The Facile Reversed-Phase HPLC Resolution of Tetrahydrofurofuran Nucleus Lignans in Traditional Chinese Medicine: Quantitative Analysis of Asarinin and Sesamin inAsariRadix

Development of a Simultaneous Normal-Phase HPLC Analysis of Lignans, Tocopherols, Phytosterols, and Squalene in Sesame Oil Samples

The objective of this study was to develop a simultaneous analytical method for the determination of lignans, tocols, phytosterols, and squalene using high-performance liquid chromatography coupled with a diode array and fluorescence detector (HPLC-DAD-FLD). The method employed a VertisepTM UPS silica HPLC column (4.6 × 250 mm, 5 µm) with a mobile phase mixture of n-hexane/tetrahydrofuran/2-propanol. This approach enabled the simultaneous analysis of ten compounds within 22 min. The linear correlation (R2) exceeded 0.9901. The limit of detection (LOD) and limit of quantitation (LOQ) were up to 0.43 µg mL-1 for lignans and tocopherols and up to 326.23 µg mL-1 for phytosterol and squalene. The precision and accuracy of the intra-day and inter-day variation were less than 1.09 and 3.32% relative standard deviations (RSDs). Furthermore, the developed method was applied for the analysis of targeted compounds in twenty-eight sesame oil samples (1775-8965 µg g-1 total lignans, 29.7-687.9 µg g-1 total tocopherols, 2640-9500 µg g-1 phytosterol, and 245-4030 µg g-1 squalene). The HPLC method that has been developed was proven to be a reliable and effective tool for the determination of those functional compounds among sesame oil samples.

Rapid and Simultaneous Quantification of Six Aristolochic Acids and Two Lignans in Asari Radix et Rhizoma Using Ultra-Performance Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

Asari Radix et Rhizoma (AR) is a widely-used Chinese herbal medicine containing multiple active lignans and rare nephrotoxic components-aristolochic acids derivatives (AAs). However, the current quality control method carried out by Chinese Pharmacopoeia has defects in trace AAs detection and insufficient marker ingredients, which is unable to comprehensively evaluate the efficacy and safety of AR. To improve the quality control method of AR, a rapid, sensitive, and reliable chromatographic analytic method based on ultra-high-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS) was established for the simultaneous analysis of multiple AAs and lignans in AR samples. Positive electrospray ionization mode with multiple reaction monitoring (MRM) was applied for the detection of the eight analytes. The method showed available linearity (R ² ≥ 0.991), the limit of quantification (2-5 ng/mL), precision (RSD <8.12%), and accuracy (89.78-112.16%). A total of 6 AAs and 2 lignans were quantified for their content in 15 AR samples. The content of AA-IVa, AA-VIIa, and aristololactam I (AL-I) was much higher than the AA-I controlled by pharmacopoeia. Considering the potential toxicity of AAs, AA-IVa, AA-VIIa, and AL-I should also be controlled in AR. A considerable amount of active sesamin was detected in AR, suggesting that it could be added as a quality marker for the quality control of AR. The newly developed analytical method could be applied for the fast evaluation of toxic AA's content and quality during quality control of AR or preparations containing AR.

LC-MS- and (1)H NMR-Based Metabolomic Analysis and in Vitro Toxicological Assessment of 43 Aristolochia Species

Species of Aristolochia are used as herbal medicines worldwide. They cause aristolochic acid nephropathy (AAN), a devastating disease associated with kidney failure and renal cancer. Aristolochic acids I and II (1 and 2) are considered to be responsible for these nephrotoxic and carcinogenic effects. A wide range of other aristolochic acid analogues (AAAs) exist, and their implication in AAN may have been overlooked. An LC-MS- and (1)H NMR-based metabolomic analysis was carried out on 43 medicinally used Aristolochia species. The cytotoxicity and genotoxicity of 28 Aristolochia extracts were measured in human kidney (HK-2) cells. Compounds 1 and 2 were found to be the most common AAAs. However, AA IV (3), aristolactam I (4), and aristolactam BI (5) were also widespread. No correlation was found between the amounts of 1 or 2 and extract cytotoxicity against HK-2 cells. The genotoxicity and cytotoxicity of the extracts could be linked to their contents of 5, AA D (8), and AA IIIa (10). These results undermine the assumption that 1 and 2 are exclusively responsible for the toxicity of Aristolochia species. Other analogues are likely to contribute to their toxicity and need to be considered as nephrotoxic agents. These findings facilitate understanding of the nephrotoxic mechanisms of Aristolochia and have significance for the regulation of herbal medicines.

The effect of sesamin on airway fibrosis in vitro and in vivo

Airway fibrosis, which is a crucial pathological condition occurring in various types of pulmonary disorders, is characterized by accumulation and activation of fibroblast cells, deposition of extracellular matrix (ECM) proteins, and increase of airway basement membrane. Transforming growth factor beta 1 (TGF-β1) is the principal profibrogenic cytokine that is responsible for fibrotic responses. In the present study, we aimed to investigate the antifibrotic effects of the natural polyphenolic compound, sesamin, on TGF-β1-induced fibroblast proliferation and activation, epithelial-mesenchymal transition (EMT), and ovalbumin (OVA)-induced airway fibrosis in vivo. We found that sesamin attenuated TGF-β1-induced proliferation of cultured lung fibroblasts. Sesamin inhibited TGF-β1-stimulated expression of alpha smooth muscle actin (α-SMA), suggesting that sesamin plays an inhibitory role in fibroblast activation. Sesamin blocked upregulation of the mesenchymal markers (fibronectin and vimentin) and downregulation of the epithelial marker (E-cadherin), indicating an inhibitory effect on TGF-β1-induced EMT in A549 cells. TGF-β1-induced Smad3 phosphorylation was also significantly reduced by sesamin in both cultured fibroblast and A549 cells. In the airway fibrosis induced by OVA in mice, sesamin inhibited the accumulation of α-SMA-positive cells and expression of collagen I in the airway. Histological studies revealed that sesamin protected against subepithelial fibrosis by reducing myofibroblast activation and collagen accumulation in the ECM. OVA-induced thickening of basement membrane was significantly alleviated in animals receiving sesamin treatments. These results suggest a therapeutic potential of sesamin as an antifibrotic agent.

The constituents of Michelia compressa var. formosana and their bioactivities

Phytochemical investigation of the heartwood of Michelia compressa afforded forty-four compounds, which were identified by comparison of experimental and literature analytical and spectroscopic data. Some compounds were evaluated for their anti-inflammatory and anticancer bioactivities. The result showed that soemerine (1) and cyathisterol (2) exhibited significant nitric oxide (NO) inhibition, with IC50 values of 8.5±0.3 and 9.6±0.5 µg/mL, respectively. In addition, liriodenine (3) and oliveroline (4) exhibited cytotoxicity to human nasopharyngeal carcinoma (NPC-TW01), non-small cell lung carcinoma (NCI-H226), T cell leukemia (Jurkat), renal carcinoma (A498), lung carcinoma (A549) and fibrosarcoma (HT1080) cell lines with IC50 values in the range of 15.7-3.68 μM.

Constituents of Asarum sieboldii with inhibitory activity on lipopolysaccharide (LPS)-induced NO production in BV-2 microglial cells

Bioassay-guided fractionation of the root extract of Asarum sieboldii led to the isolation of the four active compounds (-)-sesamin (1), (2E,4E,8Z,10E)-N-(2-methylpropyl)dodeca-2,4,8,10-tetraenamide (2), kakuol (3), and '3,4,5-trimethoxytoluene' (=1,2,3-trimethoxy-5-methylbenzene; 4), in terms of inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production. Compounds 1-4 showed potent inhibition of NO production, with IC(50) values in the low nanomolar-to-micromolar range. Also isolated were the known compounds methylkakuol (5), '3,5-dimethoxytoluene', safrole, asaricin, methyleugenol, and (-)-asarinin, which were found to be inactive in the above assay. Among the ten known isolates, compounds 1, 2, and 5 were found for the first time in this plant.

Chromatographic analysis of lignans

Methods and procedures for analysis of lignans in trees and other plants are reviewed. The importance of cautious sample handling and pretreatment procedures to avoid contamination, loss of sample, and unwanted chemical reactions is discussed. Sequential extraction with a non-polar solvent followed by extraction with acetone or ethanol is recommended to separate the lignans from the plant matrix. An additional step of acid, alkaline, or enzymatic hydrolysis may be necessary for some plant matrixes. Flash chromatography is a convenient method for preparative separation and isolation of pure lignans from raw extracts. TLC is very suitable for qualitative screening of extracts and for monitoring of lignan isolation and purification steps. Trimethylsilyl ethers of lignans can be separated and quantified by GC even in the case of complex mixtures of lignans and other polyphenols, and the lignans can be identified by GC-MS in a routine manner. HPLC on reversed-phase columns is especially suited for analysis of lignans and their metabolites in biological matrixes. The recent development of HPLC-electrospray ionisation (ESI)-iontrap MS (MS(n)) and corresponding techniques with high sensitivity and selectivity has proven valuable in lignan analysis. Lignan enantiomers can be separated on chiral HPLC columns.

Dietary Sesamin Is Converted to Enterolactone in Humans

Sesamin, a major sesame seed lignan, has many biological actions. The specific mechanisms for most of these actions as well as the full metabolic pathway of sesamin in humans are unclear. Two experiments were carried out to determine whether postprandial plasma enterolactone is related to sesamin concentration in sesame seeds and whether enterolactone is the major product of the in vitro fermentation of sesamin. Four subjects (3 women, 1 man) were given a single dose of sesame seeds after they consumed a low-lignan diet for 1 wk. Blood was collected at baseline and at time intervals after intake and plasma was analyzed for plant and mammalian lignan concentrations. Additionally, pure sesamin standard was incubated in vitro with human fecal inoculum to mimic the fermentation process in human gut. We calculated individual pharmacokinetic variables and found high interindividual variation in the plasma plant lignan concentrations. The mammalian lignan appearance rate in plasma shows that sesamin is a major precursor of enterolactone in vivo. In the in vitro experiment, enterolactone was the major metabolite and 3 intermediates were identified, allowing the elucidation of sesamin metabolism in humans. Enterolactone was the major metabolite of sesamin both in vivo and in vitro. The abundance of sesamin in sesame seeds indicates that they are a major food source of enterolactone precursors.

Recent advances in analysis of Chinese medical plants and traditional medicines

Chinese herbal medicine is gaining increasing popularity worldwide for health promotion and adjuvant therapy. Thus, selective and efficient analytical methods are required not only for quality assurance but also for authentication of the plant material. Applications of both chromatographic and electrophoretic techniques to the analysis of medicinal plants and Chinese traditional medicine preparations over the last 3 years are outlined in this review. The role of chemical fingerprinting is highlighted and a brief survey of determination of toxic components, natural and synthetic adulterants is also included. Moreover, different sample pretreatment and extraction methods are discussed.