High-performance Liquid Chromatography With Photodiode Array Detection Research Articles

HPLC-DAD Analysis and Investigation of Biological Properties of the Leaves of Globularia alypum (L.), Infusion Extract.

Globularia alypum L. (GA) belonging to the Globulariaceae family is a Mediterranean plant which is widely used in traditional Tunisian medicine. The aim of this study was to investigate the phytochemical composition, antioxidant, anti-arthritic, antiproliferative, antibacterial and antibiofilm potential of aqueous GA leaf extracts (AGAL). Quantitative analyses of the different constituents of extracts were evaluated by high-performance liquid chromatography with photodiode-array detection (HPLC-DAD). Spectrophotometric methods and chemical tests were used for antioxidant and anti-arthritic activities. The antiproliferative study was evaluated using colorectal cancer SW620 cells, while the antibacterial assessment and analysis of the antibiofilm effects were determined by the microdilution method and the crystal violet assay, respectively. AGAL extracts presented several components, mainly Nepetin-7-Glucoside and trans-ferrulic acid. The results showed that they had an important antioxidant (IC50 = 0.34; 0.38 and 1.20 mg/mL) and anti-arthritic (IC50 = 2.94 mg/mL) properties, and these effects are displayed in a dose-dependent manner. In addition, this extract demonstrated significant antiproliferative (IC50 = 50 µg/mL), antibacterial (MIC = 6.25 mg/mL and MBC = 6.25 mg/mL), and antibiofilm (59.70% at 25 mg/mL) properties especially against S. aureus. The results achieved confirm the important role of this plant as a source of therapeutic activities.

Chemical characterization and biological abilities of Anthocleista djalonensis collected from two locations of Ivory Coast

AbstractIn this study, the total phenolic and flavonoid contents, HPLC‐DAD detected phytochemicals, antioxidant and enzyme inhibitory potential of methanolic and aqueous (as infusion) extracts of the medicinal plant, Anthocleista djalonensis (leaf and stem bark) collected from two locations, Mafiblé and Prikro, in Ivory Coast, were investigated. The ranges of total phenolic and flavonoid contents obtained were 14.17–46.95 mg gallic acid equivalent (GAE)/g and 2.96–34.76 mg rutin equivalent (RE)/g, respectively. Antioxidant abilities in terms of radical scavenging, reducing and metal chelating activity of the extracts in different assays were as follows: DPPH (4.90–48.82 mg trolox equivalent [TE]/g), ABTS (21.05–81.89 mg TE/g), CUPRAC (29.54–122.33 mg TE/g), FRAP (17.53–94.06 mg TE/g) and metal chelating (10.09–28.49 mg EDTAE/g. The extracts of A. djalonensis collected from Mafiblé, especially those of stem bark, contained higher level of total bioactive contents compared to Prikro extracts, detected by high‐performance liquid chromatography with photodiode‐array detection (HPLC‐DAD). Only the methanolic extracts irrespective of plant parts/location, showed inhibition against acetylcholinesterase (1.42–2.12 mg galantamine equivalent (GALAE)/g), while only the stem bark methanolic extract of A. djalonensis from Mafiblé was found to inhibit butyrylcholinesterase (0.65 mg GALAE/g). Thus, findings from this study could be useful for better application of the medicinal benefits from this plant.

Mechanistic insights into the anti-tumor and anti-metastatic effects of Patrinia villosa aqueous extract in colon cancer via modulation of TGF-β R1-smad2/3-E-cadherin and FAK-RhoA-cofilin pathways

BackgroundPatrinia villosa, a traditional medicinal herb commonly used for treating intestinal-related diseases, has been commonly prescribed by Chinese medicine practitioners as a key component herb to treat colon cancer, although its anti-tumor effect and mechanisms of action have not been fully elucidated. Hypothesis/purposeThis study aimed to investigate the anti-tumor and anti-metastatic effects of Patrinia villosa aqueous extract (PVW), and its underlying mechanisms. MethodThe chemical profile of PVW was analysed by high-performance liquid chromatography with photodiode-array detection (HPLC-DAD) method. Cell-based functional assays MTT, BrdU, scratch, and transwell were conducted to evaluate the effects of PVW on human colon cancer HCT116 and murine colon26-luc cells, assessing cytotoxicity, cell proliferation, motility, and migration, respectively. Western blotting was performed to assess the effect of PVW on the expression of key intracellular signaling proteins. In vivo studies were conducted using zebrafish embryos and tumor-bearing mice to evaluate the anti-tumor, anti-angiogenesis, and anti-metastatic effects of PVW in colon cancer. ResultsFive chemical markers were identified and quantified in PVW. PVW exhibited significant cytotoxicity and anti-proliferative activity, as well as inhibitory effects on cell motility and migration in both HCT116 and colon 26-luc cancer cells via modulating protein expressions of TGF-β R1, smad2/3, snail, E-cadherin, FAK, RhoA, and cofilin. PVW (0.01–0.1 mg/ml) could significantly decrease the length of subintestinal vessels of zebrafish embryos through decreasing mRNA expressions of FLT1, FLT4, KDRL, VEGFaa, VEGFc, and Tie1. PVW (> 0.05 mg/ml) also significantly suppressed colon cancer cells migration in the zebrafish embryos. Furthermore, oral administration of PVW (1.6 g/kg) significantly inhibited tumor growth by decreasing the expressions of tumor activation marker Ki-67 and CD 31 in tumor tissues of HCT116 tumor-bearing mice. PVW could also significantly inhibit lung metastasis in colon 26-luc tumor-bearing mice by modulating their tumor microenvironment, including immune cells populations (T cells and MDSCs), levels of cytokines (IL-2, IL-12, and IFN-γ), as well as increasing the relative abundance of gut microbiota. ConclusionThis study revealed for the first time the anti-tumor and anti-metastatic effects of PVW through regulation of TGF-β-smad2/3-E-cadherin, and FAK-cofilin pathways in colon cancer. These findings provide scientific evidence to support the clinical use of P. villosa in patients with colon cancer.

Correlations of flavonoids content and antioxidant activity in bee honey from Bosnia and Herzegovina

In this study, it was performed identification and quantification of flavonoids (apigenin, chrysin, hesperetin, kaempferol, luteolin, naringenin, and quercetin) and flavonoid glycosides (rutin and vitexin) in total 49 samples of five different honey types from Bosnia and Herzegovina: meadow honey (MH, 22 samples), forest (FH, 10), acacia (AH, 7), chestnut (CH, 5), and heather honey (HH, 5). Additionally, evaluation of correlations between FC and total hydrophilic antioxidant score (antioxidant activity against both: ROO· + OH·) in supernatants (s) and in bulk (noncentrifuged) solution (b) of these honey types was performed. Moreover, correlations between flavonoids content (FC) and previously reported antioxidant activity against both peroxyl and hydroxyl free radicals (AC(ROO·) and AC(OH·)) for the same honey samples was examined. High performance liquid chromatography with photodiode array detector (HPLC-DAD) and isocratic elution mode was used as method of analysis. Flavonoids were extracted by solid phase extraction (SPE). The average contents of three flavonoids (chrysin, naringenin, and luteolin) in MH were statistically higher than in AH (p**<0.01). Also, the average content of naringenin in FH was statistically higher than in CH (p*<0.05). We observed a high (positive) linear correlation between FC and AC(ROO·) in s of four honey types (FH, AH, HH, CH) (R2=0.920). If we correlate FC and AC(ROO·)s of three honey types (FH, AH, HH), linearity is very high (R2=0.968), and for FH, AH, CH linearity is complete. The correlation between FC and AC(ROO·) in b of the same honey types is similar, but lower. The correlation does not exist between FC and AC(OH·) neither in s nor in b of five or four honey types, but for FC to both (AC(OH·)s and AC(OH·)b) of three honey types (FH, AH, CH), linearity is moderate (R2=0.732 and R2=0.696, respectively). Keywords: antioxidant activity, correlations, flavonoids, honey, HPLC-DAD.

Tetracycline residues in tilapia and catfish tissue and the effect of different cooking methods on oxytetracycline and doxycycline residues

Fish such as tilapia (Oreochromis niloticus) and catfish (Clarias gariepinus) is an important source of high biological value animal protein. Fish can be exposed to antimicrobials in intensive aquaculture systems or exposed to remnants of the antimicrobials released to various water bodies via drainage systems. This study aimed at screening for antimicrobial residues in two major fish species commonly consumed in Egypt, namely, tilapia, and catfish, either in wild or cultured fish using a microbial inhibition assay. Besides, quantitative estimation of tetracycline (oxytetracycline and doxycycline) residues in the edible fish muscles was carried out using the solid phase extraction (SPE) technique and high-performance liquid chromatography with photodiode-array detection (HPLC-PAD). In addition, the effects of different cooking methods (pan-frying, grilling, and microwaving) on oxytetracycline and doxycycline residues in tilapia and catfish were investigated. The microbiological inhibition assay revealed that 2, 24, 18, and 32% of the examined wild tilapia, cultured tilapia, wild catfish, and cultured catfish, respectively, contained antibiotic residues. Cultured tilapia, wild catfish, and cultured catfish had mean concentrations of oxytetracycline residues of 0.147 ± 0.067, 0.106 ± 0.046, and 0.313 ± 0.044 µg/g. 3 (6%), 4 (8%), and 9 (18%) of the sampled cultured tilapia, wild catfish, and cultured catfish exceeded the established maximum permissible limits (MPL) of tetracycline (0.100 ng/g). The mean concentrations of doxycycline residues were 0.276 ± 0.045, 0.026 ± 0.004, and 0.070 ± 0.010 µg/g in cultured tilapia, wild catfish, and cultured catfish, respectively, with 2 (4%) of the cultured tilapia exceeding the MPL of doxycycline. Consumption of fish with high residual levels of tetracyclines might pose potential health risks to consumers. In an experimental trial, heat treatment of tilapia and catfish could significantly reduce both oxytetracycline and doxycycline residues, particularly grilling had the highest reduction rates.

Identification of p-Coumaric Acid and Ethyl p-Coumarate as the Main Phenolic Components of Hemp (Cannabis sativa L.) Roots.

Hemp (Cannabis sativa L.) contains a variety of secondary metabolites, including cannabinoids, such as psychoactive (−)-trans-Δ⁹-tetrahydrocannabinol. The present study was conducted to identify the major phenolic components contained in hemp root, which has been relatively under-researched compared to other parts of hemp. The aqueous ethanol extract of hemp roots was fractionated into methylene chloride (MC), ethyl acetate (EA), and water (WT) fractions, and high-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis was performed. The main ultraviolet (UV)-absorbing phenolic compound contained in the EA fraction was identified as p-coumaric acid by comparing the retention time and UV absorption spectrum with a standard. Silica gel column chromatography was performed to isolate a hydrophobic derivative of p-coumaric acid contained in the MC fraction. Nuclear magnetic resonance (NMR) analysis identified the isolated compound as ethyl p-coumarate. For comparative purposes, ethyl p-coumarate was also chemically synthesized by the esterification reaction of p-coumaric acid. The content of p-coumaric acid and ethyl p-coumarate in the total extract of hemp root was estimated to be 2.61 mg g−1 and 6.47 mg g−1, respectively, by HPLC-DAD analysis. These values correspond to 84 mg Kg−1 dry root and 216 mg Kg−1 dry root, respectively. In conclusion, this study identified p-coumaric acid and ethyl p-coumarate as the main phenolic compounds contained in the hemp roots.

Antioxidant Effects of Korean Propolis in HaCaT Keratinocytes Exposed to Particulate Matter 10

Air pollution causes oxidative stress that leads to inflammatory diseases and premature aging of the skin. The purpose of this study was to examine the antioxidant effect of Korean propolis on oxidative stress in human epidermal HaCaT keratinocytes exposed to particulate matter with a diameter of less than 10 μm (PM10). The total ethanol extract of propolis was solvent-fractionated with water and methylene chloride to divide into a hydrophilic fraction and a lipophilic fraction. The lipophilic fraction of propolis was slightly more cytotoxic, and the hydrophilic fraction was much less cytotoxic than the total extract. The hydrophilic fraction did not affect the viability of cells exposed to PM10, but the total propolis extract and the lipophilic fraction aggravated the toxicity of PM10. The total extract and hydrophilic fraction inhibited PM10-induced ROS production and lipid peroxidation in a concentration-dependent manner, whereas the lipophilic fraction did not show such effects. High-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis showed that the hydrophilic fraction contained phenylpropanoids, such as caffeic acid, p-coumaric acid, and ferulic acid, whereas the lipophilic faction contained caffeic acid phenethyl ester (CAPE). The former three compounds inhibited PM10-induced ROS production, lipid peroxidation, and/or glutathione oxidation, and ferulic acid was the most effective among them, but CAPE exhibited cytotoxicity and aggravated the toxicity of PM10. This study suggests that Korean propolis, when properly purified, has the potential to be used as a cosmetic material that helps to alleviate the skin toxicity of air pollutants.

Simultaneous Analysis of Sexual Stimulants and Anabolic Steroids as Adulterants in Dietary Supplements by High Performance Liquid Chromatography with Photodiode Array Detection

Background:The illegal virtual market for food supplements facilitates fraud and adulteration. Worldwide concern for consumer safety is growing on the part regulatory agencies, healthcare professionals and consumers.Objective:This work aimed to evaluate the presence of sexual stimulants and anabolic steroids commonly used in the adulteration of dietary supplements through the development of a high performance liquid chromatography with photodiode array detection (HPLC-DAD) method for the identification and quantification of these compounds.Method:The mobile phase composed of an ammonium acetate solution, acetonitrile and methanol leaded to the efficient separation of vardenafil, testosterone base, testosterone propionate, tadalafil, sildenafil and yohimbine.Results:The assay was linear (r2> 0.999), precise (RSD% <0.5), accurate (99.1 to 105.2%), and the limits of detection and quantification were less than 0.05 and 0.15 μg/mL, respectively. Four samples of dietary supplements contained testosterone (n=1), tadalafil (n=2) and yohimbine (n=1) as adulterants. The adulterants found were in subtherapeutic doses, probably to reduce possible adverse effects and the action expected to appear natural. Since about 80% of adverse drug reactions are dose dependent, unpredictable adverse drug reactions are dose independent and based on idiosyncratic or allergic mechanisms or intolerance.Conclusion:The developed method is convenient and easily applicable for adulteration detection of the analyzed drugs in the multicomponent supplements.

A new liquid phase microextraction method-based reverse micelle for analysis of dexketoprofen in human plasma by HPLC-DAD

A new liquid phase microextraction method was developed by used reverse micelle-based coacervates as microextraction agents for the separation of dexketoprofen (DKT) from human plasma before its determination by high-performance liquid chromatography with photodiode-array detection (HPLC-DAD). The change in the concentration of dexketoprofen in the plasma of the male and female patients was successfully monitored by using this method. The proposed method involves the use of reverse micelles of decanoic acid (DA) are dispersed in tetrahydrofuran (THF) and aqueous system. After addition of the DA and THF to the aqueous sample phase, the formation of micelles of nano and molecular size was observed in an ultrasonic bath. The solution was centrifuged, and the DKT extracted into the DA phase was analyzed by HPLC-DAD. Some analytical parameters that important in the developed procedure were examined in detail. The limit of detection (LOD), the limit of quantification (LOQ), the intraday, and inter day relative standard deviation (RSD, %) of the developed method in the plasma sample were found to be 12.8 ng mL−1, 38.8 ng mL−1, 1.7 and 3.9%, respectively. Additional/recovery studies were performed in plasma samples with proposed method, and quantitative recoveries were obtained in the range of 97–100%. The developed microextraction method was applied to human plasma that taken from volunteer patients for the determination of DKT.Graphical abstract

The different toxic effects of metalaxyl and metalaxyl-M on Tubifex tubifex

Metalaxyl and Metalaxyl-M are the fungicides that widely used in many countries. In this study, the environmental behaviors between metalaxyl and metalaxyl-M in Tubifex tubifex (T. tubifex) were quantitative analyzed by using a high performance liquid chromatography with photo-diode-array-detector (HPLC-DAD). Results demonstrated that there was no significant difference (p > 0.05) in the concentration of metalaxyl and metalaxyl-M in T. tubifex during the exposure process. However, the dissipation behaviors of metalaxyl and metalaxyl-M in T. tubifex were different (p < 0.05) during the non-exposure culture process. Meanwhile, the toxic effects were also evaluated by comparing the different influences of these two compounds on related physiological indicators, and functional enzyme activities. The survival rates of T. tubifex were 63.33 ± 15.28% (20 mg L−1), 63.33 ± 5.77% (200 mg L−1) treated with metalaxyl and were 50.00 ± 10.00% (20 mg L−1), 46.67 ± 11.55 (200 mg L−1) treated with metalaxyl-M at the non-exposure culture process. The autotomy rates were increased significantly compared with the initial in all treatments. Besides, the activities of CAT, SOD, and GST in T. tubifex were also inhibited by metalaxyl and metalaxyl-M treatments. Finally, the high-throughput transcriptome sequencing technology was applied to investigate the metabolic pathways of target analytes in T. tubifex, and results proved that the metabolic pathways associated with human diseases (such as viral myocarditis) were up-regulated expression for metalaxyl and metalaxyl-M treatments, and metalaxyl-M up-regulated more significantly. All the results demonstrated that metalaxyl-M had a higher toxicity than metalaxyl on T. tubifex.

Analysis, Formation and Inhibition of Heterocyclic Amines in Foods: An Overview

Heterocyclic amines (HAs), an important class of toxicological compounds, can be formed through heating of four precursors, amino acids, creatinine, creatine and sugars. Numerous studies have shown that most HAs are mutagenic and carcinogenic, and the safety of HAs-containing foods has become a major concern for the public. This paper deals with an overview of analysis, formation and inhibition of HAs in foods. Analysis of HAs from foods is routinely conducted by protein precipitation, followed by acid-base solvent partition, purification with column chromatography and identification and quantification by high-performance liquid chromatography (HPLC), or gas chromatography-mass spectrometry (GC-MS). However, most of these methods result in low recovery. With HPLC, all 16 HAs can be simultaneously separated by a binary or ternary gradient solvent system and detected by UV. Using fluorescence detection, only nine HAs can be detected. For GC-MS, only a number of HAs are separated and identified by employing a temperature programming method. GC-MS provides rapid identification and quantification of HAs in foods, however, this technique requires a time-consuming derivatization and the number of HAs separation is limited. Also, some HAs may degrade and result in peak tailing. The application of HPLC with photodiode-array detection (HPLC-DAD) can not only permit rapid identification and quantification of HAs, but also enhance sensitivity and selectivity. Broiling and frying are two major processing methods causing the formation of high amount of HAs. The formation of HAs in foods during cooking can be inhibited by incorporating additives such as antioxidants and amino acids. However, the results have been controversial. Further research is necessary to study the effect of various additives on inhibition of HAs formation in foods.

TiO2 thin films sensitization with natural dyes extracted from Bactris guineensis for photocatalytic applications: Experimental and DFT study

TiO2 thin films, sensitized by an anthocyanins-rich extract of a common species found in the Colombian Caribbean region (Bactris guineensis fruits), were used for the photocatalytic degradation of methylene blue. The sensitization process was verified by diffuse reflectance spectroscopy (DRS). The qualitative and quantitative analyses of the anthocyanins were carried out using high-performance liquid chromatography with photodiode array detection (HPLC-DAD), which provided the total content anthocyanin equivalent to delphinidin chloride (TAEDC) per mL of the extract, of 10.0 ± 0.8 µg TAEDC/mL. Here, three main anthocyanins were identified, being cyanidin-3-rutinoside the most abundant constituent (ca. 76%). The interaction of the dyes with a TiO2 slab model and their adsorption energies were determined through computational simulations. In addition, the molecular modelling evidenced that the sensitization of the semiconductor improved the light absorption in the visible range of the spectrum. As a final point, the photocatalytic test showed that the photocatalytic activity increased 26% for TiO2/B. guineensis thin films under visible radiation respect to bare TiO2.

Identification of ‘Voodoo’: an emerging substance of abuse in Egypt

ABSTRACT Background: ‘Voodoo’ is a new substance of abuse that recently spread among youth in Egypt. It has numerous potentially dangerous effects on humans. However, to date the composition of the main constituents of this compound is unknown. Purpose: We sought to identify the active components of this unknown substance”voodoo”. Methods: Three samples were collected and analysed by high-performance liquid chromatography with photodiode array detector (HPLC-PAD), gas chromatography/mass spectrometry (GC/MS), and ultra-performance liquid chromatography/mass spectrometry (UPLC-MS/MS) using targeted multiple reaction monitoring (MRM). Results: HPLC-PAD analysis showed that samples 1 and 2 had some common major peaks, the same retention time, and similar spectra, whereas sample 3 showed different peaks. GC/MS analysis revealed the presence of various putatively identified bioactive compounds, including quinazolines, morphinan alkaloid, cannabinoids, penitrem A, and the well-known synthetic cannabinoid FUB-AMB (methyl(2S)-2-{[1-[(4-fluorophenyl)methyl]indazole-3-carbonyl]amino}-3 methylbutanoate). UPLC-MS/MS analysis revealed the presence of common compounds such as tetrahydrocannabinol (THC), amphetamine, 3,4-methylenedioxyamphetamine, tramadol, and oxazepam. Conclusion: We concluded that Voodoo is a mixture of substances of abuse at varying concentrations.

&lt;i&gt;Dalbergia ecastaphyllum&lt;/i&gt; leaf extracts: &lt;i&gt;in vitro&lt;/i&gt; inhibitory potential against enzymes related to metabolic syndrome, inflammation and neurodegenerative diseases

For the first time, the anti-hemolytic activity and the enzyme inhibitory activities of Dalbergia ecastaphyllum leaves extracts were tested against α-amylase, α-glucosidase, lipase, acetylcholinesterase, butyrylcholinesterase, tyrosinase and hyaluronidase. The phenolic profile of the obtained extracts was also investigated by high-performance liquid chromatography with photodiode array detection (HPLC-PAD). The extracts showed inhibitory activity against all enzymes evaluated, with the highest inhibitory activity reported for the enzyme hyaluronidase (28.28 ± 2.43 to 72.19 ± 1.40 μg mL-1). The obtained extracts also demonstrate anti-hemolytic activity (52.22 ± 1.62 to 71.17 ± 1.82%). Among the phenolic compounds identified, protocatechuic, vanillic and β-resorcylic acids were the most abundant (1.13 ± 0.06 to 2.53 ± 0.06, 0.90 ± 0.06 to 2.19 ± 0.06 and 1.03 ± 1.62 to 22.11 ± 1.62 mg L-1, respectively). In the statistical analysis, a significant correlation was found between the flavonoids content and all enzymes inhibitory activities. The present study showed that D. ecastaphyllum leaves extracts may have the potential to be used in the therapeutic treatment of several diseases such as Alzheimer, Parkinson, type 2 diabetes mellitus, hyperglycemia, and pigmentation, as well as those associated with oxidative stress.

Assessment of Degradation of Sulfonylurea Herbicides in Water by Chlorine Dioxide

The degradation of two sulfonylurea herbicides, nicosulfuron and thifensulfuron methyl in water by chlorine dioxide, was studied for the first time in this paper. In order to examine the optimal parameters for degradation of both herbicides, degradation was investigated under light or dark conditions with different amount of chlorine dioxide, different degradation periods, and at different pH values. Degradation efficiency of herbicides was monitored using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). The degradation products were analyzed by gas chromatography with triple quadrupole mass detector (GC–QQQ). Three products were identified after degradation of nicosulfuron and two products after degradation of thifensulfuron methyl. Total organic analysis (TOC) gave insight into some differences in degradation mechanisms and degrees of mineralization after degradation of the herbicides using chlorine dioxide. A simple mechanism of herbicide degradation was proposed. Acute toxicity tests were performed on the products produced after degradation with chlorine dioxide, and the results showed that the degradation products were less toxic than the parent compounds. The findings of the present study are very useful for the treatment of wastewaters contaminated with herbicides.

Relationship between the flavonoid composition and flower colour variation in Victoria.

Victoria (Nymphaeaceae), an annual or perennial aquatic plant genus, contains only two species: V. amazonica (Poepp.) J. C. Sowerby and V. cruziana A. D. Orb. Both species have large floating leaves and variable flower colour. Both Victoria species are night bloomers, which have white petals on the first blooming night that then turn pink or ruby red on the second blooming day. The mechanism of the colour change of Victoria petals during anthesis is still unclear. In this study, flavonoids in Victoria petals of both species were evaluated and quantified by high-performance liquid chromatography with photodiode array detection (HPLC-DAD) and by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) for the first time. In total, 14 flavonoids were detected in Victoria petals, including 4 anthocyanins and 10 flavonols. The flavonoid compositions differed across the two species, resulting in different colours between the inner and outer petals. With increased anthocyanin content across blooming days, the colour of Victoria flowers changed over time. The results of this study will improve understanding of the chemical mechanism of colour formation and lay the foundation for selective colour breeding in Victoria.

Handling of highly coeluted chromatographic peaks by multivariate curve resolution for a complex bioanalytical problem: Quantitation of selected corticosteroids and mycophenolic acid in human plasma

The present study describes the analytical performance of a fast-elution protocol and smart methodology based on multivariate curve resolution-alternating least square (MCR-ALS) modeling of high performance liquid chromatography with photodiode-array detection (HPLC-DAD) data for simultaneous determination of prednisolone (Predl), methylprednisolone (Mpredl) and mycophenolic acid (MPA) in plasma samples. The LC method optimized at two isocratic reverse phase over a symmetric C18 column, a 60:40 (v/v) mixture of acetonitrile and water (0.02 M KH2PO4 (pH = 3.7) buffer solution) and a 10:70:20 (v/v/v) mixture of acetonitrile, methanol and water. The most challenges in the present study were the severe coelution of analytes of interest with each other and the matrix interferences, and high spectral similarity of selected corticosteroids, depending on the mobile phase method. To circumvent these drawbacks, the whole chromatographic runs were divided into two sections. Then, the matrix augmentation in spectra and retention time direction were implemented for the first and second regions, respectively. Highly acceptable resolution and quantification results were obtained. The average recoveries were 97.3% and 102.1% for Predl, 96% and 98.6% for Mpredl and 97.7% and 100.8% for MPA, using two mobile phase conditions, respectively. Accurate and precise results, elimination of expensive and time consuming sample pretreatment steps and a very short chromatographic run time, are among the advantages of the presented method.

Improvement of the photocatalytic activity of TiO2 using Colombian Caribbean species (Syzygium cumini) as natural sensitizers: Experimental and theoretical studies

Natural dyes composed by anthocyanins extracted from natural Caribbean species S. cumini, were employed to evaluate their effects on the photocatalytic properties of TiO2 thin films. The qualitative and quantitative analyses of the anthocyanins were carried out using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). From the chemical characterization of the S. cumini extract three main anthocyanins were identified and the most abundant compound was delphinidin-3,5-diglucoside (44%). The total anthocyanin content expresses as delphinidin chloride (TAEDC) per mL of the extract was equal to 124 ± 5 μg TAEDC/mL. After the identification, a sensitization process was performed and verified by infrared spectroscopy (IR) and absorption diffuse reflectance. Afterwards, the Methylene Blue photodegradation process was studied under visible light irradiation on the S. cumini-sensitized TiO2 material (TiO2/S. cumini). The results indicated that the photocatalytic activity of the sensitized material TiO2/S. cumini was ∼3 times greater than unmodified TiO2 thin films, which let us to propose that the extract from Caribbean Colombian S. cumini could have a great potential as source of photosensitizers for photocatalytic applications. Finally, the electronic structure of each anthocyanin found in the extract (delphinidin-3,5-diglucoside, malvidin-3-5-diglucoside and petunidin-3-5-diglucoside) and their interaction with a TiO2 model was studied by means of the density functional theory (DFT).

Feasibility of supramolecular solvent-based microextraction for simultaneous preconcentration of herbicides from natural waters with posterior determination by HPLC-DAD

A supramolecular solvent-based microextraction procedure for preconcentration of four most common sugarcane herbicides (diuron, hexazinone, ametryn and tebuthiuron) from groundwater and surface water samples with further determination by High Performance Liquid Chromatography with Photodiode Array detector (HPLC-DAD) is proposed. The proposed method involves the use of a supramolecular solvent in which reverse micelles of 1-decanol are dispersed in tetrahydrofuran/water. The extraction of four herbicides performed at pH4.0 requires low sample volume (10.0mL), low extraction time (30s of extraction and 10min of centrifugation), low amount of organic solvents (50μL of 1-decanol and 100μL of THF) and provides high preconcentration factors (48.5 to diuron, 15.1 to hexazinone, 47.4 to ametryn and 21.0 to tebuthiuron). The limits of detection (LOD), quantification (LOQ), the precision (RSD) and the accuracy (RE) of the developed method ranged between 0.13 and 1.45μgL−1, 0.43–4.85μgL−1, 2.4–6.8% and 0.6–6.2%, respectively. Recovery values obtained by applying the proposed method in spiked groundwater and surface water samples at μgL−1 levels varied in the range of 95–111%. The quantification of some analyzed herbicides in natural waters showed clearly the importance of investigates herbicides concentrations in regions of sugarcane cultivation predominance.

Spectrum-effect relationships between high performance liquid chromatography fingerprint and analgesic property of Anisodus tanguticus (Maxim) Pascher (Solanaceae) roots

Purpose: To investigate the spectrum-effect relationships between high performance liquid chromatography with photodiode array detection (HPLC-DAD) fingerprint and analgesic activity of Anisodus tanguticus (Maxim.) Pascher (Solanaceae) (AT) roots.Methods: Analgesic activity of AT roots was evaluated by acetic acid-induced writhing test in mice. Fingerprint of AT roots was established by HPLC-DAD. After oral administration of AT roots extract, intra-gastric contents of caffeoylputrescine, anisodine, fabiatrin, scopolin, scopolamine, anisodamine and atropine in mice were determined by HPLC-DAD. Spectrum-effect relationships between HPLCDAD fingerprint and analgesic activity were investigated using bivariate correlation analysis.Results: Following treatment with different batches of AT roots extract, acetic acid-induced writhing responses in mice were inhibited significantly (p &lt; 0.05 or 0.01), with inhibitions of 26.62 - 55.13 %, relative to the control group. Sixteen common peaks were obtained by fingerprint analysis. Peaks 1, 2, 6, 7, 8, 9 and 12 were identified as caffeoylputrescine, anisodine, fabiatrin, scopolin, scopolamine, anisodamine and atropine, respectively. Bivariate correlation analysis between analgesic activity of AT roots and 16 common peaks areas indicated the contributions of 16 common peaks to analgesic activity of AT roots. Surprisingly, bivariate correlation analysis between analgesic activity of AT roots and intragastric contents of above-named 7 constituents revealed that the contributions of the 7 constituents to analgesic activity of AT roots were different from those based on their peak areas.Conclusion: This study provides scientific justification for the investigation of the active constituents of AT root with a view to its standardization.Keywords: Anisodus tanguticus root, Analgesic activity, HPLC-DAD fingerprint, Bivariate correlation analysis