Inhibitory effects of luteolin and its derivatives on osteoclast differentiation and differences in luteolin production by Capsicum annuum varieties.

Luteolin, an abundant flavonoid in the leaves of Capsicum annuum, has antioxidant activity and is, thus, a key chemical for promoting plant residue utilization, especially for the development of healthcare products. We assessed the inhibitory effect of luteolin and its glycosides on osteoclastic differentiation in human cells and found that the differentiation was effectively inhibited at noncytotoxic concentrations. We also screened 47 varieties of C. annuum for the accumulation of luteolin and apigenin to determine the prevalence of luteolin in diverse cultivars and identify varieties with high and/or selective luteolin production. The glycosides of luteolin and apigenin were found in all the tested varieties, with luteolin predominant over apigenin in most varieties. The identification and characterization of highly productive varieties of C. annuum is expected to be beneficial for the effective development of useful luteolin-based products from plant residues.

Identification of the gene encoding 3-(5-oxo-2-thioxoimidazolidin-4-yl) propionic acid desulfhydrase in Burkholderia sp. HME13.

Here, we report the identification of the gene encoding a novel enzyme, 3-(5-oxo-2-thioxoimidazolidin-4-yl) propionic acid desulfhydrase, in Burkholderia sp. HME13. The enzyme converts 3-(5-oxo-2-thioxoimidazolidin-4-yl) propionic acid and H2O to 3-(2,5-dioxoimidazolidin-4-yl) propionic acid and H2S. Amino acid sequence analysis of the enzyme indicates that it belongs to the DUF917 protein family, which consists of proteins of unknown function.

The evaluation of the synergistic effect of 3-(2,4-dihydroxyphenyl)propionic acid and l-ascorbic acid on tyrosinase inhibition.

3-(2,4-Dihydroxyphenyl)propionic acid (DDPA) and l-ascorbic acid (vitamin C) show tyrosinase inhibition activity. A synergistic effect on tyrosinase inhibition was observed when the two compounds were mixed. The effect significantly decreased the IC50 value of both compounds.

Studies on the probing stimulants for the white-backed planthopper, Sogatella furcifera (Homoptera: Delphacidae) in rice plant (Oryza sativa L.).

To elucidate the probing stimulants in rice plants for the white-backed planthopper, Sogatella furcifera, bioassay-guided separations were conducted, which led to the isolation of four active compounds. Using NMR and LC-MS spectra, their structures were determined as isoorientin 2″-O-(6‴-(E)-feruloyl)glucoside, isoorientin 2″-O-(6‴-(E)-p-coumaroyl)glucoside, tricin 5-O-glucoside, and isoscoparin 2″-O-(6‴-(E)-feruloyl)glucoside.

Feeding stimulants for larvae of Graphium sarpedon nipponum (Lepidoptera: Papilionidae) from Cinnamomum camphora.

The feeding response of larvae of the swallowtail butterfly, Graphium sarpedon nipponum (Lepidoptera: Papilionidae), is elicited by a methanolic extract from camphor tree (Cinnamomum camphora) leaves. Based on bioassay-guided fractionation, three compounds, isolated from the methanolic extract of fresh leaves of the camphor tree, were revealed to be involved in a multi-component system of feeding stimulants. Structures of these feeding stimulants were identified as sucrose, 5-O-caffeoylquinic acid and quercetin 3-O-ß-glucopyranoside by NMR and LC-MS.

Structural determination of elicitors in Sogatella furcifera (Horváth) that induce Japonica rice plant varieties (Oryza sativa L.) to produce an ovicidal substance against S. furcifera eggs.

Certain Japonica rice plant varieties (Oryza sativa L.) show resistance to the eggs of the white backed planthopper (Sogatella furcifera Horváth) by the formation of watery lesions and production of benzyl benzoate, an active ovicidal compound. Benzyl benzoate results in high ovicidal activity of S. furcifera eggs and reduces egg hatchability. The production of benzyl benzoate by the rice plants is only induced by an unknown elicitor(s) from the female S. furcifera. Therefore, we tried to isolate and identify these elicitors. An active 80% MeOH extract of S. furcifera was separated on a reverse-phase ODS MPLC, and the elicitor(s) was eluted in 100% MeOH and 100% EtOH fractions. Further separation of the active 100% MeOH fraction using a HPLC led to the isolation of four active compounds. The structures of each compound were determined by using NMR, LC-MS, and GC-MS spectra. The compounds were 1,2-dilinoleoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1-palmitoyl-2-oleoyl-X-glycero-3-phosphoethanolamine, and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine.

Elicitor(s) in Sogatella furcifera (Horváth) causing the Japanese rice plant (Oryza sativa L.) to induce the ovicidal substance, benzyl benzoate.

We elucidate the mechanism for inducing the production of ovicidal benzyl benzoate by Japonica rice varieties to kill eggs of the whitebacked planthopper, Sogatella furcifera (Horváth), lying in the rice plant. Even when subjected to physical damage by a needle or damage with water, the rice plant produced no benzyl benzoate. However, significant benzyl benzoate was produced when the plant was damaged with a methanol extract or homogenate of S. furcifera. The extract of the male did not induce the production of benzyl benzoate, but that of the female did. We concluded from these results that benzyl benzoate was induced by some elicitor(s) in the female of S. furcifera.

Clarification of the Mechanism of Inhibiting the Maillard Reaction between Phosphatidylethanolamine and Sugars by Adding Fatty Acid Calcium Salts.

Lecithin is known to undergo heat induced deterioration by the Maillard reaction between 1 mol of any sugar, except 2-deoxy sugar, and 2 mol of phosphatidylethanolamine (PE). However, we have previously reported that adding fatty acid metal salts can inhibit heat deterioration of soybean lecithin (SL). To clarify the mechanism of inhibition, 1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE), d-glucose, and calcium stearate or calcium decanoate were heated in octane. When DSPE and d-glucose with calcium stearate or calcium decanoate were heated in the octane, the heat deterioration of DSPE was significantly inhibited, and no increase in UV absorption at 350 nm was observed. From these reactant solutions, one compound having a phosphate group and no primary amine was isolated, and NMR spectra confirmed that two molar of stearic acid derived from DSPE were coordinated to the amino group and phosphate group of DSPE. Therefore, we concluded that adding fatty acid metal salts reduced the nucleophilic reactivity of the amino group of PE and inhibited the Maillard reaction with sugars because two molar of fatty acid derived from PE coordinated to the amino group and phosphate group of PE.

Use of Fatty Acid Metal Salts for Preventing Maillard Reaction-Driven Browning of Lecithins.

We previously reported that fluid soybean lecithin (SL) undergoes heat deterioration by the newly reported pseudo-Maillard rearrangement reaction. To inhibit heat deterioration, SLs were treated with metal silicates, such as magnesium silicate and calcium silicate. When soybean fatty acid was added to SL before treatment with calcium silicate, the color index after heating improved significantly as the acid value increased from 10 to 35 mg KOH/g. To elucidate the role of soybean fatty acid, calcium silicate treatment was carried out by adding several fatty acids to SL. Although saturated fatty acids had no effect on the heat deterioration of SL, unsaturated fatty acids were significantly more effective at inhibiting heat deterioration. Furthermore, for unsaturated fatty acids, it was confirmed that the calcium concentration increased in SL. Based on these results, several fatty acid metal salts were added to confirm whether heat deterioration while heating SL could be inhibited. It was observed that the heat deterioration of SL could be inhibited with fatty acid metal salts, regardless of whether the fatty acids were saturated or unsaturated and whether the metal was monovalent, divalent, or trivalent. Therefore, in this study, we clarified that the heat deterioration of SL could be inhibited by adding fatty acid metal salts to SL. Among sodium stearate, calcium stearate, magnesium stearate, barium stearate, and aluminum tristearate, the divalent fatty acid metal salts had a stronger inhibitory effect on heat deterioration than the monovalent and trivalent salts.

Volatile attractants for the common bluebottle, Graphium sarpedon nipponum, from the host, Cinnamomum camphora.

Floral scent has been shown to elicit behavioral responses by butterflies which forage for flowers after receiving appropriate signals. In comparison with investigations about the role of floral scent, those of foliar odor are, however, very few. In this study, the foliar volatiles of Cinnamomum camphora (Lauraceae), which had been collected by air entrainment, exhibited activities toward Graphium sarpedon nipponum (Papilionidae) in both electrophysiological and behavioral tests. The volatiles were analyzed by capillary gas chromatography with electro-antennographic detection (GC-EAD). Two electrophysiological active compounds were found which were determined as nonanal and decanal by using gas chromatography-mass spectrometry (GC-MS). Female butterflies generally tend to show a greater EAG response than males to the headspace volatiles and EAG-active aldehydes. Two EAG-active aldehydes were found in attractant tests to be attractive to both sexes of the butterfly when treated individually. Although the difference between the sexes was not significant, the female butterflies' preference tended to be more active than that of the males.

Feeding stimulant in Cinnamomum camphora for the common bluebottle, Graphium sarpedon nipponum (Lepidoptera: Papilionidae).

The acceptance of camphor tree (Cinnamomum camphora) as a host plant for the larvae of common bluebottle (Graphium sarpedon nipponum) was explained by the presence of feeding stimulants in the leaves. When the active methanol extract of C. camphora leaves was separated into hexane and water layers, both layers showed high feeding activities for the larvae of G. sarpedon nipponum. Bioassay-guided fractionation of the hexane layer resulted in the isolation of a highly active compound, which was identified as a-linolenic acid by nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry.

Pesticide residues in soils, sediments, and vegetables in the Red River Delta, northern Vietnam.

This study assessed pesticide residues in soils, sediments, and vegetables in the Xuan Khe and Hop Ly communes located along the Chau Giang River in the Red River Delta, northern Vietnam. Samples were collected from agricultural areas within and outside of embankments built to prevent flooding. In Xuan Khe, the soils outside of the embankment were more clayey with higher organic matter contents compared with the inside, due to selective deposition during river flooding. Many of the soils contained significant amounts of pesticides including dichlorodiphenyltrichloroethane (DDT), dicofol, isoprothiolane, and metalaxyl although their levels were below the maximum allowable concentration set by the Vietnamese government. The spectrum of DDT derivatives found suggested that the source of DDTs was not contaminated dicofol. Soils in Hop Ly resembled soils in Xuan Khe but were relatively sandy; one field showed appreciable contents of DDT derivatives. The ratios of (p,p(')-dichlorodiphenyldichloroethylene + p,p(')-dichlorodiphenyldichloroethane)/ summation operatorDDT in the surface and subsurface soils in Hop Ly were 0.34 and 0.57, suggesting that the DDTs originated from recent application. Pesticide residues in soils were not likely to translocate into vegetable crops, except for metalaxyl. High concentrations of cypermethrins in kohlrabi leaves could be ascribed to foliar deposition.

Insecticidal activities of cinnamic acid esters isolated from Ocimum gratissimum L. and Vitellaria paradoxa Gaertn leaves against Tribolium castaneum Hebst (Coleoptera: Tenebrionidae).

BACKGROUND: Pest management using botanicals has been widely practiced in sub-Saharan Africa and other parts of the world in recent times. The natural compounds present in these botanicals are known to be responsible for the protection they offer against insect pests. Some of these compounds may act as single compounds to produce an effect or they may be synergistically effective. In the present study using a bioassay guided approach, two cinnamic acid derivatives, methyl cinnamate and sitosterol cinnamate, were isolated from the leaves of Ocimum gratissimum and Vitellaria paradoxa, respectively. RESULTS: The two cinnamic acid derivatives were found to show higher levels of insecticidal, larvicidal and larval growth inhibition activities against Tribolium castaneum. The LC50 of methyl cinnamate was determined to be 26.92 mg mL-1 (95% CL: 1.18.66-38.84 mg mL-1 ; slope ± SE: 2.84 ± 0.81) for the adult 8.31 mg mL-1 (95% CL: 2.39-28.83 mg mL-1 ; slope ± SE: 0.66 ± 0.28) for the larvae while the LC50 of sitosterol cinnamate was determined to be 6.92 mg mL-1 (95% CL: 3.97-12.06 mg mL-1 ; slope ± SE: 1.59 ± 0.12) the adult and 3.91 mg mL-1 (95% CL: 2.21-6.93 mg mL-1 ; slope ± SE: 1.52 ± 0.13) for the larvae. CONCLUSION: Generally, the susceptibility of adult T. castaneum to these cinnamic acid esters can be directly associated with the concentration as well as time of exposure to the compounds. The isolated compounds support the use of O. gratissimum and V. paradoxa as important botanicals for the management of storage pests. © 2019 Society of Chemical Industry.

Gene cloning and characterization of thiourocanate hydratase from Burkholderia sp. HME13.

A novel enzyme, thiourocanate hydratase, which catalyses the conversion of thiourocanic acid to 3-(5-oxo-2-thioxoimidazolidin-4-yl) propionic acid, was isolated from the ergothioneine-utilizing strain, Burkholderia sp. HME13. When the HME13 cells were cultured in medium containing ergothioneine as the sole nitrogen source, thiourocanate-metabolizing activity was detected in the crude extract from the cells. However, activity was not detected in the crude extract from HME13 cells that were cultured in Luria-Bertani medium. The gene encoding thiourocanate hydratase was cloned and expressed in Escherichia coli, and the recombinant enzyme was purified to homogeneity. The enzyme showed maximum activity at pH 7.5 and 55°C and was stable between pH 5.0 and 10.5, and at temperatures up to 45°C. The Km and Vmax values of thiourocanate hydratase towards thiourocanic acid were 30 µM and 7.1 µmol/min/mg, respectively. The enzyme was strongly inhibited by CuCl2 and HgCl2. The amino acid sequence of the enzyme showed 46% identity to urocanase from Pseudomonas putida, but thiourocanate hydratase had no urocanase activity.

Three new acylated flavone C-glycosides from the flowers of Trollius chinensis.

Three new flavone C-glycosides with the substitution of the unusual acyl, 2''-O-veratroylisoswertisin (1), 3''-O-2-methylbutyrylisoswertiajaponin (2), and 3''-O-2-methylbutyrylvitexin (3), together with the known compounds of 2''-O-2-methylbutyrylisoswertisin (4), 3''-O-2-methylbutyrylisoswertisin (5), and trollisin I (6) were isolated from the antibacterial fraction of the aqueous extract of the flowers of Trollius chinensis. The structural elucidations of these compounds were carried out by a detailed analysis of the NMR and MS spectra.

Antifeedants against Locusta migratoria from the Japanese Cedar, Cryptomeria japonica II.

A methanol extract of Cryptomeria japonica completely inhibited feeding by Locusta migratoria. Based on bioassay-guided fractionation, two active terpenols, (+)-ferruginol and (-)-cubebol, were isolated and identified as antifeedants against this insect species. Each compound separately showed weak activity, but they showed intense activity against this insect species when they were combined.

Antifeedants of Indian barnyard millet, Echinochloa frumentacea link, against brown planthopper, Nilaparvata lugens (Stål).

Eight compounds isolated from Indian barnyard millet have been identified as L-malic acid, trans-aconitic acid, (+)-isocitric acid, 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, isocarlinoside, 2"-O-rhamnosylisoorientin, and 7-O-(2"-O-glucuronosyl)glucuronosyltricin, respectively. These compounds showed high antifeeding activity against brown planthopper only when they were combined.

A new oviposition deterrent to the leafminer, Liriomyza trifolii: cucurbitane glucoside from Momordica charantia.

A new cucurbitane glucoside, 23-O-beta-D-glucopyranosyl-7-hydroxy-3-O-malonylcucurbita-5,24-dien-19-al, named momordicine V, has been isolated from Momordica charantia leaves, along with the previously reported compounds, momordicines I, II, IV and 3-O-malonylmomordicine I. The structure of the new compound was established on the basis of spectral analysis, as well as by its conversion to momordicine II by alkaline catalyzed hydrolysis. Momordicine V deterred significantly the oviposition by L. trifolii on host plant leaves treated at 26.16 microg/cm2 leaf surface.

Cucurbitane glucosides from Momordica charantia leaves as oviposition deterrents to the leafminer, Liriomyza trifolii.

The American serpentine leaf mining fly, Liriomyza trifolii, whose larva feeds on more than 120 plant species is well characterized by its high degree of polyphagy. Observations on the oviposition behavior by L. trifolii demonstrated that among cucurbitaceous plants, Momordica charantia is rarely attacked by L. trifolii. The methanol extract of M. charantia leaves strongly deterred the females from ovipositing on kidney bean leaves treated at a concentration of 1 g leaf equivalent extract/ml. Analysis of the polar fraction of the methanol extract of M. charantia leaves resulted in the isolation of a novel cucurbitane glucoside, 7-O-beta-D-glucopyranosyl-3,23-dihydroxycucurbita-5,24-dien-19-al, named momordicine IV, along with another known compound, momordicine II. Momordicine II and IV deterred oviposition by L. trifolii significantly when bioassays were carried out on kidney bean leaves treated at 75.6 and 20.3 microg/cm2 leaf surface, respectively. There was no synergistic effect on oviposition deterrent when the two compounds were combined in their natural abundance.

Studies on probing stimulants for the green rice leafhopper, Nephotettix nigropictus (Stål) (Hemiptera: Cicadellidae), in the rice plant (Oryza sativa L.).

A crude rice extract caused a higher probing response than did the control in the green rice leafhopper, Nephotettix nigropictus. Bioassay-guided separation led to the isolation of four active compounds, isoscoparin 2″-O-glucoside, isoscoparin 2″-O-(6‴-(E)-feruloyl)glucoside, isoscoparin 2″-O-(6‴-(E)-p-coumaroyl)glucoside, and isovitexin 2″-O-(6‴-(E)-feruloyl)glucoside from ODS 40% methanol in water faction. Each of the compounds, or any combination without one of the four compounds, caused weaker probing responses than the crude rice extract. The activity was recovered only when all the compounds were combined.