bluuebunny/crossref_metadata_2025 huggingface dataset:
Dramatic decrease of the cis content and molecular weight of cis‐transoidal polyphenylacetylene at 23 °C in solutions prepared in air
Authors: Percec Virgil , Rudick Jonathan G. , Nombel Paul , Buchowicz Wlodzimierz
Published: August 2002

The thermal cis–trans isomerization of cis‐transoidal polyphenylacetylene (PPA) synthesized with Noyori's catalyst [Rh(CCPh)(norbornadiene)(PPh3)2] has been investigated under both ambient and inert atmospheres in solution and in bulk. In all cases, an intramolecular cyclization results in cis–trans isomerization, and subsequent chain cleavage produces 1,3,5‐triphenylbenzene. This reaction is accelerated by the presence of air, particularly when the reaction takes place in solution. Decreases in the cis content and molecular weight show that the intramolecular cyclization process takes place at 23 °C in solution. The mechanism of this reaction is identical to that reported previously for cis‐cisoidal and cis‐transoidal PPA synthesized with Ziegler–Natta catalysts. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3212–3220, 2002
Copolymerization of ethene and propene in the presence of Cs symmetric group 4 metallocenes and methylaluminoxane
Authors: Longo Pasquale , Siani Ermelinda , Pragliola Stefania , Monaco Guglielmo
Published: August 2002

Ethene–propene copolymerizations were performed in the presence of Cs symmetric group 4 metallocenes. The reactivity ratios were strongly influenced by both the transition metal and the ancillary ligands. Substantially alternate, almost random, and blocky copolymers were obtained with titanocene, zirconocene, and hafnocene, respectively, with the bis(dimethylsilyl)‐1,1′‐2,2′‐diyl‐(3′,5′‐diisopropyl)(4‐isopropyl)‐(cyclopentadienyl) ligand, and a blocky copolymer was obtained with (diphenyl methylidene)(cyclopentadienyl)(9‐fluorenyl)TiCl2. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3249–3255, 2002
Structural analysis of polyethene prepared with rac‐dimethylsilylbis(indenyl)zirconium dichloride/methylaluminoxane in a high‐temperature, continuously stirred tank reactor
Authors: Kokko Esa , Wang Wen‐Jun , Seppälä Jukka V. , Zhu Shiping
Published: August 2002

A study of ethene solution polymerization with the rac‐dimethylsilylbis(indenyl)‐zirconium dichloride/methylaluminoxane catalyst system in a high‐temperature (140 °C), continuously stirred tank reactor system was carried out. 13C NMR, gel permeation chromatography, Fourier transform infrared, and rheological measurements were used for polymer analyses. Polyethylenes with low molecular weights (weight‐average molecular weight ≈ 35–55 kg/mol) and small amounts of methyl, ethyl, and long‐chain branching were produced. 13C NMR measurements showed that the long‐chain and methyl branches increased and that the ethyl branch contents decreased with decreasing monomer concentrations. At high monomer concentrations, the chain transfer to the coordinated monomer was concluded to be the predominant chain termination mechanism, whereas the chain transfer to aluminum was dominant at low monomer concentrations, which was evidenced by the fact that the selectivity of end groups was reduced to about 50%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3292–3301, 2002
Phytophthora infestans: populations, pathogenicity and phenylamides
Authors: Shattock Richard C
Published: August 2002

Isolates of Phytophthora infestans (Mont) de Bary (the potato and tomato late blight pathogen) resistant to phenylamides appeared in Europe and North America in the late 1970s and early 1990s respectively. Concurrent, but coincidentally, with both these events there were radical structural shifts in the pathogen populations as immigrant genotypes from Mexico displaced the indigenous populations. Both A1 and A2 mating type isolates are now present in blighted crops, permitting alternative inoculum via germinating sexually produced oospores to influence dynamics of late blight populations. Studies of inheritance of ploidy, host‐specific pathogenicity, mating type and resistance to antibiotics and phenylamide fungicides have provided insight into mechanisms of variation in this potent pathogen.

© 2002 Society of Chemical Industry
EU regulatory aspects of resistance risk assessment
Authors: Heimbach Udo , Kral Gregor , Niemann Peter
Published: August 2002

The EPPO Standard PP 1/213(1) on resistance risk analysis is the basis for risk assessment within the authorisation process in Germany. Data for resistance risk analysis have to be provided by the applicant and risk‐mitigation strategies prepared if necessary. The extent of data requirements and the intensity of the evaluation process depend mainly on the type of target organism, crop, mode of action of the active substance and the resistance history of the organism in combination with products of similar mode of action as the one being applied for. Because resistance risk is a very complicated issue during the authorisation of plant‐protection products, intensive co‐operation between applicants and regulators is essential prior to submission of the dossier, with due consideration of the amount of data necessary and, where required, the proposed resistance‐management strategy.

© 2002 Society of Chemical Industry
A non‐Mendelian inheritance of resistance to strobilurin fungicides in Ustilago maydis
Authors: Ziogas Basil N , Markoglou Anastasios N , Tzima Aliki
Published: August 2002

Mutants of Ustilago maydis (DC) Corda with high resistance to azoxystrobin (RF 164 to 4714, based on EC50 values), an inhibitor of mitochondrial electron transport at the cytochrome bc1 complex, were isolated in a mutation frequency of 2.3 × 10−7 after nitrosoguanidine mutagenesis and selection on media containing 1 µg ml−1 azoxystrobin in addition to 0.5 mM salicylhydroxamate (SHAM), a specific inhibitor of cyanide‐resistant (alternative) respiration. Oxygen uptake in whole cells was strongly inhibited in the wild‐type strains by azoxystrobin (1.5 µg ml−1) in addition to SHAM (1 mM), but not in the mutant isolates. Genetic analysis with nine such mutant isolates resulted in progeny phenotypes which did not follow Mendelian segregation, but satisfied the criteria of non‐Mendelian (cytoplasmic) heredity. In crosses between three mutant isolates with the compatible wild‐type strains, the sensitivity was inherited by progeny maternally from the wild‐type parent strain (criterion of uniparental inheritance). In crosses between wild‐type strains and remaining mutant isolates, a continuous distribution of sensitivity in the progeny was found (criterion of vegetative segregation). The third criterion of cytoplasmic resistance (criterion of intracellular selection) was fulfilled by experiments on the stability of resistance phenotypes. With two exceptions, a reduction of resistance was observed in the mutant strains when they were grown on inhibitor‐free medium. Recovery of the high resistance level was observed after they were returned to the selection medium. Cross‐resistance studies with other fungicides, which also inhibit electron transport through complex III of respiratory chain, showed that mutations for resistance to azoxystrobin were also responsible for reduced sensitivity to kresoxim‐methyl (RF 18 to 1199) and to antimycin‐A (RF 20 to 305), which act at the Qo and Qi sites of the cytochrome bc1 complex, respectively. Studies of the fitness of azoxystrobin‐resistant isolates showed that these mutations appeared to be pleiotropic, having significant adverse effects on growth in liquid culture and pathogenicity on young corn plants.

© 2002 Society of Chemical Industry
Amplified esterase genes and their relationship with other insecticide resistance mechanisms in English field populations of the aphid, Myzus persicae (Sulzer)
Authors: Field Linda M , Foster Stephen P
Published: August 2002

Myzus persicae samples were collected from populations present on a range of field crops between 1997 and 2000. A combination of biochemical, DNA‐based diagnostics and bioassays was used to assess the presence of three insecticide resistance mechanisms: elevated carboxylesterase (E4 or FE4), insensitive acetylcholinesterase and insensitive sodium channels (knockdown resistance, kdr). For the carboxylesterases, both the levels of enzyme and the type of gene present (E4 or FE4) were determined. The results showed that during the time period studied there was a dramatic reduction in the proportion of aphids with very high levels of E4 and an increase in those with lower levels of FE4. There was also a slightly different E4 gene present in a limited number of samples. The change in esterase genes was accompanied by a virtual loss of the insensitive AChE variant and a maintenance of aphids with kdr. The selection pressures and other factors leading to these changes in field populations of M persicae are discussed.

© 2002 Society of Chemical Industry
Temporal and spatial dynamics of insecticide resistance in Myzus persicae (Hemiptera: Aphididae)
Authors: Foster Stephen P , Harrington Richard , Dewar Alan M , Denholm Ian , Devonshire Alan L
Published: August 2002

Advances in understanding insecticide resistance in the peach‐potato aphid, Myzus persicae (Sulzer), at the genotypic, biochemical and molecular levels have led to rapid and precise methods for the detection of several resistance mechanisms (elevated carboxylesterase, modified acetylcholinesterase or MACE, and knockdown resistance or kdr) in individual insects, and for monitoring their frequencies over space and time. This paper summarises the results of two long‐term surveys of resistance dynamics in M persicae in England, based on samples collected directly from field and glasshouse crops or from four 12.2‐m suction traps. The study showed marked fluctuations in resistance frequencies that probably reflect the counteracting forces of selection imposed by insecticides for aphids possessing more copies of esterase resistance genes, and selection against these forms when insecticide use is relaxed. There is growing evidence that several different resistance mechanisms in M persicae have associated fitness costs. In the case of esterase and MACE, these costs are apparently strong enough to effect a decline in resistance frequency over winter, and a more prolonged decline over successive cropping seasons when aphid numbers are insufficient to trigger intensive chemical applications. Changes in the overall frequency of resistance genotypes may also be influenced by the predominance of year‐round parthenogenesis in M persicae in the UK, leading to non‐random associations between mechanisms and selection operating on clonal lineages rather than individual genotypes.

© 2002 Society of Chemical Industry
Activity of mesotrione on resistant weeds in maize
Authors: Sutton Peter , Richards Claire , Buren Larry , Glasgow Les
Published: August 2002

Mesotrione is a new callistemone herbicide that inhibits the HPPD enzyme (p‐hydroxyphenylpyruvate dioxygenase) and introduces a new naturally selective tool into weed‐management programmes for use in maize. Mesotrione provides control of the major broad‐leaved weeds, and it can be used in integrated weed‐management programmes depending on the grower's preferred weed‐control strategy. At post‐emergence rates of 150 g AI ha−1 or less, mesotrione provides naturally selective control of key species that may show triazine resistance (TR), eg Chenopodium album L, Amaranthus species, Solanum nigrum L, as well as species of weed that show resistance to acetolactase synthase (ALS) inhibitors eg Xanthium strumarium L, Amaranthus spp and Sonchus spp. The data presented show that resistant and susceptible biotypes of these species with resistance to triazine herbicides, such as atrazine, simazine, terbutylazine and metribuzin, or ALS‐inhibitor herbicides, such as imazethepyr, remain susceptible to mesotrione. These results confirm that there is no cross‐resistance in biotypes with target site resistance to triazine or ALS‐inhibiting herbicides. It is important that herbicide choice and rotation becomes an integral part of planning weed management, so as to minimise the risks of crop losses from weed competition, build‐up of weed seed in the soil and the further development of weed resistance across a range of herbicide modes of action.

© 2002 Society of Chemical Industry
Cross‐resistance to imidazolinone herbicides in chlorsulfuron‐resistant Raphanus raphanistrum
Authors: Hashem Abul , Dhammu Harmohinder S
Published: August 2002

Raphanus raphanistrum L has evolved widespread resistance to sulfonylureas in the Western Australia (WA) wheat belt. With the introduction of imidazolinone‐tolerant (IT) wheat (Tritcum aestivum L) and IT canola (Brassica napus L) in the WA wheat belt, it is important to understand the status of cross‐resistance in this weed to sulfonylurea and imidazolinone (Imi) herbicides. A study was conducted to examine cross‐resistance between chlorsulfuron and Imi herbicides (a mixture of imazapic and imazapyr) in 46 R raphanistrum populations collected from across the WA wheat belt. Plants were treated with herbicides and assessed for phytotoxicity under glasshouse conditions. Of the 46 R raphanistrum populations, 32 were resistant to chlorsulfuron and four were resistant to imazapic + imazapyr. Of the 70% chlorsulfuron‐resistant populations, 13% showed cross‐resistance to imazapic + imazapyr. However, the cross‐resistant populations treated with imazapic + imazapyr showed a lower resistance level than the chlorsulfuron‐treated populations. These results suggest that weed populations with such cross‐resistance will not be controlled effectively by Imi herbicides. Although the resistance levels of the cross‐resistant populations to Imi herbicides were low, the cross‐resistance levels of R raphanistrum should be determined before growing IT crops, particularly IT canola.

© 2002 Society of Chemical Industry
Quinoxyfen—resistance management and sensitivity monitoring in wheat: 1995–2000
Authors: Bernhard Uli , Leader Andrew , Longhurst Chris , Felsenstein Friedrich G
Published: August 2002

Wheat powdery mildew, Blumeria ( = Erysiphe) graminis DC f sp tritici Marschal is one of the most important foliar diseases of cereals in Europe, and has shown a high potential for adaptability in sensitivity towards modern fungicides during the last 20 years. Quinoxyfen is a surface‐mobile fungicide from a new chemical class that has been commercially used for the control of B graminis in Europe since 1997. When the compound was launched, a Resistance Management Strategy was implemented which included: no seed treatments, no autumn use, a specified window of application and recommendations for appropriate tank‐mixing. To assess the success of this Management Strategy, a European‐wide resistance monitoring programme was carried out between 1995 and 2000 using spore trap sampling, and a whole plant assay. The mean EC50 values found by year were 0.060 mg litre−1 in 1995, 0.052 mg litre−1 in 1996, 0.071 ml litre−1 in 1997, 0.039 mg litre−1 in 1998, 0.039 mg litre−1 in 1999 and 0.063 mg litre−1 in 2000. No new sensitivity classes were found. The slight shift to lower sensitivity in 1998 and 1999 was correlated with similar shifts in three wild‐type isolates, and was ascribed to experimental variation. The monitoring programme will continue to assess the long‐term impact of the management recommendations on the resistance status of quinoxyfen.

© 2002 Society of Chemical Industry
Population changes in Phytophthora infestans in Taiwan associated with the appearance of resistance to metalaxyl
Authors: Deahl Kenneth L , Cooke Louise R , Black Lowell L , Wang Tien Chen , Perez Frances M , Moravec Brian C , Quinn Michele , Jones Richard W
Published: August 2002

In recent years, late blight, caused by Phytophthora infestans (Mont) De Bary, has increased in severity in many parts of the world, and this has been associated with migrations which have introduced new, arguably more aggressive, populations of the pathogen. In Taiwan, late blight has been endemic on outdoor tomato crops grown in the highlands since the early 1900s, but recent epidemics have been more damaging. To ascertain the present status of the Taiwanese population of P infestans, 139 isolates of the pathogen collected and maintained by the Asian Vegetable Research and Development Center (AVRDC) were characterized using mating type, metalaxyl sensitivity, allozyme genotype, mitochondrial haplotype and RFLP fingerprinting. Up to 1997, all isolates were found to belong to the old clonal lineage of P infestans (US‐1 and variants), but in isolates from 1998 a new genotype appeared, and by 2000 this had apparently completely displaced the old population. This new genotype was an A1 mating type and has the dilocus allozyme genotype 100/100/111, 100/100 for the loci coding for glucose‐6‐phosphate isomerase and peptidase, respectively. These characters, together with RG57 fingerprinting, indicated that these isolates belonged to the US‐11 clonal lineage, a minority (11%) being a previously unreported variant of US‐11. Whereas metalaxyl‐resistant isolates were not detected in the old population, 96% of the new genotypes proved resistant, with the remainder being intermediate in sensitivity. It may be inferred from this sudden, marked change in the characteristics of the Taiwanese P infestans that a new population of the pathogen was introduced around 1997–98 and that this may well have already been metalaxyl‐resistant when it arrived, although a role for in situ selection cannot be excluded.

© 2002 Society of Chemical Industry
Establishment of the baseline sensitivity and monitoring response of Papaver rhoeas populations to florasulam
Authors: Paterson E A , Shenton Z L , Straszewski A E
Published: August 2002

In accordance with the EPPO guideline for the efficacy evaluation of plant protection products, resistance risk analysis PP 1/213(1), a method was established to determine the baseline sensitivity of key weed species to florasulam, a new triazolopyrimidine sulfonanilide herbicide for post‐emergence control of dicotyledonous weeds in cereals. The aim of the baseline monitoring project was to understand the natural variation in response to florasulam of diverse populations of Papaver rhoeas at the time of product launch. The method entailed seed collection from representative agricultural areas throughout Europe. The seed was subjected to glasshouse tests where dose‐response studies were conducted and ED80 values generated. This enabled a sensitivity index to be calculated for each country, giving an indication of the variation in P rhoeas response to florasulam in the populations tested.

© 2002 Society of Chemical Industry
What impact will EPPO's new resistance risk assessment guideline have on selection pressure in the European Union?
Authors: Leonard Paul K , Dutton Robert
Published: August 2002

This paper examines practical and regulatory implications, including both costs and benefits, resulting from implementation of EPPO's new resistance risk analysis guideline. Crop‐protection companies operating in Europe are preparing risk analyses and management strategies, and are monitoring for resistance. However, this is a complex and expensive process involving technical, commercial and regulatory functions. The actual cost of filling these data gaps is consequently greater than many would have anticipated. The agrochemical industry has a vested interest in managing resistance and is committed to maintaining the essential contribution of crop‐protection products to sustainable agriculture. However, with increasing regulatory costs, it is important that regulatory authorities concentrate requirements for resistance risk analyses, management strategies and monitoring where these are most needed. Should these requirements be applied indiscriminately, crop‐protection companies will have to consider whether or not it is economically justifiable to make these investments, or whether to remove less profitable uses from product labels. In such situations, minor crops stand to be disproportionately effected. One year after publication, it is too early to measure the guideline's impact on selection pressure. It is already clear that the guideline represents an unprecedented step forward in the regulation and harmonisation of resistance management. There are, however, valid arguments against regulation of resistance management. One of the most important criticisms that is levelled against the latter approach is that, with the best motivation and with appropriate use restrictions on labels, these actions alone do not solve the problem. It is critical that all stakeholders in the crop protection process are made aware of the importance of resistance management and of complying with prescribed strategies.

© 2002 Society of Chemical Industry
Analysis of insecticide‐resistant Myzus persicae (Sulzer) populations collected in Italian peach orchards
Authors: Mazzoni Emanuele , Cravedi Piero
Published: August 2002

Several populations of the green peach aphid, Myzus persicae (Sulzer), were collected in the most important Italian peach‐growing areas. In these populations, collected as primary colonies or as secondary ones, total esterase content and acetylcholinesterase sensitivity towards pirimicarb was assessed using biochemical assays. Most of the individuals analysed generally exhibited an elevated esterase content, and in some cases acetylcholinesterase insensitivity. The implications of resistance levels and distribution on M persicae control strategies are discussed. © 2002 Society of Chemical Industry
Mechanisms of resistance to fungicides in field strains of Botrytis cinerea
Authors: Leroux Pierre , Fritz René , Debieu Danièle , Albertini Catherine , Lanen Catherine , Bach Jocelyne , Gredt Michel , Chapeland Florence
Published: August 2002

Field strains of Botrytis cinerea Pers ex Fr, the causal agent of grey mould diseases, were collected from French vineyards between 1993 and 2000. Several phenotypes have been characterized according to the inhibitory effects of fungicides towards germ‐tube elongation and mycelial growth. Two types of benzimidazole‐resistant strains (Ben R1 and Ben R2) could be detected; negative cross‐resistance to phenylcarbamates (eg diethofencarb) was only found in Ben R1. Benzimidazole resistance was related to point mutations at codon 198 (Ben R1) or 200 (Ben R2) of the β‐tubulin gene. Most dicarboximide‐resistant strains were also weakly resistant to aromatic hydrocarbon fungicides (eg dicloran) but remained sensitive to phenylpyrroles (eg fludioxonil). These resistant field strains (Imi R1) contained a single base pair mutation at position 365 in a two‐component histidine kinase gene, probably involved in the fungal osmoregulation. Three anilinopyrimidine‐resistant phenotypes have been identified. In the most resistant one (Ani R1), resistance was restricted to anilinopyrimidines, but no differences were observed in the amino‐acid sequences of cystathionine β‐lyase (the potential target site of these fungicides) from Ani R1 or wild‐type strains. In the two other phenotypes (Ani R2 and Ani R3), resistance extended to various other groups of fungicide, including dicarboximides, phenylpyrroles and sterol biosynthesis inhibitors. This multi‐drug resistance was probably determined by over‐production of ATP‐binding cassette transporters. The hydroxyanilide fenhexamid is a novel botryticide whose primary target site is the 3‐keto reductase involved in sterol C‐4 demethylations. Apart from the multi‐drug‐resistant strain Ani R3, three other fenhexamid‐resistant phenotypes have been recognized. For two of them (Hyd R1 and Hyd R2) fenhexamid‐resistance seemed to result from P450‐mediated detoxification. Reduced sensitivity of the target site could be the putative resistance mechanism operating in the third resistant phenotype (Hyd R3). Increased sensitivity to inhibitors of sterol 14 α‐demethylase recorded in Hyd R1 strains was related to two amino‐acid changes at positions 15 and 105 of this enzyme.

© 2002 Society of Chemical Industry
Insecticide resistance in field populations of Frankliniella occidentalis (Pergande) in Murcia (south‐east Spain)
Authors: Espinosa Pedro J , Bielza Pablo , Contreras Josefina , Lacasa Alfredo
Published: August 2002

Thirty‐nine field populations of Frankliniella occidentalis (Pergande) were collected from different crops (sweet pepper, tomato, lettuce, artichoke, melon, cucumber, carnation, broad bean, peach and plum) in Murcia (south‐east Spain). All populations were reared separately in the laboratory to obtain enough individuals for bioassays. Female thrips were bioassayed, using a standard topical application method, against methiocarb, methamidophos, acrinathrin, endosulfan, deltamethrin and formetanate. Methiocarb was the only insecticide that showed a high efficacy against F occidentalis at field dose rates. Acrinathrin and methamidophos were moderately effective, while endosulfan and deltamethrin were ineffective. Only moderate levels of resistance (Resistance Ratios at LC50 of 10–30) were detected for the selective insecticides methiocarb, formetanate and acrinathrin used against F occidentalis in crops where these insecticides are used intensively. This generalized and low level of resistance to these insecticides, coupled with a lack of efficacy for the three broad‐spectrum insectides, was observed even in intensively managed vegetable crops. Implementation of IPM strategies in Murcia has contributed to more successful insecticide anti‐resistance management.

© 2002 Society of Chemical Industry
Field and laboratory selection of Frankliniella occidentalis (Pergande) for resistance to insecticides
Authors: Espinosa Pedro J , Bielza Pablo , Contreras Josefina , Lacasa Alfredo
Published: August 2002

Response of western flower thrips, Frankliniella occidentalis (Pergande), to selection for resistance to insecticides commonly used to control this pest in Murcia (south‐east Spain) was studied under field and laboratory conditions. In the field, plots within sweet pepper crops in commercial and experimental greenhouses were treated under different selection strategies: insecticide rotation versus formetanate reiteration, formetanate reiteration versus acrinathrin reiteration, and formetanate reiteration versus methiocarb reiteration. Thrips populations were sampled monthly and bioassayed against methiocarb, methamidophos, acrinathrin, endosulfan, deltamethrin and formetanate. In the laboratory, F occidentalis strains were selected against each insecticide for several generations. To evaluate cross‐resistance, each selected strain was bioassayed with the other insecticides. Frankliniella occidentalis populations showed a rapid development of acrinathrin resistance, reaching high levels in field and laboratory conditions. Formetanate and methiocarb resistance were also observed, although development was slower and at moderate levels. Cross‐resistances between acrinathrin/deltamethrin and acrinathrin/formetanate were detected under field and laboratory conditions. Formetanate/methiocarb cross‐resistance was suspected in laboratory selections, but not in field assays. Simultaneous moderate resistance levels to the three specific insecticides against thrips (formetanate, methiocarb and acrinathrin) were shown in laboratory selection strains, indicating a general mechanism of resistance, probably metabolic.

© 2002 Society of Chemical Industry
Introduction
Authors: Holloman Derek W
Published: August 2002

© 2001 Society of Chemical Industry
Spatial organization and conformational peculiarities of the callatostatin family of neuropeptides
Authors: Alieva I. N. , Velieva L. I. , Aliev D. I. , Godjaev N. M.
Published: August 2002

The structures and conformational peculiarities of five members of the callatostatin family of neuropeptides, i.e. Leu‐ and Met‐callatostatins, ranging in size from 8 to 16 amino acid residues have been investigated by a theoretical conformational analysis method. A comparative analysis of the conformational flexibilities of Met‐callatostatin with those of the hydroxylated analogues, [Hyp2]‐ and [Hyp3]‐ Met‐callatostatin has been carried out. Helically packed C‐terminal pentapeptide in the structure of all investigated Leu‐callatostatins are shown to be possible. The reason for the great number low‐energy conformers for the callatostatin N‐terminus is discussed. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Mass spectrometric and chemical stability of the Asp‐Pro bond in herpes simplex virus epitope peptides compared with X‐Pro bonds of related sequences
Authors: Skribanek Zsolt , Mező Gábor , Mák Marianna , Hudecz Ferenc
Published: August 2002

The mass spectrometric analysis of the immunodominant epitope region (273–284) of herpes simplex virus type 1 (HSV‐1) glycoprotein D (gD) showed a favoured fission at the Asp‐Pro peptide bond. The fast atom bombardment collision induced dissociation (FAB‐CID) study of closely related X‐Pro peptides documented that neither the length nor the amino acid composition of the peptide has a significant influence on this preferential cleavage. At the same time the DP bond proved to be sensitive to acidic conditions in the course of peptide synthesis. These observations prompted us to compare the chemical and mass spectrometric stability of a new set of nonapeptides related to the 273–284 epitope region of gD, i.e. SALLEDPVG and SALLEXPVG peptides, where X = A, K, I, S, F, E or D, respectively. The chemical stability of these peptides during acidic hydrolysis was investigated by electrospray ionization mass spectrometry (ESI‐MS) and the products were identified by ESI‐MS and on‐line high performance liquid chromatography—mass spectrometry (HPLC‐MS). The mass spectrometric fragmentation and bond stability of the untreated peptide samples were also studied using ESI‐MS and liquid secondary ion mass spectrometry (LSIMS). Both the chemical hydrolysis and the mass spectrometric fragmentation showed that the Asp‐Pro bond could easily be cleaved, while the KP bond proved to be stable under both circumstances. On the other hand, the XP bond (X = A, I, S, F or E) fragmented easily under the mass spectrometric conditions, but was not sensitive to the acidolysis. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and biological properties of the seven alanine‐modified analogues of the marine cyclopeptide hymenamide C
Authors: Napolitano Assunta , Bruno Ines , Rovero Paolo , Lucas Rut , Payà Peris Miguel , Gomez‐Paloma Luigi , Riccio Raffaele
Published: August 2002

The synthesis and biological activity of the marine cyclopeptide hymenamide C(1), showing an inhibitory effect on human neutrophil elastase degranulation release, were recently described. Based on this result, it was decided to undertake a systematic structure–activity relationship study of this cyclopeptide, based on the Ala‐scan technique, in order to obtain useful information for the rational design of additional analogues. The synthesis and characterization of the seven Ala modified analogues are reported and their biological and pharmacological properties are described. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Antimicrobial activity of short arginine‐ and tryptophan‐rich peptides
Authors: Strøm Morten B. , Rekdal Øystein , Svendsen John S.
Published: August 2002

Highly antimicrobial active arginine‐ and tryptophan‐rich peptides were synthesized ranging in size from 11 to five amino acid residues in order to elucidate the main structural requirement for such short antimicrobial peptides. The amino acid sequences of the peptides were based on previous studies of longer bovine and murine lactoferricin derivatives. Most of the peptides showed strong inhibitory action against the Gram‐negative bacteria Escherichia coli and Pseudomonas aeruginosa, and the Gram‐positive bacterium Staphylococcus aureus. For the most active derivatives, the minimal inhibitory concentration values observed for the Gram‐negative bacteria were 5 µg/ml (3.5 µM), whereas it was 2.5 µg/ml (1.5 µM) for the Gram‐positive bacterium. It was essential for the antimicrobial activity that the peptides contained a minimum of three tryptophan and three arginine residues, and carried a free N‐terminal amino group and an amidated C‐terminal end. Furthermore, a minimum sequence size of seven amino acid residues was required for a high antimicrobial activity against Pseudomonas aeruginosa. The insertion of additional arginine and tryptophan residues into the peptides resulted only in small variations in the antimicrobial activity, whereas replacement of a tryptophan residue with tyrosine in the hepta‐ and hexapeptides resulted in reduced antimicrobial activity, especially against the Gram‐negative bacteria. The peptides were non‐haemolytic, making them highly potent as prospective antibiotic agents. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Antiproliferative action of valorphin in cell cultures
Authors: Blishchenko Elena , Sazonova Olga , Surovoy Andrei , Khaidukov Sergei , Sheikine Yury , Sokolov Dmitry , Freidlin Irina , Philippova Marina , Vass Arpad , Karelin Andrei , Ivanov Vadim
Published: August 2002

The antiproliferative effects of the haemoglobin β‐chain fragment (33–39) (valorphin or VV‐haemorphin‐5) were studied in a panel of tumour cell lines and normal cells of different origin, using various methods of activity determination (trypan blue inclusion test, sulphorhodamine B staining, MTT staining, flow cytometry and clonogenic test). Valorphin suppressed the proliferation of tumour cells by 25%–95%, depending on the cell line. The maximal valorphin activity was detected in transformed cells of fibroblastic (L929) and epithelial (MCF‐7) origin, transformed haematopoietic cells (K562, HL‐60) being less sensitive. In normal cells, valorphin activity was several fold lower (10%–15%). A study of the dynamics of cell proliferation in L929 cells using a visual cell count and flow cytometry showed that valorphin induced reversible and relatively short (24 h) S‐phase arrest of cell proliferation, accompanied by a reversible increase of cell size. The proliferation delay was followed by a comparatively long period of reversible resistance of the cells to the peptide (96 h) when the cells are dividing at normal rate. The same dynamics were demonstrated for A549, MCF‐7 and primary murine breast carcinoma cells. On the basis of the data obtained, a pattern of regulation of cell growth by valorphin is suggested. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
HP (2–20) derived from the amino terminal region of Helicobacter pylori ribosomal protein L1 exerts its antifungal effects by damaging the plasma membranes of Candida albicans
Authors: Lee Dong Gun , Kim Pyoung Il , Park Yoonkyung , Jang Seung‐Hwan , Park Seong‐Cheol , Woo Eun‐Rhan , Hahm Kyung‐Soo
Published: August 2002

The fungicidal effects of the peptide HP (2–20), derived from the N‐terminal sequence of Helicobacter pylori ribosomal protein L1 (RPL1), have been investigated. HP (2–20) displays a strong fungicidal activity against various fungi, without haemolytic activity against human erythrocyte cells, and the fungicidal activity is inhibited by Ca2+ and Mg2+ ions. In order to investigate the fungicidal mechanism(s) of HP (2–20), the amount of intracellular trehalose was measured in C. albicans. It was found that the amounts of intracellular trehalose were decreased when HP (2–20) was used. The action of the peptide against fungal cell membranes was further examined by the potassium‐release test; HP (2–20) was found to increase the amount of K+ released from the cells. Furthermore, HP (2–20) caused significant morphological changes, as shown by scanning electron microscopy, and by testing the membrane disrupting activity using liposomes (phosphatidyl choline/cholesterol; 10 : 1, w/w). Our results suggest that HP (2–20) may exert its antifungal activity by disrupting the structure of cell membranes, via pore formation or direct interaction with the lipid bilayers. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Systematic optimization of a lead‐structure identities for a selective short peptide agonist for the human orphan receptor BRS‐3
Authors: Weber Dirk , Berger Claudia , Heinrich Timo , Eickelmann Peter , Antel Jochen , Kessler Horst
Published: August 2002

The orphan receptor, human bombesin receptor subtype 3 (BRS‐3) was assigned to the G‐protein coupled bombesin receptor family because of its high sequence homology with the neuromedin B receptor (NMB‐R) and gastrin‐releasing peptide receptor (GRP‐R). Since its pharmacology is still unknown, new highly potent and selective tool‐substances are needed, that may be able to elucidate its possible role in obesity and cancer.

We have performed structure activity relationship studies on the high affinity peptide agonists [D‐Phe6,β‐Ala11,Phe13,Nle14]Bn(6–14) and [D‐Phe6,Phe13]Bn(6–13)propylamide, using their ability to mobilize intracellular calcium in BRS‐3 transfected CHOGα‐16 cells combined with receptor binding studies. It was demonstrated that for [D‐Phe6,β‐Ala11,Phe13,Nle14]Bn(6–14) the side chains of the residues Trp8 and Phe13, and to a smaller extent β‐Ala11, are the important amino acid side chains for receptor activation and binding, however for [D‐Phe6,Phe13]Bn(6–13) propylamide His12 seems to be more important than Phe13. C‐ and N‐terminal deletions and amino acid substitutions allowed further understanding. It was demonstrated that substitution of His12 by Tyr leads to a high selectivity towards GRP‐R. Using the acquired information, a small tetrapeptide library was designed with compounds presenting Trp and Phe at varying stereochemistry and distances, which led to the discovery of the lead‐structure H‐D‐Phe‐Gln‐D‐Trp‐Phe‐NH2. Systematic SAR revealed the important structural features of this peptide, C‐terminal optimization resulted in the highly active and selective BRS‐3 agonist H‐D‐Phe‐Gln‐D‐Trp‐1‐(2‐phenylethyl)amide. In summary, the size of the peptide was reduced from 8 or 9 amino acids to a tripeptide for BRS‐3. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Conformational analysis of the Gαs protein C‐terminal region
Authors: D'ursi Anna Maria , Albrizio Stefania , Greco Giovanni , Mazzeo Sonia , Mazzoni Maria R. , Novellino Ettore , Rovero Paolo
Published: August 2002

The C‐terminal domain of the heterotrimeric G protein α‐subunits plays a key role in selective activation of G proteins by their cognate receptors. Several C‐terminal fragments of Gαs (from 11 to 21 residues) were recently synthesized. The ability of these peptides to stimulate agonist binding was found to be related to their size. Gαs(380–394) is a 15‐mer peptide of intermediate length among those synthesized and tested that displays a biological activity surprisingly weak compared with that of the corresponding 21‐mer peptide, shown to be the most active. In the present investigation, Gαs(380–394) was subjected to a conformational NMR analysis in a fluorinated isotropic environment. An NMR structure, calculated on the basis of the data derived from conventional 1D and 2D homonuclear experiments, shows that the C‐terminal residues of Gαs(380–394) are involved in a helical arrangement whose length is comparable to that of the most active 21‐mer peptide. A comparative structural refinement of the NMR structures of Gαs(380–394) and Gαs(374–394)C379A was performed using molecular dynamics calculations. The results give structural elements to interpret the role played by both the backbone conformation and the side chain arrangement in determining the activity of the G protein C‐terminal fragments. The orientation of the side chains allows the peptides to assume contacts crucial for the G protein/receptor interaction. In the 15‐mer peptide the lack as well as the disorder of some N‐terminal residues could explain the low biological activity observed. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Antioxidant and non‐toxic properties of Piper betle leaf extract: in vitro and in vivo studies
Authors: Choudhary Dharamainder , Kale Raosaheb K.
Published: August 2002

Piper betle leaves are used in folk medicine for the treatment of various disorders and is commonly chewed among Asians. The present study investigates the protective efficacy of P. betle leaf extract. The presence of the extract inhibited the radiation induced lipid peroxidation process effectively. This could be attributed to its ability to scavenge free radicals involved in initiation and propagation steps. Oral supplementation with extract (1, 5 and 10 mg/kg) was administered daily for 2 weeks to Swiss albino mice and the hepatic antioxidant status was analysed. The GSH content was enhanced and no appreciable change was found in the levels of oxidative damage in terms of lipid peroxidation. Also, the specific activity of SOD increased in a dose dependent manner. These factors indicate the elevation of antioxidant status in the animals. The effect on the glyoxalase system which is considered to be activated under stress conditions was also investigated. Our findings did not observe any significant change in gly I and gly II activities, implying a non‐stress condition after oral treatment of the extract. The present study indicates the antioxidant activity of P. betle leaf extract and its potential to elevate the antioxidant status. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of Acanthopanax senticosus Harms on biogenic monoamine levels in the rat brain
Authors: Fujikawa Takahiko , Soya Hideaki , Hibasami Hiroshige , Kawashima Hitoshi , Takeda Hidekatsu , Nishibe Sansei , Nakashima Kunio
Published: August 2002

The extract of the stem bark of Acanthopanax senticosus Harms (ASH) is known to have healing and protective effects on stress‐induced disturbance of mental status. We have analysed whether a single or chronic (2 week) administration of ASH can affect concentrations of noradrenaline (NA), dopamine (DA) and their metabolites in the normal rat brain. A single p.o. administration of ASH elevated the NA and DA levels in the whole brain of rats in a dose‐dependent manner. A single or 2 week administration of ASH (500 mg/kg) showed a marked increase in the DA level only in the striatum. However, NA levels were increased by a single dose of ASH in a wide range of brain regions such as the cortex, hypothalamus, striatum, hippocampus, substantia nigra and pons. When administered for 2 weeks no increase in NA levels was seen in these brain regions, except for an increase in the frontal cortex and anterior hypothalamus. The present results suggest that ASH may act by regulating NA and DA levels in specific brain regions related to stress response and Parkinson's disease. Copyright © 2002 John Wiley & Sons, Ltd.
In vitro antioxidant activity of non‐cultivated vegetables of ethnic Albanians in southern Italy
Authors: Pieroni A. , Janiak V. , Dürr C. M. , Lüdeke S. , Trachsel E. , Heinrich M.
Published: August 2002

A total of 27 extracts from non‐cultivated and weedy vegetables traditionally consumed by ethnic Albanians (Arbëreshë) in the Vulture area (southern Italy) were tested for their free radical scavenging activity (FRSA) in the DPPH (1,1‐diphenyl‐2‐picrylhydrazil radical) screening assay, for their in vitro non‐enzymatic inhibition of bovine brain lipid peroxidation and for their inhibition of xanthine oxidase (XO). In both antioxidant assays strong activity was shown for Leopoldia comosa (bulbs, syn.: Muscari comosum) and Centaurea calcitrapa (young whorls). In the lipid peroxidation assay, extracts from leaves of Origanum heracleoticum, Urtica dioica and Tordylium apulum showed a remarkable inhibitory activity (>50%), too. In the case of Leopoldia comosa and Origanum heracleoticum this activity was comparable to quercetin (at a concentration of 50 μM) and Rhodiola rosea extract. Extracts from non‐cultivated Cichorium intybus, Chondrilla juncea and Stellaria media showed strong in vitro inhibition of xanthine oxidase, with an activity higher than that of a reference extract from Ledum groenlandicum. These findings suggest that weedy vegetables may be useful antioxidants of interest in the prevention of ageing related diseases, CNS disorders and as potential sources of phytomedicines against hyperuricaemia and gout. Copyright © 2002 John Wiley & Sons, Ltd.
Estrogenic activity of Nigella damascena extracts, evaluated using a recombinant yeast screen
Authors: Agradi E. , Fico G. , Cillo F. , Francisci C. , Tomè F.
Published: August 2002

We used the yeast estrogen screen (YES) containing a human estrogen receptor to evaluate the estrogenic activity of extracts obtained from Nigella damascena seeds. Alcohol extracts obtained by direct extraction of seeds showed a low estrogenic activity, while the alcohol extract obtained after extraction with solvents of increasing polarity showed a strong estrogenic activity. This suggests the presence in Nigella of polar components whose activity can be clearly demonstrated after previous elimination of interacting apolar components that may mask the activity of more polar components. The response of both alcohol fractions follow a bell‐shaped curve indicating a concentration‐dependent relationship. Copyright © 2002 John Wiley & Sons, Ltd.
Bioactivity studies on β‐sitosterol and its glucoside
Authors: Villaseñor Irene M. , Angelada Jennifer , Canlas Arlyn P. , Echegoyen Deborah
Published: August 2002

β‐Sitosterol and β‐sitosteryl‐β‐D‐glucoside were isolated as analgesic constituents from the leaves of Mentha cordifolia Opiz. The acetic acid‐induced writhing test showed that β‐sitosterol and β‐sitosteryl‐β‐D‐glucoside decreased the number of squirms induced by acetic acid by 70.0% and 73.0%, respectively, at a dose of 100 mg / kg mouse. Statistical analysis using the Kruskall Wallis one‐way analysis of variance by ranks showed that these isolates approximate the analgesic activity of mefenamic acid at a 0.001 level of significance. The hot plate method confirmed their analgesic activities, as β‐sitosterol and β‐sitosteryl‐β‐D‐glucoside exhibited a 300% and 157% increase in pain tolerance, respectively, while mefenamic acid, a known analgesic, showed a 171% increase. Neither isolate exhibited antiinflammatory activity using the carrageenan‐induced mouse paw oedema assay.

β‐Sitosterol also exhibited anthelminthic and antimutagenic activities. In vitro tests using live Ascaris suum as test animals showed that the behaviour of worms treated with β‐sitosterol approximated that of the positive controls, Combantrin and Antiox. An in vivo micronucleus test showed that β‐sitosterol inhibited the mutagenicity of tetracycline by 65.3% at a dose of 0.5 mg /kg mouse. At the same dose, it did not exhibit chromosome‐breaking activity. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibitory effects of Korean medicinal plants and camelliatannin H from Camellia japonica on human immunodeficiency virus type 1 protease
Authors: Park Jong Cheol , Hur Jong Moon , Park Ju Gwon , Hatano Tsutomu , Yoshida Takashi , Miyashiro Hirotsugu , Min Byung Sun , Hattori Masao
Published: August 2002

To identify substances with anti‐human immunodeficiency virus (HIV) activity in traditional medicines, 101 extracts of Korean medicinal plants were screened for their inhibitory effects on HIV type 1 protease (PR). The enzyme activity was determined by HPLC. Of the extracts tested, strong inhibitory effects were observed in the acetone extracts of the pericarp and leaves of Camellia japonica, the water extract of the leaves of Sageretia theezans and the methanol extract of the aerial part of Sophora flavescens. Camelliatannin H from the pericarp of C. japonica, showed a potent inhibitory activity on HIV‐1 PR with IC50 of 0.9 μM. Copyright © 2002 John Wiley & Sons, Ltd.