European pennyroyal (Mentha pulegium) from Portugal: Chemical composition of essential oil and antioxidant and antimicrobial properties of extracts and essential oil

There is a growing interest of industry to replace synthetic chemicals by natural products with bioactive properties from plant origin. The aim of this study was to determine the chemical composition of European pennyroyal (Mentha pulegium) essential oil and to characterize the in vitro antioxidant and antimicrobial activities of its water (hot and cold) and ethanolic extracts and of the essential oil. The essential oil revealed menthone, pulegone and neo-menthol as the main constituents, comprising 35.9, 23.2 and 9.2% of the essential oil, respectively. The hot water extract exhibited the highest antioxidant activity and phenol content. In contrast, the extracts were not very effective to inhibit the growth of the seven foodborne spoilage and pathogenic bacteria tested, but the essential oil showed antibacterial activity against all bacterial strains. In conclusion, extracts and essential oil of M. pulegium from Mediterranean origin have huge potential as an alternative to chemical additives for the food industry.     

Demographic Parameters of Nezara viridula (Heteroptera: Pentatomidae) Reared on Two Diets Developed for Lygus spp.

Two artificial diets developed for rearing Lygus spp., a fresh yolk chicken egg based-diet (FYD) and a dry yolk chicken egg based-diet (DYD), were evaluated as an alternative food source for rearing the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae). Survival to adult was 97.3 and 74.67%, respectively, on the fresh and dry yolk diets. Insects fed FYD had 100% survival of nymphs from first through fourth instars. Adult development was significantly shorter on FYD (30.37 ± SE 0.30 d) as compared with DYD (32.77 ± SE 0.16 d). Increased male and female longevity, higher fecundity, and larger egg mass sizes were also observed with N. viridula-fed FYD. However, fertility and hatchability was higher on DYD. A complete cohort life table was constructed to describe the development of N. viridula on both diets.     

Effects of fungicide seed treatments on germination, population, and yield of maize grown from seed infected with fungal pathogens

Seedborne fungi can reduce survival, growth, and yield of maize (Zea mays L.). Laboratory, field, and growth chamber experiments were conducted to determine the effects of the seed treatment fungicides fludioxonil, mefenoxam, and azoxystrobin on germination, plant population, and grain yield of maize grown from low-quality hybrid seed infected with seedborne fungal pathogens. Study I used seed of four hybrids infected at 0-54% incidence with Fusarium spp., Stenocarpella maydis, Penicillium spp., Rhizopus spp., and/or Aspergillus spp. Study II used three seed lots for each of two hybrids infected at 7-37% incidence with S. maydis. Warm and cold germination for untreated seed varied among hybrids in both studies. Warm germination of the seed lot with the highest incidence of S. maydis in study II treated with azoxystrobin and fludioxonil was significantly greater (+7%) than the nontreated control. Plant population in study I was significantly affected by seed treatment, hybrid, and their interactions. Populations were greater (≥9%) for fludioxonil, fludioxonil + mefenoxam, and fludioxonil + mefenoxam + azoxystrobin treatments compared to controls. In growth chamber experiments with pasteurized soil, emergence (≥5%) and plant dry weight (≥14%) were both greater than controls only with the triple seed treatment. Plant populations in study II for all seed treatments except mefenoxam and azoxystrobin alone were greater (≥4%) than controls. Yield in study I was significantly affected by hybrid and seed treatment. Yield for one hybrid was higher (≥20%) than the control with all seed treatments except fludioxonil, whereas yield with another hybrid was consistently greater (≥26%) only with the triple seed treatment. Yield in study II was significantly affected by hybrid, seed treatment, and their interactions. Yield was greater (≥8%) than the controls for all seed treatments with one hybrid and with all (≥5%) except azoxystrobin for the other hybrid. Highest yields occurred with the triple seed treatment. Results indicate that fludioxonil and azoxystrobin can increase germination, population, and yield of maize grown from seed infected by S. maydis and other fungi.     

Prospects of Miscanthus x giganteus for PAH phytoremediation: A microcosm study

Phytoremediation of large surface areas using crop cultivation appears as an attractive strategy to allow for long-term but economically viable site rehabilitation programs. The contribution of Miscanthus x giganteus root exudates to the biostimulation of PAH degradation was recently demonstrated using in vitro assays. The aim of this work was to characterize the phytoremediation potential of this perennial grass in the situation of PAH polluted soils. For this purpose, three factors affecting bioremediation, namely the nature of soil organic contaminants (spiked phenanthrene and pyrene each at 100 mg/kg dry soil), bioaugmentation (with a PAH-degrading microflora) and planting (with Miscanthus x giganteus), were arranged according to a full factorial design in pot experiments. Effects of each factor (alone or in combination) were assessed on soil bacterial communities (total culturable bacteria and PAH-degrader enumerations, 16S rDNA molecular diversity analysis) and PAH dissipation. Results showed that contamination was the main factor positively influencing the development of degrader populations. Phenanthrene dissipation was observed regardless the presence of plants or initial PAH-degrading bacterial inoculum whereas significant decreases in pyrene contents were positively influenced by bioaugmentation and to a lesser extent by planting. The ability of plants to maintain a degrading rhizosphere microflora thus enhancing the dissipation of recalcitrant compounds in polluted soils would deserve further investigations.     

Structure of Fucoidan from Brown Seaweed Turbinaria ornata as Studied by Electrospray Ionization Mass Spectrometry (ESIMS) and Small Angle X-ray Scattering (SAXS) Techniques

The purpose of this study is to elucidate both the chemical and conformational structure of an unfractionated fucoidan extracted from brown seaweed Turbinaria ornata collected at Nha-trang bay, Vietnam. Electrospray ionization mass spectrometry (ESI-MS) was used for determining the chemical structure and small angle X-ray scattering (SAXS) provided conformational of the structure at the molecular level. The results showed that the fucoidan has a sulfate content of 25.6% and is mainly composed of fucose and galactose residues (Fuc:Gal ≈ 3:1). ESIMS analysis suggested that the fucoidan has a backbone of 3-linked α-l-Fucp residues with branches, →4)-Galp(1→ at C-4 of the fucan chain. Sulfate groups are attached mostly at C-2 and sometimes at C-4 of both fucose and galactose residues. A molecular model of the fucoidan was built based on obtained chemical structure and scattering curves estimated from molecular model and observed SAXS measurement were fitted. The results indicated that fucoidan under study has a rod-like bulky chain conformation.     

Creams Formulated with Ocimum gratissimum L. and Lantana camara L. Crude Extracts and Fractions as Mosquito Repellents Against Aedes aegypti L. (Diptera: Culicidae)

Mosquitoes are the most deadly vectors of parasites that cause diseases such as malaria, yellow fever, and filariasis. In view of the recent increased interest in developing plant origin insecticides as an alternative to chemical insecticides, the objective of this study was to determine the repellent activity of creams formulated with methanol crude extract (MCE), hexane fraction (HF), and ethyl acetate fractions (EAFs) of Ocimum gratissimum and Lantana camara leaves in single and combined actions against female Aedes aegypti. Evaluation was carried out in the net cages (30 by 30 by 30 cm) containing 60 blood-starved female mosquitoes each and were assayed in the laboratory condition following World Health Organization 2009 protocol. All formulations (single and mixture) were applied at 2, 4, 6, and 8 mg/cm² in the exposed area of human hands. Only acetone + white soft paraffin served as negative control and odomos (12% DEET) as positive control. All the formulations presented good protection against mosquito bites without any allergic reaction by the human volunteers. The repellent activity was dependent on the strength of the extracts and fractions. Among the tested formulations, the maximum protection time was observed in MCE (120 min) and EAF (150 min) of O. gratissimum; MCE:MCE (150 min) and HF:HF (120 min) mixtures of both plants. In addition, MCE:MCE and HF:HF mixtures from both plants showed possible synergistic effect. From the results, the combination of O. gratissimum and L. camara to formulate natural mosquito repellent using small amount of extracts can be encouraging to be an alternative to conventional DEET.     

Structural and Immunological Activity Characterization of a Polysaccharide Isolated from Meretrix meretrix Linnaeus

Polysaccharides from marine clams perform various biological activities, whereas information on structure is scarce. Here, a water-soluble polysaccharide MMPX-B2 was isolated from Meretrix meretrix Linnaeus. The proposed structure was deduced through characterization and its immunological activity was investigated. MMPX-B2 consisted of d-glucose and d-galctose residues at a molar ratio of 3.51:1.00. The average molecular weight of MMPX-B2 was 510 kDa. This polysaccharide possessed a main chain of (1→4)-linked-α-d-glucopyranosyl residues, partially substituted at the C-6 position by a few terminal β-d-galactose residues or branched chains consisting of (1→3)-linked β-d-galactose residues. Preliminary immunological tests in vitro showed that MMPX-B2 could stimulate the murine macrophages to release various cytokines, and the structure-activity relationship was then established. The present study demonstrated the potential immunological activity of MMPX-B2, and provided references for studying the active ingredients in M. meretrix.     

Abundance and Frequency of the Asiatic Oak Weevil (Coleoptera: Curculionidae) and Defoliation on American,Chinese, and Hybrid Chestnut (Castanea)

The Asiatic oak weevil, Cyrtepistomus castaneus Roelofs (Coleoptera: Curculionidae), is a nonnative defoliator of trees in the Fagaceae family in the United States but has not been studied on Castanea species in the southern Appalachian Mountains. Planted trees of Castanea dentata (Marsh.) Borkh. (Fagales: Fagaceae), Castanea mollissima Blume (Fagales: Fagaceae), and four hybrid breeding generations were evaluated in 2012 for insect defoliation and C. castaneus abundance and frequency. Defoliation was visually assessed throughout the growing season at two sites in the southern Appalachian Mountains (western North Carolina and eastern Tennessee). C. castaneus abundance and frequency were monitored on trees using beat sheets and emergence was recorded from ground traps. Asiatic oak weevils were more abundant and more frequently collected on American chestnut (Ca. dentata) and its most closely related BC₃F₃ hybrid generation than on the Asian species Ca. mollissima. In most months, C. castaneus colonization of hybrid generations was not significantly different than colonization of parental species. Frequency data for C. castaneus suggested that adults were distributed relatively evenly throughout the study sites rather than in dense clusters. Emergence of C. castaneus was significantly higher under a canopy dominated by Quercus species than under non-Quercus species or open sky. C. castaneus emergence began in May and peaked in late June and early July. These results may be useful for resource managers trying to restore blight-resistant chestnut to the Southern Appalachians while minimizing herbivory by insect pests.     

Studies on the utilization of Hura crepitans L. seed oil in the preparation of alkyd resins

The utilization of Hura crepitans seed oil in the formulation of alkyd resins was investigated using a two-stage alcoholysis-polyesterification method. The percentage yield of the oil was 36.4%; and the physicochemical characterization revealed that the seed oil is an unsaturated semi-drying oil. The fatty acid profile of the oil showed that it contains linoleic acid (81.6%) as the most abundant fatty acid, and two other fatty acids: palmitic acid (16.92%) and stearic acid (1.76%). Short (I), medium (II) and long (III) oil alkyds were synthesized using the oil, glycerol and phthalic anhydride in different ratios. Properties of the three prepared samples of H. crepitans seed oil alkyds having oil content of 30% (I), 50% (II), and 65% (III) were evaluated. The alkyd resins synthesized compared favourably with the commercially available alkyd resin. The presence of unsaturation in the oil was confirmed by infra-red peak at 2930 cm⁻¹ attributed to CC stretch. The infra-red peaks of the sample also compared well with that of the commercial sample indicating that H. crepitans seed oil has been successfully converted to alkyd resin. Evaluation of prepared alkyds by determination of acid values, solubility in butanol and toluene, resistance of dry film to acid, alkali and water, and drying time revealed that H. crepitans seed oil is a potential raw material for the coating industry.     

Some factors affecting the toxicity of poisons to the slug Deroceras reticulatum (Müller) (Pulmonata: Limacidae)

The toxicities of 52 phenolic and other chemicals to the grey field slug, Deroceras reticulatum (Müller 1774) (Mollusca: Pulmonata: Limacidae) were compared in laboratory tests. Stomach-poison activity was assessed by injecting measured amounts into the gut and contact-action activity by confining crawling slugs on coated glass plates. Chemical uptake into slugs was measured from aqueous solution and from a dry glass surface. Stomach-poison activity increased generally with substitution by groups increasing lipophilicity and acidity. Uptake was related to lipophilicity when slugs were immersed in aqueous solutions but not when slugs crawled on dry deposits. An expression was derived, using water solubilities and octanol/water partition coefficients, which correctly predicted uptake from an inert surface. The implications for developing chemical control methods for slugs in the field are discussed.     

Potential use of selected citrus rootstocks and interstocks against HLB disease in Malaysia

Huanglongbing (HLB), also known as citrus greening disease, has spread to and is seriously threatening the citrus industry in more than 40 countries. The HLB pathogen is a phloem limited bacteria, Candidatus Liberibacter spp. There is little information pertaining to the effects of different citrus rootstocks and interstocks against HLB in Citrus reticulata. The objective of this study was to evaluate the beneficial effects of different combinations of citrus rootstocks and interstocks against HLB using side grafting. There were no symptoms of HLB when C. grandis was used as rootstock with C. hystrix as the interstock and vice versa six months after inoculation. However, C. Liberbribacter asiaticus was detected in the scion using second PCR amplification. A high rate of disease severity was observed when C. aurantum was used as rootstock and C. aurantifolia as the interstock and vice versa. This study showed that C. Liberibacter asiaticus can be detected by conventional PCR and characteristics of their detrimental effects include low rate of vegetative growth and reduction of dry matter, root dry matter, plant height and stem diameter.     

Isolation and Characterization of Collagen and Antioxidant Collagen Peptides from Scales of Croceine Croaker (Pseudosciaena crocea)

Acid soluble collagen (ASC) from scales of croceine croaker (ASC-C) was successfully isolated with the yield of 0.37% ± 0.08% (dry weight basis), and characterized as type I collagen on the basis of amino acid analysis and electrophoretic pattern. The antioxidant hydrolysate of ASC-C (ACH) was prepared through a two-stage in vitro digestion (4-h trypsin followed by 4-h pepsin), and three antioxidant peptides (ACH-P1, ACH-P2, and ACH-P3) were further isolated from ACH using ultrafiltration, gel chromatography, and RP-HPLC, and their amino acid sequences were identified as GFRGTIGLVG (ACH-P1), GPAGPAG (ACH-P2), and GFPSG (ACH-P3). ACH-P1, ACH-P2, and ACH-P3 showed good scavenging activities on hydroxyl radical (IC₅₀ 0.293, 0.240, and 0.107 mg/mL, respectively), DPPH radical (IC₅₀ 1.271, 0.675, and 0.283 mg/mL, respectively), superoxide radical (IC₅₀ 0.463, 0.099, and 0.151 mg/mL, respectively), and ABTS radical (IC₅₀ 0.421, 0.309, and 0.210 mg/mL, respectively). ACH-P3 was also effectively against lipid peroxidation in the model system. The antioxidant activities of three collagen peptides were due to the presence of hydrophobic amino acid residues within the peptide sequences. The collagen peptides might be used as antioxidant for the therapy of diseases associated with oxidative stress, or reducing oxidative changes during storage.     

Feeding disruption tests for monitoring the frequency of larval lepidopteran resistance to Cry1Ac, Cry1F and Cry1Ab

An alternative to traditional larval lepidopteran resistance-monitoring bioassays was developed. Feeding disruption tests were developed for detecting insects resistant to three Bacillus thuringiensis (Bt) proteins: Cry1Ac, Cry1F and Cry1Ab. The assays rely on a diagnostic dose of Bt toxin in 100-μl hydratable meal pads of artificial diet containing blue indicator dye. The assay was formatted as a portable (palm-sized) plastic plate containing an array of 16 test wells, each containing a single hydratable meal pad with one insect added per well. The diagnostic dose was the concentration of Bt in meal pad rehydration solution that reduced 24 h dyed fecal production of Bt-susceptible neonates to ≤2 fecal pellets per larva. Bt-resistant neonates were able to consume the diagnostic dose of the insecticidal protein and produce >2 blue fecal pellets. The feces were distinctly visible on the white background of the feeding disruption test plate. Diagnostic doses were determined with lab-strain Bt-susceptible Heliothis virescens and Helicoverpa zea. For H. virescens, the diagnostic doses were 10, 20 and 15 μg/ml for Cry1Ac, Cry1F and Cry1Ab, respectively. For H. zea, the diagnostic doses were 40, 200 and 500 μg/ml, respectively. The assays were validated against a lab-strain of Bt-resistant H. virescens and with susceptible larval H. virescens collected as eggs from field-grown tobacco in North Carolina.     

Isolation and Structural Characterization of a Novel Antioxidant Mannoglucan from a Marine Bubble Snail,Bullacta exarata (Philippi)

Bullacta exarata is one of the most economically important aquatic species in China, noted for not only its delicious taste and nutritional value, but also for its pharmacological activities. In order to explore its potential in medical applications, a mannoglucan designated as BEPS-IB was isolated and purified from the foot muscle of B. exarata after papain digestion. Chemical composition analysis indicated BEPS-IB contained mainly d-glucose and d-mannose in a molar ratio of 1:0.52, with an average molecular weight of about 94 kDa. The linkage information was determined by methylation analysis, and the anomeric configuration and chain linkage were confirmed by IR and 2D NMR. The results indicated BEPS-IB was composed of Glcp₆Manp heptasaccharide repeating unit in the backbone, with occasional branch chains of mannose residues (14%) occurring in the backbone mannose. Further antioxidant assay indicated BEPS-IB exhibited positive antioxidant activity in scavenging superoxide radicals and reducing power. This is the first report on the structure and bioactivity of the mannoglucan from the B. exarata.     

Quality characteristics and field performance of selectable marker-free transgenic rice with antisense Wx gene and improved quality derived from the elite parents of hybrid indica rice

In rice grains, high amylose content (AC) is correlated with poor grain quality, particularly in indica hybrid rice. To obtain indica hybrid rice with improved cooking and eating qualities, we introduced the antisense Waxy (Wx) gene into 2 elite parental lines of indica hybrid rice by using co-transformation methods. Subsequently, we selected several elite homozygous transgenic lines that did not contain the selectable marker. The expression of the endogenous Wx gene of the selected transgenic lines was significantly downregulated, resulting in low AC in the mature seeds; moreover, the AC in some lines reduced to the level observed in glutinous rice. With the decrease in AC, the gel consistency of the transgenic rice became softer, and the gelatinization temperature tended to be higher than those of the wild types, especially in the case of the Longtefu-derived transformants. We also analyzed the pasting properties of the selected transgenic low-AC lines, and we noted an improvement in the pasting properties of the transgenic rice lines. The results from a field trial indicated that the grain weights of the transgenic lines with lower AC exhibit remarkable reduction compared with those of the wild types.     

Adventitious root cultures of Castilleja tenuiflora Benth. as a source of phenylethanoid glycosides

Castilleja tenuiflora is a highly valued medicinal plant that grows in pine-oak woods in Mexico. In this study, we identified for the first time verbascoside and isoverbascoside as the major phenylethanoid glycosides (PhGs) in C. tenuiflora. These compounds have proven biological activities, including anti-inflammatory, antioxidant, and cytotoxic activities, which may be related to the traditional uses of this plant. We developed a reverse-phase high-performance liquid chromatography (RP-HPLC) procedure to analyze PhGs, and determined their concentrations in various different tissues of wild plants. Verbascoside accumulated mainly in roots and inflorescences (9.23 and 7.88 mg g⁻¹ dry biomass, respectively), while isoverbascoside accumulated mainly in the roots (7.13 mg g⁻¹ dry biomass). To provide an alternative source of material for production of bioactive compounds, we established in vitro adventitious root cultures in which roots were grown in B5 medium containing either 10 μM indole 3-acetic acid (IAA) or 10 μM α-naphthaleneacetic acid (NAA). The greatest dry biomass yield (30 g L⁻¹) was achieved at 30 days after transfer of roots into IAA-containing medium. The highest specific yields of PhGs were also obtained using this auxin; the maximum level of verbascoside was 14.62 mg g⁻¹ dry root biomass (438.6 mg L⁻¹) at 30 days after root transfer, and the maximum yield of isoverbascoside was 37.32 mg g⁻¹ dry root biomass (522.48 mg L⁻¹) at 23 days after root transfer. Adventitious root cultures of C. tenuiflora are a promising system for further studies on scale-up and phenylethanoid glycosides biosynthesis.     

Evaluation of the yield potential and physicochemical properties of the biomass of Salix viminalis × Populus tremula hybrids

This study presents the characteristics of four Salix viminalis × Populus tremula hybrids, produced for the first time in the world grown in a three-year field experiment. Shoot weight per plant and major biomass yield components, including plant height, number of shoots per rootstock and shoot diameter, were determined. The infection severity caused by leaf rust (Melampsora sp.) was also evaluated. The biomass of three-year-old hybrid plants was subjected to chemical analyses and calorimetric tests to determine the energy value of biomass as solid fuel. Among the studied genotypes the highest yield was achieved by one of the studied hybrids. Its biometric parameters did not differ significantly from the standard genotype, and they were superior to the parameters of the maternal form. All Salix × Populus hybrids were more susceptible to rust infections than their maternal form and one hybrid was more resistant to infections caused by fungi of the genus Melampsora. Two hybrids have optimal biomass parameters as regards both calorific value and amount of carbon, hydrogen, sulfur and nitrogen.     

Susceptibility of Helicoverpa armigera from different host plants in northern China to Bacillus thuringiensis toxin Cry1Ac

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a serious pest of cotton and many other crops in northern China. To evaluate the contribution of alternative hosts as an effective refuge for transgenic cotton expressing the Bacillus thuringiensis (Bt) Cry1Ac toxin, the susceptibility to this toxin was measured in progeny derived from field-collected H. armigera larvae and pupae from different hosts in the Xiajin’s region of the Shandong Province in northern China. During 2008-2010, progeny from a total of 258,56,184 and 160 single-pair crosses derived from wheat (first-generation), Bt cotton (second-generation), Bt cotton (third-generation), and corn (third-generation) were screened on Cry1Ac diets, respectively. Based on relative average development rates (RADR) of H. armigera larvae in these F₁ tests, the second and third-generation moths emerging from Bt cotton fields were more tolerant to the Bt toxin than the first and third-generation moths emerging from wheat and corn each year. These results suggest that there is significant variation in susceptibility to Bt toxins among H. armigera populations derived from different host crops. Alternate crops, such as corn, that maintain Bt susceptible populations of H. armigera could be used as refugia to minimize the evolution of resistance to Bt cotton.     

Histological development of the sunflower fruit pericarp as affected by pre- and early post-anthesis canopy shading

The dynamics of pericarp development compared to that of the embryo, as well as the effect of pre-anthesis and post-anthesis shading on pericarp histogenesis and dry weight dynamics of fruits from two sunflower (Helianthus annuus L.) hybrid cultivars along three capitulum positions, peripheral, mid and central were studied. During fruit formation, the cell division phase of the carpel takes place before anthesis. Eight days after anthesis the pericarp reached its final size, while its cell wall's sclerification was almost complete 13 days after anthesis. Pre-anthesis shading affected the carpel cell division period reducing (17–33%) the number of pericarp middle layer strata and increased the thickenings of the cell wall of the mid (19%) and central (33–63%) fruits. In central fruits, the dry weight accumulation period was reduced. In contrast, post-anthesis shading reduced both the cell wall thickness (16–64%) and the number (38–58%) of pericarp middle layer sclerified strata of fruits in the three positions of the capitulum. In the mid and central fruits, the dry weight accumulation period extended 11–16 and 3–4 days, respectively, over those of the control. Both shading treatments produced thinner and lighter pericarps, but with different anatomical features that were associated with differences in the efficiency of use of the fruit for industrial oil extraction.