Simultaneous determination of three active components in rat plasma by UPLC-MS/MS: Application to pharmacokinetic study after oral administration of Herba Sarcandrae extract.

A rapid, specific and sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for determination of isofraxidin, rosmarinic acid and kaempferol-3-O-glucuronide in rat plasma using warfarin as an internal standard (IS). Separation was conducted on a Thermo Hypersil GOLD C18 column with linear gradient elution using methanol and water. Mass spectrometric detection was conducted using selected reaction monitoring (SRM) via an electrospray ionization (ESI) source. All analytes exhibited good linearity within their concentration ranges (r > 0.9990). The lower limits of quantitations of isofraxidin, rosmarinic acid, and kaempferol-3-O-glucuronide were 1.31, 0.67 and 0.92 ng/mL, respectively. Intra- and inter-day precisions of these investigated components exhibited an RSD within 11.7%, and the accuracy ranged from -12.5 to 15.0% at all QC levels. The developed method was successfully applied to a pharmacokinetic study of isofraxidin, rosmarinic acid, and kaempferol-3-O-glucuronide in rats after oral administration of Herba Sarcandrae Extract.

Bioavailability of the flavonol quercetin in neonatal calves after oral administration of quercetin aglycone or rutin.

Polyphenols, such as flavonoids, are secondary plant metabolites with potentially health-promoting properties. In newborn calves flavonoids may improve health status, but little is known about the systemically availability of flavonoids in calves to exert biological effects. The aim of this study was to investigate the oral bioavailability of the flavonol quercetin, applied either as quercetin aglycone (QA) or as its glucorhamnoside rutin (RU), in newborn dairy calves. Twenty-one male newborn German Holstein calves were fed equal amounts of colostrum and milk replacer according to body weight. On d 2 and 29 of life, 9 mg of quercetin equivalents/kg of body weight, either fed as QA or as RU, or no quercetin (control group) were fed together with the morning meal. Blood samples were taken before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 12, 24, and 48 h after feed intake. Quercetin and quercetin metabolites with an intact flavonol structure (isorhamnetin, tamarixetin, and kaempferol) were analyzed in blood plasma after treatment with glucuronidase or sulfatase by HPLC with fluorescence detection. Maximum individual plasma concentration was depicted from the concentration-time-curve on d 2 and 29, respectively. Additional blood samples were taken to measure basal plasma concentrations of total protein, albumin, urea, and lactate as well as pre- and postprandial plasma concentrations of glucose, nonesterified fatty acids, insulin, and cortisol. Plasma concentrations of quercetin and its metabolites were significantly higher on d 2 than on d 29 of life, and administration of QA resulted in higher plasma concentrations of quercetin and its metabolites than RU. The relative bioavailability of total flavonols (sum of quercetin and its metabolites isorhamnetin, tamarixetin, and kaempferol) from RU was 72.5% on d 2 and 49.6% on d 29 when compared with QA (100%). Calves fed QA reached maximum plasma concentrations of total flavonols much earlier than did RU-fed calves. Plasma metabolites and hormones were barely affected by QA and RU feeding in this experiment. Taken together, orally administrated QA resulted in a greater bioavailability of quercetin than RU on d 2 and 29, respectively, and quercetin bioavailability of quercetin and its metabolites differed markedly between calves aged 2 and 29 d.

[Determination of plasma concentration of quercetin, kaempferid and isorhamnetin in Hippophae rhamnoides extract by HPLC-MS/MS and pharmacokinetics in rats].

To establish an HPLC-MS/MS method for the analysis of quercetin, kaempferid and isorhamnetin in rats plasma and study its pharmamacokinetics after an intragastrical administration of Hippophae rhamnoides extracts. Five healthy male Sprague-Dawley (SD) rats were given single doses of H. rhamnoides extracts (quercetin 26.35 mg x kg(-1), kaempferid 4.040 mg x kg(-1), isorhamnetin 31.37 mg x kg(-1)), and then their orbital sinus blood samples were collected at different time points. The drug plasma concentration of the three flavonoids was determined by HPLC-MS/MS method. After that, the main pharmacokinetics parameters were calculated by using Kinetica 5. 0. 11 software. The methodological test showed that the linear concentration ranges of quercetin, kaempferid and isorhamnetin were 7.500-600.0 µg x L(-1) (R2 = 0.998 5), 1.000-80.00 µg x L(-1) (R2 = 0.998 5 ) and 10.00-800.0 µg x L(-1) (R2 = 0.998 0), respectively. The inner and inter-days precisions were both less than 14.0%. The plasma samples showed a good stability and consistency with the requirement of biological sample analysis after the samples were frozen once and placed at - 20 degrees C for 15 d and room temperature for 6 h and the treated analytes were placed at -20 degrees C for 24 h. For quercetin, the pharmacokinetic parameter t(½ß), AUC(0-∞), MRT(0.∞), C.(max) and T(max) were (113.3 ± 19.37) min, (12 542.14 ± 3 504.05) µg x h x L(-1), (119.6 ± 13.29) h, (164.6 ± 27.33) µg x L(-1) and (5.199 ± 0.840 3) h, respectively. For kaempferid, the pharmacokinetic parameters t(½ß), AUC(0-t), MRT(0-∞), C(max) and T(max) were (79.85 ± 17.15) min, (934.51 ± 94.59) µg x h x L(-1), (81.50 ± 13.75) h, (80.15 ± 14.24) µg x L(-1) and (3.827 ± 0.902 7) h, respectively. For isorhamnetin, the pharmacokinetic parameters t1,2,, AUC(0-t), MRT(0-∞), C(max) and T(max) were (118.3 ± 20.73) min, (26 067.77 ± 4 124.60) µg x h x L(-1), (129.0 ± 16.30) h, (269.6 ± 29.32) µg x L(-1) and (6.513 ± 1.450) h, respectively. The HPLC-MS/MS analysis method established in this study was proved to be sensitive and accurate and could be applied in the pharmacokinetic study of quercetin, kaempferid and isorhamnetin in rat plasma.

[Study on determination and pharmacokinetics of metabolites from Folium Mori extract in rats].

OBJECTIVE: To establish a RP-HPLC method for simultaneous determination of total quercetin, kaempferol and isorhamnetin in rat plasma after oral administration of Folium Mori extract (FME). METHODS: After a single dose of FME (110 mg/kg) was taken, rat plasma samples were collected. The samples were hydrolyzed with hydrochloric acid (c=3.0 mol/L), the mixed solution was extracted with ether acetone mixture. The total quercetin, kaempferol and isorhamnetin in plasma samples were determined by HPLC, pharmacokinetic parameters were calculated by DAS 3.0 software. RESULTS: The method was linear over the concentration ranges of 0.0545-8.70, 0.0954-14.7 and 0.0545-8.55 µg/ml for quercetin, kaempferol and isorhamnetin, respectively (r=0.9979, 0.9993, 0.9981). The absolute recoveries were 85.3%-86.1%, 79.4%-86.7% and 62.8%-89.7%, respectively and the assay recoveries were all from 94.7% to 107%. The relative standard deviation (RSD) of intra-and inter-day were less than 9.5% and 9.8%, respectively. The main pharmacokinetic parameters were as follows: T(1/2z) was 92.7, 67.9 and 54.2 h; Tmax was 0.400, 0.400 and 3.87 h; AUC(0-∞) was 68.0, 67.5 and 32.8 mg/h/L; MRT(0-∞) was 128, 85.2 and 72.0 h for quercetin, kaempferol and isorhamnetin, respectively. CONCLUSION: The method established in this study is accurate, reliable and reproducible, and can be applied for determination of total quercetin, kaempferol and isorhamnetin in rat plasma after oral administration of FME; the pharmacokinetic studies showed that the distribution of drugs is rapid and elimination is very slow.

The relationship between fasting plasma concentrations of selected flavonoids and their ordinary dietary intake.

Epidemiological studies suggest that a diet high in flavonoids protects against chronic diseases such as CVD and cancer. The objective of the present study was to evaluate the relationship between the intake of quercetin, kaempferol, isorhamnetin, apigenin and luteolin and their corresponding plasma concentrations, and further to explore whether these flavonoids can serve as biomarkers of their intake. Flavonoid intake and their plasma concentrations were analysed in ninety-two subjects consuming their habitual diet. Flavonoid intake was estimated with 7-d dietary records using available data on the flavonoid content of food. Plasma flavonoid concentrations were quantified by HPLC. In addition, we undertook a dietary intervention study to investigate plasma apigenin concentration after the consumption of celery leaf. The mean intake estimates of quercetin, kaempferol, isorhamnetin, apigenin and luteolin amounted to 13.58, 14.97, 12.31, 4.23 and 8.08 mg/d, respectively. The corresponding mean plasma concentrations were 80.23, 57.86, 39.94, 10.62 and 99.90 nmol/l. The mean 7 d intake of five flavonoids was positively correlated to their corresponding plasma concentrations, with correlation coefficients ranging from 0.33 to 0.51 (P < 0.05). In the dietary intervention study, the plasma apigenin concentration rose after celery leaf ingestion, and fell within 28 h to below the limit of detection (2.32 nmol/l). The present results suggest that quercetin, kaempferol, isorhamnetin, apigenin and luteolin are bioavailable from the diet. The levels of fasting plasma flavonoids seem to be suitable biomarkers of short-term intake. The combination of plasma flavonoids with their intake may prove useful when the possible health-protective effects of flavonoids are studied.

Plasma levels and distribution of flavonoids in rat brain after single and repeated doses of standardized Ginkgo biloba extract EGb 761®.

It is undisputed that terpene lactones and flavonoid glycosides of Ginkgo biloba are responsible for most of the extracts (e.g., EGb 761®) pharmacological actions. This investigation focused on the pharmacokinetic and the ability of the flavonoid constituents to cross the blood-brain barrier in rats, after single (600 mg/kg) or repeated (8 days, 100, or 600 mg/kg) oral administration of EGb 761®, and their distribution in different areas of the brain. For this purpose, we developed an HPLC-fluorescence method for the determination of the Ginkgo flavonoid metabolites (quercetin, kaempferol, and isorhamnetin derivatives) in the brain and plasma. A single dose of 600 mg/kg EGb 761® resulted in maximum plasma concentrations of 176, 341, and 183 ng/mL for quercetin, kaempferol, and isorhamnetin/tamarixetin, respectively and in maximum brain concentrations of 291 ng/g protein for kaempferol and 161 ng/g protein for isorhamnetin/tamarixetin. In comparison, the repeated administration of the same dose for 8 days led to an approximate 4.5-fold increase in the plasma concentration for quercetin, 11.5-fold increase for kaempferol, and 10-fold increase for isorhamnetin/tamarixetin. In the brain, an approximate 2-fold increase was observed for kaempferol and isorhamnetin/tamarixetin. About 90% of the determined flavonoids were distributed in the hippocampus, frontal cortex, striatum, and cerebellum, which together represent only 38% of the whole brain.

Effects of Egb 761 on bone mineral density, bone microstructure, and osteoblast function: Possible roles of quercetin and kaempferol.

The effects of standardized and concentrated extract of Ginkgo biloba, Egb 761, were studied on estrogen deficiency-induced bone loss in ovariectomized (OVx) rats rendered osteopenic. Upon osteopenia development, Egb 761 was administered at a dose of 100mgkg(?1)day(?1) by oral gavage to OVx rats whereas control group received vehicle. Following 5 weeks of treatment, the OVx+Egb 761 group (n=12) of rats exhibited significantly higher whole body BMD and lower bone turnover markers (serum alkaline phosphatase and osteocalcin) than OVx rats that were given vehicle (n=12). BMD levels in excised bones were also found to be higher in both trabecular (most robustly in lumbar vertebrae) and cortical bones of OVx+Egb 761 compared with OVx+vehicle group. Egb 761 did not exhibit estrogen agonistic activity at the uterine level. Microcomputed tomography demonstrated that OVx+Egb 761 group had better bone microarchitectural parameters compared with OVx+vehicle group. Moreover, OVx+Egb 761 group had higher femoral mRNA levels of osterix, type I collagen and osteocalcin compared with OVx+vehicle group. Determination of levels of three flavonoids of Egb 761, that are known to have bone conserving property, in serum and bone marrow suggests that kaempferol and quercetin, and not rutin, likely mediate the beneficial actions observed with Egb 761 treatment. These results show for the first time that oral administration of Egb 761 restores bone mass in aged OVx rats.

Blood micromolar concentrations of kaempferol afford protection against ischemia/reperfusion-induced damage in rat brain.

The slow time course of neurodegeneration after brain ischemia/reperfusion opened a realistic time window for the application of protective therapies to prevent spreading of brain damage. In this work, we studied the ability of micromolar concentrations of this flavonoid in the blood to protect against brain damage induced by transient focal cerebral ischemia in rats. Transient focal cerebral ischemia was induced by middle cerebral artery occlusion in adult rats and brain damage has been monitored by 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H-E) staining, 'in situ' terminal deoxyribonucleotidyl transferase-mediated dUTP-fluorescein nick end labeling (TUNEL), 'in situ' metalloproteinase activity using DQ-gelatin and loss of anti-laminin staining. Intravenous injections of kaempferol, at a dose of 10-15 mumol/L of blood 30 min before the induction of a 60 min ischemia-episode and just after reperfusion, led to >90% and 70-80% (TTC, H-E, TUNEL) decrease of brain damage in the temporal-frontal areas of neocortex and striatum, respectively, but only 40-50% decrease of brain damage was observed in the hippocampus and vicinal caudal areas of the striatum. This treatment with kaempferol also produced a similar reduction of metalloproteinase activation and loss of anti-laminin staining in cortical and striatum infarct areas. Kaempferol treatment efficiently protected against nitrosative-oxidative stress after ischemia/reperfusion, as shown by nearly complete protection against the increase of protein nitrotyrosines, and also afforded strong protection against the increase of apoptotic cell death (TUNEL) and biochemical markers of apoptosis, such as caspase-9 activity and poly-(ADP-ribose) polymerase degradation. On these grounds, a potential new therapeutic role of kaempferol to acute treatment of ischemic stroke is suggested.

An UHPLC-MS/MS method for simultaneous determination of quercetin 3-O-rutinoside, kaempferol 3-O-rutinoside, isorhamnetin 3-O-rutinoside, bilobalide and ligustrazine in rat plasma, and its application to pharmacokinetic study of Xingxiong injection.

The present study was designed to develop and validate a rapid, sensitive, and reliable ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of five major active constituents in the traditional Chinese medicinal preparation Xingxiong injection (XXI) in rat plasma, including quercetin 3-O-rutinoside (QCR), kaempferol 3-O-rutinoside (KFR), isorhamnetin 3-O-rutinoside (ISR), bilobalide (BB), and ligustrazine (LGT). The plasma samples were pretreated by protein precipitation with acetonitrile. The chromatographic separation was achieved on a Waters Symmetry C18 analytical column (2.1 mm × 100 mm, 3.5 µm) with a mobile phase of 0.1% aqueous formic acid (A)-acetonitrile (B). Quantitation of the five bioactive constituents was achieved. Naringin was used as the internal standard (IS). All the calibration curves showed good linearity (r > 0.996) over the concentration range, with the lowest limit of quantification (LLOQ) between 2-18 ng·mL-1. The intra- and inter-day accuracy and precision of the analytes were both within acceptable limits. Moreover, satisfactory extraction recoveries (90.92%-104.03%) were obtained by protein precipitation. The validated method was successfully applied to a pharmacokinetic study of XXI in rats after intravenous administration at three doses. The pharmacokinetic parameters of the five compounds varied in a dose-dependent manner within the tested dosage range. The present study was the first report of pharmacokinetic study for XXI.

Pharmacokinetics of dietary kaempferol and its metabolite 4-hydroxyphenylacetic acid in rats.

SCOPE: Kaempferol is a major flavonoid in the human diet and in medicinal plants. The compound exerts anxiolytic activity when administered orally in mice, while no behavioural changes were observed upon intraperitoneal administration, or upon oral administration in gut sterilized animals. 4-Hydroxyphenylacetic acid (4-HPAA), which possesses anxiolytic effects when administered intraperitoneally, is a major intestinal metabolite of kaempferol. Pharmacokinetic properties of the compounds are currently not clear. METHODS AND RESULTS: UHPLC-MS/MS methods were validated to support pharmacokinetic studies of kaempferol and 4-HPAA in rats. Non-compartmental and compartmental analyses were performed. After intravenous administration, kaempferol followed a one-compartment model, with a rapid clearance (4.40-6.44l/h/kg) and an extremely short half-life of 2.93-3.79min. After oral gavage it was not possible to obtain full plasma concentration-time profiles of kaempferol. Pharmacokinetics of 4-HPAA was characterized by a two-compartment model, consisting of a quick distribution phase (half-life 3.04-6.20min) followed by a fast elimination phase (half-life 19.3-21.1min). CONCLUSION: Plasma exposure of kaempferol is limited by poor oral bioavailability and extensive metabolism. Both compounds are rapidly eliminated, so that effective concentrations at the site of action do not appear to be reached. At present, it is not clear how the anxiolytic-like effects reported for the compounds can be explained.

Production, Characterization and Evaluation of Kaempferol Nanosuspension for Improving Oral Bioavailability.

CONTEXT: Kaempferol has a large particle size and poor water solubility, leading to poor oral bioavailability. The present work aimed to develop a kaempferol nanosuspension (KNS) to improve pharmacokinetics and absolute bioavailability. METHODS: A nanosuspension was prepared using high pressure homogenization (HPH) techniques. The physico-chemical properties of the kaempferol nanosuspension (KNS) were characterized using photon correlation spectroscopy (PCS), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and x-ray diffractometry (XRD). A reversephase high performance liquid chromatography (RP-HPLC) method for the analysis of the drug in rat plasma was developed and validated as per ICH guidelines. In vivo pharmacokinetic parameters of oral pure kaempferol solution, oral kaempferol nanosuspension and intravenous pure kaempferol were assessed in rats. RESULTS AND DISCUSSION: The kaempferol nanosuspension had a greatly reduced particle size (426.3 ± 5.8 nm), compared to that of pure kaempferol (1737 ± 129 nm). The nanosuspension was stable under refrigerated conditions. No changes in physico-chemical characteristics were observed. In comparison to pure kaempferol, kaempferol nanosuspension exhibited a significantly (P<0.05) increased in Cmax and AUC(0-∞) following oral administration and a significant improvement in absolute bioavailability (38.17%) compared with 13.03% for pure kaempferol. CONCLUSION: These results demonstrate enhanced oral bioavailability of kaempferol when formulated as a nanosuspension.

Pharmacokinetic evaluation of the interaction between oral kaempferol and ethanol in rats.

This study was aimed at investigating the effect of ethanol on oral bioavailability of kaempferol in rats, namely, at disclosing their possible interaction. Kaempferol (100 or 250 mg kg-1 bm) was administered to the rats by oral gavage with or without ethanol (600 mg kg-1 bm) co-administration. Intravenous administration (10 and 25 mg kg-1 bm) of kaempferol was used to determine the bioavailability. The concentration of kaempferol in plasma was estimated by ultra high performance liquid chromatography. During coadministration, a significant increase of the area under the plasma concentration-time curve as well as the peak concentration were observed, along with a dramatic decrease in total body clearance. Consequently, the bioavailability of kaempferol in oral control groups was 3.1 % (100 mg kg-1 bm) and 2.1 % (250 mg kg-1 bm). The first was increased by 4.3 % and the other by 2.8 % during ethanol co-administration. Increased permeability of cell membrane and ethanolkaempferol interactions on CYP450 enzymes may enhance the oral bioavailability of kaempferol in rats.

Sensitive determination of kaempferol using carbon dots as a fluorescence probe.

In this study, a new sensitive and convenient method for the determination of kaempferol (Kae) based on the fluorescence quenching of fluorescent carbon dots (C-dots) was developed. The C-dots were prepared by simply mixing acetic acid, water and diphosphorus pentoxide. This green synthesis approach proceeds rapidly and gives large quantities of C-dots. The fluorescence of the C-dots decreased obviously with the increase of Kae concentration. The effect of other interfering substances on the fluorescence intensity of C-dots showed low interference. Under the optimum conditions, a linear correlation was established between fluorescence intensity ratio Fo/F and the concentration of Kae in the range of 3.5-49 µM with a detection limit (S/N=3) of 38.4 nM. The proposed method has been successfully applied to determination of Kae in xindakang tablets and human serum samples with recovery in the range of 94.6-109.0%. The C-dots could be a promising fluorescence probe for the detection of Kae owing to its low-cost production, easy operation, low cytotoxicity, and excellent biocompatibility.

Quercetin and its metabolites inhibit the membrane NADPH oxidase activity in vascular smooth muscle cells from normotensive and spontaneously hypertensive rats.

Quercetin, the most abundant dietary flavonol, exerts antioxidant effects reducing vascular superoxide (O2(-)) and improving endothelial function in animal models of cardiovascular disease. Herein we evaluated the effects of quercetin, and its plasma metabolites, on the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase activity, the main source of O2(-) in the vessel wall, in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Quercetin and its metabolites isorhamnetin and kaempferol inhibited the NADPH-stimulated lucigenin-chemiluminescence signal in VSMCs from both strains. The inhibitory effect of quercetin-3-glucuronide increased after prolonged incubation and was inhibited in the presence of the ß-glucuronidase inhibitor saccharolactone. These effects were unrelated to their O2(-) scavenging properties, since they induced only a small inhibition of the rate of pyrogallol autoxidation at high concentrations. All bioflavonoids tested acted as non-competitive inhibitors with respect to NADPH. In conclusion, quercetin and its metabolites inhibit the NADPH oxidase activity in VSMCs reducing O2(-) generation more efficiently than their effect as O2(-) scavengers. The effect of quercetin-3-glucuronide was due to deconjugation and release of free quercetin. The effect is similar in VSMCs from normotensive and hypertensive animals.

HPLC Plasma Assay of a Novel Anti-MRSA Compound, Kaempferol-3-O-Alpha-L-(2",3"-di-p-coumaroyl)rhamnoside, from Sycamore Leaves.

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious pathogen that is resistant to current antibiotic therapy. Thus, there is an urgent need for novel antimicrobial agents that can effectively combat these new strains of drug-resistant "superbugs". Recently, fractionation of an extract from Platanus occidentalis (American sycamore) leaves produced an active kaempferol molecule, 3-O-alpha-L-(2",3"-di-p-coumaroyl)rhamnoside (KCR), in four isomeric forms; all four isomers exhibit potent anti-MRSA activity. In order to further the preclinical development of KCR as a new antibiotic class, we developed and validated a simple analytical method for assaying KCR plasma concentration. Because KCR will be developed as a new drug, although comprising four stereoisomers, the analytical method was devised to assay the total amount of all four isomers. In the present work, both a plasma processing procedure and an HPLC method have been developed and validated. Mouse plasma containing KCR was first treated with ethanol and then centrifuged. The supernatant was dried, suspended in ethanol, centrifuged, and the supernatant was injected into an HPLC system comprising a Waters C18, a mobile phase composing methanol, acetonitrile, and trifluoroacetic acid and monitored at 313 nm. The method was validated by parameters including a good linear correlation, a limit of quantification of 0.27 microg/mL, and high accuracy. In summary, this method allows a rapid analysis of KCR in the plasma samples for pharmacokinetics studies.

Absorption of kaempferol from endive, a source of kaempferol-3-glucuronide, in humans.

OBJECTIVE: To determine the absorption, excretion and metabolism of kaempferol in humans. DESIGN: A pharmacokinetic study of kaempferol from endive over 24 h. SUBJECTS: Four healthy males and four healthy females. RESULTS: Kaempferol, from a relatively low dose (9 mg), was absorbed from endive with a mean maximum plasma concentration of 0.1 microM, at a time of 5.8 h, indicating absorption from the distal section of the small intestine and/or the colon. Although a 7.5-fold interindividual variation between the highest and lowest maximum plasma concentration was observed, most individuals showed remarkably consistent pharmacokinetic profiles. This contrasts with profiles for other flavonoids that are absorbed predominantly from the large intestine (eg rutin). An average of 1.9% of the kaempferol dose was excreted in 24 h. Most subjects also showed an early absorption peak, probably corresponding to kaempferol-3-glucoside, present at a level of 14% in the endive. Kaempferol-3-glucuronide was the major compound detected in plasma and urine. Quercetin was not detected in plasma or urine indicating a lack of phase I hydroxylation of kaempferol. CONCLUSIONS: Kaempferol is absorbed more efficiently than quercetin in humans even at low oral doses. The predominant form in plasma is a 3-glucuronide conjugate, and interindividual variation in absorption and excretion is low, suggesting that urinary kaempferol could be used as a biomarker for exposure.

The antibacterial activity of phytochemically characterised fractions from Folium Syringae.

To identify the most active antimicrobial fraction of Folium Syringae, four common pathogens were used in an in vitro screening. The results indicated that the combination of the 30% and 60% ethanol fraction (FSC) obtained from the water extraction was the most active fraction with a minimal inhibitory concentration of 0.65 mg mL(-1). FSC was also found to be able to protect mice from a lethal infection of Staphylococcus aureus at clinical dosage (0.2 g kg(-1)) with a survival rate of 83.3%. The antibacterial activity of FSC was then tested using the serum pharmacology method which revealed that FSC exhibits a more long-lasting activity than the positive control (levofloxacin hydrochloride). The main components were confirmed to be iridoid glycosides and flavones by HPLC-MS analysis.

[HPLC-MS/MS for determination of astragalin in rat plasma and its pharmacokinetics].

OBJECTIVE: To develop a LC-MS/MS method for determination of astragalin in rat plasma and study its pharmacokinetics in rats. METHODS: The analytical column was packed with ZORBAX SB-C18, and the mobile phase was methanol-water containing 10 mmol/L ammonium acetate-formic acid (80:20:0.15, V/V/V). Quercetin was used as the internal standard (IS). Multiple reaction monitoring (MRM) mode was employed, and the transition of m/z was m/z 449.1→m/z 287.1 for astragalin, and m/z 301.1→m/z 151.1 for IS. RESULTS: A good liner relationship was obtained within the range of 1.00-1000 ng/ml (r(2)=0.9929), and the lower limit of quantification of astragalin was 1.00 ng/ml in rat plasma. The extraction recoveries were all above 93%. After oral administration of astragalin, the maximum plasma concentration of astragalin was 231.1∓67.3 ng/ml and the time to reach this value was 0.5∓0.1 h, with a half-life of 3.9∓1.3 h and an AUC of 782.6∓152.8 ng·h/ml. CONCLUSION: The method is highly sensitive, selective and rapid for determination of the concentration of astragalin in rat plasma to facilitates the study of its pharmacokinetics.

A rapid and sensitive liquid chromatography-tandem mass spectrometric method for determination of actinoside E in rat plasma and application to a pharmacokinetic study.

A highly sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of actinoside E in rat plasma. The analytes were extracted by ethyl acetate and an analogue of actinoside F was used as the internal standard. The mobile phase consisted of methanol-water (50: 50, V/V) containing 0.1% formic acid was delivered at a flow rate of 0.3 mL·min(-1) to a Zorbax SB-C18 column (100 mm × 2.1 mm, 3.5 µm). The detection was performed by electrospray ionization mass spectrometry in the negative multiple reaction monitoring mode with a chromatograph run time of 3.0 min. Calibration curves of actinoside E were linear in the range of 0.5-2 500 ng·mL(-1). In this range, intra- and inter-day precision ranged from 1.7% to 7.5% and 2.0% to 8.9%, respectively. The accuracy ranged from 95.7% to 108.6%, and extraction recovery from 83.2% to 85.5%. This method was successfully applied to a pharmacokinetic study of actinoside E in rats after intravenous (5 mg·kg(-1)) and oral (100 mg·kg(-1)) administration, and the results showed that actinoside E was poorly absorbed with an absolute bioavailability being approximately 0.27%.

Pharmacokinetic study of major bioactive components in rats after oral administration of extract of Ilex hainanensis by high-performance liquid chromatography/electrospray ionization mass spectrometry.

Ilex hainanensis Merr. is commonly used as a folk remedy for treating hypertension, dyslipidemia and inflammation in Traditional Chinese Medicine (TCMs) and it also has great potential to treat non-alcoholic fatty liver disease (NAFLD). Chlorogenic acid, kaempferol-7-O-ß-d-glucoside, and ilexgenin A are three major bioactive components in I. hainanensis extract. In this study, a rapid, sensitive and convenient LC-MS method was developed for their simultaneous determination in the plasma of normal and NAFLD rats. The method was validated in terms of selectivity, linearity and sensitivity, and shows advantages in monitoring the pharmacokinetic behaviors of these three compounds. Results revealed the pharmacokinetic behaviors of chlorogenic acid, kaempferol-7-O-ß-d-glucoside, and ilexgenin A could be significantly changed in NAFLD rats after oral administration of I. hainanensis extract compared with normal rats. The areas under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) of the three analytes were greatly decreased and the plasma clearance (CL) for kaempferol-7-O-ß-d-glucoside, Ilexgenin A were greatly increased in NAFLD rats. Meanwhile, the mean residence time (MRT) of kaempferol-7-O-ß-d-glucoside and Ilexgenin A were increased in the NAFLD rats. This is the first report on the determination of the major bioactive components in rat plasma after oral administration of I. hainanensis extract. These results provided a meaningful basis for evaluating the clinical application of this medicine.