In vitro evaluation of native entomopathogenic fungi and neem (Azadiractha indica) extracts on Spodoptera frugiperda

The control of Spodoptera frugiperda is based on synthetic insecticides, so some alternatives are the use of entomopathogenic fungi (EF) and neem extract. The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S. frugiperda larvae. Six EF were identified by DNA sequencing of ITS regions from three EF (Fusarium solani, Metarrhizium robertsii, Nigrospora spherica and Penicillium citrinum). They were evaluated in concentrations of 1 × 10⁸ spores/ mL. In addition, a second bioassay was carried out evaluating only F. solani, M. robertsii and N. sphaerica and the addition of vegetable oil. On the other hand, extraction of secondary metabolites from neem seed (Azadirachta indica) was carried out by performing, mass (g) and solvent volume (mL ethanol and water) combinations, which were subjected to microwaves and ultrasound. Subsequently, these extracts were evaluated in concentrations of 3%, 4% and 5%. A survival analysis was performed for each of the bioassays. With respect to the results of the first bioassay, F. solani obtained a probability of survival of 0.476 on the seventh day, while in the second bioassay, M. robertsii obtained 0.488 survival probability. This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%. However, in the evaluation of the neem extract the combination 1:12/70% to 4% caused 84% mortality of larvae. The use of native HE and neem extracts has potential for the control of S. frugiperda.     

变形链球菌中的次级代谢产物及其在口腔生物被膜中的生态功能

口腔生物被膜是由数百种微生物构成的复杂微生物群体。变形链球菌作为其中的重要一员,被认为是引起龋病的主要病原菌。变形链球菌在牙齿表面以生物被膜形式生长的能力和它产酸耐酸的特点赋予其致龋性。不同的变形链球菌菌株之间保留了多样的次级代谢形式,这是与宿主长期共进化的结果。迄今为止,变形链球菌中报道的次级代谢产物包括10种细菌素(又称变链素)和一种聚酮/非核糖体肽类化合物。这些化合物多样的活性形式暗示了它们参与口腔生物被膜中跨种间和跨界间的相互作用。未来随着变形链球菌菌株数目的增加和更多菌株全基因组序列的完成,可以预见会有更多新颖活性次级代谢产物的出现。对变形链球菌次级代谢的研究不仅有助于治疗和预防口腔疾病,而且新颖活性次级代谢产物的发现对新药的研发也具有重要意义。     

Production of biopesticide azadirachtin using plant cell and hairy root cultures

The extensive use of nondegradable chemical pesticides for pest management has developed serious environmental hazards. This has necessitated the urgent need to switch over to an alternative mode of biopesticide development for mass agriculture and field crop protection. Azadirachta indica A. Juss (commonly known as neem) houses a plethora of bioactive secondary metabolites with azadirachtin being the most active constituent explored in the sector of ecofriendly and biodegradable biopesticides characterized by low toxicity toward nontarget organisms. It has been reported that the highest content of azadirachtin and related limonoids is present in the seeds, available once in a year. Moreover, the inconsistent content and purity of the metabolites in whole plant makes it imperative to tap the potential of in vitro plant tissue culture applications, which would allow for several controlled manipulations for better yield and productivities. This review gives a summarized literature of the applied research and achievements in plant cell/hairy cultures of A. indica A. Juss mainly in context with the biopesticide azadirachtin and applications thereof.     

Peltate glandular trichomes of Colquhounia seguinii harbor new defensive clerodane diterpenoids

Glandular trichomes produce a wide variety of secondary metabolites that are considered as major defen-sive chemicals against herbivore attack. The morphology and secondary metabolites of the peltate g...     

植物丝氨酸羧肽酶样酰基转移酶的结构、功能和应用

植物丝氨酸羧肽酶样酰基转移酶与丝氨酸羧肽酶相比具有相似的结构特点和很高的同源性,能够催化酰基葡萄糖酯的酰基转移反应,参与植物次生代谢产物的酰基化修饰,丰富天然产物结构多样性,改善化合物水溶性、稳定性等理化性质.本文重点介绍植物来源丝氨酸羧肽酶样酰基转移酶家族的结构特点、催化机制、功能鉴定及其生物催化应用等方面的研究进展...     

Incorporation of caffeine into the macromicete fungus Pleurotus sajor-caju growing on coffee pulp

TWhen the chemical composition of secondary metabolites from the Pleurotus sajor-caju growing on coffee pulp were study, it was found that the fungus has the faculty of incorporating caffeine inside its fructiferous body. Component of the substrate (around 1.3% on dry basis) did not show a structural change over the alkaloid; this constitutes an unexpected outcome for a species belonging to realm of the fungi.     

Streptomyces genetics: a genomic perspective

Streptomycetes are gram-positive, soil-inhabiting bacteria of the order Actinomycetales. These organisms exhibit an unusual, developmentally complex life cycle and produce many economically important secondary metabolites, such as antibiotics, immunosuppressants, insecticides, and anti-tumor agents. Streptomyces species have been the subject of genetic investigation for over 50 years, with many studies focusing on the developmental cycle and the production of secondary metabolites. This information provides a solid foundation for the application of structural and functional genomics to the actinomycetes. The complete DNA sequence of the model organism, Streptomyces coelicolor M145, has been published recently, with others expected to follow soon. As more genomic sequences become available, the rational genetic manipulation of these organisms to elucidate metabolic and regulatory networks, to increase the production of commercially important compounds, and to create novel secondary metabolites will be greatly facilitated. This review presents the current state of the field of genomics as it is being applied to the actinomycetes.     

Integrated management of fusarial wilt of tomato with implementation of soil solarisation

Fusarial wilt of tomato (Lycopersicon esculentum Mill.) is a very common and severe disease occurring in most of the vegetable fields in West Bengal, India. Potenciation and formulation of different fungicidal chemicals and phytoextracts were evaluated against the growth of the pathogen wherein carbendazim (bavistin) and leaf extracts of Azadirachta indica (neem) were recorded to be most effective. Combined treatment with 4 ml neem leaf extract and 1 ml captan (0.01%) or with 4 ml garlic bulb extract and 1 ml captan (0.01%) exhibited 100% growth inhibition of the pathogen. Integrated control of the pathogen with phytoextracts, fungicide and biocontrol agents was carried out. Among the treatments, a combination with extracts of neem, captan (0.01%) and metabolites of Trichoderma harzianum was proved to be superior over the other. Field experiment with three fungicides at 0.5% concentration was carried out in randomised block design where application of bavistin showed up to 62.27% reduction of wilt infection in tomato plants. Soil solarisation of tomato field showed 62.50 and 66.69% reduction of infection during the trial years. However, integration of soil solarisation with the applications of T. harzianum, captan (0.01%) and neem resulted in 100% reduction of infection and thus it was recorded as the most effective treatment in reducing the incidence of the disease.     

Effects of metabolites on the structural dynamics of rabbit muscle pyruvate kinase

The activity of rabbit muscle pyruvate kinase (PK) is regulated by metabolites. Besides requiring the presence of its substrates, PEP and ADP, the enzyme requires Mg(2+) and K(+) for activity. PK is allosterically inhibited by Phe for activity. The presence of PEP or Phe has opposing effects on the hydrodynamic properties of the enzyme without an apparent change in secondary structure. In this study, the structural perturbation induced by ligand binding was investigated by Fourier transform infrared (FT-IR) spectroscopy. Furthermore, the structural dynamics of PK was probed by H/D exchange monitored by FT-IR. Substrates and activating metal ions induce PK to assume a more dynamic structure while Phe exerts an opposite effect. In all cases there is no significant interconversion of secondary structures. PEP is the most efficient ligand in inducing a change in the microenvironments of both helices and sheets so much so that they can be detected spectroscopically as separate bands. These results provide the first evidence for a differential effect of ligand binding on the dynamics of structural elements in PK. Furthermore, the data support the model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the observed change in hydrodynamic properties represent the two extreme end states.     

Anti-inflammatory, pro-apoptotic, and anti-proliferative effects of a methanolic neem (Azadirachta indica) leaf extract are mediated via modulation of the nuclear factor-κB pathway

Azadirachta indica (neem tree) is used in traditional Indian medicine for its pharmacological properties including cancer prevention and treatment. Here, we studied a neem extract's anti-inflammatory potential via the nuclear factor-κB (NF-κB) signaling pathway, linked to cancer, inflammation, and apoptosis. Cultured human leukemia cells were treated with a methanolic neem leaf extract with or without tumor necrosis factor (TNF)-α stimulation. Inhibition of NF-κB activity was demonstrated by luciferase assay and electrophoretic mobility shift assay (EMSA). Inhibition of viability by neem extracts was assessed by luminescent assays. Western blot analysis allowed assessing the inhibitory effect of the neem extract on TNF-α-induced degradation of inhibitor of κB (IκB) and nuclear translocation of the NF-κB p50/p65 heterodimer. Inhibition of IκB kinase (IKK) activity was shown as well as the effect of neem extract on the induction of apoptotic cell death mechanisms by nuclear fragmentation analysis and flow cytometry analysis. In conclusion, our data provide evidence for a strong effect of the neem extract on pro-inflammatory cell signaling and apoptotic cell death mechanisms, contributing to a better understanding of the mechanisms triggered by Azadirachta indica.     

An endophytic fungus from <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss. that produces azadirachtin

Azadirachtin A and its structural analogues are a well-known class of natural insecticides having antifeedant and insect growth-regulating properties. These compounds are exclusive to the neem tree, Azadirachta indica A. Juss, from where they are currently sourced. Here we report for the first time, the isolation and characterization of a novel endophytic fungus from A. indica, which produces azadirachtin A and B in rich mycological medium (Sabouraud dextrose broth), under shake-flask fermentation conditions. The fungus was identified as Eupenicillium parvum by ITS analysis (ITS1 and ITS2 regions and the intervening 5.8S rDNA region). Azadirachtin A and B were identified and quantified by LC-HRMS and LC-HRMS², and by comparison with the authentic reference standards. The biosynthesis of azadirachtin A and B by the cultured endophyte, which is also produced by the host neem plant, provides an exciting platform for further scientific exploration within both the ecological and biochemical contexts.     

青霉属真菌次级代谢产物的结构类型及其药用活性的研究进展

青霉属(Penicillium)真菌属于腐生类真菌,是自然界中一类重要的分解者。其可以产生多种多样的次级代谢产物。这些结构新颖、功能特殊的次级代谢产物在抗菌、抗氧化、抗肿瘤等药物开发中发挥重要作用,主要由聚酮类、生物碱、萜类、大环内酯等化学结构类型组成。本文综述了青霉属真菌次级代谢产物的结构类型以及丰富的生物药用活性,该内容可为后续青霉属真菌新型天然药物的开发提供研究思路。     

Biodegradable polymer based encapsulation of neem oil nanoemulsion for controlled release of Aza-A

Azadirachtin a biological compound found in neem have medicinal and pesticidal properties. The present work reports on the encapsulation of neem oil nanoemulsion using sodium alginate (Na-Alg) by cross linking with glutaraldehyde. Starch and polyethylene glycol (PEG) were used as coating agents for smooth surface of beads. The SEM images showed beads exhibited nearly spherical shape. Swelling of the polymeric beads reduced with coating which in turn decreased the rate of release of Aza-A. Starch coated encapsulation of neem oil nanoemulsion was found to be effective when compared to PEG coated encapsulation of neem oil nanoemulsion. The release rate of neem Aza-A from the beads into an aqueous environment was analyzed by UV-visible spectrophotometer (214nm). The encapsulated neem oil nanoemulsion have the potential for controlled release of Aza-A. Neem oil nanoemulsion encapsulated beads coated with PEG was found to be toxic in lymphocyte cells.     

Metabolite profiling and quantification of phenolic compounds in methanol extracts of tomato fruit

The consumption of tomatoes and tomato products has been associated with a reduction in the risk of contracting some types of cancer and other chronic diseases. These beneficial properties may be attributed to the presence of key metabolites and the interactions among them. We have developed and validated an analytical method for the comprehensive profiling of semi-polar metabolites in the methanol extract of three cultivars of raw tomatoes (Daniela, Raf and Rambo) grown in Almería, in south-east Spain. Diode-array and time-of-flight/ion-trap mass spectrometry detectors were used to ensure the wide detection of metabolites with highly divergent properties. The masses thus detected were assigned by matching their accurate mass-signals with tomato compounds reported in the literature, and supplemented by UV and MS/MS information, reference compounds and existing metabolite databases. In this way we were able to identify tentatively 135 compounds belonging to various structural classes, 21 of which are to our knowledge reported for the first time in the tomato fruit. Among the metabolites identified, the most abundant were phenolic compounds. This class of secondary metabolites is attracting considerable attention from producers and consumers due to their antioxidant activity and nutritional properties. Their quantitative analysis was achieved by using closely related derivatives for each family.     

Azadirachta indica metabolites interfere with the host-endosymbiont relationship and inhibit the transmission of potato leafroll virus by Myzus persicae

The effects of neem (Azadirachta indica A. Juss) seed kernel extracts (NSKE) and azadirachtin on the ability of Myzus persicae (Sulz.) to transmit potato leafroll luteovirus (PLRV) was studied. Moreover, it was investigated whether treatments with these compounds would exert an effect on larval growth and mortality, and on the aphid intracellular symbionts. Endosymbiotic bacteria play an essential role in the performance of aphids, and in luteovirus transmission by aphids. NSKE and azadirachtin were offered to one-day-old M. persicae nymphs via a membrane feeding system. The neem metabolites displayed a 100% mortality at doses higher than 2560 ppm. At intermediate doses, ranging between 320 and 2560 ppm, larval growth and mortality were affected in a dose-dependent manner. The transmission of PLRV by M. persicae was inhibited by 55–90%. The endosymbiont population of the aphid was clearly affected by a treatment with neem metabolites as the release of their most abundant protein, Buchnera GroEL, into the haemocoel of the aphid was inhibited. Moreover, morphological aberrations on the bacterial endosymbionts were observed in aphids which fed on 2560 ppm of azadirachtin. At doses lower than 160 ppm of NSKE or azadirachtin, the endosymbiont population of M. persicae, and mortality, growth and feeding behaviour were similar to that of the untreated groups of aphids. However, PLRV transmission was still inhibited by 40–70%. The possible targets of the neem metabolites in the aphid are discussed.     

Determination of protein secondary structure using factor analysis of infrared spectra

A method is presented for determining the secondary structural composition of a protein in aqueous solution from its infrared spectrum. A factor analysis approach is used to analyze the infrared spectra of 18 proteins whose crystal structures are known from X-ray studies. Factor analysis followed by multiple linear regression identifies those eigenspectra that correlate with the variation in properties described by the calibration set. The properties of interest in this study are % alpha-helix, % beta-sheet, and % turns. In the analysis of an unknown, the factor loadings required to reproduce its spectrum are substituted in the regression equation for each property to predict its secondary structural composition. The accuracy of the method was determined by removing each standard, in turn, from the calibration set and using a calibration set generated from the remainder to predict its composition. By this method we obtain standard errors of prediction of 3.9% for alpha-helix, 8.3% for beta-sheet, and 6.6% for turns. The method may also be applied to the spectra of proteins in 2H2O. The method has important advantages over those currently in use for the quantitative analysis of the infrared spectra of proteins. Manipulation of the spectrum is kept to a minimum, no curve-fitting is necessary, and the several amide I band components need not be assigned.     

Hybrid isoprenoid secondary metabolite production in terrestrial and marine actinomycetes

Terpenoids are among the most ubiquitous and diverse secondary metabolites observed in nature. Although actinomycete bacteria are one of the primary sources of microbially derived secondary metabolites, they rarely produce compounds in this biosynthetic class. The terpenoid secondary metabolites that have been discovered from actinomycetes are often in the form of biosynthetic hybrids called hybrid isoprenoids (HIs). HIs include significant structural diversity and biological activity and thus are important targets for natural product discovery. Recent screening of marine actinomycetes has led to the discovery of a new lineage that is enriched in the production of biologically active HI secondary metabolites. These strains represent a promising resource for natural product discovery and provide unique opportunities to study the evolutionary history and ecological functions of an unusual group of secondary metabolites.     

Evaluation of neem, Azadirachta indica, with and without water management, for the control of culicine mosquito larvae in rice-fields

Applications of neem, Azadirachta indica (Meliaceae), to rice-fields were evaluated with the dual objective of controlling the culicine mosquito vectors of Japanese encephalitis virus (JEV) and enhancing the grain yield. Since crude neem products deteriorate under improper storage conditions, a laboratory bioassay was developed to screen neem cake powder against mosquito larvae, Culex quinquefasciatus. Only samples of neem giving over 90% bioassay mortality were used in field trials. When good quality neem cake powder was applied at the dose of 500 kg/ha, either alone or coated over urea, there was a striking reduction in the abundance of late instar culicine larvae and pupae. Only fourteen pupae were obtained over a period of 13 weeks in neem cake powder treated plots, and four in those treated with neem coated urea, compared with 101 in control plots. Both treatments were significantly less than the control, but on par with one another. In another field trial, neem cake coated urea was tested at 500 and 250 kg neem/ha in combination with water management practices. No reduction in efficacy was noted at the lower dose. Larval abundance in plots under water management alone did not differ significantly from the controls, but was significantly reduced when water management was combined with neem products. Two stable formulations, 'Neemrich-I' (lipid rich) and 'Neemrich-II' (azadirachtin rich), also gave good suppression of immature culicines. All the treatments with neem also gave higher grain yield than the control.(ABSTRACT TRUNCATED AT 250 WORDS)