Forecasting structure of natural products through color formation process by thin layer chromatography

Colorimetric analysis platform based on thin layer chromatography for monitoring gluten cross-contamination in food industry

Monitoring of the accidental presence of gluten (Glu), resulting from cross-contamination, is imperative in different industries, in particular food industry. The objective of this study was the development of an analytical platform utilizing thin-layer chromatography (TLC) with colorimetric read-out for making binary (yes/no) decisions on surfaces and/or point of these industries. The composition of the extractive phase was optimized with commercial products used in cleaning processing lines. Subsequently, an exploration of TLC separation and detection was undertaken. CN-modified nanosilica plates and 30:70 acetonitrile:water were used to achieve a selective signal for Glu residues. The study of the detection performance showed that both spectroscopic measurement and image analysis were resulted in satisfactory results for quantitate analysis (RSD = 5 %, LOD = 0.12 mg). The practical application of the proposed methodology on surfaces of the food processing lines. This work demonstrated the operational feasibility in detecting gluten cross-contaminations within the food processing industry.

Reversible polarity-switch of thin-layer chromatography by photo-induction with multi-regulation in spatial dimension

Generally, thin-layer chromatography always undertakes the indispensable role in rapid screening and identification of specific compounds. Stationary phase is the core part of thin-layer chromatography with fixed property, which leading to the limitations of separation mode of only regulating the composition of mobile phase. This work was an attempt to fabricate the unique photosensitive thin-layer chromatography to make up the above major drawback. 4-[3-(Triethoxysilyl)propoxy]azobenzene (azo-PTES) was synthesized as photosensitive modifier to fabricate the photosensitive stationary phase, and the transformation of cis-trans structure of azo-PTES proceeds along with polarity difference under 365 nm and 473 nm irradiation. Based on this, the proposed photosensitive thin-layer chromatography shows the reversible switch of polarity of stationary phase by photoinduction, followed by the deserved reversible separation behavior. Furthermore, multi-regulation in spatial dimension was achieved based on the high freedom of spatial regulation of photoinduction, which brings about the integration of stationary phase with different polarity, just by photoinduction. The concept of photosensitive thin-layer chromatography provides new idea for improving separation efficiency and developing multi-dimensional thin-layer chromatography on the one plate.

HPTLC+SRES screening of pesticide for point-of-care application as shown with thiram in juice

In this study, a HPTLC-platformed SERS detection was established for screening thiram in juice. After a simple extraction, the sample liquid was separated on HPTLC plates, which resulted in a specific zone for the analyte. Following infiltration with atomize water, the band of interest was easily scraped off and eluted. In parallel, a flexible and SERS-active substrate was fabricated by the in-situ synthesis of gold nanoparticles within cotton fabrics. Under optimized conditions, fingerprint-like signal at 1376 cm^-1 of the analyte were easily recorded by a hand-held Raman spectrometer with enough LOD (0.5 mg/L), LOQ (0.9 mg/L) and reproducibility (<11.7%). The optimized screening system was further validated with pear, apple and mango juice by determining the spike-and-recovery rates (75.6 to 112.8%). It was demonstrated that this method could be a facile point-of-care testing system tailored for pesticide screening.

HPTLC-Bioluminescent Bioautography Screening of Herbal Teas for Adulteration with Hypolipidemic Drugs

Teas based on nutraceutical herbs are an effective tool against hyperlipidemia. However, the adulteration with chemical drugs is frequently detected. By coupling bioluminescent bioautography with high performance thin-layer chromatography (HPTLC), we developed a facile method suitable for screening hypolipidemic drugs (ciprofibrate and bezafibrate) adulteration in five different herbal teas (lotus leaf, Apocynum, Ginkgo biloba, Gynostemia and chrysanthemum). First, the sensitivity of a bioluminescent bacteria to the analyte was evaluated on different HPTLC layer materials, revealing that the best performance was achieved on the silica gel layer. On this basis, sample extracts were separated on silica gel plates via a standardized HPTLC procedure, forming a selective detection window for the targeted compound. Then, the separation results were rapidly visualized by the bioluminescence inhibition of bacteria cells within 6 min after dipping. The observed inhibition displayed an acceptable limit of detection (<20 ng/zone or 2 mg/kg) and linearity (R² ≥ 0.9279) within a wide concentration range (50-1000 ng/zone). Furthermore, the optimized method was performed with artificially adulterated samples and the recovery rates were determined to be within the range of 71% to 91%, bracing its practical reliability. Showing superiorly high simplicity, throughput and specificity, this work demonstrated that the analytical method jointly based on HPTLC and bioautography was an ideal tool for screening bioactive compounds in complex biological matrix.

An accurate, cost-effective and simple colorimetric method for the quantification of total triterpenoid and steroidal saponins from plant materials

Saponins are heterosides widely distributed in the plant kingdom. Their properties are used in many industrial sectors, such as food, cosmetics, agriculture, and pharmaceuticals, and their use is increasing due to the market trend to use natural ingredients. Although many techniques exist to quantify saponins (e.g., gravimetric, foaming, spectrophotometric or chromatographic), none of these allow simultaneous accurate, rapid and inexpensive analysis of both triterpenoid and steroidal saponins. A new colorimetric method constituted of p-anisaldehyde and sulfuric acid was developed and avoids all of the above disadvantages. Parameters used in this method allow a similar molar absorptivity for steroidal and triterpenoid saponins with high specificity in complex matrices reducing the sample preparation step and allowing quantification of saponins blends.

An Integrated Chromatographic Strategy for the Large-Scale Extraction of Ergosterol from Tulasnellaceae sp

A reliable chromatographic strategy is crucial for the extraction of target compounds from natural sources as it is related to the preparation efficiency, as well as the purity of the compounds. In this study, medium-pressure normal-phase liquid chromatography and high-pressure reverse-phase liquid chromatography were combined to prepare and purify ergosterol from Tulasnellaceae sp. of Gymnadenia orchidis. First, Tulasnellaceae sp. was extracted three times (2.0 L and 2 h each time) with ethyl acetate, and the 6.0 L of extract solution was concentrated under reduced pressure to yield 2.2 g of crude sample. Then, the crude sample was pretreated utilizing silica gel medium-pressure liquid chromatography to enrich the target ingredient (586.0 mg). Finally, high-pressure reversed-phase liquid chromatography was used to purify the target compound, and the compound was characterized as ergosterol (purity > 95%) using spectral data. Overall, the simple and reproducible integrated chromatographic strategy developed in this study has the potential for the large-scale purification of steroids for laboratory and even industrial research. To the best of our knowledge, this is also the first report of ergosterol in Tulasnellaceae sp.

Traditional Kenyan herbal medicine: exploring natural products' therapeutics against schistosomiasis

Praziquantel (PZQ) remains the only drug of choice for the treatment of schistosomiasis, caused by parasitic flatworms. The widespread use of PZQ in schistosomiasis endemic areas for about four decades raises concerns about the emergence of resistance of Schistosoma spp. to PZQ under drug selection pressure. This reinforces the urgency in finding alternative therapeutic options that could replace or complement PZQ. We explored the potential of medicinal plants commonly used by indigenes in Kenya for the treatment of various ailments including malaria, pneumonia, and diarrhoea for their antischistosomal properties. Employing the Soxhlet extraction method with different solvents, seven medicinal plants Artemisia annua, Ajuga remota, Bredilia micranta, Cordia africana, Physalis peruviana, Prunus africana and Senna didymobotrya were extracted. Qualitative phytochemical screening was performed to determine the presence of various phytochemicals in the plant extracts. Extracts were tested against Schistosoma mansoni newly transformed schistosomula (NTS) and adult worms and the schistosomicidal activity was determined by using the adenosine triphosphate quantitation assay. Phytochemical analysis of the extracts showed different classes of compounds such as alkaloids, tannins, terpenes, etc., in plant extracts active against S. mansoni worms. Seven extracts out of 22 resulted in <20% viability against NTS in 24 h at 100 μg/ml. Five of the extracts with inhibitory activity against NTS showed >69.7% and ≥72.4% reduction in viability against adult worms after exposure for 24 and 48 h, respectively. This study provides encouraging preliminary evidence that extracts of Kenyan medicinal plants deserve further study as potential alternative therapeutics that may form the basis for the development of the new treatments for schistosomiasis.