Nematic reorientation effects on resonant modes, wavelength mismatch, and slow-light phenomena in one-dimensional magnetophotonic crystals with a dual anisotropic defect

The present study is devoted to the investigation of spectral properties of an alternated sequence of magnetic and dielectric layers containing a dual defect based on magnetic and nematic layers. Combining the Hydrodynamic Continuum Theory for nematic liquid crystals and Berreman's formalism, we determine how the nematic ordering affects the light localization, polarization rotation, and slow-light phenomena observed in the magnetophotonic system. In particular, we analyze the effects associated with a field-induced reorientation of the director in a nematic defect with strong planar boundary conditions. Our results reveal that field-induced reorientation of the nematic ordering can be used as an efficient mechanism to tune and control the spectral properties of magnetophotonic structure, anomalies in group velocity, and the wavelength mismatch between resonant mode and maximum polarization. The effects of nematic layer thickness are also analyzed.

Metabolomic fingerprinting of Cissampelos sympodialis Eichler leaf extract and correlation with its spasmolytic activity

ETHNOPHARMACOLOGICAL RELEVANCE

Cissampelos sympodialis Eichler (Menispermaceae) is popularly used in northeastern Brazil for the treatment of respiratory diseases such as bronchitis and asthma. Despite many pre-clinical pharmacological studies, the compounds mediating the anti-asthma activity of polar extracts of Cissampelos sympodialis leaves have not been definitively identified.

AIM OF THE STUDY

Aim of the study: The aim of the study was to investigate the correlation between the bioactivity of polar extracts prepared from the leaves of C. sympodialis and the chemical composition using a ¹H-NMR-based metabolomics approach.

MATERIAL AND METHODS

The metabolic profile of the leaf polar extract during different phenological stages of the plant was investigated using ¹H NMR spectroscopy while simultaneously screening for spasmolytic activity using guinea-pig tracheal preparations. The content of the alkaloids previously implicated in the bioactivity of Cissampelos sympodialis was determined by HPLC.

RESULTS

PCA analysis of the ¹H NMR data discriminated the extracts from different plant phenological stages. The contents of the major alkaloids decrease (from 2 ± 0.32 μg/mL for warifteine and 1 ± 0.14 μg/mL for methylwarifteine) to undetectable levels from 90 (CsL₉₀ extract) and 120 (CsL₁₂₀) days onwards for warifteine and methylwarifteine, respectively. All six extracts relaxed the trachea pre-contracted with carbachol, but the CsF₂₁₀ extract was more potent (EC₅₀ = 74.6 ± 7.9 μg/mL) compared to both CsL₉₀ extracts and CsL₁₈₀ in the presence of functional epithelium. PLS regression analysis of ¹H-NMR spectral data demonstrated that the spasmolytic activity was better correlated with signals for flavonol derivatives.

CONCLUSIONS

Our data challenge the idea that warifteine and methylwarifteine mediate the spasmolytic activity of the polar extract of C. sympodialis leaves.

Cleaning cassava genotypes infected with cassava frogskin disease via in vitro shoot tip culture

This study aimed to develop a methodology for eliminating cassava frogskin disease (CFSD) from in vitro shoot tip culture by associating thermotherapy and tetracycline. Cuttings from different accessions (BGM0232, BGM0315, BGM0464, BGM584, BGM0841, and BGM1342), infected with CFSD according to visual inspection of the disease symptoms, were used for cleaning. To verify the absence of other diseases, the plants were indexed for Cassava common mosaic virus - CsCMV (by ELISA) and Cassava vein mosaic virus - CsVMV (by polymerase chain reaction, PCR), proving that the accessions were free of these viruses, except for BGM0315 and BGM0464, which were infected with CsVMV. Subsequently, the cuttings were submitted to different tetracycline concentrations for 3 min, and then subjected to thermotherapy under different temperatures (35°, 38°, 40°, 45°, and 55°C). Shoots of 2 cm were harvested, and their surfaces were sterilized in a laminar flow chamber. Subsequently, the shoot tips of different sizes were removed (0.2, 0.4, 0.5, and 1.0 mm) for inoculation in a culture medium with tetracycline at the same concentrations in which the cuttings were dipped. After 60 days of cultivation, the explants were transferred to a multiplication medium without antibiotics. Thirty days after the transfer, the viability of the regenerated plants was evaluated, which were then acclimatized for 70 days in a greenhouse and transferred to the field. After 7 months, a visual analysis of the symptomatic roots and a PCR analysis were held to prove the elimination of CFSD and CsVMV from the accessions infected with these viruses (BGM0315 and BGM0464), respectively. Most of the treatments resulted in 100% cleaning of CFSD-infected plants. From accessions that were also infected with CsVMV, only 2% of the plants remained infected, also demonstrating the cleaning efficiency of this protocol for this disease.

Phenotypic diversity of starch granules in cassava germplasm

Demand for the development of cassava varieties with different native starches has guided the search for these characteristics in the germplasm of Manihot esculenta Crantz. Therefore, the objective of this study was to estimate the genetic diversity of cassava accessions for root and starch granule characteristics to guide the future industrial application of this species. Starches from 56 accessions were evaluated for the number of granules in 1 g of starch (NTG), area (AG, μm²), length (LG, μm), width (WG, μm), starch granule roundness (Round), dry matter content in the roots (DMC, %), pulp color (PulCo), and cyanogenic compounds (HCN). Images captured by light microscopy were used to determine the average phenotypic values, and these were further analyzed by principal component analysis (PCA) considering mixed data (quantitative and qualitative). Significant differences between the cassava accessions for all traits measured revealed wide variability in starch granule characteristics. Four diversity groups with better fitness for the classification of cassava accessions based on PulCo were identified, in comparison with HCN. Accessions with differential starch characteristics were identified, and crossings for the generation of segregating populations in order to obtain table and industry varieties have been proposed.

New accuracy estimators for genomic selection with application in a cassava (Manihot esculenta) breeding program

Genomic selection is the main force driving applied breeding programs and accuracy is the main measure for evaluating its efficiency. The traditional estimator (TE) of experimental accuracy is not fully adequate. This study proposes and evaluates the performance and efficiency of two new accuracy estimators, called regularized estimator (RE) and hybrid estimator (HE), which were applied to a practical cassava breeding program and also to simulated data. The simulation study considered two individual narrow sense heritability levels and two genetic architectures for traits. TE, RE, and HE were compared under four validation procedures: without validation (WV), independent validation, ten-fold validation through jacknife allowing different markers, and with the same markers selected in each cycle. RE presented accuracies closer to the parametric ones and less biased and more precise ones than TE. HE proved to be very effective in the WV procedure. The estimators were applied to five traits evaluated in a cassava experiment, including 358 clones genotyped for 390 SNPs. Accuracies ranged from 0.67 to 1.12 with TE and from 0.22 to 0.51 with RE. These results indicated that TE overestimated the accuracy and led to one accuracy estimate (1.12) higher than one, which is outside of the parameter space. Use of RE turned the accuracy into the parameter space. Cassava breeding programs can be more realistically implemented using the new estimators proposed in this study, providing less risky practical inferences.

Inducing autotetraploids in cassava using oryzalin and colchicine and their in vitro morphophysiological effects

Polyploid induction has been used for plant breeding to produce bigger and more robust plants than diploid types. The present study aimed to develop a methodology for in vitro induction of polyploidy in cassava. Apical and lateral microcuttings from the BRS Formosa variety were treated with six oryzalin concentrations for 24 and 48 h. The same methodology was used for colchicine with different concentrations. After 45 days of cultivation and an additional 45 days of subculture, the viability of the explants was assessed and plant acclimatization was performed. Ploidy was determined using flow cytometry. Oryzalin dose and exposure negatively affected cassava explant growth and development compared to untreated explants. Furthermore, apical and lateral explants responded differently to the treatments, showing a diversity in antimitotic sensitivity and effect that is tissue-type specific. In contrast, the doses of 1.25 to 6.25 mM colchicine resulted in high mortality of cassava explants. Therefore, the type of antimitotic affects the morphophysiological behavior of cassava plants in vitro, although apical explants have higher viability and regenerative capacity compared to lateral explants. In addition, the lateral explants have lower mixoploid rates compared to apical explants. Of the 310 plants generated by oryzalin treatments, 277 were diploid, 31 were mixoploid, and 2 were tetraploid. Exposure to oryzalin led to low rate of tetraploids and colchicine caused phytotoxic reactions and death of the explants. The tetraploids were multiplied in vitro to evaluate their yield in the field as well as their behavior against abiotic and biotic stress.

A proteomic road to acquire an accurate serological diagnosis for human tegumentary leishmaniasis

Diagnostic tools are important for clinical management and epidemiological evaluation of Tegumentary (TL) and Visceral (VL) Leishmaniasis. Serology is not frequently used for the diagnosis of the TL form because low antibody titers and cross-reaction with VL. Therefore, it is crucial to identify specific and immunogenic antigens from species associated with the TL form. Here we employed a proteomic approach coupled to an in silico analysis and identified the most abundant and immunogenic proteins from Leishmania amazonensis, Leishmania braziliensis and Leishmania infantum. Of 16 species specific proteins, nine were from the species causative of the TL form (L. amazonensis and L. braziliensis). In silico analysis revealed 18 B-cell epitopes with 0% similarity to Trypanosoma cruzi orthologs and, therefore, less likely to crossreact with sera of patients with Chagas disease. Two proteins reacted exclusively with serum from TL patients and presented several B-cell epitopes without similarity to T. cruzi orthologs: the hypothetical protein GI 134063939 and the metallo-peptidase Clan MA(E)-Family M3. The immunoassay revealed nine peptides with strong reactivity to sera from TL patients. These proteins and peptides may be good candidates to improve the specificity and sensibility of serological tests aiming to diagnose the TL of this neglected human disease.

BIOLOGICAL SIGNIFICANCE

As no gold-standard test for tegumentary leishmaniasis (TL) exists, a combination of different diagnostic techniques is often necessary to obtain precise results. Thus, the identification of species-specific, highly immunogenic and abundant proteins that stimulate the humoral immune response in the host should help in the development of serological tests for human TL. Herein we searched for these potential antigens in Leishmania species related to American Leishmaniasis (L. amazonensis, L. braziliensis and L. infantum). To this end, we employed an immunoproteomic approach using proteins from these Leishmania species and sera from TL and Visceral Leishmaniasis (VL) patients. Our study unveils specific proteins and peptides that may represent antigens that will help the efforts to improve the accuracy of serological tests to diagnose the TL form.

Variation in cassava germplasm for tolerance to post-harvest physiological deterioration

Tolerant varieties can effectively control post-harvest physiological deterioration (PPD) of cassava, although knowledge on the genetic variability and inheritance of this trait is needed. The objective of this study was to estimate genetic parameters and identify sources of tolerance to PPD and their stability in cassava accessions. Roots from 418 cassava accessions, grown in four independent experiments, were evaluated for PPD tolerance 0, 2, 5, and 10 days post-harvest. Data were transformed into area under the PPD-progress curve (AUP-PPD) to quantify tolerance. Genetic parameters, stability (Si), adaptability (Ai), and the joint analysis of stability and adaptability (Zi) were obtained via residual maximum likelihood (REML) and best linear unbiased prediction (BLUP) methods. Variance in the genotype (G) x environment (E) interaction and genotypic variance were important for PPD tolerance. Individual broad-sense heritability (hg(2)= 0.38 ± 0.04) and average heritability in accessions (hmg(2)= 0.52) showed high genetic control of PPD tolerance. Genotypic correlation of AUP-PPD in different experiments was of medium magnitude (ȓgA = 0.42), indicating significant G x E interaction. The predicted genotypic values o f G x E free of interaction (û + ĝi) showed high variation. Of the 30 accessions with high Zi, 19 were common to û + ĝi, Si, and Ai parameters. The genetic gain with selection of these 19 cassava accessions was -55.94, -466.86, -397.72, and -444.03% for û + ĝi, Si, Ai, and Zi, respectively, compared with the overall mean for each parameter. These results demonstrate the variability and potential of cassava germplasm to introduce PPD tolerance in commercial varieties.

Informativeness of minisatellite and microsatellite markers for genetic analysis in papaya

The objective of this study was to evaluate information on minisatellite and microsatellite markers in papaya (Carica papaya L.). Forty minisatellites and 91 microsatellites were used for genotyping 24 papaya accessions. Estimates of genetic diversity, genetic linkage and analyses of population structure were compared. A lower average number of alleles per locus was observed in minisatellites (3.10) compared with microsatellites (3.57), although the minisatellites showed rarer alleles (18.54 %) compared with microsatellite (13.85 %). Greater expected (He = 0.52) and observed (Ho = 0.16) heterozygosity was observed in the microsatellites compared with minisatellites (He = 0.42 and Ho = 0.11), possibly due to the high number of hermaphroditic accessions, resulting in high rates of self-fertilization. The polymorphic information content and Shannon-Wiener diversity were also higher for microsatellites (from 0.47 to 1.10, respectively) compared with minisatellite (0.38 and 0.85, respectively). The probability of paternity exclusion was high for both markers (>0.999), and the combined probability of identity was from 1.65(-13) to 4.33(-38) for mini- and micro-satellites, respectively, which indicates that both types of markers are ideal for genetic analysis. The Bayesian analysis indicated the formation of two groups (K = 2) for both markers, although the minisatellites indicated a substructure (K = 4). A greater number of accessions with a low probability of assignment to specific groups were observed for microsatellites. Collectively, the results indicated higher informativeness of microsatellites. However, the lower informative power of minisatellites may be offset by the use of larger number of loci. Furthermore, minisatellites are subject to less error in genotyping because there is greater power to detect genotyping systems when larger motifs are used.

Distinct effects of novel naphtoquinone-based triazoles in human leukaemic cell lines

Objectives

The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines.

Methods

The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed.

Key findings

C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 μm and 41 μm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level.

Conclusion

Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Classification of cassava genotypes based on qualitative and quantitative data

We evaluated the genetic variation of cassava accessions based on qualitative (binomial and multicategorical) and quantitative traits (continuous). We characterized 95 accessions obtained from the Cassava Germplasm Bank of Embrapa Mandioca e Fruticultura; we evaluated these accessions for 13 continuous, 10 binary, and 25 multicategorical traits. First, we analyzed the accessions based only on quantitative traits; next, we conducted joint analysis (qualitative and quantitative traits) based on the Ward-MLM method, which performs clustering in two stages. According to the pseudo-F, pseudo-t2, and maximum likelihood criteria, we identified five and four groups based on quantitative trait and joint analysis, respectively. The smaller number of groups identified based on joint analysis may be related to the nature of the data. On the other hand, quantitative data are more subject to environmental effects in the phenotype expression; this results in the absence of genetic differences, thereby contributing to greater differentiation among accessions. For most of the accessions, the maximum probability of classification was >0.90, independent of the trait analyzed, indicating a good fit of the clustering method. Differences in clustering according to the type of data implied that analysis of quantitative and qualitative traits in cassava germplasm might explore different genomic regions. On the other hand, when joint analysis was used, the means and ranges of genetic distances were high, indicating that the Ward-MLM method is very useful for clustering genotypes when there are several phenotypic traits, such as in the case of genetic resources and breeding programs.

Adaptability and stability analysis of the juice yield of yellow passion fruit varieties

This study analyzed the genotype x environment interaction (GE) for the juice productivity (JuProd) of 12 yellow passion fruit varieties (Passiflora edulis Sims. f. flavicarpa Deg.) using additive main effects and multiplicative interaction (AMMI) model and auxiliary parameters. The experiments were conducted in eight environments of Bahia State, Brazil, using a randomized block design with three replications. Analysis of variance showed significant effects (P ≤ 0.01) for environments, genotypes, and GE interaction. The first two interaction principal component axes (IPCAs) explained 81.00% of the sum of squares of the GE interaction. The AMMI1 and AMMI2 models showed that varieties 09 and 11 were the most stable. Other parameters, namely, the AMMI stability value (ASV), yield stability (YSI), sustainability, and stability index (StI), indicated that other varieties were more stable. These varying results were certainly a consequence of methodological differences. In contrast, the ranking of varieties for each of the stability parameters showed significant positive correlations (P ≤ 0.05) between IPCA1 x (ASV, YSI), JuProd x (StI, YSI), YSI x ASV, and StI x YSI. Cluster analysis based on the genotypic profile of the effects of the GE interaction identified three groups that correlated with the distribution of varieties in the AMMI1 biplot. However, the classification of stable genotypes was limited because the association with the productivity was not included in the analysis. Variety 08 showed the most stable and productive behavior, ranking above average in half of the environments, and it should be recommended for use.

Development of a cassava core collection based on single nucleotide polymorphism markers

Single nucleotide polymorphism (SNP) markers were used in the largest cassava (Manihot esculenta Crantz) germplasm collection from Brazil to develop core collections based on the maximization strategy. Subsets with 61, 64, 84, 128, 256, and 384 cassava accessions were selected and named PoHEU, MST64, PoRAN, MST128, MST256, and MST384, respectively. All the 798 alleles identified by 402 SNP markers in the entire collection were captured in all core collections. Only small alterations in the diversity parameters were observed for the different core collections compared with the complete collection. Because of the optimal adjustment of the validation parameters representative of the complete collection, the absence of genotypes with high genetic similarity and the maximization of the genetic distances between accessions of the PoHEU core collection, which contained 4.7% of the accessions of the complete collection, maximized the genetic conservation of this important cassava collection. Furthermore, the development of this core collection will allow concentrated efforts toward future characterization and agronomic evaluation of accessions to maximize the diversity and genetic gains in cassava breeding programs.

First Report of a 16SrIII-L Phytoplasma Associated with Frogskin Disease in Cassava (Manihot esculenta Crantz) in Brazil

Cassava (Manihot esculenta Crantz) is a major staple crop in developing countries and a large source of raw material for industrial purposes as flour, starch, and ethanol. In July 2012, 24 cassava genotypes (corresponding to 1.85% of the accessions) with typical symptoms of frogskin disease (CFSD) were observed in one of the maintenance areas of the Brazilian Cassava Germplasm (located at Embrapa Cassava & Fruits, Cruz das Almas, Bahia State, Brazil). All diseased plants were asymptomatic on the aboveground parts (leaves and stem). However, for accessions BGM 880, BGM 1094, BGM 1100, BGM 1212, BGM 1218, and BGM 1526, all roots showed a woody appearance, thickened cork-like peel with opaque aspect, and coalescent lip-like slits in a honeycomb pattern. Based on literature description, two pathogens could be associated with CFSD: a dsRNA virus (belonging to family Reoviridae) and a 16SrIII-L phytoplasma (1). To investigate the presence of phytoplasma associated with the CFSD symptoms, total DNA was extracted from 0.5 g of root tissue collected from both symptomatic and asymptomatic roots by scratching the secondary vessel at the center of the cassava root with a CTAB method. The nested PCR was carried out using phytoplasma-specific primer set P1/Tint followed by R16F2n/R16R2, targeting the 16S rRNA gene sequence of 1.2 kb in length, for the final reaction (4). No phytoplasma was detected in asymptomatic cassava roots that were sampled from the same field. A posterior extraction of total RNA was made but no dsRNA was noticed on the agarose gel, and reaction of RT-PCR with specific primers (2) had no amplification. In order to characterize the strains, the 1.2-kb amplicon was digested with BamHI, MseI, MspI, KpnI, and TaqI endonucleases. The resulting patterns indicated that the symptomatic accessions were infected with a phytoplasma belonging to the 16SrIII group, sharing similarities with pseudo gel mapping from the reference strain of Peach X-Disease Phytoplasma (GenBank Accession No. L33733). Nested PCR products from accessions BGM 1526 and BGM 1212 were purified and sequenced by Macrogen, (Seoul, South Korea) in both directions, manually edited, and the consensus sequences were deposited in the NCBI database (GenBank Accession Nos. KF019184 and KF019185). Phylogenetic studies were conducted based on maximum parsimony, neighbor-joining, and maximum likelihood analysis for 16S rRNA. The phytoplasma 16S rRNA gene sequences from both strains had 99% identity (P < 0.0001) with the 16SrIII-L CFSD phytoplasma (EU346761 and AY737647), described by Alvarez et al. (1) infecting cassava in Colombia. To our knowledge, this is the first report of a phytoplasma associated with Cassava Frogskin Disease in Brazil, where only the dsRNA virus was recognized as causing this symptom (3). This is not likely to be an isolated case, and possibly more cassava plants are infected with this phytoplasma in Brazil. Due to the difficulties to observe the symptoms at the field level, this could be an emerging disease in that country. References: (1) E. Alvarez et al. Plant. Dis. 93:1139, 2009. (2) L. A. Calvert et al. J. Phytopathol. 156:647, 2008. (3) L. S. Poltroniere et al. Comun. Tec., Belem-PA. 006:2p, 1999. (4) C. D. Smart et al. Appl. Environ. Microb. 62:2988, 1996.

A validated method for the simultaneous quantitation of bioactive alkaloid markers in the leaf ethanolic extract of Cissampelos sympodialis Eichl.: a phenological variation study

INTRODUCTION

The leaf hydroalcoholic extract of Cissampelos sympodialis Eichl. (Menispermaceae) has shown promising activity in different animal models of asthma. Several alkaloids have been identified in the extract, including warifteine and methylwarifteine (bisbenzylisoquinoline), as well as milonine (morphinandienone).

OBJECTIVE

To develop and validate an analytical method for the simultaneous quantitation of the bioactive markers of C. sympodialis hydroalcoholic leaf extract and to apply the method to a seasonal (phenological) study of the concentration of the alkaloid markers.

METHODOLOGY

The method used reversed phase high performance liquid chromatography with UV detection and calibration by standard addition. Separation was achieved using a C₁₈-column (250 × 4.6 mm, 5 µm) and a mobile phase consisting of a mixture of 0.05% aqueous (Et)₃NH₂ (A):MeOH(B) in gradient mode at a flow rate of 1.0 mL/min.

RESULTS

The method proved to be linear in the concentration range tested (2-100 µg/mL, r² > 0,99), precise (RSD ≤ 15%), accurate (85-115%), selective and robust. Detection limits for warifteine, methyl-warifteine and milonine were 0.39, 1.10 and 1.77 µg/mL respectively. The highest concentration of total alkaloids (determined as the sum of the three alkaloids) in the hydroalcoholic extract of the leaves was 2.9 ± 0.2 mg/g extract (n = 3), prior to fruit development. Both warifteine and methylwarifteine were detected in the total alkaloid fraction of the ripened fruits.

CONCLUSION

The results demonstrated that significant variations in the concentration of the biomarkers occurred throughout the vegetative cycle. The lowest concentration of the alkaloids in the leaves coincided with their appearance in the ripened fruits.

An outbreak of conjunctivitis caused by multiresistant Pseudomonas aeruginosa in a Brazilian Newborn Intensive Care Unit

We report an outbreak of conjunctivitis due to Pseudomonas aeruginosa involving seven infants admitted in the Neonatal Intensive Care Unit (NICU) of the Uberlândial Federal University Hospital between March and September 2001. Three infants developed systemic complications (01 sepsis and 02 pneumonias). Ten isolates were obtained from conjunctival cultures and all were resistant to ceftazidime and aminoglycosides. Fast identification of the organism and treatment with imipenem were important in containing the outbreak of P. aeruginosa.

A simple microanalytical technique for the determination of paracetamol and its main metabolites in blood spots

The use of blood spot collection cards is a simple way to obtain specimens for analysis of drugs with a narrow therapeutic window. We describe the development and validation of a microanalytical technique for the determination of paracetamol and its glucuronide and sulphate metabolites from blood spots. The method is based on reversed phase high-performance liquid chromatography with ultraviolet detection. The limit of detection of the method is 600 pg on column for paracetamol. Intra- and inter-day precision of the determination of paracetamol was 7.1 and 3.2% respectively. The small volume of blood required (20 microl), combined with the simplicity of the analytical technique makes this a useful procedure for monitoring paracetamol concentrations. The method was applied to the analysis of blood spots taken from neonates being treated with paracetamol.

Metabolism of quercetin and kaempferol by rat hepatocytes and the identification of flavonoid glycosides in human plasma

1. The metabolism of the flavonoids quercetin and kaempferol by rat hepatocytes was investigated using liquid chromatography coupled with electrospray mass spectrometry (LC-ESI MS). Quercetin and kaempferol were extensively metabolized (98.8 +/- 0.1% and 81.0 +/- 5.1% respectively, n = 4), with four glucuronides of quercetin and two of kaempferol being detected after incubation. 2. The glucuronides of quercetin and kaempferol formed upon incubation with rat hepatocytes were identified as the same ones formed after incubation with the UDP-glucuronosyltransferase isoform UGT1A9. 3. In addition, plasma samples from human volunteers taken after consumption of capsules of Ginkgo biloba, a plant rich in flavonoid glycosides, were analysed by LC-MS for the presence of flavonoid glucuronides and flavonoid glycosides. Reported is evidence for the presence of flavonoid glycosides in samples of plasma. 4. The results suggest that UGT1A9 is a key UDP-glucuronosyltransferase isoform for the metabolism of flavonoids, and that absorption of intact flavonoid glycosides is possible.

Chromatographic techniques for the determination of putative dietary anticancer compounds in biological fluids

Although a great number of papers demonstrate an association between high intake of fruits and vegetables and reduced risk of certain types of cancer, the epidemiological evidence is not conclusive. The identification and quantification of specific dietary anticancer compounds in plasma, urine and tissues is an important aspect of this research. We surveyed the recent literature for original papers which involved the use of separation techniques for the detection and quantification in biological fluids and tissues of putative anticancer compounds which are present in the diet. The compounds included in this review are flavonoids, phytoestrogens, carotenoids, retinoids, vitamin E and ascorbic acid. The review covers papers published in the last 3 years. For each class of compounds we discuss the sample preparation, chromatographic conditions, and validation of the methods used, in order to identify current trends in the bioanalysis of each class of these substances.

Intracellular calcium mobilization as a target for the spasmolytic action of scopoletin

The coumarin scopoletin was isolated in a pure form from the roots of Brunfelsia hopeana Benth. (Solanaceae). In isolated rat aortic rings, scopoletin (26-520 microM) inhibited to approximately the same extent the contractions induced by a variety of substances, including phenylephrine, potassium chloride, serotonin and PGF(2) (alpha). The effect of the coumarin on phenylephrine-induced contractions was not affected by endothelium removal or NO-synthase blockade by L-NAME (100 microM). Scopoletin (78 - 590 microM) antagonized in a concentration-dependent manner (IC(50) = 300 +/- 20 microM, n = 5), transient contractions in Ca(2+)-free media induced by noradrenaline, but not those induced by caffeine. Also, scopoletin did not interfere with the refilling of noradrenaline-sensitive intracellular calcium stores. It is suggested that the non-specific spasmolytic action of scopoletin can be attributed, at least in part, to its ability to inhibit the intracellular calcium mobilization from the noradrenaline-sensitive stores.

A rapid and sensitive method for the determination of the amount of theophylline in blood spots

Monitoring of drugs (such as theophylline) with a narrow therapeutic window could be simplified if patients were able to submit blood spots for analysis. This could reduce clinic attendance for venous blood sampling and save staff time. A rapid sensitive method utilizing liquid chromatography-mass spectrometry has been developed to determine the amount of theophylline in blood spots. The lowest level of theophylline analysed in a blood spot was 15 ng extracted into 250 microL and this was still considerably above the limit of quantification (3 ng in 250 microL). The levels of theophylline in blood spots correlated well with theophylline levels in plasma samples obtained from the same patients. The assay might be of use in therapeutic drug monitoring of theophylline and blood spot sampling could be applied to other drugs where therapeutic monitoring is required.

Liquid chromatography-mass spectrometry in the study of the metabolism of drugs and other xenobiotics

The application of liquid chromatography-mass spectrometry (LC/MS) to the study of metabolism of drugs and other xenobiotics is reviewed. Original research papers covering the period from 1998 to early 2000 and concerning the use of LC/MS in the study of xenobiotic metabolism in humans and other mammalian species are reviewed. LC/MS interfaces, sample preparation steps, column types, mobile phases and additives, and the type of metabolites detected are summarized and discussed in an attempt to identify the current and future trends in the use of LC/MS for metabolism studies. Applications are listed according to the parent xenobiotic type and include substances used in therapeutics, drug candidates, compounds being evaluated in clinical trials, environmental pollutants, adulterants and naturally occurring substances.

In vitro glucuronidation of kaempferol and quercetin by human UGT-1A9 microsomes

Flavonoids are important polyphenolic substances with widespread occurrence in plants and therefore in the human diet. Although considerable work has been done on the pharmacology of flavonoids, the understanding of their metabolism is still incomplete. In this work, the in vitro glucuronidation of the common dietary flavonoids quercetin and kaempferol by human UDP-glucuronosyltransferase microsomes (UGT-1A9) was investigated using HPLC and LC-MS. The two flavonoids were extensively metabolised by this enzyme with four monoglucuronides of quercetin and two of kaempferol being detected after incubation. The presence of a quercetin monoglucuronide in the urine of a volunteer after consumption of Ginkgo biloba tablets was demonstrated.

Solid-phase extraction and gas chromatography-mass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets

A method was developed for the quantification of the flavonoids quercetin and kaempferol in human urine using a solid-phase extraction procedure followed by gas chromatography-mass spectrometry. Deuterated internal standards of the analytes were spiked into the samples prior to extraction. The limit of detection of the method was ca. 10 pg on column and precision of the method for quantification in a sample of urine was +/-9.40% for kaempferol and +/-7.34% for quercetin (n = 6). The levels of quercetin and kaempferol found in urine samples were only a small fraction of the amount ingested. The treatment of urine samples with beta-glucuronidase markedly increased the levels of flavonoids detected, supporting the view that kaempferol and quercetin are eliminated in the urine as glucuronides.