Structure and synthesis of malformin A1

The structure of malformin A₁, a metabolic product of Aspergillus niger, was reexamined and the sequence of its amino acid constituents established as

The cyclopentapeptide-disulfide corresponding to this structure was prepared through stepwise synthesis of the protected pentapeptide derivative, benzyloxy-carbonyl-l-isoleucyl-S-benzyl-d-cysteinyl-S-benzyl-d-cysteinyl-l-valyl-d-leucine methylester, which in turn was converted to the hydrazide, partially deprotected, and cyclized via the azide. On removal of the S-benzyl groups and oxidation to the disulfide, a synthetic material was obtained that was indistinguishable from natural malformin A₁ and was as equally potent in causing curvatures on corn roots.     

Influence of extracellular pH on the cytotoxicity, cellular accumulation, and DNA interaction of novel pH-sensitive 2-aminoalcoholatoplatinum(II) complexes

Extracellular acidity is a frequent pathophysiological condition of solid tumors offering possibilities for improving the tumor selectivity of molecular therapy. This might be accomplished by prodrugs with low systemic toxicity, attaining their full antitumor potency only under acidic conditions, such as bis(2-aminoalcoholato-κ²N,O)platinum(II) complexes that are activated by protonation of alcoholato oxygen, resulting in cleavage of platinum–oxygen bonds. In this work, we examined whether the pH dependency of such compounds is reflected in differential biological activity in vitro. In particular, the pH dependence of cytotoxicity, cellular accumulation, DNA platination, GMP binding, effects on DNA secondary structure, cell cycle alterations, and induction of apoptosis was investigated. Enhanced cytotoxicity of five of these complexes in non-small-cell lung cancer (A549) and colon carcinoma (HT-29) cells at pH 6.0 in comparison with pH 7.4 was confirmed: 50 % growth inhibition concentrations ranged from 42 to 214 μM in A549 cells and from 35 to 87 μM in HT-29 cells at pH 7.4 and decreased at pH 6.0 to 11–50 and 7.3–25 μM, respectively. The effects induced by all five pH-sensitive compounds involve increased 5′-GMP binding, cellular accumulation, and DNA platination as well as stronger effects on DNA secondary structure at pH 6.0 than at pH 7.4. As exemplified by treatment of A549 cells with a 2-amino-4-methyl-1-pentanolato complex, induction of apoptosis is enhanced at pH 6.5. These results confirm the increased reactivity and in vitro activity of these compounds under slightly acidic conditions, encouraging further evaluation of ring-closed aminoalcoholatoplatinum(II) derivatives in solid tumors in vivo.     

Hyaluronan bound mature sperm count (HB-MaSC) is a more informative indicator of fertility than conventional sperm parameters: Correlations with Body Mass Index (BMI)

The relationship between overweight and male fertility is well studied, still the correlation of obesity and decreased sperm quality is a subject to debate. The widely used conventional spermatological examinations alone seem to be inadequate to assess fertilization potential. Hyaluronan Binding Assay (HBA^®) is one of the available validated tests that allows the functional examination of sperm. Data of 72 male patients (mean age 33.9 (24–43) years) from infertile couples were analysed. Body Mass Index (BMI) determination, conventional semen analysis and HBA were performed. Additionally, a relatively new Hyaluronan Bound Matured Sperm Count (HB-MaSC) -index, first introduced by the authors in 2015, was calculated. This index reflects fertilization potential of sperm more precisely. With the increase of BMI, sperm count decreased significantly until about 25?kg/m², above 25?kg/m² no further decrease was observed, although sperm count remained permanently low. Greater body weight (in the 70–90?kg range) was observed to have a significant negative effect only on the progressive sperm motility. In addition to sperm concentration and motility, sperm fertilization potential is also negatively affected by obesity, but is irrespective of body weight, as evaluated using BMI + HB-MaSC linear regression analyses adjusted for age and weight. This correlation between male BMI and sperm fertilization potential – as opposed to the conventional correlations with sperm concentration or motility – appears to provide more helpful information in the identification of real capability for fertilization.     

Recruitment of histone modifications by USF proteins at a vertebrate barrier element

The chicken beta-globin 5'HS4 insulator element acts as a barrier to the encroachment of chromosomal silencing. Endogenous 5'HS4 sequences are highly enriched with histone acetylation and H3K4 methylation regardless of neighboring gene expression. We report here that 5'HS4 elements recruit these histone modifications when protecting a reporter transgene from chromosomal silencing. Deletion studies identified a single protein binding site within 5'HS4, footprint IV, that is necessary for the recruitment of histone modifications and for barrier activity. We have determined that USF proteins bind to footprint IV. USF1 is present in complexes with histone modifying enzymes in cell extracts, and these enzymes specifically interact with the endogenous 5'HS4 element. Knockdown of USF1 expression leads to a loss of histone modification recruitment and subsequent encroachment of H3K9 methylation. We propose that barrier activity requires the constitutive recruitment of H3K4 methylation and histone acetylation at multiple residues to counteract the propagation of condensed chromatin structures.     

De novo design,synthesis and evaluation of a non-steroidal diphenylnaphthyl propylene ligand for the estrogen receptor

There is still a strong need for additional diversity and new chemical scaffolds to allow for the exploration of improved tissue selectivity and finding better selective estrogen receptor modulators (SERMs). Using a de novo design technology a diphenylnaphthyl propylene scaffold, exemplified by (E)-9b, with ER antagonist activity has been generated. It was prepared by alkylating 1-[4-methoxyphenyl)-2-(4-(2-chloroethoxy)phenyl]-1-propanone under metal halogen exchange conditions with 1-iodo-6-methoxy-naphthalene. Following dehydration and cleavage of the methoxy groups, (E)-9b was formed by displacement of the chloro group with pyrrolidine. (E)-9b binding to ER generated calculated K(i) values of 3.7 nM for hER(alpha) and 72 nM for hER(beta). The antagonism of (E)-9b was demonstrated in cell transfection assays using the ERE from the vitA2 promotor and the natural ER-responsive pS2 promotor. With increasing concentrations of (E)-9b, the E(2)-dependent response was efficiently inhibited demonstrating that (E)-9b could function as an anti-estrogen in these assays. Interestingly, ER(alpha) activity was inhibited even below basal levels suggesting that ligand-independent activity of ER(alpha) was also inhibited. Computational docking studies suggest that the placement of the hydroxyl group on the naphthalene group may not be optimal and we are currently exploring additional analogues.     

Female sex pheromone of Cameraria ohridella Desch. and Dim. (Lepidoptera: Gracillariidae): structure confirmation,synthesis and biological activity of (8E,10Z)-8,10-tetradecadienal and some analogues

Mass spectrometric investigations confirmed the structure of the female produced sex pheromone of the horse-chestnut leafminer Cameraria ohridella Desch. and Dim. to be (8E,IOZ)-8,10-tetradecadienal. Pure samples, prepared in a straightforward synthesis, were highly attractive in field tests and proved to be suitable for monitoring of flight activities and population dynamics. In mixtures with the synthetic pheromone, analogues like 9-tridecynal and 7-dodecynyl formate were shown to reduce trap catches. In electroantennographic experiments, pheromone analogues were less active than the pheromone. 9-Tridecynal was the most EAG active analogue tested, followed by 7-dodecyn-1-yl formate and 7-undecyn-1-yl formate.     

On filtering false positive transmembrane protein predictions

While helical transmembrane (TM) region prediction tools achieve high (>90%) success rates for real integral membrane proteins, they produce a considerable number of false positive hits in sequences of known nontransmembrane queries. We propose a modification of the dense alignment surface (DAS) method that achieves a substantial decrease in the false positive error rate. Essentially, a sequence that includes possible transmembrane regions is compared in a second step with TM segments in a sequence library of documented transmembrane proteins. If the performance of the query sequence against the library of documented TM segment-containing sequences in this test is lower than an empirical threshold, it is classified as a non-transmembrane protein. The probability of false positive prediction for trusted TM region hits is expressed in terms of E-values. The modified DAS method, the DAS-TMfilter algorithm, has an unchanged high sensitivity for TM segments ( approximately 95% detected in a learning set of 128 documented transmembrane proteins). At the same time, the selectivity measured over a non-redundant set of 526 soluble proteins with known 3D structure is approximately 99%, mainly because a large number of falsely predicted single membrane-pass proteins are eliminated by the DAS-TMfilter algorithm.     

Brassinosteroid and systemin: two hormones perceived by the same receptor

Brassinosteroids, coordinating developmental events, and systemin, inducing systemic wound responses to attacks by insect pests, are newly recognized plant hormones that are perceived by plasma membrane-localized leucine-rich repeat receptor kinases. The recent characterization of the brassinosteroid receptor BRI1 from tomato revealed that this protein is identical to the previously isolated SR160 systemin receptor, strongly suggesting that both brassinosteroid and systemin signalling use the same surface receptor.     

Partial 7q Isochromosome in Bone Marrow Following Treatment of Hodgkin's Disease

We report on a 29-year-old female followed for relapsed Hodgkin's disease. She had been diagnosed with Hodgkin's disease at 20 years of age and had been treated with chemotherapy. She had been in remission for six years when she relapsed, at which time she received chemotherapy for bone marrow transplant (BMT). After failure of BMT, she received additional chemotherapies with growth factors and radiation treatment. A bone marrow biopsy showed moderate hypercellularity with erythroid hyperplasia, but the karyotype had an abnormal clone containing an isochromosome derived from a 7q22 deletion.