Identification and characterization of major flavonoids and caffeoylquinic acids in three Compositae plants by LC/DAD-APCI/MS

Relative contribution of small and large intestine to deglycosylation and absorption of flavonoids from Chrysanthemun morifolium extract

The flower of Chrysanthemum morifolium Ramat (CM) is an established part of traditional Chinese medicine (TCM). Luteolin and apigenin flavonoids are the effective components of the CM extract (CME); however, they exist in the orally consumed CME as glycosides. The present study was carried out to determine the relative contribution of the small and large intestine to the deglycosylation and absorption of flavonoids from CME using a rat model system. The distribution of luteolin and apigenin in rat gastrointestinal (GI) luminal contents, tissues, and plasmas was assessed after the oral administration of CME. The hydrolysis and absorption of CME flavonoids in different rat GI segments were further evaluated by using in situ ligated models and cell-free extracts prepared from rat GI segments. The results demonstrated that after the oral administration of CME, the magnitude of deglycosylation in rats was surprisingly high (about 30%) in the stomach and upper intestine within the first 5 min after ingestion, and early absorption in the plasma was detected. The results from site-limited administration revealed that the stomach was the initial hydrolysis site, while the duodenum was the first effective absorption site for CME flavonoids. Diminishing microbial flora in the jejunum had no significant effect on the hydrolysis of the flavonoids from CME, but the cell-free extracts prepared from rat GI segments demonstrated a strong ability to hydrolyze. Taken together, our findings suggest that enteric disposition contributes to the pharmacokinetics of luteolin and apigenin after oral administration of CME. Moreover, the upper digestive tract plays a key role in the hydrolysis and absorption of flavonoids in CME.

Rapid screening and identification of caffeic acid and its esters in Erigeron breviscapus by ultra-performance liquid chromatography/tandem mass spectrometry

Caffeic acid and its esters (CAEs) are widely distributed in the plant kingdom and have been reported to elicit a wide range of exceptional biological activities. Present methods for screening and characterization of CAEs normally need the use of liquid chromatography diode-array detection/multistage mass spectrometry (LC-DAD/MS(n)). In this report, a rapid and efficient method coupling ultra-performance liquid chromatography (UPLC) with fragment-targeted multi-reaction monitoring (MRM) has been developed for screening CAEs in a crude extract of Erigeron breviscapus, while a UPLC/quasi-MS(n) method has been applied in the structural identification of these compounds. Furthermore, a simple quasi-UPLC/MS/MS method based on in-source collision-induced dissociation (CID) has been proposed for rapid identification of the CAEs. As a result, a total of more than 34 CAEs were detected and their structures characterized. Nine of them were reported from E. breviscapus for the first time. Applications of these strategies in the chemical investigation of an injection of E. breviscapus resulted in the identifications of 16 CAEs. These strategies, if appropriate modifications are made, will be very useful in screening and characterization not only of CAEs, but of other structural types of compounds in various complex matrices.

Flavonoids from Artemisia annua L. as antioxidants and their potential synergism with artemisinin against malaria and cancer

Artemisia annua is currently the only commercial source of the sesquiterpene lactone artemisinin. Since artemisinin was discovered as the active component of A. annua in early 1970s, hundreds of papers have focused on the anti-parasitic effects of artemisinin and its semi-synthetic analogs dihydroartemisinin, artemether, arteether, and artesunate. Artemisinin per se has not been used in mainstream clinical practice due to its poor bioavailability when compared to its analogs. In the past decade, the work with artemisinin-based compounds has expanded to their anti-cancer properties. Although artemisinin is a major bioactive component present in the traditional Chinese herbal preparations (tea), leaf flavonoids, also present in the tea, have shown a variety of biological activities and may synergize the effects of artemisinin against malaria and cancer. However, only a few studies have focused on the potential synergistic effects between flavonoids and artemisinin. The resurgent idea that multi-component drug therapy might be better than monotherapy is illustrated by the recent resolution of the World Health Organization to support artemisinin-based combination therapies (ACT), instead of the previously used monotherapy with artemisinins. In this critical review we will discuss the possibility that artemisinin and its semi-synthetic analogs might become more effective to treat parasitic diseases (such as malaria) and cancer if simultaneously delivered with flavonoids. The flavonoids present in A. annua leaves have been linked to suppression of CYP450 enzymes responsible for altering the absorption and metabolism of artemisinin in the body, but also have been linked to a beneficial immunomodulatory activity in subjects afflicted with parasitic and chronic diseases.

Chrysanthemum morifolium Ramat. reduces the oxidized LDL-induced expression of intercellular adhesion molecule-1 and E-selectin in human umbilical vein endothelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

The flower of Chrysanthemum morifolium Ramat. (CM) with antioxidant, cardiovascular protective and anti-inflammatory functions, has been widely used in China for hundreds of years as a healthy beverage and medicine.

AIMS OF THE STUDY

The purpose of the present study is to investigate the effects of HCM (a hot water extract of the flower of Chrysanthemum morifolium Ramat. [CM]), ECM (an ethanol extract of CM), and the abundant flavonoids apigenin and luteolin in CM on the oxidized LDL (oxLDL)-induced expression of ICAM-1 and E-selectin in human umbilical vein endothelial cells (HUVECs). The possible mechanism of these effects was also determined.

MATERIALS AND METHODS

MTT assay was for cell viability. Western blot was used for ICAM-1 and E-selection protein expression, and for activation of protein kinase B (PKB) and cAMP responsive element binding protein (CREB) proteins. Fluorescence flow cytometry was for ICAM-1 and E-selectin expression on cell surface. DCF-DA flow cytometric assay was used for reactive oxygen species (ROS) production.

RESULTS

HCM, ECM, apigenin, and luteolin dose-dependently inhibited ICAM-1 and E-selectin expression and adhesion of HL-60 by oxLDL. HCM, ECM, apigenin, and luteolin reversed the inhibition of phosphorylation of Akt and CREB by oxLDL; however, this reversion was abolished by wortmannin. In addition, wortmannin abrogated the inhibitory effects of CM extracts, apigenin and luteolin on adhesion molecule expression. The ROS scavenging capability of HCM, ECM, apigenin, and luteolin proceeded dose-dependently in the presence of oxLDL.

CONCLUSION

CM is a plant with cardiovascular-protective potential and the inhibitory effects of CM on ICAM-1 and E-selectin expression are, at least partially, attributed to its antioxidant activity and modulation of the PI3K/Akt signaling pathway.

Drying affects artemisinin, dihydroartemisinic acid, artemisinic acid, and the antioxidant capacity of Artemisia annua L. leaves

There is limited information on how postharvest drying of Artemisia annua affects artemisinin (ART) biosynthesis and A. annua antioxidant capacity. Antioxidants may boost the bioactivity of ART and the crop commercial value. We evaluated the effect of freeze, oven, shade, and sun drying, time of drying, and light intensity on the leaf concentration of ART, dihydroartemisinic acid (DHAA), artemisinic acid (AA), and on the leaf antioxidant capacity. Freeze-dried samples had the lowest ART concentrations as compared to the other drying methods. However, the ferric reducing antioxidant power assay showed that freeze- and oven-dried samples had similarly high antioxidant activities, which declined significantly after plants were shade- and sun-dried. Shade drying for 1, 2, and 3 weeks, under ambient or low light, did not change the ART content but significantly decreased the leaf antioxidant activity, mainly if sun-dried. A significant decrease (82% average) in DHAA was observed for all drying procedures as compared to freeze drying, with a simultaneous, significant increase in ART (33% average). The average bioconversion of DHAA to ART was 43% for oven- and shade-dried plants and 94% for sun-dried plants, reiterating the hypothesis that DHAA, not AA, is the main biosynthetic precursor of ART and suggesting that sun drying improves the bioconversion from DHAA to ART. Data also indicate that oven drying for 24 h at 45 degrees C can provide good levels of both ART and antioxidants in leaves. These findings are valuable for the commercial production of ART and of bioactive antioxidants that might synergize with the antimalarial and anticancer effects of ART when combined in traditional preparations to improve human and animal health.

Complete Characterization of Extracts of Onopordum illyricum L. (Asteraceae) by HPLC/PDA/ESIMS and NMR

The aerial parts of Onopordum illyricum L. (Asteraceae) are eaten raw in salad in the Mediterranean area, representing a food of good nutritional value. Extracts of different parts of this plant have been analyzed by HPLC/DAD/ESIMS and the major compounds identified by NMR spectroscopy. Fatty acids, sesquiterpene lactones, triterpenes and polyphenols (flavones and caffeoyl quinic acids) fully describe the plant metabolism during the vegetation year. All the metabolites are non toxic nutrients, and are reported in the literature to possess biological activities positive for health, confirming the beneficial use in the diet of this thistle

Identification of hydroxycinnamoylquinic acids of arnica flowers and burdock roots using a standardized LC-DAD-ESI/MS profiling method

A screening method using LC-DAD-ESI/MS was developed for the identification of common hydroxycinnamoylquinic acids based on direct comparison with standards. A complete standard set for mono-, di-, and tricaffeoylquinic isomers was assembled from commercially available standards, positively identified compounds in common plants (artichokes, asparagus, coffee bean, honeysuckle flowers, sweet potato, and Vernonia amygdalina leaves) and chemically modified standards. Four C18 reversed phase columns were tested using the standardized profiling method (based on LC-DAD-ESI/MS) for 30 phenolic compounds, and their elution order and retention times were evaluated. Using only two columns under standardized LC condition and the collected phenolic compound database, it was possible to separate all of the hydroxycinnamoylquinic acid conjugates and to identify 28 and 18 hydroxycinnamoylquinic acids in arnica flowers (Arnica montana L.) and burdock roots (Arctium lappa L.), respectively. Of these, 22 are reported for the first time.

Non-targeted analysis of spatial metabolite composition in strawberry (Fragariaxananassa) flowers

Formation of flower organs and the subsequent pollination process require a coordinated spatial and temporal regulation of particular metabolic pathways. In this study a comparison has been made between the metabolite composition of individual flower organs of strawberry (Fragariaxananassa) including the petal, sepal, stamen, pistil and the receptacle that gives rise to the strawberry fruit. Non-targeted metabolomics analysis of the semi-polar secondary metabolites by the use of UPLC-qTOF-MS was utilized in order to localize metabolites belonging to various chemical classes (e.g. ellagitannins, proanthocyanidins, flavonols, terpenoids, and spermidine derivatives) to the different flower organs. The vast majority of the tentatively identified metabolites were ellagitannins that accumulated in all five parts of the flower. Several metabolite classes were detected predominantly in certain flower organs, as for example spermidine derivatives were present uniquely in the stamen and pistil, and the proanthocyanidins were almost exclusively detected in the receptacle and sepals. The latter organ was also rich in terpenoids (i.e. triterpenoid and sesquiterpenoid derivatives) whereas phenolic acids and flavonols were the predominant classes of compounds detected in the petals. Furthermore, we observed extensive variation in the accumulation of metabolites from the same class in a single organ, particularly in the case of ellagitannins, and the flavonols quercetin, kaempferol and isorhamnetin. These results allude to spatially-restricted production of secondary metabolite classes and specialized derivatives in flowers that take part in implementing the unique program of individual organs in the floral life cycle.

Characterization of phenolic compounds in the Chinese herbal drug Artemisia annua by liquid chromatography coupled to electrospray ionization mass spectrometry

A simple and rapid method has been established for the screening of the main phenolic compounds in Artemisia annua by LC-DAD-ESI-MS(n). A total of 40 phenolic compounds were identified or tentatively characterized in the methanol extract of A. annua, including 8 C-glycosyl flavonoids, 5 O-glycosyl flavonoids, 3 flavonoid aglycones, 21 quinic acid derivatives, 2 benzoicacid glucosides and 1 coumarin. The C-glycosyl flavonoids were reported from A. annua for the first time and they were found to be a new type of main constituents, and might be responsible for its antioxidant and antiviral activity. Quinic acid derivatives were also found to be the major constituents of A. annua.

Influence of aqueous crude extracts of medicinal plants on the osmotic stability of human erythrocytes

This work analyzed the effects of the aqueous crude extracts of Artemisia absinthium L., Lippia sp., Bryophyllum sp., Solidago microglossa DC, Cymbopogon citratus DC and Mentha x villosa HUDSON on the osmotic stability of human erythrocytes. Hemolysis was monitored by measurement of absorbance at 540 nm following addition of erythrocytes to NaCl solutions of varying concentration. Absorbance was fitted to sigmoid regression curves given by the Boltzmann equation, and hemolysis was characterized by the NaCl concentration leading to lysis of 50% of cells (H(50)), and by the intensity (H) and the amplitude (dS) of the lysis effect. The parameters were determined in the absence and presence of the crude extracts. The extracts of Artemisia absinthium, Lippia sp., C. citratus and M. villosa protected human erythrocytes against hypotonic shock, as evidenced by a decrease in the values of H and H(50) compared to the control solution (p<0.05). The extracts of Bryophyllum sp. and S. microglossa enhanced hemolysis, since their H(50) values were higher than in the control group (p<0.05), but they also showed protective effects, as evidenced by a decrease in H and an increase in dS.

Advances of modern chromatographic and electrophoretic methods in separation and analysis of flavonoids

Flavonoids, one of the largest groups of secondary metabolites, are widespread in vegetable crops such as herbs, fruits, vegetables, grains, seeds and derived foods such as juices, wines, oils, etc. They receive considerable attention due to their biological and physiological importance. Hundreds of publications on the analysis of flavonoids have appeared over the past decade. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review intends to provide an updated, concise overview on the recent development and trends of separation, identification and quantification for flavonoids by modern chromatographic and spectrophotometric analytical techniques, including gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). The sample preparation before analysis is also briefly summarized.

Characterization of flavonoid subgroups and hydroxy substitution by HPLC-MS/MS

HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were injected into the spectrometer and produced characteristic mass spectra. The fragmentation of each compound was studied and it was shown that the dehydration and carbon monoxide losses from the [M+H]+ ion by the members of each subgroup produced specific fragments, thus allowing the characterization of the flavonoid subgroups. Moreover, fragments resulting from fission of the C-rings are specific of each subgroup and revealed the substitution pattern of A- and B-rings. In order to verify the identifying efficiency of the positive ionization mode through these characteristic fragmentations, the unknown flavonoids of an Origanum vulgare diethyl ether extract were separated with the HPLC system and the major peaks were successfully identified with the mass spectrometer.