Thin-layer Chromatograms Research Articles

The Best Extraction Technique for Kaempferol and Quercetin Isolation from Guava Leaves (Psidium guajava)

Guava leaves contain various compounds that have biological activity such as kaempferol and quercetin as anticancer. Twelve extraction techniques were performed to obtain the best extraction technique to isolate kaempferol and quercetin from the guava leaves. Toxicity of extracts was tested against Artemia salina larvae. All extracts were toxic (LC50 value less than 1000 ppm) except extract of direct soxhletation on guava leaves, and extract of sonication and soxhletation using n-hexane. The extract with high content of total phenols and total flavonoids, low content of tannins, intense color of spot on thin layer chromatogram was selected for high performance liquid chromatography analysis. Direct sonication of guava leaves was chosen as the best extraction technique with kampferol and quercetin content of 0.02% and 2.15%, respectively. In addition to high content of kaempferol and quercetin, direct sonication was chosen due to the shortest extraction time, lesser impurities and high toxicity.

Combined thin layer chromatography and gas chromatography with mass spectrometric analysis of lipid classes and fatty acids in malnourished polar bears (Ursus maritimus) which swam to Iceland

Between 2008 and 2011, four polar bears (Ursus maritimus) from the Greenland population swam and/or drifted on ice to Iceland where they arrived in very poor body condition. Body fat resources in these animals were only between 0% and 10% of the body weight (usually 25%). Here we studied the lipid composition in different tissues (adipose tissue if available, liver, kidney and muscle). Lipid classes were determined by thin layer chromatography (TLC) and on-column gas chromatography with mass spectrometry (GC/MS). The fatty acid pattern of total lipids and free fatty acids was analyzed by GC/MS in selected ion monitoring (SIM) mode. Additionally, cholesteryl esters and native fatty acid methyl esters, initially detected as zones in thin layer chromatograms, were enriched by solid phase extraction and quantified by GC/MS. The ratio of free fatty acids to native fatty acid methyl esters could be correlated with the remained body lipids in the polar bears and thus may also serve as a marker for other starving animals or even for humans.

Validated Stability – Indicating Methods for Determination of Oseltamivir Phosphate

Aims: Two simple and sensitive stability- indicating methods were developed and validated for the quantitative determination of oseltamivir phosphate in presence of its degradation product. Place and Duration of Study: Analytical Chemistry Department, Faculty of Pharmacy (Girls), Al-Azhar University, between January 2016 and Augest 2016. Methodology: The first method depends on densitomeric determination of thin layer chromatograms of the drug using a mobile phase of methanol – toluene – ammonia (8: 10: 2, v/v/v). The second method was UPLC method, in which efficient separation was carried out on phenomenex kinetex 2.6 μm C18100 A column using a mobile phase consisting of 85% potassium hydrogen phosphate - methanol (80:20, v/v), adjusted to pH 3.5 with orthophosphoric acid at a flow rate of 1 mL min-1 and UV detection at 207 nm. Results: Beer’ law was obeyed in the range of 1-15 mg/spot and 6-14 μg mL–1 of the drug using the two procedures, respectively. Conclusion: The proposed methods were successfully applied for the determination of oseltamivir phosphate in bulk powder, laboratory prepared mixtures and pharmaceutical dosage form with good accuracy and precision. The methods were validated according to ICH guidelines. The results obtained were compared with those of the reported method and were found to be in good agreement.

Sequences of stilboflavin C: towards the peptaibiome of the filamentous fungus Stilbella (= Trichoderma) flavipes.

Filamentous fungi of the genus Stilbella are recognized as an abundant source of naturally occurring α-aminoisobutyric acid-containing peptides. The culture broth of Stilbella (Trichoderma) flavipes CBS 146.81 yielded a mixture of peptides named stilboflavins (SF), and these were isolated and separated by preparative TLC into groups named SF-A, SF-B, and SF-C. Although all three of these groups resolved as single spots on thin-layer chromatograms, HPLC analysis revealed that each of the groups represents very microheterogeneous mixtures of closely related peptides. Here, we report on the sequence analysis of SF-C peptides, formerly isolated by preparative TLC. HPLC coupled to QqTOF-ESI-HRMS provided the sequences of 10 16-residue peptides and five 19-residue peptides, all of which were N-terminally acetylated. In contrast to the previously described SF-A and SF-B peptaibols, SF-C peptaibols contain Ser-Alaol or Ser-Leuol, which are rarely found as C-termini, and repetitive Leu-Aib-Gly sequences, which have not been detected in peptaibols before. Taking the previously determined sequences of SF-A and SF-B into account, the entirety of peptides produced by S. flavipes (the 'peptaibiome') approaches or exceeds 100 non-ribosomally biosynthesized peptaibiotics. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Formulation of a fish feed for goldfish with natural astaxanthin extracted from shrimp waste.

BackgroundAstaxanthin is a xanthophyll carotenoid, which exhibits many important biological activities including a high degree of antioxidant capacity (AOC) and antibacterial activity, hence has a significant applicability in food, pharmaceutical and cosmetic industries. An attempt was made towards optimization of astaxanthin extraction conditions using three different extraction conditions and a solvent series, from uncooked, cooked and acid-treated shrimp waste, which is a readily available and cheap source of the pigment. The astaxanthin extracts were analyzed by comparing their UV–visible absorbance spectra and thin layer chromatograms with a standard astaxanthin sample. The percentage of astaxanthin in each crude sample was determined using the Beer–Lambert law. The Folin–Ciocalteu assay and the disk diffusion assay were used to investigate the antioxidant capacities and antibacterial activities of extracted astaxanthin samples respectively. The extracted astaxanthin was incorporated into fish feeds to test its ability to enhance the skin color of goldfish.ResultsThe best astaxanthin percentage of 68 % was observed with the acetone:ethyl acetate (1:1) solvent system facilitated by maceration of cooked and acid treated shrimp, whereas the best crude yield of 33 % was found to be in the acetone extract of the acid-treated shrimp sample. The highest AOC of 65 µg pyrogallol equivalents/mg was observed for the EtOAc extract obtained by maceration of acid-treated shrimp waste. The highest AOC by sonication and soxhlet extraction methods were also obtained with the EtOAc solvent. The extracts exhibited antibacterial activity against four selected bacterial strains. The newly formulated astaxanthin enriched fish feed was economical and indicated a significant improvement of the skin color and healthiness of goldfish compared to the control feeds.ConclusionBiologically active astaxanthin can be successfully extracted from shrimp waste in higher percentages. The extraction technique and the solvent used to extract astaxanthin from shrimp waste should be decided depending on the desired outcome and application of astaxanthin. Moreover, the novel astaxanthin enriched fish feed formulated during this study was found to effectively enhance the skin color of goldfish within 10 days, a much shorter feeding period compared to previously reported feeding periods in similar studies.Graphical abstractFormulation of a skin color enhancing fish feed for ornamental fish using crude astaxanthin extracted from shrimp wasteElectronic supplementary materialThe online version of this article (doi:10.1186/s13065-016-0190-z) contains supplementary material, which is available to authorized users.

TLC Fingerprinting and Pattern Recognition Methods in the Assessment of Authenticity of Poplar-Type Propolis.

Propolis is a "natural" remedy with prominent biological activity, which is used as dietary supplement. In the absence of clinical studies that would substantiate these claims, information on the biological activity of propolis is valuable. This study comprises chromatographic, image processing and chemometric approach for phenolic profiling of Serbian, Croatian and Slovenian propolis test solutions. Modern thin-layer chromatography equipment in combination with software for image processing was applied for fingerprinting and data acquisition, whereas the principal component analysis was used as pattern recognition method. Characterization of phenolic profile was performed along with the determination of the botanical and geographical origin of propolis. High-performance thin-layer chromatograms reveal that Central and Southeastern European propolis samples are rich in flavonoids. In addition, phenolic compounds proved to be suitable markers for the determination of European propolis authenticity.

Frontally eluted components procedure with thin layer chromatography as a mode of sample preparation for high performance liquid chromatography quantitation of acetaminophen in biological matrix

A new concept of using thin-layer chromatography to sample preparation for the quantitative determination of solute/s followed by instrumental techniques is presented Thin-layer chromatography (TLC) is used to completely separate acetaminophen and its internal standard from other components (matrix) and to form a single spot/zone containing them at the solvent front position (after the final stage of the thin-layer chromatogram development). The location of the analytes and internal standard in the solvent front zone allows their easy extraction followed by quantitation by HPLC. The exctraction procedure of the solute/s and internal standard can proceed from whole solute frontal zone or its part without lowering in accuracy of quantitative analysis.

HPLC, Densitometric and Visible-Spectrophotometric Determination of Triclabendazole and Ivermectin

Two methods were developed for simultaneous determination of triclabendazole and ivermectin, in addition to a Vis-spectrophotometric method for the analysis of ivermectin only. The first one was HPLC method in which efficient separation of two drugs was achieved on a C18 column with isocratic elution and a mobile phase composed of acetonitrile-methanol-0.005M KH2PO4 in a ratio of (60:30:10, v/v/v), pH 6. The linearity range was found to be 2.5-50 µg mL-1 for triclabendazole and 1-20 µg mL-1 for ivermectin with mean accuracy of 100.11% ± 0.99 and 100.08% ± 0.53, respectively. The second method was a densitometric evaluation of thin-layer chromatograms of the two drugs using a mobile phase of chloroform-acetone (8: 2, v/v). The plates were visualized under UV lamp at 254 nm where spots appeared at Rf 0.79 and 0.33 for triclabendazole and ivermectin, respectively. The chromatograms of the two drugs were measured densitometrically at 306 nm in the range 2.5-25.0 µg/spot for triclabendazole and at 245 nm in the range of 0.5-5.0 µg/spot for ivermectin with mean accuracy of 100.38% ± 0.52 and 100.05% ± 0.41, respectively. The Vis-spectrophotometric method was applied for the determination of ivermectin depending on its reducing character on tetrazolium red to give highly colored red product absorbing maximally at 485 nm in the range of 10-200 µg mL-1 with mean accuracy of 100.61% ± 0.43. The first two methods provided selective recovery of triclabendazole and ivermectin (100.53% ± 0.97 and 100.03% ± 0.82, 99.94% ± 1.60 and 98.77% ± 0.72; respectively). While the third Vis-spectrophotometric method provided selective recovery of ivermectin (100.86% ± 0.93) in presence of triclabendazole. Successful application of the methods for analyzing triclabendazole and ivermectin in their pharmaceutical formulations was obtained. The validity of the method was evaluated in terms of linear regression analysis, precision, accuracy and selectivity.

Methods of Analysis (Extraction, Separation, Identification and Quantification) of Carotenoids from Natural Products

Developing techniques for isolation and identification of biocompounds, from natural products, resulted in a rapid enrichment of carotenoid pigments number. For their isolation from biometabolites mixtures, the physical and chemical properties are taken into account. Carotenoids are sensitive to light, heat, oxygen, acids and alkaline bases. The exposure to light (direct sunlight/ UltraViolet), causes cis–trans photoisomerization, which may lead to their photodestruction. Biological materials containing carotenoids and their solutions must be protected from the action of light. Many carotenoids are thermolabile (xanthophylls); their heating being indicated only when it is absolutely necessary. The separation of carotenoids is done at room temperature or up to –20°C, in the dark. In the case of hot saponification they should be protected by a low–boiling solvent (30–60°C). Carotenoids may be oxidized in the presence of oxygen or peroxides, because of their sensitivity to oxygen in the adsorbed state (in thin layer or column chromatograms). It is necessary to operate in inert conditions (under nitrogen or vacuum). The oxidation during the extraction and saponification can be minimized if it is carried out in a nitrogen atmosphere. The exposure of carotenoids to acids, leads to changes such as: the oxidative decomposition, cis–trans isomerization and isomerization of 5,6–epoxides and 5,8–epoxides. The inconveniences are minimized by neutralization (calcium carbonate, pyridine, dimetilalanine). It works with purified solvents, freshly distilled, chlorinated derivatives (dichloromethane or solvents containing hydrochloric acid). The storage of carotenoids should be done in the dark, under an atmosphere of nitrogen or in vacuum, at a temperature of –20°C. The best preservation method is in the crystalline state. The current research techniques are using spectral methods, which provide accurate information on the structure and properties of organic biosubstances. Compared to chemical methods of identification, spectral methods have the advantage that it provides data faster, are accurate, require small amounts of material and enable continuous analysis at different stages of processing of the compound extracted without changing the composition of the biosubstance investigated, which enables its recovery. This chapter presents the main methods of extraction, separation and identification of organic compounds with direct applications on carotenoids.

Micro Two-Dimensional Thin-Layer Chromatography and Chemometric Analysis of Essential Oils from Selected Mentha Species and Its Application in Herbal Fingerprinting

Micro two-dimensional thin-layer chromatographic systems (micro-2D-TLCs) were optimized using some popular nonaqueous mobile phases on 5 cm × 5 cm silica plates. The optimal 2D TLC systems were chosen based on correlations of RF values vs. mobile phases concentrations performed for 1D separations. Finally plates were developed using the following mobile phases: in the first direction – ethyl acetate/toluene (5/95; v/v) and in the second direction – ethyl acetate/n-heptane (15/85; v/v). Eleven essential oils obtained by hydrodistillation in Deryng apparatus from various mint specimens were separated and then 2D thin-layer chromatograms were densitometrically scanned at the wavelength of 254 nm. Digital images (exported from densitometer software as ASCII files) were processed using ImageJ free software, and then some chemometric parameters were calculated (determination coefficient, congruence coefficient, Euclidean’s distance, Manhattan’s distance, Chebyshev’s distance) and additionally, principal component analysis (PCA) was performed to determine the goodness of matching for individual essential oils. The chemometric analysis allows one to identify individual essential oils and the examined plant materials.

Combination of planar chromatography with matrix-assisted laser desorption/ionization mass spectrometry for the analysis of biologically active compounds

MALDI mass spectra of 33 pharmacological substances recorded from standard metal targets using four different matrices (HABA, DHB, IAA and AT) have been obtained for the first time. They revealed only peaks for ions [M + H]+, [M + Na]+, and [M + K]+ with different intensities. It has been shown that MALDI spectra of the compounds can be obtained as a result of the desorption/ionization of analytes from spots on thin-layer chromatogram (TLC) (silica stationary phase) in the presence of the same tested matrices. It has been found that graphite can be efficiently used as a matrix in combination of TLC with MALDI mass spectrometry, as it eliminates the danger of the broadening of spots on TLC plates in the treatment with matrix solution and reduces the time of sample preparation.

Two sensitizing oxidation products of p-phenylenediamine patch tested in patients allergic to p-phenylenediamine.

The results from a previous study indicated the presence of several possible sensitizers formed during oxidation of the potent sensitizer p-phenylenediamine (PPD) to which PPD-sensitized patients might react, in various patterns. To extract and analyse a yellow spot from a thin-layer chromatogram with oxidized PPD, to which 6 of 14 (43%) PPD-positive patients had reacted in a previous study, in order to identify potential sensitizer(s) and to patch test this/these substance(s) in the 14 PPD-positive patients. The yellow spot was extracted from a thin-layer chromatogram of oxidized PPD, and two substances, suspected to be allergens, were identified by analysis with gas chromatography mass spectrometry (GCMS). The 14 PPD-positive patients, who had been previously tested with the thin-layer chromatogram of oxidized PPD, participated in the investigation, and were tested with dilutions of the two substances. GCMS analysis identified 4-nitroaniline and 4,4'-azodianiline in the yellow spot. Of the 14 PPD-positive test patients, 5 (36%) reacted to 4-nitroaniline and 9 (64%) reacted to 4,4'-azodianiline. The results show that 4-nitroaniline and 4,4'-azodianiline, formed during oxidation of PPD, are potent sensitizers. PPD-sensitized patients react to a high extent to concentrations equimolar to PPD of 4-nitroaniline and 4,4'-azodianiline.

Employment of High-Performance Thin-Layer Chromatography for the Quantification of Oleuropein in Olive Leaves and the Selection of a Suitable Solvent System for Its Isolation with Centrifugal Partition Chromatography.

A high-performance thin-layer chromatographic methodology was developed and validated for the isolation and quantitative determination of oleuropein in two extracts of Olea europaea leaves. OLE_A was a crude acetone extract, while OLE_AA was its defatted residue. Initially, high-performance thin-layer chromatography was employed for the purification process of oleuropein with fast centrifugal partition chromatography, replacing high-performance liquid-chromatography, in the stage of the determination of the distribution coefficient and the retention volume. A densitometric method was developed for the determination of the distribution coefficients, KC = CS/CM. The total concentrations of the target compound in the stationary phase (CS) and in the mobile phase (CM) were calculated by the area measured in the high-performance thin-layer chromatogram. The estimated Kc was also used for the calculation of the retention volume, VR, with a chromatographic retention equation. The obtained data were successfully applied for the purification of oleuropein and the experimental results confirmed the theoretical predictions, indicating that high-performance thin-layer chromatography could be an important counterpart in the phytochemical study of natural products. The isolated oleuropein (purity > 95%) was subsequently used for the estimation of its content in each extract with a simple, sensitive and accurate high-performance thin-layer chromatography method. The best fit calibration curve from 1.0 µg/track to 6.0 µg/track of oleuropein was polynomial and the quantification was achieved by UV detection at λ 240 nm. The method was validated giving rise to an efficient and high-throughput procedure, with the relative standard deviation % of repeatability and intermediate precision not exceeding 4.9% and accuracy between 92% and 98% (recovery rates). Moreover, the method was validated for robustness, limit of quantitation, and limit of detection. The amount of oleuropein for OLE_A, OLE_AA, and an aqueous extract of olive leaves was estimated to be 35.5% ± 2.7, 51.5% ± 1.4, and 12.5% ± 0.12, respectively. Statistical analysis proved that the method is repeatable and selective, and can be effectively applied for the estimation of oleuropein in olive leaves' extracts, and could potentially replace high-performance liquid chromatography methodologies developed so far. Thus, the phytochemical investigation of oleuropein could be based on high-performance thin-layer chromatography coupled with separation processes, such as fast centrifugal partition chromatography, showing efficacy and credibility.

Two dimensional chromatographic analysis as a quality measure of herbal extracts – Salvia officinalis

Background: Homoeopathic mother tinctures and herbal extracts are used worldwide for medicinal purposes on the basis that the plant extract contains the active components essential for medicinal use. Quality analysis of samples ensures that the correct active components are present for medicinal use. Thin layer chromatography has been used extensively to determine the quality of plant extracts and could just as readily be applied to the assessment of quality of homoeopathic mother tinctures. The development of a multidimensional technique allows for greater quality analyses of these extracts. Materials and Methods: The Salvia officinalis sample was extracted and the one dimensional thin layer chromatographic plate development of extracted sample was performed according to the German Homoeopathic Pharmacopoeia (GHP). Before the two dimensional thin layer chromatographic plates where run, different solvent systems were tested through a comparison of the resultant one dimensional thin layer chromatographic plates with that of the plate developed according to the GHP. The two dimensional thin layer chromatographic plate was developed in one direction using the eluent given in the GHP, the plate was then rotated 90 degrees and further developed using neat dichloromethane. Results and Conclusion: The two dimensional thin layer chromatogram for the selected sample Salvia officinalis was successfully established. This results in a more extensive profile regarding the identification of the individual components present in the homoeopathic mother tincture. The further production of two dimensional chromatograms is essential to the expanded detailed analysis of individual products and potential raw material production of even higher standards.

탈지유채박으로부터 추출된 표면활성물질 중 Sinapine 제거에 관한 연구

In this study, the process of sinapine removal from surface-active substances extracted from defatted rapeseed cake was established by using a mixed organic solvent system (diethylether:ethyl acetate = 1:1, v/v). The emulsifying properties of the purified surface-active substances were investigated. Thin layer chromatogram showed that sinapine was removed and purified surface-active substances were found to have better emulsifying properties compared to a non-purified one or commercial soy lecithin. As for interfacial tension data, purified surface-active substances showed values lower (10-1 wt%: 3.20±0.57 mN/m) than the non-purified ones (10-1 wt%: 14.16±0.27 mN/m). In addition, we found that fat globule size in emulsions with purified surface-active substances was much smaller than in emulsions with non-purified substances or commercial soy lecithin. These results could be attributable to the increased amount of phospholipids in purified substances following sinapine-removal.

TWO DIMENSIONAL CHROMATOGRAPHIC ANALYSIS AS A QUALITY MEASURE OF HERBAL EXTRACTS – SALVIA OFFICINALIS

Background: Homoeopathic mother tinctures and herbal extracts are used worldwide for medicinal purposes on the basis that the plant extract
 contains the active components essential for medicinal use. Quality analysis of samples ensures that the correct active components are present
 for medicinal use. Thin layer chromatography has been used extensively to determine the quality of plant extracts and could just as readily be
 applied to the assessment of quality of homoeopathic mother tinctures. The development of a multidimensional technique allows for greater
 quality analyses of these extracts.
 Materials and Methods: The Salvia officinalis sample was extracted and the one dimensional thin layer chromatographic plate development of
 extracted sample was performed according to the German Homoeopathic Pharmacopoeia (GHP). Before the two dimensional thin layer
 chromatographic plates where run, different solvent systems were tested through a comparison of the resultant one dimensional thin layer
 chromatographic plates with that of the plate developed according to the GHP. The two dimensional thin layer chromatographic plate was
 developed in one direction using the eluent given in the GHP, the plate was then rotated 90 degrees and further developed using neat
 dichloromethane.
 Results and Conclusion: The two dimensional thin layer chromatogram for the selected sample Salvia officinalis was successfully established.
 This results in a more extensive profile regarding the identification of the individual components present in the homoeopathic mother tincture.
 The further production of two dimensional chromatograms is essential to the expanded detailed analysis of individual products and potential raw
 material production of even higher standards.

Review and application of functional data analysis to chemical data—The example of the comparison, classification, and database search of forensic ink chromatograms

Functional data analysis is a relatively recent statistical method that can be applied to any dataset that can be thought of as a function. Functional data analysis considers functions as random elements. Modern chromatographic or spectroscopic techniques typically record analytical outputs as a function of time or wavelength. The purpose of this paper is to investigate the potential of functional data analysis for the characterization, comparison, and classification of chemical data. Forensic examination of ink is used as the main example in this paper as it covers different aspects of functional data analysis: (a) thin-layer chromatograms resulting from analysis of ink samples are characterized as functions of time and wavelength; (b) multiple samples analyzed at different times, or by different analysts, are registered into a common space; (c) a dimension reduction technique is applied to the sample functions to enable (d) their use for comparing between ink samples and for clustering large databases of inks. Our algorithms showed excellent performance and can readily be implemented to search and retrieve chemical profiles in large databases. From a theoretical standpoint, functional data analysis allows for a natural extension of multivariate analysis to datasets that can be thought of as functions. Algorithmically, functional data analysis proves to be a powerful technique that enables to detect functions minima and maxima, register multiple functions to a common space, and control the dimensionality and smoothness of a functional dataset. Nevertheless, we found that the implementation of functional data analysis is computationally complex when compared to classic multivariate analysis.

Characterization of Date Palm (Phoenix dactylifera L.) Cultivars on the Basis of Amino Acid Spectrum

Acquaintance with genetic diversity among date palm (Phoenix dactylifera L.) cultivars is essential for cross breeding. Objectives of this study were characterization of date palm cultivars on amino acid spectrum and evaluation of phylogenetic relationship among date palm cultivars. Five date palm cultivars were investigated and rich diversity was demonstrated among these cultivars. A total of 14 amino acid spots were recognized on thin layer chromatogram (TLC). The similarity coefficient worked out for five date palm cultivars ranged from 0.29 to 0.67. Cultivar Khalas and Sewi were most similar cultivars having similarity coefficient of 0.67 and made a cluster with cultivar Dayri. Whereas, cultivar Halawy and Khuneizi constructed a separate cluster with similarity coefficient of 0.55. Cultivar Khalas and Dayri revealed minimum similarity and maximum diversity among all the investigated cultivars.

In vitro effect of ursolic acid on the inhibition of Mycobacterium tuberculosis and its cell wall mycolic acid

Mycobacterium tuberculosis is a dangerous intracellular pathogen. In order to protect against mycobacterium infection, novel agents with anti-mycobacterial activity should be given emergency priority for evaluation. Ursolic acid (UA), a plant triterpenoid, shows promising bioactivities, including anti-mycobacterial potency. In this study, the action of UA against Mycobacterium tuberculosis H37Ra was evaluated, and the inhibitory concentration was found to range between 10 and 20 μg/ml in a resazurin assay and MGIT 960 instrument. The total mycolic acid in UA-treated H37Ra was detected and compared with INH-treated and non-treated bacterium by LC-MS/MS. Quantitative LC-MS/MS data confirmed that both UA and INH decreased mycolic acid biosynthesis in a dose-dependent manner. Thin-layer chromatogram (TLC) analysis showed that all mycolic acid subtypes were affected by UA treatment in the wild type but not in strains resistant to UA. Electron microscopy images also confirmed that UA treatment affected both H37Ra cell and intracellular content of H37Ra. Altogether, these data confirmed the promise of the inhibitory action of UA in mycolic acid, which might further delineate the mechanistic pathway of mycobacterial inhibition by UA.

Signaling molecules from Lactuca sativa L. induced quorum sensing phenotypes in bacteria

Abstract The outcome of the present investigation revealed that lettuce (Lactuca sativa L.) extract strongly interferes with acyl homoserine lactone (AHL) regulated physiological functions in the bioreporter strain, Chromobacterium violaceum CV026. Extracts of L. sativa also promoted production of virulence factors in plant pathogen, Pectobacterium carotovorum, and significantly increased tissue maceration on potato tubers when there was a low concentration (103 cfu · ml−1) of the bacterium was used. The thin layer chromatogram which visualised with AHL bioreporter strain, CV026, showed that L. sativa extract produced a circular spot with a diffuse edge tail and migrated with the same mobility as standard N-hexanoyl-L-homoserine lactone (C6-HSL). Gas Chromatography Mass Spectroscopy (GC-MS) analysis of the lettuce extract resulted in the identification of 19 compounds of which homoserine was identified for the first time in plants. Homoserine accounted for 2.37% of the total constituents. It is a new finding that lettuce contains AHL like substances (homoserine) which excite AHL related quorum sensing (QS) in bacteria.