Selectively Increased Production of Acidic Actinomycin Congener,B-1625 FA2β, on Combined Use of Sarcosine and Ferrous Sulfate

In addition to actinomycins D, X₂ and X_0β, Streptomyces antibioticus No. B-1625 produces minor acidic actinomycin congeners (FA-components). To increase the production of the FA-components, improvement of medium constituents was attempted for both chemically defined and complex media. Addition of trace metals, especially FeSO₄, increased FA-components production and, moreover, the addition of sarcosine was found to increase the production of a selected component, B-1625 FA_2β. Finally, a complex medium, consisting of starch 3.0, Polypepton 0.1, meat extract 0.1, corn steep liquor 3.0, NaCl 0.3, CaCO₃ 0.3, sarcosine 0.1 and FeSO₄ · 7H₂O 0.05%, was developed for the increased production of FA-components, in particular, the selected component of B-1625 FA_2β.     

Production of Acidic Actinomycin Congeners by a Mutant Strain of Streptomyces antibioticus,No. B-1625

Streptomyces sp. No. B-1625, which was identified as a strain of Streptomyces antibioticus, is a typical producer of actinomycin, but also produces minor acidic antibiotic components (FA), besides actinomycins X₂, D and X_0β. The FA-components, which were obtained with a high-producing mutant, 11M-21, showed antibacterial and antitumor activities, and also similar visible and UV absorption spectra to those characteristic of actinomycin. The FA-components were separated into five components, FA₁ FA_2α, FA_2β, FA_3α and FA_3β, on TLC. Among them, one component, FA_3β, isolated in a purified state as an orange powder, has a composition of C, 52.97: H, 6.34: N, 10.48%, and is active against B. subtilis at a MIC of 5mcg/ml. The FA_3β component showed pK_a′ of 5.4 and 12.0 and λ_max at 443, 427 and 233 nm. From these properties, FA_3β is considered to be an acidic actinomycin congener.     

Antibacterial Activity of Enrofloxacin and Ciprofloxacin Derivatives of β‐Octaarginine

β³‐Octaarginine chains were attached to the functional groups NH and CO₂H of the antibacterial fluoroquinolones ciprofloxacin (→ 1 ) and enrofloxacin (→ 2 ), respectively, in order to find out whether the activity increases by attachment of the polycationic, cell‐penetrating peptide (CPP) moiety. For comparison, simple amides, 3 – 5 , of the two antimicrobial compounds and β³‐octaarginine amide ( βR₈ ) were included in the antibacterial susceptibility tests to clarify the impact of chemical modification on the microbiological activity of either scaffold (Table).     

Association of β-amyloid peptide fragments with neuronal nitric oxide synthase: Implications in the etiology of Alzheimers disease

Neuronal nitric oxide synthase (nNOS) was purified on DEAE-Sepharose anion-exchange in a 38% yield, with 3-fold recovery and specific activity of 5 µmol.min^?1.mg^?1. The enzyme was a heterogeneous dimer of molecular mass 225?kDa having a temperature and pH optima of 40°C and 6.5, K_m and V_max of 2.6 μM and 996 nmol.min^?1.ml^?1, respectively and was relatively stable at the optimum conditions (t_½?=?3?h). β-Amyloid peptide fragments Aβ_17–28 was the better inhibitor for nNOS (K_i?=?0.81 µM). After extended incubation of nNOS (96?h) with each of the peptide fragments, Congo Red, turbidity and thioflavin-T assays detected the presence of soluble and insoluble fibrils that had formed at a rate of 5?nM.min^?1. A hydrophobic fragment Aβ_17–21 [Leu₁₇ – Val₁₈ – Phe₁₉ – Phe₂₀ – Ala₂₁] and glycine zipper motifs within the peptide fragment Aβ_17–35 were critical in binding and in fibrillogenesis confirming that nNOS was amyloidogenic catalyst.     

Paenibacillus lentimorbus enhances growth of chickpea (Cicer arietinum L.) in chromium-amended soil

Chromium (Cr), with its great economic importance in industrial use, is a major metal pollutant of the environment. It affects soil microbial activity and soil fertility, resulting in losses in yield of plants. Paenibacillus lentimorbus B-30488^r (B-30488^r) tolerated 200 μg ml⁻¹ of Cr under in vitro conditions and produced the plant growth promoting substance indole acetic acid in the presence of Cr. Our in vitro study indicates enhancement in B-30488^r biofilm formation by sodium alginate (SA) and calcium chloride (CaCl₂) both in absence and presence of supplemented Cr(VI) as compared to unsupplemented control. The plant growth promoting effects caused by the B-30488^r biofilm in rhizosphere of chickpea under Cr(VI) stress suggests a phytoprotective role of B-30488^r biofilm. Our study reflects the multifarious role of strain B-30488^r and presents it as a potent plant growth promoting and bioremediation agent useful in Cr-contaminated rhizosphere soil, whereby the SA and CaCl₂ induced B-30488^r biofilm on plant root acts as a shield in preventing the direct access of toxic Cr to plant tissues, thus reducing its uptake in plants.     

New Thymoquinol Glycosides and Neuroprotective Dibenzocyclooctane Lignans from the Rattan Stems of Schisandra chinensis

Three new lignans ( 1 – 3 ), together with four new thymoquinol glycosides ( 4 – 7 ), were isolated from 70%‐EtOH extract of the rattan stems of Schisandra chinensis. The structures of 1 – 7 were elucidated by detailed spectroscopic analyses, and these new compounds were identified as pinobatol‐9‐O‐β‐d ‐glucopyranoside ( 1 ), 1,2,13,14‐tetramethoxydibenzocyclooctadiene 3,12‐O‐β‐d ‐diglucopyranoside ( 2 ), 3,7‐dihydroxy‐1,2,13,14‐tetramethoxydibenzocyclooctadiene 12‐O‐β‐d ‐glucopyranoside ( 3 ), thymoquinol 2‐O‐β‐d ‐apiofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 4 ), thymoquinol 2‐O‐α‐d ‐arabinofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 5 ), thymoquinol 5‐O‐β‐d ‐apiofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 6 ), and thymoquinol 5‐O‐α‐d ‐arabinofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 7 ). The neuroprotective activity of 1 – 7 was evaluated on PC12 cells with neurotoxicity induced by amyloid‐beta 1 – 42 (Aβ_{1 – 42}). Compounds 2 and 3 showed protecting activity against Aβ‐induced toxicity in PC12 cells.     

Production and properties of a dextransucrase from Leuconostoc mesenteroides IBT-PQ isolated from ‘pulque’, a traditional Aztec alcoholic beverage

Dextransucrase was produced from a Leuconostoc mesenteroides isolated from pulque, a traditional Aztec alcoholic beverage produced from agave juice containing sucrose as the main carbon source. Almost all the dextransucrase activity (87%) was associated with the cells, and was unusually high (1.04 U mg⁻¹ of cells). The culture medium composition was optimized through a Box-Behnken method resulting in a process yielding 2.2 U ml⁻¹ of insoluble glucosyltransferase activity. The enzyme had a molecular weight of 166 kDa. Optimal temperature was 35°C with a half-life of 137 min at the same temperature. As with dextransucrase from the industrial strain L. mesenteroides NRRL B-512F, the enzyme showed Michaelis–Menten kinetic behavior with excess substrate inhibition (K _m and K _i values of 0.026 M and 1.23 M respectively); produced soluble linear dextran with glucose molecules linked mainly in α(1–6) with branching in α(1–3) in a proportion of 4:1 as shown by NMR studies; and produced a high yield of isomalto-oligosaccharides in the presence of maltose. Received 4 February 1998/ Accepted in revised form 25 July 1998     

Production of high activity Aspergillus niger BCC4525 β-mannanase in Pichia pastoris and its application for mannooligosaccharides production from biomass hydrolysis

A cDNA encoding β-mannanase was cloned from Aspergillus niger BCC4525 and expressed in Pichia pastoris KM71. The secreted enzyme hydrolyzed locust bean gum substrate with very high activity (1625 U/mL) and a relatively high k_cat/K_m (461 mg^?1 s^?1 mL). The enzyme is thermophilic and thermostable with an optimal temperature of 70 °C and 40% retention of endo-β-1,4-mannanase activity after preincubation at 70 °C. In addition, the enzyme exhibited broad pH stability with an optimal pH of 5.5. The recombinant enzyme hydrolyzes low-cost biomass, including palm kernel meal (PKM) and copra meal, to produce mannooligosaccharides, which is used as prebiotics to promote the growth of beneficial microflora in animals. An in vitro digestibility test simulating the gastrointestinal tract system of broilers suggested that the recombinant β-mannanase could effectively liberate reducing sugars from PKM-containing diet. These characteristics render this enzyme suitable for utilization as a feed additive to improve animal performance.     

Design,Synthesis, and Evaluation of Chalcone Derivatives as Multifunctional Agents against Alzheimer's Disease

Fifteen chalcone derivatives 3a – 3o were synthesized, and evaluated as multifunctional agents against Alzheimer's disease. In vitro studies revealed that these compounds inhibited self-induced Aβ_1-42 aggregation effectively ranged from 45.9–94.5 % at 20 μM, and acted as potential antioxidants. Their structure-activity relationships were summarized. In particular, (2E)-3-[4-(dimethylamino)phenyl]-1-(pyridin-2-yl)prop-2-en-1-one ( 3g ) exhibited an excellent inhibitory activity of 94.5 % at 20 μM, and it could disassemble the self-induced Aβ_1-42 aggregation fibrils with ratio of 57.1 % at 20 μM concentration. In addition, compound 3g displayed good chelating ability for Cu²⁺, and could effectively inhibit and disaggregate Cu²⁺-induced Aβ aggregation. Moreover, compound 3g exerted low cytotoxicity, significantly reversed Aβ_1-42-induced SH-SY5Y cell damage. More importantly, compound 3g remarkably ameliorated scopolamine-induced memory impairment in mice. In summary, all the results revealed compound 3g was a potential multifunctional agent for AD therapy.     

Release of vitamin B-12 in vitro from intrinsic factor-vitamin B-12 complex Purification and characterization of a releasing factor from rat ileal brush border

Vitamin B-12 is released from the purified gastric intrinsic factor-[⁵⁷Co]vitamin B-12 (intrinsic factor- [⁵⁷Co]vitamin B-12) complex, when incubated with rat intestinal mucosa. Maximum specific activity for splitting the complex is localized in ileal brush border. Release of [⁵⁷Co]vitamin B-12 is not due to its mere exchange during incubation with endogenous non-radioactive vitamin B-12. The splitting process has specific requirement for Ca²⁺ and ATP and it is thermolabile, time- as well as temperature-dependent. It is also inactivated by the presence of p-chloromercuribenzoate. Further, the vitamin B-12-releasing factor has been isolated from solubilized brush border and is purified 70-fold by (NH₄)₂SO₄ precipitation, gel filtration and Con. A-Sepharose 4B affinity chromatography. In SDS-polyacrylamide gel electrophoresis, it is resolved into a single band of about 25 kDa, indicating its purity. The releasing factor exhibits maximum activity at pH 7.4; isoelectric focusing reveals only one major form with pI 7.52. With intrinsic factor-[⁵⁷Co]vitamin B-12-complex as the substrate, apparent K_m and V_max values obtained are 128.2·10⁻¹² M/1 and 117.6 pg·h⁻¹ 100 μg protein, respectively. Amino acid and carbohydrate analyses reveal the glycoprotein nature of the factor. Intrinsic factor-[⁵⁷Co]vitamin B-12 complex is not susceptible to unspecific proteolytic digestion/ Similarly, the releasing factor does not hydrolyse other proteins. Thus, the observed substrate-specificity of the releasing factor differentiates it from other known proteolytic enzymes of ileal brush borders.     

Chemical Constituents from Aerial Parts of Baccharis sphenophylla and Effects against Intracellular Forms of Trypanosoma cruzi

The hexane extract from aerial parts Baccharis sphenophylla Dusén ex Malme (Asteraceae) displayed activity against amastigote forms of Trypanossoma cruzi and was subjected to chromatographic steps to afford one unreported – 7α-hydroxy-ent-abieta-8(14),13(15)-dien-16,12β-olide ( 1 ) and three known diterpenes – ent-kaur-16-en-19-oic acid, ( 2 ), grandifloric acid ( 3 ), and 15β-tiglinoyloxy-ent-kaur-16-en-19-oic acid ( 4 ), two sesquiterpenes – spathulenol ( 5 ) and oplopanone ( 6 ) – as well as hexacosyl p-coumarate ( 7 ). Isolated compounds were characterized by NMR and ESI-HR-MS spectra and were evaluated in vitro for activity against amastigote forms of the parasite T. cruzi – the relevant clinical form in the chronic phase of Chagas disease. In addition, the activity of compounds 1 – 7 against NCTC cells was evaluated. Compounds 1 and 7 showed effectiveness with EC₅₀ values of 21.3 and 16.9 μM, respectively. Both compounds also exhibited reduced toxicity against NCTC cells (CC₅₀>200 μM) with SI values higher than 9.4 and 11.9. Obtained results suggest that the new ent-abietane diterpene 1 and alkyl coumarate 7 could be used as prototypes for the development of novel and selective semisynthetic derivatives against intracellular forms of T. cruzi.     

Antioxidant Activity of a New Xanthone Derivative from Aspidistra Letreae: In Vitro and In Silico Studies

A new xanthone derivative, aspidxanthone A ( 1 ), and three known compounds ((2S)-1-(β-D-galactopyranosyloxy)-3-(hexadecanoyloxy)propan-2-yl (9Z,12Z)-octadeca-9,12-dienoate ( 2 ), (25S)-spirostane-1β,3α,5β-triol ( 3 ), and asparenyldiol ( 4 )) were isolated from the whole of the endemic species Aspidistra letreae in Vietnam. Their structures were elucidated by means of extensive spectroscopic analyses and comparison with published data. In this study, we report the isolation and structure elucidation of a new compound aspidxanthone A, antioxidant activities of the extract and isolates 1 – 4 , and in silico molecular docking of aspidxanthone A. The ethyl acetate extract had good antioxidant activity with an IC₅₀ value of 26.3 μg mL⁻¹. Among the isolates, aspidxanthone A exhibited DPPH reduction activity with an IC₅₀ value of 11.2 μM, which is in the same range as that of the positive control, ascorbic acid. The mechanism of action of aspidxanthone A on the tyrosinase and xanthine oxidase proteins have been clarified by in silico studies.     

Plasma transforming growth factor β1 as a biomarker of psoriasis activity and treatment efficacy

Transforming growth factor-β₁ (TGFβ₁) is thought to be an inhibitor of the keratinocyte hyperproliferation associated with psoriasis. The aim of this study was to evaluate plasma TGFβ₁ and TGFβ₂ concentrations in psoriatic patients as possible indicators of treatment efficacy. TGFβ concentrations were measured in the plasma of 26 patients with psoriasis using an enzyme immunoassay and analysed with respect to the psoriasis area and severity index (PASI) before and after treatment with salicylic acid and/or sulphur followed by dithranol ointment. Baseline plasma concentrations of both TGFβ₁ and TGFβ₂ (20.3±2.2 ng ml^?1 and 0.14±0.02 ng ml^?1, respectively) did not differ significantly from control values (18.3±1.6 ng ml^?1 and 0.14±0.03 ng ml^?1, respectively). However, a significant positive correlation (r=0.69) between the baseline PASI and TGFβ₁, but not TGFβ₂, values was demonstrated. The pretreatment TGFβ₁ concentration in patients with a PASI ≥15 (26.6±3.2 ng ml^?1) was significantly higher than control values. There were no significant elevation of pretreatment TGFβ₁ concentrations in patients with a PASI<15, or with respect to TGFβ₂ in both groups. Treatment caused a significant decrease in TGFβ₁, but only in patients with a PASI≥15. Patients with baseline TGFβ₁ concentrations exceeding the mean of the control group had a PASI value that was significantly higher than that of patients with a TGFβ₁ concentration below the mean of the controls. These results confirmed an association between plasma TGFβ₁ concentration and psoriasis severity, and demonstrated its normalization during treatment. Measurement of TGFβ₁ in plasma should be considered as a possible biomarker of psoriasis activity during its management.     

The β1a Subunit of the Skeletal DHPR Binds to Skeletal RyR1 and Activates the Channel via Its 35-Residue C-Terminal Tail

Although it has been suggested that the C-terminal tail of the β_1a subunit of the skeletal dihyropyridine receptor (DHPR) may contribute to voltage-activated Ca²⁺ release in skeletal muscle by interacting with the skeletal ryanodine receptor (RyR1), a direct functional interaction between the two proteins has not been demonstrated previously. Such an interaction is reported here. A peptide with the sequence of the C-terminal 35 residues of β_1a bound to RyR1 in affinity chromatography. The full-length β_1a subunit and the C-terminal peptide increased [³H]ryanodine binding and RyR1 channel activity with an AC₅₀ of 450–600 pM under optimal conditions. The effect of the peptide was dependent on cytoplasmic Ca²⁺, ATP, and Mg²⁺ concentrations. There was no effect of the peptide when channel activity was very low as a result of Mg²⁺ inhibition or addition of 100 nM Ca²⁺ (without ATP). Maximum increases were seen with 1–10 μM Ca²⁺, in the absence of Mg²⁺ inhibition. A control peptide with the C-terminal 35 residues in a scrambled sequence did not bind to RyR1 or alter [³H]ryanodine binding or channel activity. This high-affinity in vitro functional interaction between the C-terminal 35 residues of the DHPR β_1a subunit and RyR1 may support an in vivo function of β_1a during voltage-activated Ca²⁺ release.     

Biosynthesis of (1→3),(1→4)-β-glucan in developing endosperms of barley (Hordeum vulgare)

A (1→3),(1→4)-β-glucan synthase catalysing the synthesis of (1→3),(1→4)-β-glucan (mixed-linkage glucan) was investigated using microsomal membranes prepared from developing barley (Hordeum vulgare L. cv. Shikokuhadaka 97) endosperms harvested 21 days after flowering. The microsomal fraction produced (1→3),(1→4)-β-glucan by incorporation of [¹⁴C]Glc from UDP-[¹⁴C]Glc. The production of (1→3),(1→4)-β-glucan was ascertained by specific enzymatic digestion with endo-(1→3),(1→4)-β-glucanase (lichenase; EC 3.2.1.73) from Bacillus amyloliquefaciens, which released a radiolabelled trisaccharide (3-O-β-cellobiosyl-glucose) and a tetrasaccharide (3-O-β-cellotriosyl-glucose), the diagnostic oligosaccharides for the identification of (1→3),(1→4)-β-glucan. Digestion of the products with exo-(1→3)-β-glucanase (EC 3.2.1.58) from Basidiomycete QM806 released radiolabelled Glc, indicating that not only (1→3),(1→4)-β-glucans but also (1→3)-β-glucans (callose) had been formed due to the presence of (1→3)-β-glucan (callose) synthase (EC 2.4.1.34) in the microsomal fraction. The activity of (1→3),(1→4)-β-glucan synthase was maximal at pH 9.0 and at 25°C and in the presence of at least 2 mM Mg²⁺. The apparent K_m and V_max values for UDP-Glc were 0.33 mM and 480 pmol min⁻¹ mg protein⁻¹, respectively. Investigating the dependence of enzyme activity on developmental stage (7–35 days after flowering) of the endosperms, we found an increase of activity during the initial development reaching a maximum at 19 days, followed by a gradual decrease as the endosperms matured. The amount of (1→3),(1→4)-β-glucan in the cell walls of the endosperms, however, increased gradually towards maturation, even after 19 days. Analysing the relationship between enzyme activity and (1→3),(1→4)-β-glucan deposition in cell walls of endosperms prepared from 12 different barley varieties harvested 11–22 days after flowering showed that some varieties had both low activity and low glucan content, and in some both were high. But for several other varieties, the availability of donor substrate and other factors seem to influence the production of (1→3),(1→4)-β-glucan as well.     

γ-Lactones from Persea americana and Persea fulva – in Vitro and in Silico Evaluation of Trypanosoma cruzi Activity

In the present study, five known γ-lactones (majoranolide B – 1 , majorenolide – 2 , majorynolide – 3 , lincomolide D – 4 , and isolinderanolide E – 5 ), as well as a new one (perseanolide – 6 ), were isolated from Persea fulva and P. americana. All isolated compounds exhibited potential activity against trypomastigote forms of Trypanosoma cruzi, whereas compounds 2 (EC₅₀ of 4.8 μM) and 6 (EC₅₀ of 3.6 μM) displayed superior activity than the positive control benznidazole (EC₅₀ of 16.4 μM), with selectivity index (SI) values of 17.8 and >55.6, respectively (benznidazole, SI>12.2). Molecular docking studies were performed for 1 – 6 against six T. cruzi molecular targets. Using this approach, we observed that, even though perseanolide ( 6 ) showed favorable docking to several studied targets, the results were especially promising for hypoxanthine phosphoribosyl transferase (PDB 1TC1). As PDB 1TC1 is associated to the transference of a monophosphorylated ribose from phosphoribosylpyrophosphate (PRPP) in the ribonucleotide synthesis pathway, this interaction may affect the survival of T. cruzi in mammalian cells. The data herein also indicate that possible intermolecular interactions between 6 and PDB 1TC1 derive from (i) hydrogen bonds in the α,β-unsaturated-γ-lactone unity and (ii) hydrophobic interactions in the long-chain alkyl group. Based on our results, perseanolide ( 6 ), reported for the first time in this work, can auspiciously contribute to future works regarding new trypanocidal agents.     

Disaccharide 1-phosphate polymers of some representatives of the Bacillus subtilis group

Disaccharide 1-phosphate polymers as well as teichoic acids of various structures have been found in the cell walls of the representatives of the Bacillus subtilis group, namely Bacillus subtilis subsp. spizizenii VKM B-720 and VKM B-916, B. subtilis VKM B-517, and Bacillus vallismortis VKM B-2653^T. Disaccharide 1-phosphate polymers are composed of repeating units of the following structure: -P-4)-β-D-GlcpNAc-(1→6)-α-D-Galp-(1-, the N-acetylglucosamine residues are partially acetylated at positions O3 and O6 (VKM B-720 and VKM B-916); -P-4)-β-D-Glcp-(1→6)-α-D-GlcpNAc-(1-, the glucopyranose residues are partially acetylated at positions O2 or O3 (VKM B-517); -P-6)-α-D-GlcpNH ₃ ⁺ /α-D-GlcpNAc-(1→2)-α-D-Glcp-(1-, the N-acetylglucosamine residues are partially deacetylated (VKM B-2653^T). The structures of the two last disaccharide 1-phosphate polymers have not been reported so far for Gram-positive bacteria. The teichoic acids in the studied strains are O-D-alanyl-1,5-poly(ribitol phosphates) substituted with β-D-glucopyranose (VKM B-517, VKM B-720, VKM B-916) or 2-acetamido-2-deoxy-β-D-glucopyranose (VKM B-2653^T). The structures of the phosphate-containing polymers have been studied by chemical methods and by NMR spectroscopy.     

Evidence for a Role of Protein Kinase C Substrate B-50 (GAP-43) in Ca2+-Induced Neuropeptide Cholecystokinin-8 Release from Permeated Synaptosomes

Abstract: To study the involvement of the protein kinase C (PKC) substrate B-50 [also known as growth-associated protein-43 (GAP-43), neuromodulin, and F1] in presynaptic cholecystokinin-8 (CCK-8) release, highly purified synaptosomes from rat cerebral cortex were permeated with the bacterial toxin streptolysin O (SL-O). CCK-8 release from permeated synaptosomes, determined quantitatively by radioimmunoassay, could be induced by Ca²⁺ in a concentration-dependent manner (EC₅₀ of ～10^-5M). Ca²⁺-induced CCK-8 release was maximal at 10⁴M Ca²⁺, amounting to ～10% of the initial 6,000 ± 550 fmol of CCK-8 content/mg of synaptosomal protein. Only 30% of the Ca^a+-induced CCK-8 release was dependent on the presence of exogenously added ATP. Two different monoclonal anti-B-50 antibodies were introduced into permeated synaptosomes to study their effect on Ca²⁺-induced CCK-8 release. The N-terminally directed antibodies (NM2), which inhibited PKC-mediated B-50 phosphorylation, inhibited Ca²⁺-induced CCK-8 release in a dose-dependent manner, whereas the C-terminally directed antibodies (NM6) affected neither B-50 phosphorylation nor CCK-8 release. The PKC inhibitors PKC_19–36 and 1 ?(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), which inhibited B-50 phosphorylation in permeated synaptosomes, had no effect on Ca²⁺-induced CCK-8 release. Our data strongly indicate that B-50 is involved in the mechanism of presynaptic CCK-8 release, at a step downstream of the Ca²⁺ trigger. As CCK-8 is stored in large densecored vesicles, we conclude that B-50 is an essential factor in the exocytosis from this type of neuropeptide-containing vesicle. The differential effects of the monoclonal antibodies indicate that this B-50 property is localized in the N-terminal region of the B-50 molecule, which contains the PKC phosphorylation site and calmodulin-binding domain.     

Synthesis and biological activities of new hydrazide derivatives

The synthesis of a new series of imidazo[1,2-a]pyrazine-2-carboxylic acid arylidene-hydrazides is described. The chemical structures of the compounds were elucidated by IR, ¹H-NMR, FAB⁺-MS spectral data. Their biological activity against various bacteria, fungi species, and Mycobacterium tuberculosis was investigated. Antibacterial activity was measured against Escherichia coli (NRRL B-3704), Staphylococcus aureus (NRRL B-767), Salmonella typhimurium (NRRL B-4420), Proteus vulgaris (NRLL B-123), Enterococcus faecalis (isolated obtained from Faculty of Medicine Osmangazi University, Eskisehir, Turkey), Pseudomonas aeruginosa (NRRL B-23 27853), Klebsiella spp. (isolated obtained from Faculty of Medicine Osmangazi University, Eskisehir, Turkey), while antifungal activity was evaluated against Candida albicans (isolates obtained from Osmangazi Uni. Fac.of Medicine), Candida glabrata (isolates obtained from Osmangazi Uni. Fac.of Medicine). Compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H₃₇Rv using the BACTEC 460 radiometric system and BACTEC 12B medium. The compounds showed moderate inhibitor effects against human pathogenic microorganisms., whereas the preliminary results indicated that all of the tested compounds were inactive against Mycobacterium tuberculosis H₃₇Rv.     

Mycotoxin Production by Fusarium proliferatum isolates from rice with Fusarium sheath rot disease

Twenty samples of unpolished (rough) rice collected in Arkansas and Texas during the 1995 harvesting season from fields exhibiting Fusarium sheath rot disease or panicle blight were previously shown to include 8 samples positive for fumonisin B₁(FB₁) in the range 2.2–5.2 ppm, and moniliformin (MON), but no beauvericin (BEA), deoxynivalenol, its derivatives or zearalenone were detected. Fifteen cultures of F. proliferatum were established from the 20 rough rice samples. Single spore isolates of each culture were grown on rice and tested for the production of fumonisins (FB₁, FB₂, FB₃, etc.), MON and BEA. All 15 isolates produced FB₁, FB₂, MON and BEA in culture on rice. No deoxynivalenol, its derivatives orzearalenone were detected. Seven cultures produced FB₁ at >50ppm (range 80–230 ppm), with therest producing FB₁ in the range 14–43 ppm.FB₂ was produced in the range 5–47 ppm, and those cultures which produced the most FB₁ also produced the most FB₂. Of the 15 cultures producing MON, 11 produced it at >100 ppm in the range 188–6018 ppm, with the rest producing in the range 7–64 ppm. BEA was produced in the range 109–1350 ppm. Other derivatives of fumonisins, including FA₁, FA₂ and partially hydrolyzed FB₁, as well asseveral unknown metabolites including a compound with MW 414, were identified in culture extracts by continuous flow fast atom bombardment with ion spraymass spectrometry (CF/FAB/MS). Further study is needed to identify the factors that control production of FB₁, MON and BEA by F.proliferatu in culture and in field samples. This revised version was published online in June 2006 with corrections to the Cover Date.