Quality evaluation and pattern recognition analyses of bioactive marker compounds from Farfarae Flos using HPLC/PDA

A review of the ethnobotanical value, phytochemistry, pharmacology, toxicity and quality control of Tussilago farfara L. (coltsfoot)

ETHNOPHARMACOLOGICAL RELEVANCE

Tussilago farfara L. (commonly called coltsfoot), known as a vital folk medicine, have long been used to treat various respiratory disorders and consumed as a vegetable in many parts of the world since ancient times.

AIM OF THE REVIEW

This review aims to provide a critical evaluation of the current knowledge on the ethnobotanical value, phytochemistry, pharmacology, toxicity and quality control of coltsfoot, thus provide a basis for further investigations.

MATERIALS AND METHODS

A detailed literature search was obtained using various online search engines (e.g. Google Scholar, Web of Science, Science Direct, Baidu Scholar, PubMed and CNKI). Additional information was sourced from ethnobotanical literature focusing on Chinese and European flora. The plant synonyms were validated by the database 'The Plant List' (www.theplantlist.org).

RESULTS

Coltsfoot has diverse uses in local and traditional medicine, but similarities have been noticed, specifically for relieving inflammatory conditions, respiratory and infectious diseases in humans. Regarding its pharmacological activities, many traditional uses of coltsfoot are supported by modern in vitro or in vivo pharmacological studies such as anti-inflammatory activities, neuro-protective activity, anti-diabetic, anti-oxidant activity. Quantitative analysis (e.g. GC-MS, UHPLC-MRM^HR) indicated the presence of a rich (>150) pool of chemicals, including sesquiterpenes, phenolic acids, flavonoids, chromones, pyrrolizidine alkaloids (PAs) and others from its leaves and buds. In addition, adverse events have resulted from a collection of the wrong plant which contains PAs that became the subject of public concern attributed to their highly toxic.

CONCLUSIONS

So far, remarkable progress has been witnessed in phytochemistry and pharmacology of coltsfoot. Thus, some traditional uses have been well supported and clarified by modern pharmacological studies. Discovery of therapeutic natural products and novel structures in plants for future clinical and experimental studies are still a growing interest. Furthermore, well-designed studies in vitro particularly in vivo are required to establish links between the traditional uses and bioactivities, as well as ensure safety before clinical use. In addition, the good botanical identification of coltsfoot and content of morphologically close species is a precondition for quality supervision and control. Moreover, strict quality control measures are required in the studies investigating any aspect of the pharmacology and chemistry of coltsfoot.

Cellular Target Proteome in Breast Cancer Cells of an Oplopane Sesquiterpenoid Isolated from Tussilago farfara

Tussilago farfara is a traditional herbal medicine used to treat coughs, bronchitis, and asthma. Its bioactive compounds include sesquiterpenoids with anti-inflammatory, antiproliferative, neuroprotective, and other effects. Biochemical studies have highlighted the mechanisms of action, but the investigations of related molecular pathways have not specified direct molecular targets. Therefore, this study profiled cellular target proteins of a sesquiterpenoid isolated from T. farfara using quantitative chemical proteomics in MDA-MB-231 and MCF-7 human breast cancer cells. Compound 8, 7β-(3'-ethyl-cis-crotonoyloxy)-1α-(2'-methyl butyryloxy)-3,14-dehydro-Z-notonipetranone, exhibited potent antiproliferative activity based on its α,β-unsaturated carbonyl moiety, and its potential cellular target proteins were identified using a compound 8-based clickable probe. Among >200 identified proteins, 17 showed enrichment ratios of >3 in both cell lines, while recombinant 14-3-3 protein zeta and peroxiredoxin-1 were verified using isothermic calorimetry and their alkylation sites. Considering the interaction between the α,β-unsaturated carbonyl moiety of compound 8 and cysteine residues of the proteins, peptides containing Cys25 and Cys94 of 14-3-3 protein zeta and Cys83 of peroxiredoxin-1 were significantly reduced by this sesquiterpene ester. Although the results did not elucidate the effects of compound 8 in breast cancer cells, identification of potential target proteins contributes to enhanced understanding of its antiproliferative and anti-inflammatory effects.

Development of UPLC-Q-TOF-MS Coupled with Cation-exchange Solid-phase Extraction Method for the Determination of Ten Pyrrolizidine Alkaloids in Herbal Medicines

Pyrrolizidine alkaloids are secondary metabolites of plants and can cause significant hepatotoxicity in humans. In this study, a fast and simple method was developed to determine ten pyrrolizidine alkaloids (PAs) in six types of herbal medicines using ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS). An efficient solid-phase extraction procedure was carried out by using strong cation-exchange cartridges and the parameters were optimized. The established analytical method was validated and the results showed that the method presented satisfactory accuracy and precision. The established method was successfully applied for the determination of PAs in six herbal plants, including Senecionis Scandentis Hebra, Arnebiae Radix, Asteris Radix Et Rhizoma, Farfarae Flos, Senecionis Cannabifolii Herba and Emilia sonchifolia. PAs were found in all of these herbal plant samples. Eight types of related commercial herbal drugs were also detected, six of them were detected with different amounts of PAs. This work not only provided a powerful technical platform for both qualitative and quantitative analysis of PAs in herbal medicines, but also obtained information concerning PAs in these herbal samples, which could provide reference to the government regulatory authorities and non-governmental organizations.

Effects of Flower Buds Extract of Tussilago farfara on Focal Cerebral Ischemia in Rats and Inflammatory Response in BV2 Microglia

OBJECTIVE

To investigate the effects of the flower buds extract of Tussilago farfara Linné (Farfarae Flos; FF) on focal cerebral ischemia through regulation of inflammatory responses in activated microglia.

METHODS

Brain ischemia was induced in Sprague-Dawley rats by a transient middle cerebral artery occlusion (tMCAO) for 90 min and reperfusion for 24 h. Twenty rats were randomly divided into 4 groups (n=5 per group): normal, tMCAO-induced ischemic control, tMCAO plus FF extract 300 mg/kg-treated, and tMCAO plus MK-801 1 mg/kg-treated as reference drug. FF extract (300 mg/kg, p.o.) or MK-801 (1 mg/kg, i.p.) was administered after reperfusion. Brain infarction was measured by 2,3,5,-triphenyltetrazolium chloride staining. Neuronal damage was observed by haematoxylin eosin, Nissl staining and immunohistochemistry using anti-neuronal nuclei (NeuN), anti-glial fibrillary acidic protein (GFAP), and anti-CD11b/c (OX42) antibodies in ischemic brain. The expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF-α), and hypoxia-inducible factor-1a (HIF-1α) were determined by Western blot. BV2 microglial cells were treated with FF extract or its main bioactive compound, tussilagone with or without lipopolysaccharide (LPS). Nitric oxide (NO) production was measured in culture medium by Griess assay. The expressions of iNOS, COX-2 and pro-inflammatory cytokines mRNA were analyzed by reverse transcription-polymerase chain reaction. The expression of iNOS, and COX-2 proteins, the phosphorylation of ERK1/2, JNK, and p38 MAPK and the nuclear expression of NF-κB p65 in BV2 cells were determined by Western blot.

RESULTS

FF extract significantly decreased brain infarctions in ischemic rats (P<0.01). The neuronal death and the microglia/astrocytes activation in ischemic brains were inhibited by FF extract. FF extract also suppressed iNOS, TNF-α, and HIF-1α expression in ischemic brains. FF extract (0.2 and 0.5 mg/mL, P<0.01) and tussilagone 20 and 50 μmol/L, P<0.01) significantly decreased LPS-induced NO production in BV2 microglia through downregulation of iNOS mRNA and protein expression. FF extract and tussilagone significantly inhibited LPS-induced expression of TNF-α, IL-1β, and IL-6 mRNA, and also suppressed the phosphorylation of ERK1/2, JNK and p38 MAPK and the nuclear expression of NF-κB in a dose-dependent manner.

CONCLUSIONS

FF extract has a neuroprotective effect in ischemic stroke by the decrease of brain infarction, and the inhibition of neuronal death and microglial activation-mediated inflammatory responses.

Analysis of Three Compounds in Flos Farfarae by Capillary Electrophoresis with Large-Volume Sample Stacking

The aim of this study was to develop a method combining an online concentration and high-efficiency capillary electrophoresis separation to analyze and detect three compounds (rutin, hyperoside, and chlorogenic acid) in Flos Farfarae. In order to get good resolution and enrichment, several parameters such as the choice of running buffer, pH and concentration of the running buffer, organic modifier, temperature, and separation voltage were all investigated. The optimized conditions were obtained as follows: the buffer of 40 mM NaH₂P0₄-40 mM Borax-30% v/v methanol (pH 9.0); the sample hydrodynamic injection of up to 4 s at 0.5 psi; 20 kV applied voltage. The diode-array detector was used, and the detection wavelength was 364 nm. Based on peak area, higher levels of selective and sensitive improvements in analysis were observed and about 14-, 26-, and 5-fold enrichment of rutin, hyperoside, and chlorogenic acid were achieved, respectively. This method was successfully applied to determine the three compounds in Flos Farfarae. The linear curve of peak response versus concentration was from 20 to 400 µg/ml, 16.5 to 330 µg/mL, and 25 to 500 µg/mL, respectively. The regression coefficients were 0.9998, 0.9999, and 0.9991, respectively.