - AIDS acquired immune deficiency syndrome - FACS fluorescence-activated cell sorter - IFN interferon - dNTP deoxynucleosides-triphosphate - PCR polymerase chain reaction - kb kilobase(s) - bp base pair(s)     

Synthesis and biological activity of brassinolide analogues, 26,27-bisnorbrassinolide and its 6-oxo analogue

Two hitherto unknown brassinolide analogues, (22R,23R)-2α,3α,22,23-tetrahydroxy-B-homo-7-oxa-24-nor-5α-cholestan-6-one (9b) and (22R,23R)-2α,3α,22,23-tetrahydroxy-24-nor-5α-cholestan-6-one (8a), were stereoselectively synthesized. In both the Raphanus and rice-lamina inclination tests, 9b exhibited almost the same activity as brassinolide (1) and 8a also showed ca 10–50% of the activity of 1.