Thin-Layer Chromatography (TLC) in the Screening of Botanicals-Its Versatile Potential and Selected Applications

Phytochemical screening, UPLC analysis, evaluation of synergistic antioxidant and antibacterial efficacy of three medicinal plants used in Kinshasa, D.R. Congo

Plant extracts are used worldwide due to their biologically active compounds, which support food preservation and help combat various diseases through their antimicrobial and antioxidant properties. In the capital city of the Democratic Republic of the Congo, an ethnobotanical survey revealed the use of Dysphania ambrosioides (L.) Mosyakin & Clemants, Ocimum gratissimum L. and Tetradenia riparia (Hochst.) Codd, often in combination, for treating oral microbial diseases. While these plants have been widely studied individually; their combined potential has not been investigated. The present research aims to explore the phytochemical composition, the synergistic antimicrobial, and antioxidant potential of different extracts from these three mentioned plants. Phytochemical composition of the decocted and percolated extracts from the three plants was determined using qualitative analysis and the ultra-performance liquid chromatography quadrupole time of flight tandem mass spectrometry (UPLC-QTOF-MS). Antimicrobial activity was assessed using the broth dilution method, while antioxidant activity was evaluated using the DPPH method. For the antimicrobial studies, the decocted and percolated extracts were tested against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Qualitative phytochemical analysis revealed the presence of alkaloids, saponins, flavonoids, iridoids, and anthraquinones in all the plant extracts. The methanolic extract of T. riparia exhibited the highest phenolic content (299.146 ± 0.143 mg GAE/g extract), while O. gratissimum had the highest flavonoid content (138.256 ± 0.277 mg QE/g extract). UPLC analysis identified several metabolites in the plant extracts including rosmarinic acid, cirsimaritin, xanthomicrol and kaempferol derivatives. Rosmarinic acid was consistently identified across all the plant extract combinations, while other flavonoids such as apigenin 7-glycosides, kaempferitin and luteolin 7-O-glucoside, were detected in specific plant extract combinations. The decocted plant extracts exhibited higher antioxidant activity than the percolated extracts, with O. gratissimum showing the highest antioxidant activity (11.744 ± 0.584 µg/mL), followed by T. riparia (12.916 ± 0.972 µg/mL). The extract combinations from O. gratissimum and T. riparia demonstrated synergistic antioxidant activity (CI = 0.57). Amongst all extracts, the highest antibacterial activity was observed in the decocted extracts of O. gratissimum and T. riparia against S. aureus (MIC = 500 µg/mL), with their combination showing additive antibacterial activity (FICI = 1). The aim of this study was primarily to evaluate the combinatory potential of these three plants as reliable sources of antimicrobials and antioxidants for the treatment of various microbial diseases in the future. The study provides evidence of the synergistic antioxidant and antibacterial potential of O. gratissimum and T. riparia. These results suggest that these plant extracts are promising sources of natural antimicrobial and antioxidant agents, with potential application in the pharmaceutical and food industries for combating several infectious diseases.

Improved Point-of-Care Mass Spectrometry Analysis with Thin-Layer Chromatography-Based Two-Dimensional Separation and Spray Ionization

Point-of-care testing (POCT) involves administering rapid on-site analysis to provide fast biochemical testing results. POCT reduces delays in clinical decision-making and eliminates the need to transport and prepare clinical samples for immediate diagnosis or clinical intervention by healthcare professionals. Herein, a novel methodology integrating thin-layer chromatography-based two-dimensional separation with miniature mass spectrometry was developed for rapid on-site clinical analysis. As a proof-of-concept demonstration, γ-aminobutyric acid, 2-hydroxyglutarate, and N-acetyl-l-aspartic acid, which are widely known as biomarkers for brain gliomas, were selected as model analytes for method development and validation. The proposed approach exhibited satisfactory analytical performance, with 1 ng/mL limits of detection, 2 ng/mL limits of quantitation, and recoveries in the range of 85.9-107.2%. Additionally, on-TLC derivatization and reactive spray ionization strategies were utilized to enhance the mass spectrometric signals compared to underivatized analysis. This method was applied to analyze clinical samples, showcasing its attractive potential outside the laboratory.

Emerging advances in biosensor technologies for quorum sensing signal molecules

Quorum sensing is a physiological phenomenon of microbial cell-to-cell information exchange, which relies on the quorum sensing signal molecules (QSSMs) to communicate and coordinate collective processes. Quorum sensing enables bacteria to alter their behavior as the population density and species composition of the bacterial community change. Effective detection of QSSMs is paramount for regulating microbial community behavior. However, traditional detection methods face the shortcomings of complex operation, high costs, and lack of portability. By combining the advantage of biosensing and nanomaterials, the biosensors play a pivotal significance in QSSM detection. In this review, we first briefly describe the QSSM classification and common detection techniques. Then, we provide a comprehensive summary of research progress in biosensor-based QSSM detection according to the transduction mechanism. Finally, challenges and development trends of biosensors for QSSM detection are discussed. We believe it offers valuable insights into this burgeoning research area.

Tissue-specific chemical expression and quantitative analysis of bioactive components of Moutan Cortex by laser-microdissection combined with UPLC-Q-Orbitrap-MS technique

Moutan Cortex, is the root bark of Paeonia suffruticosa Andrews, which is classified into three specifications according to whether or not it is peeled and cored: Liandanpi, Guadanpi and whole root. In this study, the cork layer, cortex, phloem and xylem of P. suffruticosa fresh root were precisely separated by laser microdissection technique. UPLC-Q-Orbitrap-MS and UPLC-QQQ-MS techniques were used to analyse the differences in the chemical composition of different tissue parts of P. suffruticosa fresh root and Liandanpi, and to determine the optimal processing method of P. suffruticosa root. As a result, a total of 90 compounds were characterised, among which the cork layer had more types and higher contents of chemical constituents, and the xylem had fewer types and lower contents of chemical constituents. The proportion of xylem is larger, while the type and content of active ingredients is smaller. Therefore, the processing method of removing the wood core and retaining the cork bark can be used in the processing of Moutan Cortex. In this study, laser microdissection and ultra performance liquid chromatography-mass spectrometry were used to provide a theoretical basis for optimising the processing method of Moutan Cortex to enhance its pharmacological effects.

Microscopic characterization, TLC fingerprinting and optimization of total lipid content from Euphorbia neriifolia (L.) using response surface methodology

Euphorbia neriifolia (EN) is a medicinal plant used to treat a variety of ailments in traditional systems. Despite numerous studies on pharmacological activities, no information was available on the microscopic study of this plant. This is the first study that has been attempted to fill this need by performing the light and field emission scanning electron microscopy (FESEM) of leaf, stem, and latex. The powder microscopy of several organs (leaves, stem, and bark) and exudate (latex) of EN was carried out using safranine, fast green, phloroglucinol, and other standard solutions at different magnifications. The chemical fingerprinting of petroleum ether extract was accomplished by using thin layer chromatography. The optimization of total lipid content from the EN leaf under ultrasound-assisted extraction (UAE) and soxhlet extraction (SE) procedure was determined using response surface methodology (RSM). The studied factors that affect the lipid content were: solvent ratio, extraction temperature, and extraction time. Several notable characteristics observed in the leaf of EN are amphistomatic leaves with anticlinical cell walls, anomocytic stomata, spongy mesophyll cells, elongated palisade cells, angular collenchyma, and U-shaped vascular bundle. The plano-convex midrib is covered by polygonal to oval-shaped cuticles and contains anomocytic stomata. The circular petiole has no trichomes and contains laticifers, crystals, and idioblasts. The circular stem was observed with trichomes, hypodermis, collenchyma, parenchymatous cells, central pith, pentagonal stellar region, cambium, and 2-4 times more xylem that of phloem. All of the powdered plant parts and exudate under study contained trichomes, xylem vessels, wood fibers, cork cells, starch grains, calcium oxalate crystals, idioblasts, lignified cork, tannin content, stone cells, and oil globules. The blackish-green colored petroleum ether extract with semi-solid consistency showed the greatest percent (%) yield of 4% in the latex of EN. The thin layer chromatography (TLC) examination of petroleum ether extract of EN leaf produced a maximum 6 spots with Rf values of 0.16, 0.58, 0.62, 0.73, and 0.96 in the mobile phase of petroleum ether-acetone (8:2). In terms of optimization, the dark green colored UAE extract with semi-sticky consistency showed highest % yield of 4.5% whereas the yellowish green colored SE extract of sticky consistency showed the highest % yield of 4.9%. The findings showed that there were not many differences in the total lipid content between UAE (0.16%) and SE (0.11%). However, the best optimum condition for lipid content extraction analysis was obtained as follows: solvent ratio (PE:HE) 50:50, extraction temperature 50°C, extraction time 45 min for UAE, and solvent ratio (PE:HE) 60:40, extraction temperature 45°C, and extraction time of 24 h for SE. Hence, this study signifies the various noteworthy microscopic features along with the presence of different phytocompounds through TLC and best optimized condition for the extraction of lipids from different parts of EN. As no previous study has been reported, the outcomes obtained from the current study prove to be beneficial in the identification of species, quality control, and detection of any adulteration from the laboratory and commercial samples of EN. RESEARCH HIGHLIGHTS: The percent yield was found to be maximum in latex extract (4%). The leaf pet ether extract was separated into 6 bands with different Rf values. The extracted compounds from Euphorbia neriifolia leaves were categorized into non-polar heat tolerant. The highest total lipid yield (0.1119) was obtained at solvent ratios 60:40 of PE:HE (petroleum ether: petroleum hexane).

Existing status and future advancements of adulteration detection techniques in herbal products

BACKGROUND

Herbal products have been commonly used all over the world for centuries. Its products have gained remarkable acceptance as therapeutic agents for a variety of disorders. However, following recent research disclosing discrepancies between labeling and actual components of herbal products, there is growing concern about the efficacy, quality and safety of the products. The admixture and adulteration of herbal medicinal products pose a risk of serious health compromise and the well-being of the consumers. To prevent adulteration in raw ingredients and final herbal products, it is necessary to use approaches to assess both genomes as well as metabolomics of the products; this offers quality assurance in terms of product identification and purity. The combinations of molecular and analytical methods are inevitable for thorough verification and quality control of herbal medicine.

METHODS AND RESULTS

This review discusses the combination of DNA barcoding, DNA metabarcoding, mass spectroscopy as well as HPLC for the authentication of herbal medicine and determination of the level of adulteration. It also discusses the roles of PCR and real-time PCR techniques in validating and ensuring the quality, purity and identity of the herbal products.

CONCLUSIONS

In conclusion, each technique has its own pros and cons, but the cumulative of both the chemical and molecular methods is proven to be the best strategy for adulteration detection. Moreover, CRISPR diagnosis tools equipped with multiplexing techniques may be implemented for screening adulteration from herbal drugs, this will play a crucial role in herbal product authentication in the future.