Search

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant growth-promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds were analyzed using gas chromatography–mass spectrometry. Larvae fed inoculated corn exhibited lower weights and relative growth rate than noninoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. Volatile organic compound ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura , making it a promising candidate for crop protection strategies. [ABSTRACT FROM AUTHOR]

Apples Malus domestica , known as a rich source of triterpene acids, induced more variety and quantity of triterpene acids in response to herbivory or mechanical damage. There were 3 major induced compounds: pomaceic acid and euscaphic acid, both of which are known apple triterpene acids, and 2α,19α-dihydroxy-3-oxours-12-en-28-oic acid (named eriobotoric acid), which was first identified in apples. In this study, the 3 compounds' induction curves after damage, varietal differences in induction amounts, and physiological roles against pest insects were further investigated. Eriobotoric acid showed clear antifeedant activity against lepidopteran insect Spodoptera litura but not against apple pests. [ABSTRACT FROM AUTHOR]

Chemical ecology is the highly interdisciplinary study of biochemicals that mediate the behavior of organisms and the regulation of physiological changes that alter intraspecific and/or interspecific interactions. Significant advances are often achieved through the collaboration of chemists and biologists working to understand organismal survival strategies with an eye on the development of targeted technologies for controlling agricultural, forestry, medical, and veterinary pests in a sustainable world. We highlight recent advances in chemical ecology from multiple viewpoints and discuss future prospects for applications. [ABSTRACT FROM AUTHOR]

Chitin, poly (β-(1→4)-N-acetyl-d-glucosamine), is an important biopolymer for insects that is utilized as a major component of peritrophic membrane. The chitin content in peritrophic membrane is of expedient interest from a pest control perspective, although it is hard to quantify chitin. In this study, we establish a facile method for the quantification of chitin in peritrophic membrane by image processing. In this method, chitin was indirectly quantified using chitosan–I3− complex, which exhibited a specific red-purple color. A calibration curve using a chitosan solution showed good linearity in a concentration range of 0.05–0.5 μg/μL. We quantified the amount of chitin in peritrophic membrane of Spodoptera litura (Lepidoptera: Noctuidae) larvae using this method. Throughout the study, only common inexpensive regents and easily attainable apparatuses were employed. This method can be easily applied to the sensitive quantification of the amounts of chitin and chitosan in materials by wide range of researchers. Abbreviations: LOD: limit of detection; LOQ: limit of quantification; ROI: region of interest; RSD: relative standard deviation. Chitin in peritrophic membrane of insects was quantified by image processing with an easy, inexpensive and sensitive method. [ABSTRACT FROM AUTHOR]

The monoterpene isolated from Mentha haplocalyx, 3,3,5-trimethyl-2-oxabicyclo[2.2.2]oct-5-en-4-ol, was synthesized according to its proposed structure. However, the NMR data of the synthetic sample were not in agreement with those reported for the natural product. After considerable efforts, the genuine structure was confirmed as (1R*,2R*)-4-(1′-hydroxy-1′-methylethyl)-1-methylycyclohex-3-ene-1,2-diol. [ABSTRACT FROM AUTHOR]

The epithelial sodium channel (ENaC) plays a pivotal role in sodium homeostasis, and the development of drugs that modulate ENaC activity is of great potential therapeutic relevance. We screened 6100 chemicals for their ability to activate sodium permeability of ENaC. We used a two-step strategy: a high throughput cell-based assay and an electrophysiological assay. Five compounds were identified showing common structural features including an indole or benzothiophene ring. ENaC consists of three subunits: α, β, and γ. Changing the heteromeric combination of human and mouse ENaC αβγ subunits, we found that all five compounds activated the human β subunit but not the mouse subunit. However, four of them exhibited lower activity when the human γ subunit was substituted by the mouse γ subunit. Our findings provide a structural basis for designing human ENaC activity modulators. Abbreviations: ENaC: Epithelial sodium channel; ΔRFU: delta relative fluorescence units; EC50: Half-maximal effective concentration; Emax: maximum effect value. [ABSTRACT FROM AUTHOR]

The first synthesis of myristicyclin A, which was isolated from the Papua New Guinean plant Horsfieldia spicata, is described. The synthesis features acid-mediated hydroarylation reaction to form a dihydrocoumarin moiety, construction of the 2,8-dioxabicyclo[3.3.1]nonane skeleton under acidic conditions, and regioselective Friedel-Crafts acylation at a later stage. [ABSTRACT FROM AUTHOR]

To aid in the identification and quantification of biologically and agriculturally significant natural products, tandem mass spectrometry can provide accurate structural information with high selectivity and sensitivity. In this study, diagnostic fragmentation patterns of isoflavonoids were examined by liquid chromatography-ion trap-time of flight-mass spectrometry (LC-IT-TOF-MS). The fragmentation scheme for [M+H−2CO]+ ions derived from isoflavones and [M+H−B-ring−CO]+ ions derived from 5-hydroxyisoflavones, were investigated using different isotopically labeled isoflavones, specifically [1′,2′,3′,4′,5′,6′,2,3,4-13C9] and [2′,3′,5′,6′,2-D5] isoflavones. Specific isotopically labeled isoflavones were prepared through the biosynthetic incorporation of pharmacologically applied 13C- and D-labelled L-phenylalanine precursors in soybean plants following the application of insect elicitors. Using this approach, we empirically demonstrate that the [M+H−2CO]+ ion is generated by an intramolecular proton rearrangement during fragmentation. Furthermore, [M+H−B-ring−CO]+ ion is demonstrated to contain a C2H moiety derived from C-ring of 5-hydroxyisoflavones. A mechanistic understanding of characteristic isoflavone fragmentation patterns contributes to the efficacy and confidence in identifying related isoflavones by LC-MSn. [ABSTRACT FROM AUTHOR]

Rice plants accumulate various specialized metabolites, including phenylamides, in response to pathogen attack. We prepared 25 phenylamides, and developed a method of analyzing them by multiple reaction monitoring with liquid chromatography coupled with tandem mass spectrometry. We analyzed phenylamides in rice leaves infected with Cochliobolus miyabeanus and Xanthomonas oryzae. The phenylamides induced included benzoyltryptamine, cinnamoyl-, p-coumaroyl-, feruloyl-, and benzoylserotonins, cinnamoyl and benzoyltyramines, feruloylagmatine, and feruloylputrescine. Some of the phenylamides exhibited antimicrobial activity against C. miyabeanus and X. oryzae, indicating that they are phytoalexins. Treatment with jasmonic acid, salicylic acid, 6-benzylaminopurine, and ethephone also induced phenylamide accumulation. The compositions of the induced amides varied depending on the plant hormone used, and cinnamoyltryptamine, cinnamoylserotonin, and cinnamoyltyramine were not induced by the plant hormones. These findings suggest that several plant hormones and additional factors are involved in phenylamide accumulation in response to pathogen infection in rice. [ABSTRACT FROM AUTHOR]

Lignans are a large class of naturally occurring secondary metabolites which are widely spread within the plant kingdom. Their diverse structures and variety of biological activities have fascinated organic chemists. For synthesizing optically active lignans, we have developed the novel asymmetric dimerization of cinnamic acid derivatives, and applied it to the enantioselective syntheses of furofuran lignans (yangambin, sesamin, eudesmin, caruilignan A) and diarylbutane lignans (sauriols A and B). This review summarizes the methodology of our asymmetric dimerization of cinnamic acid derivatives, and efficient total syntheses of furofuran and diarylbutane lignans reported by our and other groups. Optically active furofuran and diarylbutane lignans were synthesized in short steps employing the asymmetric dimerization of cinnamic acid derivatives. [ABSTRACT FROM PUBLISHER]

A concise synthesis of litseaones A and B, which were isolated from the stem barks of Litsea rubescens and L. pedunculata, is described in this study. Litseaone A was synthesized in just three steps from a known phloroglucinol derivative. The direct conversion of litseaone A into litseaone B was also achieved. The concise synthesis of (±)-litseaones A and B was accomplished. [ABSTRACT FROM AUTHOR]

The article presents a study on the species-specific glucosylation of DIMBOA in larvae of the rice armyworm. An introduction on DIMBOA which is a benzoxazinoid (Bx) chemical defense system of plants such as wheat is given. It also states the effect of artificial feeds with DIMBO when given to Mythimna separate or rice armyworm larvae and the detoxification mechanism of the rice armyworm. Furthermore it discusses the defensive role of Bxs in maize and wheat plants against insects.

The article discusses the efficient incorporation of unsaturated fatty acids into volicitin [N-(17-hydroxylinolenoyl)-L-glutamine], a fatty acid amide (FAA) and N-linolenoyl-L-glutamine in cutworms Spodoptera litura by the incubation of larval gut tissues with unsaturated or saturated fatty acids sodium salt and L-[alpha-15N]glutamine. The authors show that the results indicated that unsaturated fatty acids were more selected as substrates in FAA biosynthesis than saturated acids.

The article presents a study which shows that the L-glutamine moiety of volicitin played a more critical role than the hydroxyl moeiety. They have investigated the biological activity triggering these emissions in linolenic acids coupled to L-phenylalanine, L-threonine, L-leucine, L-proline, and L-glutamine in order to better understand the relationship between the structure and the biological activity of volicitin.

The article discusses the results of a study investigating the synthesis of enantiomerically pure sauriols A and B from the freshwater angiosperm, Saururus cernuus. Sauriols A and B exhibit antifeedant activity. The sauriols were synthesized by the reduction of two benzylic positions and two lactone carbonyls of 4, and with subsequent partial cleavage of the methyl ethers.

Reports on the synthesis of beta-acaridial, the active principle of the sex, alarm and aggregation pheromone among astigmatid mites. Preparation of the analog, beta-acaroilal 8; Resulting beta-(Z)-acaridiol from the Z-selective base in the Wittig reaction.

Identifies volicitin-related compounds and the composition of the compounds in the oral secretion from four different species of caterpillars fed on natural diets. Lack of significant differences in the amounts of N-acylamino acid conjugates in the secretions from the three noctuid species; Proportion of the volicitin-related compounds in the regurgitant.

Identifies two types of isomeric monoterpenes from the opisthonotal gland secretion of the acarid mite Caloglyphus polyphyllae. Synthesis of the monoterpenes; Structural characteristics.

The article presents a study on the stereochemistry of two female-specific normonoterpenes sex pheromone members from the acarid mite. It states that planar structures are determined by mass spectrometry with gas chromatography (GC/MS) to be 2.6-dimethyl-5-heptenal and 2.6-dimethyl-5-hepten-1-ol. It adds that the stereochemistry of the two species were identified by a GC analysis on a critical column and presumed that the two are similar in terms of biosynthetic aspects.

The article presents a study which demonstrates the incorporation of free oxygen into volicitin by Spodoptera litura larvae. The methodology involves rearing said larvae under the atmospheric conditions with 18O2 for three days. 18O-labeling of the volicitin hydroxyl group is suggestive of monoxygenase activity in volicitin biosynthesis.

Investigates specific incorporation of L-glutamine into volicitin in the regurgitant of spodoptera litura. Identification of volicitin as an elicitor of plant volatiles; Selectivity of glutamine as a substrate; Quantitative analysis of the amino acids.