Peptides with 6-Aminohexanoic Acid: Synthesis and Evaluation as Plasmin Inhibitors

Fifteen new peptide derivatives of ?-aminocaproic acid (EACA) containing the known fragment –Ala–Phe–Lys– with an affinity for plasmin were synthesised in the present study. The synthesis was carried out a solid phase. The following compounds were synthesised: H–Phe–Lys–EACA–X, H–d-Ala–Phe–Lys–EACA–X, H–Ala–Phe–Lys–EACA–X, H–d-Ala–Phe–EACA–X and H–Ala–Phe–EACA–X, where X = OH, NH₂ and NH–(CH₂)₅–NH₂. All peptides, except for those containing the sequence H–Ala–Phe–EACA–X, displayed higher inhibitory activity against plasmin than EACA. The most active and selective inhibitor of plasmin was the compound H–d-Ala–Phe–Lys–EACA–NH₂ which inhibited the amidolytic activity of plasmin (IC₅₀ = 0.02 mM), with the antifibrinolytic activity weaker than EACA. The resulting peptides did not affect the viability of fibroblast cells, colon cancer cell line DLD-1, breast MCF-7 and MDA-MB-231 cell lines.     

Wing and leg amputation induced oviposition pattern of tropical tasar silk moth,Antheraea mylitta Drury (Lepidoptera: Saturniidae) in oviposition devices – Earthen cups and paper sheets

Antheraea mylitta Drury (Lepidoptera: Saturniidae) is a tropical semi-domesticated wild tasar silkworm reared by marginal tribal farmers of India. Due to improper egg laying frequency, oviposition is generally kept for three continuous days after amputating the gravid moth wings (W^–) in earthen cups (C). In order to systematize the oviposition frequency, wing cut with leg cut (W^–L^–) was performed in ecorace Daba trivoltine (DTV) completing three life-cycles in a year. Oviposition of (C)W^–L^– was observed in all three grainages during the year 2020 and compared with (C)W^– moths. Oviposition was also accomplished on plain paper sheets (S). It is observed that (C)W^– obtained 63–67% and (C)W^–L^– obtained 72–80% egg laying on first day. Similarly, (S)W^– and (S)W^–L^– obtained 68–71% and 74–83% on first day. Further, significant high oviposition was observed within first four hours in both earthen cups and on paper sheets by W^–L^– moths laying 49–69% and 55–65% eggs compared to W^– laying 25–45% and 39–44% eggs, respectively. A total of 44–51, 47–54, 44–48 and 46–52 eggs/g moth weight was obtained in (C)W^–, (C)W^–L^–, (S)W^– and (S)W^–L^–, respectively in three consecutive grainage. Oviposition of W^– moths in earthen cups and on paper sheets are not significantly different indicating earthen cups in contemporary tasar grainage could be replaced with paper sheets. Thus, the paper demonstrates for the first time a fast, efficient and scalable cellular oviposition of A. mylitta on paper sheets comparable to Bombyx mori.     

Molecular modeling and design of regioselectively addressable functionalized templates with rigidified three‐dimensional structures

Extensive conformational analysis of a series of β‐alkyl substituted cyclopeptides—cyclo(Pro¹–Xaa²–Nle³–Ala⁴–Nle⁵–Pro⁶–Xaa⁷–Nle⁸–Ala⁹–Nle¹⁰) and cyclo[Pro¹–Xaa²–Nle³–(Cys⁴– Nle⁵–Pro⁶–Xaa⁷–Nle⁸–Cys⁹)–Nle¹⁰] as well as their corresponding unsubstituted core structures cyclo(Pro¹–Xaa²–Ala³–Ala⁴–Ala⁵–Pro⁶–Xaa⁷–Ala⁸–Ala⁹–Ala¹⁰) and cyclo(Pro¹–Xaa²–Ala³–Cys⁴– Ala⁵–Pro⁶–Xaa⁷–Ala⁸–Cys⁹–Ala¹⁰) has been performed employing both the ECEPP/2 and the MAB force fields (Xaa = Gly, L ‐Ala, D ‐Ala, Aib, and D ‐Pro). Results show that (a) possible three‐dimensional structures of the cyclo(Pro¹–Gly²–Lys³–Ala⁴–Lys⁵–Pro⁶–Gly⁷–Lys⁸–Ala⁹–Lys¹⁰) molecule are not limited to a single extended “rectangular” conformation with all Lys side chains oriented at the same side of the molecule; (b) conformational equilibrium in monocyclic analogues obtained by replacements of conformationally flexible Gly residues for L ‐Ala, D ‐Ala, Aib, or D ‐Pro is not significantly shifted towards the target “rectangular” conformational type; and (c) introduction of disulfide bridges between positions 4 and 9 is a very powerful way to stabilize the target conformations in the resulting bicyclic molecules. These findings form the basis for further design of rigidified regioselectively addressable functionalized templates with many application areas ranging from biostructural to diagnostic purposes. © 1999 John Wiley & Sons, Inc. Biopoly 50: 361–372, 1999     

The effect of temperature and salt concentration on the circular dichroism exhibited by unionized derivatives of L-alanine in aqueous solution

The circular dichroism of Ac–Ala–NHMe, cyclo(–Ala–Ala–), Ac–Ala–OMe, Ac–Ala–Ala–OMe, and Ac–Ala–Ala–Ala–OMe has been measured in water and in aqueous salt solutions as a function of temperature. Only cyclo(–Ala–Ala–) exhibits circular dichroism which is independent of temperature. Each of the linear derivatives of L -alanine exhibits a positive circular dichroism in the range 208–218 nm at 15°C in water. Heating reduces the intensity of the positive circular dichroism, and only Ac–Ala–OMe retains positive circular dichroism at 75°C in water. Isothermal addition of salts produces changes in the circular dichroism of linear derivatives of L -alanine which resemble those seen on heating. The relative effectiveness of the salts tested, at a concentration of 4M, is LiCl ? KCl = NaCl < MgCl₂ ? CaCl₂ ? NaClO₄. The circular dichroism of cyclo(–Ala–Ala–) is also affected by the salts. Extrapolation of the results obtained with Ac–Ala–OMe, Ac–Ala–Ala–OMe, and Ac–Ala–Ala–Ala–OMe to a long polypeptide with a –CH₂R side chain in the L -configuration leads to the conclusion that this polypeptide should exhibit a temperature-dependent salt-sensitive positive circular dichroism between 208 and 218 nm when it exists as a statstical coil.     

Ascidiacyclamides containing oxazoline and thiazole motifs assume square conformations and show high cytotoxicity

Four cyclic octapeptides were designed from ascidiacyclamide [cyclo(–Ile–Oxz–D ‐Val– Thz–)₂] (ASC, 1 ) to investigate the effects of oxazoline (Oxz) and thiazole (Thz) rings on the structures and cytotoxicities of the peptides. cyclo(–Ile–Thz–D ‐Val–Oxz–)₂ ( 2 ) had the same number of Oxz and Thz rings as ASC, but the ring positions were switched. cyclo(–Ile–Oxz–D ‐Val–Thz–Ile–Thz–D ‐Val–Thz–) ( 3 ) and cyclo(–Ile–Thz–D ‐Val–Oxz–Ile–Thz–D ‐Val–Thz–) ( 4 ) contained one Oxz and three Thz rings within the molecule. All Oxz rings were substituted with Thz in cyclo(–Ile–Thz–D ‐Val–Thz–)₂ ( 5 ). These analogues had new Oxz and Thz blocks forming the 24‐membered ring. Based on CD spectra and X‐ray diffraction analyses, the structures of all four analogues were classified as square ASC forms. But the structures of 2 and 5 differed from the original square form of 1 , and they showed no cytotoxicity. The structure of 3 was very similar to that of 1 , and 3 showed 10 times greater cytotoxicity than 1 . Although no definite structure of 4 was obtained, it showed three times greater cytotoxicity than 1 . It appears that the position and number of Oxz residues are essential determinants in the structure‐cytotoxicity relationship of ASC analogues.     

Calculation of the Three-Dimensional Structures of Two Antigenic Sequences, Pro–Pro–Pro–Pro–Asn–Pro–Asn–Asp–Pro and Pro–Pro–Pro–Pro–Asn–Pro–Asn–Asp–Pro–Pro–Pro, of the Circumsporozoite Protein From a Malaria-Causing Plasmodium

Using the chain build-up procedure based on the program ECEPP, we have computed the lowest energy structures for two terminally blocked subsequences from the antigenic circumsporozoite protein of Plasmodium berghei, that is known to cause malaria in animals. The full antigenic sequence is an octapeptide proline-rich tandem repeat, (Pro–Pro–Pro–Pro–Asn–Pro–Asn–Asp)₂. We computed the structures for the first octapeptide plus one Pro from the second octapeptide, terminally blocked CH₃CO–Pro–Pro–Pro–Pro–Asn–Pro–Asn–Asp–Pro–NHCH₃ as well as the first octpeptide with an additional three Pro residues from the adjoining unit, i.e., CH₃CO–Pro–Pro–Pro–Pro–Asn–Pro–Asn–Asp–Pro–Pro–Pro–NHCH₃. We find that the first sequence adopts a number of different low energy structures, the most probable of which has a probability of occurrence of 56 %. Addition of two more Pro residues results in the adoption a single, unique lowest energy structure that has a probability of occurrence of over 95 % without solvation effects and 86 % when solvation effects are included in the calculations. We predict that this structure may be the one recognized as a major antigenic determinant.     

Epitope mapping of a monoclonal antibody directed against the α‐subunit of phosphofructokinase‐1 from Saccharomyces cerevisiae by screening phage display libraries

Phosphofructokinase‐1 from Saccharomyces cerevisiae is composed of two types of subunits, α and β. Subunit‐specific monoclonal antibodies were raised to elucidate structural and functional properties of both subunits. One monoclonal antibody, α‐F3, binds to an epitope either at the C‐terminal or at the N‐terminal part of the α‐polypeptide chain. By screening a heptapeptide library with this monoclonal antibody, a set of heptapeptides was selected, which contained the consensus sequences D–A–F and D–S–F. Two heptapeptides with these motifs were synthesized in order assess their capacity to inhibit the binding of antibody α‐F3 to native phosphofructokinase‐1. The peptide G–I–K–D–A–F–L inhibited the binding more strongly (IC₅₀ = 1.5 µM) than the peptide A–P–W–H–D–S–F (IC₅₀ = 33.3 µM). Sequence matching revealed the presence of the D–A–F motif in the polypeptide chain of phosphofructokinase‐1 at amino acid position 172–174. As a control, the nonapeptide A–P–T–S–K–D–A–F–L which corresponds to the sequence of the putative epitope was tested in the inhibition assay. In view of the high inhibitory capacity (IC₅₀ = 0.3 µM) it was concluded that this nonapeptide represents the continuous epitope of phosphofructokinase‐1 that is recognized by antibody α‐F3. Copyright © 1999 John Wiley & Sons, Ltd.     

Redox properties of iron–dithiocarbamates and their nitrosyl derivatives: implications for their use as traps of nitric oxide in biological systems

While the Fe²⁺–dithiocarbamate complexes have been commonly used as NO traps to estimate NO production in biological systems, these complexes can undergo complex redox chemistry. Characterization of this redox chemistry is of critical importance for the use of this method as a quantitative assay of NO generation. We observe that the commonly used Fe²⁺ complexes of N-methyl-D-glucamine dithiocarbamate (MGD) or diethyldithiocarbamate (DETC) are rapidly oxidized under aerobic conditions to form Fe³⁺ complexes. Following exposure to NO, diamagnetic NO–Fe³⁺ complexes are formed as demonstrated by the optical, electron paramagnetic resonance and gamma-resonance spectroscopy, chemiluminescence and electrochemical methods. Under anaerobic conditions the aqueous NO–Fe³⁺–MGD and lipid soluble NO–Fe²⁺–DETC complexes gradually self transform by reductive nitrosylation into paramagnetic NO–Fe²⁺–MGD complexes with yield of up to 50% and the balance is converted to Fe³⁺–MGD and nitrite. In dimethylsulfoxide this process is greatly accelerated. More efficient transformation of NO–Fe³⁺–MGD into NO–Fe²⁺–MGD (60–90% levels) was observed after addition of reducing equivalents such as ascorbate, hydroquinone or cysteine or with addition of excess Fe²⁺–MGD. With isotope labeling of the NO–Fe³⁺–MGD with ⁵⁷Fe, it was shown that these complexes donate NO to Fe²⁺–MGD. NO–Fe³⁺–MGD complexes were also formed by reversible oxidation of NO–Fe²⁺–MGD in air. The stability of NO–Fe³⁺–MGD and NO–Fe²⁺–MGD complexes increased with increasing the ratio of MGD to Fe. Thus, the iron–dithiocarbamate complexes and their NO derivatives exhibit complex redox chemistry that should be considered in their application for detection of NO in biological systems.     

Lipid Molecular Species of Lipomyces starkeyi

The molecular species of glycerides and phospholipids of the yeast Lipomyces starkeyi IFO 0678 harvested at 60 hr, corresponding to the late exponential phase, were analyzed by gas chromatography-mass spectrometry. The major triglyceride was C_16:0–C_18:1–C_18:1. The major molecular species of phospholipid were 1–C_16:0–2–C_18:1 and 1–C_18:1–2–C_18:2. Although phosphatidylcholine and phosphatidylethanol amine were composed of several kinds of molecular species, 1–C_16:1–2–C_18:1, 1–C_18:1–2–C_18:2 and l-C_16:0–2–C_18:1, phosphatidylserine was composed of almost exclusively 1–C_16:0-2-C_18:1. The lipid and the fatty acid compositions of the yeast harvested at the different growth phases were also investigated.     

Tree-ring based spring precipitation reconstruction in western Nepal Himalaya since AD 1840

Spring (March–June) precipitation has been reconstructed since AD 1840 for the Rara National Park (RNP), western Nepal Himalaya using Abies spectabilis tree-ring width. The reconstruction accounts for 35.8% of the total variance of the instrumental precipitation from 1958 to 2012 and captured distinct wet and dry variability. The longest wet periods occurred during 1850–1862, 1878–1886, 1909–1917, 1971–1984 and 2000–2008 while dry periods were usually shorter and occurred during 1873–1877, 1921–1923, 1925–1929, 1951–1956, 1958–1962 and 1994–1996. Spectral analysis of the reconstruction shows significant peaks at periodicity ranging 2.4–6.5 year, suggesting a covariation in inter-annual variability similar to that of El Niño-Southern Oscillation (ENSO). Spectral analysis of the reconstruction shows significant quasi–cyclic (2.4–3.4 year) and multidecadal (24.8–39.2 year) periodicity, suggesting a potential association with El Niño-Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO).     

ACE Inhibitory and Antioxidant Activities of Novel Peptides from <Emphasis Type="Italic">Scorpaena notata</Emphasis> By-product Protein Hydrolysate

This study describes the isolation of angiotensin I converting enzyme and antioxidative peptides from head protein hydrolysate of red scorpionfish (Scorpaena notata) prepared by treatment with a protease from the fungus Penicillium digitatum. After ultrafiltration, three peptides were isolated by a two-step procedure: size exclusion chromatography on a Toyopearl HW-40 followed by reversed-phase high performance liquid chromatography (RP-HPLC) with a high purification yield of 2.22 mg of peptide/g of initial protein. Active peptides were then identified by nanoscale liquid chromatography coupled to tandem mass spectrometry (nanoLC/MS–MS), corresponding to the following sequences: Gln–Gln–Pro–His–Ser–Arg–Ser–Lys–Gly–Phe–Pro–Gly–Pro (1424.724 Da), Gly–Gln–Lys–Ser–Val–Pro–Glu–Val–Arg (1000.565 Da) and Val–Glu–Gly–Lys–Ser–Pro–Asn–Val (830.448 Da). Peptides D-I, E-I and F-I showed high angiotensin-I converting enzyme inhibitory activity with an IC₅₀ values of 0.98, 1.69 and 1.44 µM, respectively as well as a synergistic antioxidant activity between the different fractions. Thus, we have demonstrated that underutilized wastes can be valorized by production of peptides that can be used as potential therapeutic compounds active against oxidative stress and hypertension.     

Structure-activity relationship of the neurotransmitter alpha-bag cell peptide on Aplysia LUQ neurons: Implications regarding its inactivation in the extracellular space

Alpha-bag cell peptide [α-BCP (Ala-Pro-Arg-Leu-Arg-Phe-Tyr-Ser-Leu)] is a neurotransmitter that mediates bag cell-induced inhibition of left-upper-quadrant (LUQ) neurons L₂, L₃, L₄, and L₆ in the abdominal ganglion of Aplysia. Our recent biochemical studies have shown that α-BCP[1–9] is cleaved into α-BCP[1–2], [3–9], [1–5], [6–9], and [7–9] by a combination of three distinct peptidase activities located within the extracellular spaces of the CNS: A diaminopeptidase-IV (DAP-IV)-like enzyme cleaves α-BCP[1–9] at the 2–3 peptide bond; a neutral metalloendopeptidase (NEP)-like enzyme cleaves either α-BCP[1–9] or α-BCP[3–9] at the 5–6 bond; an aminopeptidase M-II (APM-II)-like enzyme cleaves α-BCP[6–9] at the 6–7 bond, but cleaves neither α-BCP[1–9], nor the other ganglionic peptidase products. To further understand the manner in which α-BCP is inactivated after release, that is loses its electro-physiological activity, we studied its structure-activity relationship by recording intracellularly from LUQ neurons in isolated abdominal ganglia that were arterially perfused with peptides dissolved in artificial sea water. The effects of α-BCP[1–9] and 15 of its fragments ([1–8], [1–7], [1–6], [1–5], [2–9], [3–9], [3–8], [6–9], [7–9], [8–9], [6–7], [6–8], [1–2], Phe, Tyr) indicated that the sequence Phe⁶-Tyr⁷ was both necessary and sufficient to produce LUQ inhibitory activity. The combined results of our electrophysiological and biochemical studies strongly suggest that α-BCP[1–9] is inactivated by the serial actions of the NEP-like and APM-II-like peptidases; that is, the NEP-like enzyme yields an electro-physiologically active product, α-BCP[6–9], that is cleaved by the APM-II-like enzyme to yield inactive α-BCP[7–9]. Furthermore, because α-BCP[6–9] is more active than α-BCP[1–9], cleavage by the NEP-like enzyme potentiates α-BCP's activity. © 1992 John Wiley & Sons, Inc.     

N‐terminal diproline and charge group effects on the stabilization of helical conformation in alanine‐based short peptides: CD studies with water and methanol as solvent

Protein folding problem remains a formidable challenge as main chain, side chain and solvent interactions remain entangled and have been difficult to resolve. Alanine‐based short peptides are promising models to dissect protein folding initiation and propagation structurally as well as energetically. The effect of N‐terminal diproline and charged side chains is assessed on the stabilization of helical conformation in alanine‐based short peptides using circular dichroism (CD) with water and methanol as solvent. A1 (Ac–Pro–Pro–Ala–Lys–Ala–Lys–Ala–Lys–Ala–NH₂) is designed to assess the effect of N‐terminal homochiral diproline and lysine side chains to induce helical conformation. A2 (Ac–Pro–Pro–Glu–Glu–Ala–Ala–Lys–Lys–Ala–NH₂) and A3 (Ac–d Pro–Pro–Glu–Glu–Ala–Ala–Lys–Lys–Ala–NH₂) with N‐terminal homochiral and heterochiral diproline, respectively, are designed to assess the effect of Glu...Lys (i , i  + 4) salt bridge interactions on the stabilization of helical conformation. The CD spectra of A1 , A2 and A3 in water manifest different amplitudes of the observed polyproline II (PPII) signals, which indicate different conformational distributions of the polypeptide structure. The strong effect of solvent substitution from water to methanol is observed for the peptides, and CD spectra in methanol evidence A2 and A3 as helical folds. Temperature‐dependent CD spectra of A1 and A2 in water depict an isodichroic point reflecting coexistence of two conformations, PPII and β‐strand conformation, which is consistent with the previous studies. The results illuminate the effect of N‐terminal diproline and charged side chains in dictating the preferences for extended‐β, semi‐extended PPII and helical conformation in alanine‐based short peptides. The results of the present study will enhance our understanding on stabilization of helical conformation in short peptides and hence aid in the design of novel peptides with helical structures. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

Purification and Characterization of a Co(II)-Sensitive α-Mannosidase from Ginkgo biloba Seeds

An α-mannosidase was purified from developing Ginkgo biloba seeds to apparently homogeneity. The molecular weight of the purified α-mannosidase was estimated to be 120 kDa by SDS–PAGE in the presence of 2-mercaptoethanol, and 340 kDa by gel filtration, indicating that Ginkgo α-mannosidase may function in oligomeric structures in the plant cell. The N-terminal amino acid sequence of the purified enzyme was Ala–Phe–Met–Lys–Tyr–X–Thr–Thr–Gly–Gly–Pro–Val–Ala–Gly–Lys–Ile–Asn–Val–His–Leu–. The α-mannosidase activity for Man₅GlcNAc₁ was enhanced by the addition of Co²⁺, but the addition of Zn²⁺, Ca²⁺, or EDTA did not show any significant effect. In the presence of cobalt ions, the hydrolysis rate for pyridylaminated Man₆GlcNAc₁ was significantly faster than that for pyridylaminated Man₆GlcNAc₂, suggesting the possibility that this enzyme is involved in the degradation of free N-glycans occurring in developing plant cells (Kimura, Y., and Matsuo, S., J. Biochem., 127, 1013–1019 (2000)). To our knowledge, this is the first report showing that plant cells contain an α-mannosidase, which is activated by Co²⁺ and prefers the oligomannose type free N-glycans bearing only one GlcNAc residue as substrate.     

Phytoremediation Potential of Weeds in Heavy Metal Contaminated Soils of the Bassa Industrial Zone of Douala,Cameroon

Phytoremediation is a promising option for reclaiming soils contaminated with toxic metals, using plants with high potentials for extraction, stabilization and hyperaccumulation. This study was conducted in Cameroon, at the Bassa Industrial Zone of Douala in 2011, to assess the total content of 19 heavy metals and 5 other elements in soils and phytoremediation potential of 12 weeds. Partial extraction was carried out in soil, plant root and shoot samples. Phytoremediation potential was evaluated in terms of the Biological Concentration Factor, Translocation Factor and Biological Accumulation Coefficient. The detectable content of the heavy metals in soils was Cu:70–179, Pb:8–130, Zn:200–971, Ni:74–296, Co:31–90, Mn:1983–4139, V:165–383, Cr:42–1054, Ba:26–239, Sc:21–56, Al:6.11–9.84, Th:7–22, Sr:30–190, La:52–115, Zr:111–341, Y:10–49, Nb:90–172 in mg kg^?1, and Ti:2.73–4.09 and Fe:12–16.24 in wt%. The contamination index revealed that the soils were slightly to heavily contaminated while the geoaccumulation index showed that the soils ranged from unpolluted to highly polluted. The concentration of heavy metals was ranked as Zn > Ni > Cu > V > Mn > Sc > Co > Pb and Cr in the roots and Mn > Zn > Ni > Cu > Sc > Co > V > Pb > Cr > Fe in the shoots. Dissotis rotundifolia and Kyllinga erecta had phytoextraction potentials for Pb and Paspalum orbiculare for Fe. Eleusine indica and K. erecta had phytostabilisation potential for soils contaminated with Cu and Pb, respectively.     

Life Cycle of Isospora canis Nemeséri, 1959 in the Dog*

The life cycle of I. canis Nemeséri, 1959 was studied in experimentally infected dogs. Freshly sporulated oocysts were ovoid and 34–40 × 28–32 μm. The endogenous stages were found directly beneath the epithelium of the distal portion of the small intestinal villi. Most of the endogenous stages were in the lower 1/3 of the small intestine, but occasionally they were found in other portions of the small intestine. Three asexual generations were present. First-generation schizonts were 16–38 × 11–23 μm and contained 4–24 merozoites; mature 1st-generation merozoites were 8–11 × 3–5 μm. First-generation schizogony lasted up to 7 days after inoculation. Second-generation schizonts were 12–18 × 8–13 μm and contained up to 12 merozoites which were 11–13 × 3–5 μm. Second-generation schizogony was present on postinoculation days 6 and 7. Third-generation schizonts were formed by nuclear division of 2nd-generation merozoites. Most 2nd-generation merozoites underwent nuclear division without leaving the parasitophorous vacuole of the 2nd-generation schizont. Mature 3rd-generation schizonts were 13–38 × 8–24 μm and contained 6–72 merozoites. Third-generation merozoites were 8–13 × 1–3 μm. Third-generation schizogony was present on days 6–8 after inoculation. Mature macrogametes were 22–29 × 14–23 μm. Mature microgametocytes were 20–38 × 14–26 μm. Gametes were present on postinoculation days 7–10. Oocysts were present in tissue sections on postinoculation days 8–10 and 12. The prepatent period was 9–11 days.     

Variations in essential and non-essential element composition and yield of silage corn fertilized with sulfur

Abstract

The effect of sulfur fertilization on the silage yield and essential and non-essential element composition of silage corn was investigated at the Experimental Field of Research and Experiment Station of the Ankara University during the years 2002 and 2003. The experimental design was a randomized complete block with five replications. Sulfur was applied at 1000 (S₁) and 1500 (S₂) kg ha^?1 as gypsum. Element concentration of the plants was measured by polarized energy dispersive X-ray fluorescence (PEDXRF). Sulfur fertilization increased S concentrations and improved silage corn yield for both years. Applied S reduced P and Mo concentrations, increased Fe and Mn concentrations, and had no significant effect on the K, Ca, Mg, Zn and Cl concentrations of silage corn. Non-essential element composition of silage corn was also influenced by S fertilization. Applied S significantly increased Sr and Pb, reduced Si, Ba and U, while had no effect on Na, Ti, Ni, Br and Rb concentrations of silage corn. In the current work, essential and non-essential element concentrations of silage corn in 2002 and 2003 years under our experimental conditions were as follows; 1.58–1.89 S, 1.07–1.046 P, 14.3–15.9 K, 8.35–9.20 Ca, 3.34–4.28 Mg, 0.26–0.53 Na, 1.36–2.46 Cl, 38.4–42.1 Si as g kg^?1, and 2.06–3.13 Mo, 140–144 Fe, 6.08–17.69 Zn, 104–116 Mn, 9.37–12.2 Cu, 23.9–22.6 Ti, 2.10–2.31 Ni, 6.54–6.71 Br, 7.04–8.74 Rb, 94.8–118.8 Sr, 24.0–31.51 Ba, 1.20–2.22 Pb and 3.17–4.07 U as mg kg^?1.     

Cytotoxic withanolides from the aerial parts of Tubocapsicum anomalum

Ten new withanolides (1–10) and three artificial withanolides (11–13) were isolated from the aerial parts of Tubocapsicum anomalum, together with five known analogues (14–18). Their structures were determined on the basis of extensive spectroscopic and chemical methods. They include seven acnistin–type (1–4, 11, 14 and 15), three withajardin–type (5–7), and eight normal–type (8–10, 12, 13 and 16–18) withanolides. Of normal–type withanolides, a chemical conversion from the 16α,17α–epoxywithanolide (16) to Δ^13,14–16α–hydroxywithanolide (18) was achieved by Wagner–Meerwein rearrangement. All isolates were evaluated for their cytotoxicity against four human tumor cell lines (HCT–116, HepG2, MCF–7 and A375). Among them, compounds 1–3, 6–8, 14, 16–18 showed cytotoxic activity with IC₅₀ values of 0.24–8.71 μM.