Biodegradable nanoparticles have been widely explored as carriers for controlled delivery of therapeutic molecules; however, studies describing the development of nanoparticles as carriers for ...biopesticide products are few. In this work, a new method to prepare nanoparticles loaded with neem (Azadirachta indica) extracts is presented. In this study, nanoparticles were formulated as colloidal suspension and (spray-dried) powder and characterized by evaluating pH, particle size, zeta potential, morphology, absolute recovery, and entrapment efficiency. A high-performance liquid chromatography method was used for nanoparticle characterization. The best formulations presented absolute recovery and entrapment efficiencies of approximately 100% and a release profile based on swelling and relaxation of the polymer or polymer erosion. The biological data of the formulated products against Plutella xylostella showed 100% larval mortality. The nanoparticle information improved the stability of neem products against ultraviolet radiation and increased their dispersion in the aqueous phase.
HPLC-UV and MALDI imaging on citrus with citrus variegated chlorosis (CVC) showed higher concentrations of hesperidin in infected plants than in healthy ones. Display omitted
•MALDI imaging mass ...spectrometry was applied to study the tissue distribution of hesperidin.•HPLC-UV analyses of citrus with citrus variegated chlorosis (CVC) showed hesperidin was at higher concentration in leaves.•HPLC-UV analyses can screen many samples for CVC per hour using about 1mg of leaves.•Hesperidin has a role in plant–pathogen interaction, probably as a phytoanticipin.•Increase in hesperidin content can be related to induced defense mechanisms.
A high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed for quantifying hesperidin and rutin levels in leaves and stems of Citrus limonia, with a good linearity over a range of 1.0–80.0 and 1.0–50.0μgmL−1 respectively, with r2>0.999 for all curves. The limits of detection (LOD) for both flavonoids were 0.6 and 0.5μgmL−1, respectively, with quantification (LOQ) being 2.0 and 1.0μgmL−1, respectively. The quantification method was applied to Citrus sinensis grafted onto C. limonia with and without CVC (citrus variegated chlorosis) symptoms after Xylella fastidiosa infection. The total content of rutin was low and practically constant in all analyses in comparison with hesperidin, which showed a significant increase in its amount in symptomatic leaves. Scanning electron microscopy studies on leaves with CVC symptoms showed vessel occlusion by biofilm, and a crystallized material was noted. Considering the difficulty in isolating these crystals for analysis, tissue sections were analyzed by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to confirm the presence of hesperidin at the site of infection. The images constructed from MS/MS data with a specific diagnostic fragment ion (m/z 483) also showed higher ion intensities for it in infected plants than in healthy ones, mainly in the vessel regions. These data suggest that hesperidin plays a role in the plant-pathogen interaction, probably as a phytoanticipin. This method was also applied to C. sinensis and C. limonia seedlings, and comparison with the graft results showed that the rootstock had an increased hesperidin content ∼3.6 fold greater in the graft stem than in the stem of C. sinensis seedlings. Increase in hesperidin content by rootstock can be related to induced internal defense mechanisms.
Citrus canker, caused by the bacterium
subsp.
(
), is a disease that causes serious problems to the global citrus industry. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass ...Spectrometry (MS) has been used in human medicine to diagnose various diseases caused by both fungi and bacteria. In agriculture, this technique has potential for the diagnosis of diseases due to the low cost of large-scale analysis and quickness. This study showed that MALDI-TOF MS combined with chemometric analysis was effective for differentiating the macromolecule profile of orange leaves with canker lesions, healthy leaves, and leaves with phytotoxicity symptoms, proving that this technique may be used for the rapid diagnosis of citrus canker.
Abstract
Essential oils are volatile compounds commonly used by several industries, easily degradable, which restrains their applications. Therefore, we developed and validated a methodology for ...producing microcapsules loaded with orange essential oil, using a spray-drying process. The experimental design results showed that the combination between a low flow transfer rate (0.15 L h
−1
) of the colloidal suspension, a higher drying air flow rate (536 L h
−1
), and an inlet air temperature of 150 °C to the spray-dryer were the most important parameters for the atomization efficiency. The method optimization resulted in microcapsules with powder recovery between 7.6 and 79.9% (w w
−1
), oil content ranging from 8.9 to 90.4% (w w
−1
), encapsulation efficiency between 5.7 and 97.0% (w w
−1
), and particle sizes with a high frequency of distribution less than 4 μm. In these experiments, gelatin and lignin were evaluated as biopolymers of encapsulation. We also developed an analytical method using headspace gas chromatography. The matrix effects could be addressed by using matrix-matched calibration curves. The chromatographic analysis was linear and selective for
d
-limonene between 0.025 and 3.00 µg mL
−1
, with correlation coefficients higher than 0.99. The analytical method had limits of detection and quantitation of 0.024 and 0.073 mg g
−1
for gelatin and 0.039 and 0.119 mg g
−1
for lignin, respectively.
Rationale
Xylella fastidiosa causes citrus variegated chlorosis (CVC) in sweet orange trees. A diagnostic method for detecting CVC before the symptoms appear, which would inform citrus producers in ...advance about when the plant should be removed from the orchard, is essential for reducing pesticide application costs.
Methods
Chemometrics was applied to high‐performance liquid chromatography diode array detector (HPLC‐DAD) data to evaluate the similarities and differences between the chromatographic profiles. A liquid chromatography/atmospheric pressure chemical ionization mass spectrometry selected reaction monitoring (LC/APCI‐MS‐SRM) method was developed to identify the major compounds and to determine their amounts in all samples.
Results
We evaluated the effect of this bacterium on the variation in the chemical profile in citrus plants. The organs of C. sinensis grafted on C. limonia were analyzed. Chemometrics was applied to the obtained data, and two major groups were differentiated. Flavonoids were observed in one group (leaves) and coumarins in the second (roots), both at higher concentrations in the plants with CVC symptoms than in those without the symptoms and those in the negative control. The rootstocks also interfered in the metabolism of the scion.
Conclusions
The developed LC/APCI‐MS‐SRM method for detecting CVC before the symptoms appear is simple and accurate. It is inexpensive, and many samples can be screened per hour using 1 mg of leaves. Knowledge of the influence of the rootstock on the chemical profile of the graft is limited. This study demonstrates the effect of the rootstock in synthesizing flavonoids and increasing its content in all parts of the graft.
The epidemic transmission of Zika virus (ZIKV) in Brazil has been identified as a cause of microcephaly and other neurological malformations in the babies of ZIKV-infected women. The frequency of ...adverse outcomes of Zika virus infection (ZIKVi) in pregnancy differs depending on the characteristics of exposure to infection, the time of recruitment of research participants, and the outcomes to be observed. This study provides a descriptive analysis-from the onset of symptoms to delivery-of a cohort registered as having maternal ZIKVi in pregnancy, from November 2015 to December 2016. Suspected cases were registered at a referral center for infectious and tropical diseases in Manaus, in the Amazonian region of Brazil. Of 834 women notified, 762 women with confirmed pregnancies were enrolled. Reverse-transcriptase polymerase chain reaction (RT-PCR) confirmed ZIKVi in 42.3% of the cohort. In 35.2% of the cohort, ZIKV was the sole infection identified. Severe adverse pregnancy outcomes (miscarriage, stillbirth, or microcephaly) were observed in both RT-PCR ZIKV-positive (5.0%) and ZIKV-negative (1.8%) cases (RR 3.1; 95% IC 1.4-7.3;
< 0.05), especially during the first trimester of pregnancy (RR 6.2, 95% IC 2.3-16.5;
< 0.001). Although other infectious rash diseases were observed in the pregnant women in the study, having confirmed maternal ZIKVi was the most important risk factor for serious adverse pregnancy events.
(Pax & K. Hoffm.) Ducke (Euphorbiaceae) is a singular species in the genus and is restricted and exclusive to the Brazilian Amazon. A phytochemical study of
leaves was performed, yielding the ...isolation of five major compounds: catechin/epicatechin, afzelin, quercetin 3-
-α-L-rhamnopyranoside, and astilbin. The phytochemical compositions of the methanolic extracts of leaves, roots, bark, and stem bark were determined using a dereplication approach. Forty-six compounds were annotated from the liquid chromatography-mass spectrometry (LC-MS/MS) data, while four lipids were identified using gas chromatography-mass spectrometry (GC-MS). In total, fifty compounds were detected, and they belonged to the primary metabolism and several classes of natural products such as flavonoids, flavonoids
-glycosides, flavonoids
-glycosides, biflavonoids, procyanidin, triterpene, triterpenes esterified with phenylpropanoids, phenylpropanoid derivatives, flavonolignans, coumarins, quinic acid derivatives, and benzoic acid derivatives. This is the first report on the phytochemical data of the genus
, and the results of this study will contribute to the chemosystematic knowledge of the Euphorbiaceae family and justify the need for investigation of the pharmacological potential of the species
.
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NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 ...proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44μM. Agathisflavone (1) and myricetin (4) turned out to be noncompetitive inhibitors of dengue virus serotype 2 NS2B-NS3 protease with Ki values of 11 and 4.7μM, respectively. Docking studies propose a binding mode of the flavonoids in a specific allosteric binding site of the enzyme. Analysis of biomolecular interactions of quercetin (5) with NT647-NHS-labeled Dengue virus serotype 3 NS2B-NS3 protease by microscale thermophoresis experiments, yielded a dissociation constant KD of 20μM. Our results help to understand the mechanism of inhibition of the Dengue virus serine protease by flavonoids, which is essential for the development of improved inhibitors.
The fungus
Beauveria bassiana
is widely used for pest control; however, biostability and dispersion for broth pulverization are limiting factors for its application in the field. In this context, ...formulation techniques such as microencapsulation are viable alternatives. The aim of this work is to optimize
B. bassiana
formulations by spray dryer and evaluate its stability and biological activity against
Spodoptera cosmioides
compared to ionic gelatinization formulations. The fungus was biocompatible with all evaluated biopolymers (lignin, cellulose, starch, humic substances, and alginate). The encapsulation by spray drying was optimized by factorial design in an inlet and outlet air temperature of 120°C and 68°C, respectively; aspirator rate of 35 m
3
·h
−1
, feed flow rate of 12 mL·min
−1
; and drying gas flow at 35 L·h
−1
. The ionic gelation capsules were obtained using a 0.5% quantity of conidia in a 1% sodium alginate solution dropped into a 0.5 mol·L
−1
CaCl
2
solution using a peristaltic pump. Spray drying provided smaller microcapsules than those by ionic gelation. Both techniques produced more stable conidia when exposed to temperature and UV-radiation than non-formulated
B. bassiana
. The formulations prepared by spray drying showed gains at aqueous dispersion. Biological assays against
Spodoptera cosmioides
showed a mortality rate of up to 90%. These results demonstrate the suitability of encapsulating
B. bassiana
conidia stably in aqueous dispersion without loss of viability and virulence.
Fruit processing waste, such as kernels (endocarp + seed) of avocado
Persea americana
Mill. (Lauraceae), could be used as raw material in the preparation of botanical insecticides. In light of this ...potential, this study assessed the insecticidal action of extracts and fractions from kernels of two avocado cultivars (Breda and Margarida) on
Bemisia tabaci
(Gennadius) (Hemiptera: Aleyrodidae) biotype B, an important pest species in tropical conditions. Ethanolic and aqueous extracts prepared from kernels of
P. americana
, regardless of the plant cultivar used, caused promising insecticidal activity to whitefly nymphs. Based on yield in crude extracts 10.32 and 9.85% (w/w), respectively, for cultivars Breda and Margarida, on the bioassay results with crude extracts and on the chemical profiles, the ethanolic extract of kernels of
P. americana
cv. Breda was chose for the continuation of the study. Thus, the ethanolic extract of kernels of cv. Breda (LC
50
= 197.84 ppm and LC
90
= 567.19 ppm) was selected and subjected to fractionation by the liquid-liquid partition technique. The hexane and dichloromethane fractions of this extract caused significant mortality of nymphs. The analysis using the ultraviolet (UV) and hydrogen nuclear magnetic resonance (
1
H NMR) showed the presence of long-chain aliphatic compounds (alkanols or acetogenins of Lauraceae), alkylfurans (or avocadofurans), and unsaturated fatty acids in these fractions, which are possibly related to bioactivity observed in
B. tabaci
, besides saccharides. The results show that kernels of
P. americana
are promising sources of compounds with insecticidal action for the control of
B. tabaci
biotype B, a great opportunity to transform environmental problems into eco-friendly solutions to agriculture.
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