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.
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.
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.
•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.
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.
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.
•Methods and techniques in planar chromatography (TLC/HPTLC) are reviewed.•The advantages and limitations of planar chromatography are revisited.•New developments in bioautography for “effect ...testing” are highlighted.•Advances in the detection/identification analytes by TLC/MS are described.•Future directions in the development and use of planar chromatography are considered.
Planar chromatography, in the form of thin-layer or high-performance thin-layer chromatography (TLC, HPTLC), continues to provide a robust and widely used separation technique. It is unrivaled as a simple and rapid qualitative method for mixture analysis, or for finding bioactive components in mixtures. The format of TLC/HPTLC also provides a unique method for preserving the separation, enabling further investigation of components of interest (including quantification/structure determination) separated in both time and space from the original analysis. The current practice of planar chromatography and areas of development of the technology are reviewed and promising future directions in the use of TLC/HPTLC are outlined.
Lipidomic Profile of Santos, Alberdan S; Salgado, Hugo L.C; Bonturi, Nemailla ...
South African journal of chemistry,
12/2021, Volume:
75, Issue:
1
Journal Article
Peer reviewed
Open access
This work was undertaken to evaluate the antioxidant capacity of Rhodotorula toruloides lipid extract in TLC plate, using the (DPPH) (1,1-diphenyl-2-picril-hydrazine) method as an innovative way to ...visualise lipid groups that comprise this activity. Similarly, carotenoids and crude oil were analysed for antioxidant capacity by the DPPH and β-carotene/linoleic acid methods. The lipidomic profile extract analysis was performed by GC/MS and HPLC/DAD. The sample preparation for the GC/MS analysis was made by ultrasound-assisted transesterification. Free compounds were silylated with BSTFA (N,O-Bis (trimethylsilyl) trifluoracetamide) + 1% TMCS (Trimethylchlorosilane ). The analysis of the lipid extract showed that in the saponifiable fraction saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were present; and in the unsaponifiable fraction were steroids and carotenoids. The antioxidant capacity was expressed as IC50 reaching 6.4 mg/L that means relative efficiency. The oil profile, using TLC, shows the chemical groups: carotenoids, acylglycerols, free fatty acids and steroids. Similarly, the GC/ MS analysis shows the fatty acids and steroids. The HPLC analysis describes the carotenoids profile, highlighting b-carotene as the majority and the presence of β-carotene-5,8-epoxide, zeaxanthin and b-cryptoxanthin, characterising the lipidomic study of this yeast.
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•Isoniazid (INH) oral dosage tablets are commonly used to treat tuberculosis (TB).•Use of poor-quality medications can lead to drug-resistant tuberculosis strains.•TLC with ImageJ can ...quantify isoniazid concentrations for quality screening.•Smartphone cameras can be used for low-cost imaging of TLC plates.•Cost-effective screening methods are ideal for labs in low-resource settings.
Isoniazid (INH) oral dosage tablets are an antibacterial medication commonly used to treat tuberculosis (TB). While this medication can be highly effective in managing and curing TB, manufacturing of poor-quality INH products can lead to the proliferation of drug resistant TB strains – particularly in low- and middle-income countries (LMICs). It is therefore imperative that reliable methods of quality screening of INH tablets are available for areas that have limited access to traditional testing resources. In this study, a thin layer chromatography (TLC) procedure for INH identification is validated in conjunction with smartphone image capture and open-source image analysis software to provide an alternative quantitative quality screening method for INH tablets, primarily intended for applications in LMICs. The method assessed two individual tablet formulations: 100 mg and 300 mg INH, each from different manufacturers. The modified TLC procedure used for the study was based on a validated high-performance thin layer chromatography method for the determination of rifampicin, INH, and pyrazinamide in a fixed dosage tablet. Quantitation was performed by visualizing and photographing TLC plates using a UV lamp, 3D-printed light box, and Apple iPhone SE 2nd Generation (2020) and Google Pixel 4a (5G) smartphones, and images were then analyzed using ImageJ Fiji software. The processed images’ pixel data were used to create a calibration curve from the INH standard spots to determine the concentration of an INH sample spot. Linearity, range, accuracy, repeatability and intermediate precision, specificity, and robustness were evaluated. The method was linear in the range of 0.150–0.450 mg mL−1, with coefficients of determination ≥0.98. The overall accuracy of the method was 99.2 % with an RSD of 2.4 % for image sets captured using the Apple iPhone, and 99.7 % with an RSD of 3.3 % for image sets captured using the Google Pixel. The pooled standard deviations for repeatability and intermediate precision were 2.27 % and 3.25 %, respectively, for the iPhone and 2.62 % and 3.74 %, respectively, for the Pixel. The method demonstrated sufficient specificity and robustness. The results of this method validation suggest that this procedure may provide a feasible alternative to traditional testing as a low-cost means of quality screening in LMICs.
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