In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. Therefore, a greater attention has been ...paid to antimicrobial activity screening and evaluating methods. Several bioassays such as disk-diffusion, well diffusion and broth or agar dilution are well known and commonly used, but others such as flow cy- tofluorometric and bioluminescent methods are not widely used because they require specified equip- ment and further evaluation for reproducibility and standardization, even if they can provide rapid re- sults of the antimicrobial agent＇s effects and a better understanding of their impact on the viability and cell damage inflicted to the tested microorganism. In this review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limita- tions are reported.
Thin layer chromatography (TLC) fingerprint profile analysis can be used for quality control of herbal medicinal raw materials through identification, authentication, and discrimination. This study ...aims to develop a fingerprint analysis method for tempuyung TLC (Sonchus arvensis L.), which is then used for quality control. Tempuyung was extracted with methanol using ultrasonication which was then analyzed using the developed fingerprint TLC method. The optimum mobile phase used to separate compounds from tempuyung was a composition of chloroform: ethyl acetate: dichloromethane: formic acid (7.5:2:0.5:0.1) and produced eleven bands. The mobile phase composition produced good separation and had a typical luteolin band with an Rf value of 0.22, detected under UV 366 nm and derivatized with 10% sulfuric acid reagent. This method was applied to tempuyung from three locations, including Malang, Solo, and Yogyakarta, whose fingerprint patterns did not differ significantly. The fingerprint method has been validated and met the acceptance requirements for quality control of tempuyung.
The aim of this paper is to present a comprehensive overview of the main aims and scopes in screening of botanicals, a task of which thin-layer chromatography (TLC) is, on an everyday basis, ...confronted with and engaged in. Stunning omnipresence of this modest analytical technique (both in its standard format (TLC) and the high-performance one (HPTLC), either hyphenated or not) for many analysts might at a first glance appear chaotic and random, with an auxiliary rather than leading role in research, and not capable of issuing meaningful final statements. Based on these reflections, our purpose is not to present a general review paper on TLC in screening of botanicals, but a blueprint rather (illustrated with a selection of practical examples), which highlights a sovereign and important role of TLC in accomplishing the following analytical tasks: (i) solving puzzles related to chemotaxonomy of plants, (ii) screening a wide spectrum of biological properties of plants, (iii) providing quality control of herbal medicines and alimentary and cosmetic products of biological origin, and (iv) tracing psychoactive plants under forensic surveillance.
The main aim of this study is to experimentally investigate the yield of extraction and the presence of wax in the extracted yield from Musaacuminata (banana) biomass based on various functional ...groups that are present in natural wax. Extraction of natural wax from Musaacuminata (banana) biomass has been done by using the Soxhlet apparatus method in the presence of both polar (ethyl acetate and ethanol) and non-polar (toluene and hexane) solvents. The extracted yield has been found as 3.58% from hexane, 5.16% from toluene, 7.03% from ethyl acetate, and 10.26% from ethanol. The wax was also found in the extracted yield only in the case of nonpolar solvents (toluene and hexane). The novelty of this work is that Musaacuminata (banana) waste biomass has been utilized to recover the natural wax using nonpolar solvents and also compared with that of polar solvents to check the scope of wax extraction using polar solvents. Also, statistical analysis has been performed of the extracted yield using both solvents. Thin Layer Chromatography (TLC) and Fourier Transform Infrared Spectroscopy (FTIR) methods have been used to determine the various hydrocarbon chains present in the extracted yield which is similar to that of natural wax.
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•The extracted yield has been found to be 3.58% from hexane, 5.16% from toluene.•Beeswax is a natural product, composed of a complex mixture of non-glyceride esters.•These esters are carboxylic acids and hydroxy acids.•Chitosan and wax can be utilized for packaging applications.•The natural wax has been extracted from Musaacuminata biomass.
Objective:To develop and validate an image analysis method for quantitative analysis ofγ-oryzanol in cold pressed rice bran oil.Methods:TLC-densitometric and TLC-image analysis methods were ...developed,validated,and used for quantitative analysis of γ-oryzanol in cold pressed rice bran oil.The results obtained by these two different quantification methods were compared by paired t-test.Results:Both assays provided good linearity,accuracy,reproducibility and selectivity for determination of γ-oryzanol.Conclusions:The TLC-densitomelric and TLC-image analysis methods providett a similar reproducibility,accuracy and selectivity for the quantitative determination of γ-oryzanol in cold pressed rice bran oil.A statistical comparison of the quantitative determinations of γ-oryzanol in samples did not show any statistically significant difference between TLC-densitometric and TLC-image analysis methods.As both methods were found to be equal,they therefore can be used for the determination of γ-oryzanol in cold pressed rice bran oil.
•Effect directed analysis and TLC screening of S. chinensis fruits were performed.•Inhibition of acetylcholinesterase related to lignans was confirmed.•TLC-DB showed activity against Bacillus ...subtilis.•Citric acid is probably responsible for antibacterial properties of S. chinensis.•Bioactive components were tentatively identified by ESI-LC-MS.
The fruit of Schisandra chinensis (Chinese magnolia vine), the medicinal plant well-known in Traditional Chinese Medicine, gains great popularity in the modern phytopharmacology. This phenomena is related to the wide and powerful healing properties, including supporting immune, nervous and digestive systems activity. S. chinensis is also known for its adaptogenic properties which can support the treatment of neurodegenerative disorders, particularly Alzheimer's disease. The components of S. chinensis have been analyzed mostly using chromatography, including HPLC, GC and TLC. The last technique can be easily hyphenated with biological assays performed directly on a TLC plate that is using effect directed detection.
TLC-direct bioautography (TLC-DB) for acetylcholinesterase (AChE) inhibition and TLC-DB against Bacillus subtilis were performed, followed by micro-preparative separation of fractions which were subsequently subjected to LC-MS tentative identification. Additionally, screening analysis was done using both biological detection and derivatization reagents (e.g. PMA, thymol, NP-PEG). Both TLC screening and effect-directed analysis (TLC-DB followed by MS analysis) of S. chinensis fruit revealed components with biological activity, especially antibacterials (e.g. citric acid) and inhibitors of AChE (mainly dibenzocyclooctadiene lignans).
AChE inhibition activities were confirmed by TLC-DB for nine standards that is: 6-O-benzoylgomisin, deoxyschisandrin, gomisin A, gomisin G, schisandrin, schisandrin C, schisanhenol, schisantherin A and schisantherin B. These lignans were further identified by LC-ESI-MS in the isolated fraction revealing AChE inhibition. Moreover three other lignans: γ-schisandrin, schisandrin B and gomisin J were tentatively identified by LC-ESI-MS.
This paper proposes a novel nonisolated single-input dual-output three-level dc-dc converter (SIDO-TLC) appropriate for medium- and high-voltage applications. The SIDO-TLC is an integration of the ...three-level buck and boost converters, whose output voltages are regulated simultaneously. Reducing voltage stress across semiconductor devices, improving efficiency, and reducing inductors size are among the main merits of the new topology. Moreover, due to the considerably reduced volume of the step-down filter capacitor, a small film capacitor can be used instead, whose advantages are lower equivalent series resistance and a longer lifespan. A closed-loop control system has been designed based on a small-signal model derivation in order to regulate the output voltages along with the capacitors' voltage balancing. In order to verify the theoretical and simulation results, a 300-W prototype was built and experimented. The results prove the aforementioned advantages of the SIDO-TLC, and the high effectiveness of the balancing control strategy. Furthermore, the converter shows very good stability, even under simultaneous step changes of the loads and input voltage.
Publications reporting thin layer chromatography (TLC) screening and high performance TLC (HPTLC)-densitometry quantification analyses of counterfeit pharmaceutical products are reviewed for the ...2008-2019 period. Screening using TLC methods published in the Global Pharma Health Fund (GPHF) Minilab Manual and U.S. Food and Drug Administration (FDA) Compendium, as well as in other sources, are covered. Also included are publications on TLC analysis hyphenated with Raman and mass spectrometry; analyses of counterfeit traditional herbal medicines; earlier published reviews; transfer of screening methods for counterfeit pharmaceutical products in the Minilab Manual and FDA Compendium to HPTLC-densitometry using a model process; development of HPTLC-densitometry methods for pharmaceutical products not included in the Minilab Manual or FDA Compendium using the model process followed by development of corresponding Supplemental FDA Compendium TLC screening methods; and modified Minilab methods with simplified detection based on heating of silica gel F layers to produce fluorescence quenching zones (thermochemical activation) rather than detection using spray, dip, or vapor phase derivatization reagents. Some thoughts on future prospects for the field are also offered.
The aim of this study was to evaluate the applicability of both methods, i.e. reversed-phase thin-layer chromatography (RP-TLC) and high-performance thin-layer chromatography (RP-HPTLC), and ...computational algorithms to determine the lipophilicity parameter of danazol. The values of the theoretical partition coefficients expressed as AlogPs, AClogP, AlogP, MlogP, XlogP2, XlogP3, SKlogP, and logP were obtained using different computational algorithms. The mean value of logP for danazol (logPśr) was also determined based on these data, which is 4.01±0.51. The most similar theoretical values of the partition coefficient were SKlogP (4.16), MlogP (4.15) and logP (4.08), respectively, which was calculated using CS Chem 3D Ultra 7.0 software. Chromatographic lipophilicity parameter (RMW) of danazol was determined according to Soczewinski-Wachtmeister equation using different stationary phases in the form of chromatographic plates: RP2F254, RP8F254, RP18F254, RP18WF254 and the following mobile phases: methanol-water, acetonitrile-water, 1,4-dioxane-water and acetone-water. The organic modifier content in these phases was 50-95%. The effects of mobile and stationary phases as well as computational algorithms on the differences in the values of chromatographic lipophilicity parameter and theoretical logP value of danazol, respectively, were observed. The highest similarity in RMW values of danazol was obtained using RP2F254 and RP18WF254 chromatographic plates and using acetone-water and 1,4-dioxane-water as mobile phases, respectively. On the other hand, the results of chromatographic lipophilicity parameter i.e. RMW were most similar to the mean value of logP. RP8F254 plates developed with methanol and water (RMW=4.111±0.214) and RP18F254 plates analyzed with acetone-water mobile phase (RMW=4.169±0.379), respectively. The studies carried out in this work show the usefulness of thin-layer chromatography and selected computational algorithms to determine the lipophilicity parameter of danazol, which may be applied in the future to study the bioavailability of this compound and its derivatives.
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•Research on the ACNA catalogue outlined the complex and often unexpected composition of synthetic dyes.•TLC-SERS and HPLC-DAD-HRMS analyses revealed differences between catalogue ...labels and actual dye compositions.•SERS combined with TLC effectively identifies synthetic dyes and their degradation in historical textiles.
The finding of numerous synthetic strategies between the 19th and 20th century fostered the production of an extensive spectrum of organic dyes for artistic and industrial applications. Shortly after, challenges emerged related to the rapid deterioration of these products. Nowadays, the characterization of coloured pieces of art produced in the first half of the XXth century is further complicated by the absence of reference materials with an unambiguous composition, which are frequently a mixture between the starting dyes and their degradations products. Here we demonstrate as Surface Enhanced Raman Spectroscopy coupled with the simplest separation technique, i.e. Thin Layer Chromatography, is able beyond to recognize several synthetic dyes also to identify their isomers and degradation products. The occasion was the study of a catalogue of dyed textile swatches, produced in 1951 by the well-known Italian industry ACNA (Azienda Coloranti Nazionali e Affini). An apparently easy task turned out to be, indeed, not at all obvious as we found out that the actual composition of the reference samples seldomly corresponded to the declared one. TLC-SERS investigation of historical textile swatches was complemented by the integration of liquid chromatography coupled with a diode array detector and high-resolution mass spectrometry (HPLC-DAD-HRMS). This approach allowed us to validate the findings of TLC-SERS and to distinctively characterise synthetic by-products and degradation markers resulting from the deterioration of the dyes.
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