Development of validated high-performance thin layer chromatography for quantification of aristolochic acid in different species of the Aristolochiaceae family

Ionizable copolymer functionalized magnetic nanocomposite as an adsorbent for boosting the extraction selectivity of aristolochic acids

Aristolochic acid nephropathy (AAN) has drawn increasing public attention. Organic anion transporters (OATs) are considered to be responsible for mediating nephrotoxicity of aristolochic acids (AAs), as AAs are typical OAT1 substrates that exhibit anionic properties and contain one hydrophobic domain. Inspired by the OAT1 three-dimensional structure or substrate/protein interactions involved in transport, we designed a magnetic polymeric hybrid, mimicking the effect of basic and aromatic residues of OAT1, for efficient enriching aristolochic acid I (AA I) and aristolochic acid II (AA II) in Traditional Chinese patent medicines (TCPM). N, N-dimethylaminopropyl acrylamide (DMAPAm) was used as a cationic monomer and copolymerized with divinylbenzene (DVB) onto the surface of monodisperse magnetic nanoparticles (denoted as MNs@SiO2T-DvbDam). The magnetic polymer hybrid demonstrated high selectivity and capacity for AAs, which was mainly attributed to (1) electrostatic interactions from the cationic or basic moiety of DMAPAm and (2) the hydrophobic and π-π stacking interactions from the aromatic ring of DVB. Additionally, the surface of the hybrid exhibited amphiphilic property according to the ionization of DMAPAm, thus improving the compatibility of the adsorbent with the aqueous sample matrix. This strategy was proven to be robust in the analysis of real drug samples, which was characterized by a good linearity, high recovery and satisfactory reusability. This work confirmed that the proposed tool could be a promising candidate for enhancing the extraction selectivity of AAs in Traditional Chinese medicines (TCM).

Efficient separation of aristolochic acid I from Caulis aristolochiae manshuriensis (Guan-mu-tong) with copper mediated magnetic molecularly imprinted polymer

Screening bioactive compounds from natural products is one of the most effective ways for new drug research and development. However, obtaining a single extract component on a large scale and with high purity from a complex matrix is still an arduous and challenging task. Herein, one metal mediated magnetic molecularly imprinted polymer (mMIP) was rationally designed and prepared for specifically capturing Aristolochic acid I (AAI). The preparation was done with copper(II) as binding pivot, (3-aminopropyl) triethoxysilane as functional monomer, and Fe3O4 as core, by a one-step sol-gel method. Under the optimized conditions, the apparent maximum binding amount of copper mediated mMIP (Cu-mMIP) reaches as high as 349.72 mg g-1, the highest among the reported AAI-MIPs. Moreover, the nanoparticles exhibit excellent specificity and selectivity, good reproducibility and stability, high superparamagnetism (60.32 emu g-1), and high imprinting efficiency (an imprinting factor of 7). By simulating an industrial-scale separation, 16.56 mg AAI (purity of 95.11%) is obtained after six cycles with 100 mg nanoparticles from 20 g Caulis aristolochiae manshuriensis (Guan-mu-tong). Notably, this takes only 3 hours and consumes 50 mL of methanol. The study provides a potent tool for the green, fast, and specific extraction of high-purity ingredients from natural plants in the manufacturing industry and conventional analysis in the lab.

Control of media browning during micropropagation and assessment of biochemical and clonal fidelity of in vitro-derived and mother plants in Thottea siliquosa (Lamk.) Ding Hou., an important ethnomedicinal shrub

BACKGROUND

Thottea siliquosa (Lamk.) Ding Hou., an important medicinal shrub, is widely used in both ayurvedic and indigenous systems of medicine. Root being the most useful part, the plant is constantly uprooted and thus puts pressure on the natural population. Until date, no micropropagation study is available in this plant. The objective of the study is to develop an efficient in vitro propagation protocol and assessment of clonal fidelity of T. siliquosa.

RESULTS

Media browning was a serious issue during micropropagation, and the addition of 40.0 mg/L ascorbic acid reduced the media browning. For direct shoot regeneration, the optimum response (92% frequency with 20.9 shoots per explant) was obtained when 7-day-old cotyledons were cultured on WPM supplemented with 1.0 mg/L thidiazuron and 0.25 mg/L α-naphthalene acetic acid. The cultures were transferred to WPM augmented with 0.4 mg/L thidiazuron for shoot elongation and growth. On this medium, 100% of cultures responded with a mean number of 27.6 shoots. For callus induction, MS medium with 1.0 mg/L 2,4-dichlorophenoxyacetic acid and 0.5 mg/L N₆-benzylaminopurin was used. Shoot organogenesis was initiated on the same medium, and calli with minute shoots were transferred to MS medium fortified with 0.5 mg/L N₆-benzylaminopurin and 0.25 mg/L α-naphthalene acetic acid for highest shoot regeneration (100% cultures responded with a mean number of 26.5 shoots per explant). Maximum rooting frequency (82%) and number (20.8) were obtained on half-strength MS medium with 1.0 mg/L indole-3-butyric acid. The rooted plants were acclimatized and transferred to the field. The HPTLC and SCoT analysis revealed the phytochemical and clonal similarity between the in vitro propagated plants and mother plant.

CONCLUSIONS

In this study, it is confirmed that cotyledon is an excellent explant for direct and indirect shoot organogenesis in T. siliquosa. For direct shoot induction WPM and indirect organogenesis, MS medium was found to give better response. The true-to-type nature of in vitro-derived plants were confirmed by phytochemical and SCoT analysis. The protocol described here could be used for the large-scale propagation of elite clones of T. siliquosa.

A PCR-lateral flow immunochromatographic assay (PCR-LFA) for detecting Aristolochia species, the plants responsible for aristolochic acid nephropathy

Aristolochic acids (AAs), which are strong carcinogens, have caused dietary supplements with Aristolochia plants to be discontinued worldwide. Therefore, the development of a method to identify these herbs is critical for customer safety. To support the regulation of Aristolochia-free products, a PCR coupled with lateral flow immunochromatographic assay (PCR-LFA) that is specific to the nucleotide signature in plastid rbcL gene region of Aristolochia species was developed to detect Aristolochia plants and related herbal products. Triplex primers (A397F, C357F and R502) were designed based on specific nucleotides observed exclusively in the rbcL sequences of Aristolochia. Positive results for Aristolochia occur when the three pink lines are clearly developed on the developed lateral flow strip and can be seen by the naked eye. In this study, the lateral flow strip has sensitivity for detecting amplicons amplified from genomic DNA at the concentrations as low as 0.01 ng. Various kinds of samples, including purchased crude drugs and polyherbal samples, have been investigated, and the results showed that Aristolochia crude drugs and Aristolochia-containing products are still present in dispensaries. In conclusion, with the goal of protecting consumers from the health risks associated with Aristolochia contamination, PCR-LFA was developed and demonstrated to be efficient for detecting plants belonging to Aristolochia in various kinds of samples.

The recognition of aristolochic acid I based on fluorescence quenching of bovine serum albumin-stabilized gold nanoclusters

Aristolochic acid I (AAI) is one of the nephrotoxic derivatives present in genera Aristolochia and Asarum. Although some detection strategies for monitoring AAI have been reported, the application of these methods is limited because they involve tedious preparation and require professional operation. In this work, bovine serum albumin (BSA) has been introduced as a reducing agent and stabilizing agent to synthesize gold nanoclusters with strong red fluorescence for the rapid and effective detection of AAI. Under excitation at 328 nm, the fluorescence intensity at the maximum emission wavelength of the bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) decreased with the addition of AAI, and the degree of quenching showed a linear relationship with the concentration of AAI from 0.1-12.8 μg mL^-1. The obtained BSA-AuNCs were stable, and quenching in the presence of AAI could be achieved within 10 seconds. Here, we have focused on the application of these gold nanoclusters as an optical sensing material for AAI in rat urine samples, including a discussion on the detection mechanism. The detection result of the fluorescent probe was consistent with that of the HPLC method. In view of this reality, the reported protein-AuNCs sensing platform can serve as a convenient detection strategy in toxicological analyses.

Analysis of aristolochic acid I in mouse serum and tissues by using magnetic solid-phase extraction and UHPLC-MS/MS

A method combining magnetic solid-phase extraction (MSPE) and ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the analysis of aristolochic acids I (AAI) in mouse serum and tissues. The magnetic covalent organic frameworks (MNP@COF)-based MSPE exhibited high adsorption capacity towards AAI (93.1 mg/g) in optimal conditions. After MSPE extraction, AAI was separated with C18 column using gradient elution and quantified (m/z 342.21 → 298.13) by UHPLC-MS/MS with monitor reaction monitoring (MRM) mode. This MSPE-based UHPLC-MS/MS method was validated with respected to lower limit of quantification (LLOQ), linearity, recovery, precision and accuracy of intra- and inter-day, and matrix effect. Good calibration linearities at the range of 1-500 ng/L for AAI in biological matrices (serum, kidney, and liver) with high correlation coefficient (R²) > 0.9970, and high enrichment factors (mean values from 1038 to 1045) were obtained. This method was highly sensitive to determine AAI with LLOQ within the range of 4.62-5.24 ng/L in extracted serum, kidney, and liver samples. Recoveries at 5, 50, 100 and 300 ng/L in biological samples ranged from 93.2 to 104.0%, and intra- and inter day accuracy and precision (defined as bias and coefficient of variation, respectively) were below ± 15%. The method was successfully applied in the analysis of biological samples collected from mice exposed with AAI with concentrations range of 0.007-0.041 μg/L for consecutive four days. The established method might be applied for the investigation of risk assessment and toxicity induced by long-time use of AAI-containing herbs or dietary supplements.

On-line enrichment and determination of aristolochic acid in medicinal plants using a MOF-based composite monolith as adsorbent

In this study, modified UiO-66-NH₂ and N-methylolacrylamide (NMA) were used as common monomers to prepare a metal organic framework (MOF)-based composite monolith through in-situ polymerization, which was used as a new adsorbent to purify and enrich aristolochic acid-I (AA-I) in medicinal plants. The MOF-based composite monolithic column was characterized by nitrogen adsorption-desorption isotherm, mercury intrusion porosimetry and scanning electron microscopy (SEM). The adsorption ability of MOF-based composite monolith for AA-I was compared with that of the polymer monolith without MOF added. The results proved that the addition of UiO-66-NH₂ can increase both the specific surface area and the permeability of the monolith. Moreover, the adsorption amount of AA-I on the monolith improved. This proposed on-line solid phase extraction (SPE) method showed good linear relationship in the range 0.044 ~ 400 μg/mL with r = 0.9994; the limit of detection (LOD) was 13.08 ng/mL and the limit of quantification (LOQ) was 44.00 ng/mL; the intra-day and inter-day accuracies were less than 0.97%; the inter-column accuracies was less than 6.11%; the recovery was in the range of 91.11%~106.48%. The method was found to be easy, accurate and convenient for on-line enrichment and purification of AA-I in medicinal plants.

Analytical Method Development and Validation for Simultaneous Estimation of Trimetazidine Hydrochloride and Metoprolol Succinate Using HPTLC

Introduction:

Trimetazidine and Metoprolol combination is more effective in the treatment of cardiac disorders as compared to single drug therapy.Background:

Materials and Methods:

A rapid, simple, and sensitive HPTLC method was developed for the simultaneous determination of Trimetazidine and metoprolol from its tablet dosage form and validated. In HPTLC method, standard and sample solutions of Trimetazidine hydrochloride and metoprolol succinate were applied on pre-coated silica gel G 60 F254 TLC plate, and developed by using mobile phase, n-butanol :water: methanol: ammonia as solvent (8.5:0.1:0.1: 0.85, v/v). The drugs on plate were scanned at 213 nm. The method produced compact and well-resolved bands at Rf of 0.32 ± 0.02 and 0.66 ± 0.02 for Trimetazidine Hydrochloride and Metoprolol succinate respectively. The range for linearity was observed as 500-2500 ng band-1 for Trimetazidine hydrochloride and 500-2500 ng band-1 for metoprolol succinate and correlation coefficient were 0.9991 and 0.9997 respectively.

Conclusion:

The developed method was validated according to the ICH guidelines for precision, accuracy, Limit of detection, Limit of quantitation, specificity and robustness. The method was checked for suitability in determination of Trimetazidine hydrochloride and Metoprolol succinate in their tablet dosage form. The assay result was found to be 99.64 % ± 0.45 and 99.94 % ± 0.53 of percentage label claim for Trimetazidine hydrochloride and Metoprolol succinate respectively.

HPTLC-FLD-SERS as a facile and reliable screening tool: Exemplarily shown with tyramine in cheese

The serious cytotoxicity of tyramine attracted marked attention as it induced necrosis of human intestinal cells. This paper presented a novel and facile high performance thin-layer chromatography (HPTLC) method tailored for screening tyramine in cheese. Separation was performed on glass backed silica gel plates, using methanol/ethyl acetate/ ammonia (6/4/1 v/v/v) as the mobile phase. Special efforts were focused on optimizing conditions (substrate preparation, laser wavelength, salt types and concentrations) of surface enhanced Raman spectroscopy (SERS) measurements directly on plates after derivatization, which enabled molecule-specific identification of targeted bands. In parallel, fluorescent densitometry (FLD) scanning at 380</400 nm offered satisfactory quantitative performances (LOD 9 ng/zone, LOQ 17 ng/zone, linearity 0.9996 and %RSD 6.7). Including a quick extraction/cleanup step, the established method was successfully validated with different cheese samples, both qualitatively (straightforward confirmation) and quantitatively (recovery rates from 83.7 to 108.5%). Beyond this application, HPTLC-FLD-SERS provided a new horizon in fast and reliable screening of sophisticated samples like food and herb drugs, striking an excellent balance between specificity, sensitivity and simplicity.