Ganoderic Acid A Metabolites and Their Metabolic Kinetics

Ganoderic acid A (GAA), a representative active triterpenoid from Ganoderma lucidum, has been reported to exhibit antinociceptive, antioxidative, cytotoxic, hepatoprotective and anticancer activities. The present study aims (1) to identify GAA metabolites, in vivo by analyzing the bile, plasma and urine after intravenous administration to rats (20 mg/kg), and in vitro by incubating with rat liver microsomes (RLMs) and human liver microsomes (HLMs); (2) to investigate the metabolic kinetics of main GAA metabolites. Using HPLC-DAD-MS/MS techniques, a total of 37 metabolites were tentatively characterized from in vivo samples based on their fragmentation behaviors. The metabolites detected in in vitro samples were similar to those found in vivo. GAA underwent extensive phase I and II metabolism. The main metabolic soft spots of GAA were 3, 7, 11, 15, 23-carbonyl groups (or hydroxyl groups) and 12, 20, 28 (29)-carbon atoms. Ganoderic acid C₂ (GAC₂) and 7β,15-dihydroxy-3,11,23-trioxo-lanost-26-oic acid were two main reduction metabolites of GAA, and their kinetics followed classical hyperbolic kinetics. The specific isoenzyme responsible for the biotransformation of the two metabolites in RLMs and HLMs was CYP3A. This is the first report on the comprehensive metabolism of GAA, as well as the metabolic kinetics of its main metabolites.

Pharmacokinetic profiles of the five isoflavonoids from Pueraria lobata roots in the CSF and plasma of rats

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Radix Puerariae, the roots of Pueraria lobata (Wild.) Ohwi., has been widely used for the treatment of cardiovascular and cerebrovascular diseases in China for centuries. Isoflavonoids are believed the active components of this herb.

AIM OF THIS STUDY

The present study aims to investigate the brain penetration and pharmacokinetics of five active isoflavonoids in the ventricular CSF and plasma of rats after intravenous administration of a Pueraria isoflavonoids (PIF) extract, to better understand the active components of this herb for neuro-activities.

MATERIAL AND METHODS

Under anesthesia condition, SD rats (n=6) were successively suffered two surgeries for implanting cannulas at lateral ventricle and right jugular vein for brain microdialysis and blood collection, respectively. After recovery, the rats received intravenous dose of PIF at 80mg/kg and the concentrations of puerarin (PU), 3'-methoxypuerarin (MPU), 3'-hydroxypuerarin (HPU), daidzein (DA) and daidzein-8-C-apiosyl-(1-6)-glycoside (DAC) in the ventricular dialysate and plasma samples were determined using a ultra-fast liquid chromatography tandem mass spectrometry method.

RESULTS

Complete concentration versus time profiles of the five components in plasma and four components except for HPU in ventricular CSF were obtained. After dosing, the average C0 values of PU, MPU, DA, DAC and HPU in plasma were estimated 6.53, 13.72, 1.54, 15.84 and 86.07µg/mL, and PU, MPU, DA and DAC were rapidly penetrated to the brain and reached to their Cmax of 521.52, 415.00, 74.34 and 380.03ng/mL in CSF at about 0.5-0.8h, respectively. The elimination t1/2 of PU, DA and DAC in CSF and plasma were no significant difference, while the t1/2 of MPU in ventricular CSF was longer than that in plasma which may attributable to the different physiological environment of central and peripheral compartments. The brain penetration index (AUCCSF/AUCplasma) was found to be about 9.29, 7.25, 11.96, and 4.21% for PU, MPU, DA, and DAC respectively.

CONCLUSION

PU, MPU, DA, DAC can quickly penetrate to the brain through the blood brain barrier (BBB) and might be responsible for the neuro-pharmacological activities of P. lobata.

Metabolism profiles of nuciferine in rats using ultrafast liquid chromatography with tandem mass spectrometry

Nuciferine (NF) is one of the main aporphine alkaloids existing in the traditional Chinese medicine Folium Nelumbinis (lotus leaves). Modern pharmacological studies have demonstrated that NF has a broad spectrum of bioactivities, such as anti-HIV and anti-hyperlipidemic effects, and has been recommended as a leading compound for new drug development. However, the metabolites and biotransformation pathway of NF in vivo have not yet been comprehensively investigated. The present study was performed to identify the metabolites of NF for exploring in vivo fates. Rat plasma and urine samples were collected after oral administration and prepared by liquid-liquid extraction with ethyl acetate. A method based on ultrafast liquid chromatography with tandem mass spectrometry was applied to identify the metabolites. Q1 (first quadrupole) full scan combined with a multiple reaction monitoring (MRM) survey scan were used for the detection of metabolites. MRM-information-dependent acquisition of enhanced product ions was used for the structural identification of detected metabolites. A total of 10 metabolites were identified, including phase I (demethylation, oxidation and dehydrogenation) and phase II (glucuronidation, sulfation and glutathione) biotransformation products. Demethylation is the main metabolic pathway of NF in the body. These results can help in improving understanding of the disposition and pharmacological mechanism of NF in the body. Copyright © 2016 John Wiley & Sons, Ltd.

Lotus Leaf Alkaloid Extract Displays Sedative-Hypnotic and Anxiolytic Effects through GABAA Receptor

Lotus leaves have been used traditionally as both food and herbal medicine in Asia. Open-field, sodium pentobarbital-induced sleeping and light/dark box tests were used to evaluate sedative-hypnotic and anxiolytic effects of the total alkaloids (TA) extracted from the herb, and the neurotransmitter levels in the brain were determined by ultrafast liquid chromatography-tandem mass spectrometry. The effects of picrotoxin, flumazenil, and bicuculline on the hypnotic activity of TA, as well as the influence of TA on Cl(-) influx in cerebellar granule cells, were also investigated. TA showed a sedative-hypnotic effect by increasing the brain level of γ-aminobutyric acid (GABA), and the hypnotic effect could be blocked by picrotoxin and bicuculline, but could not be antagonized by flumazenil. Additionally, TA could increase Cl(-) influx in cerebellar granule cells. TA at 20 mg/kg induced anxiolytic-like effects and significantly increased the concentrations of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and dopamine (DA). These data demonstrated that TA exerts sedative-hypnotic and anxiolytic effects via binding to the GABAA receptor and activating the monoaminergic system.

An LC-MS/MS method for simultaneous determination of three Polygala saponin hydrolysates in rat plasma and its application to a pharmacokinetic study

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Polygala has a long history of use as a sedative in traditional Chinese medicine and its major ingredients are saponins, which are recognized effective in memory improvement but highly toxic to gastricintestinal mucosa. Polygala saponin hydrolysates (PSH), an alkaline hydrolysis product and also the intestinal metabolites of the saponins, exhibited stronger effects in improving memory of mice and had less toxicity than its original saponins. The present study aims to develop a sensitive LC-MS/MS method for simultaneously determining PSH three major active components, 3,4,5-trimethoxycinnamylic acid (TMCA), p-methoxycinnamylic acid (PMCA) and tenuifolin (TF), in rat plasma and apply the method to a pharmacokinetic study.

MATERIALS AND METHODS

The acidic plasma (100μl) was treated by liquid-liquid extraction with ethyl acetate and reconstituted sample was analyzed on a C18 column eluted with acetonitrile-water (50:50) containing 0.2% formic acid at 0.4ml/min. The mass detection in negative electrospray ionization was used. The ion pairs for multiple reaction monitoring were set at m/z 237.0/103.0, 177.0/116.6 and 679.5/425.3 for TMCA, PMCA and TF, respectively. Their pharmacokinetic profiles were studied in rats after intravenous and oral dose of PSH at 20 and 100mg/kg, respectively.

RESULTS

The calibration curves had good linearity (r(2)>0.99) for TMCA, PMCA and TF within the tested concentration ranges. The limits of detection and quantification were 1, 10, 0.5ng/ml and 10.0, 20.0, 1.0ng/ml, respectively. The intra-day and inter-day precisions were less than 18.9% and accuracies between 93.2% and 113.3%, and the extraction recovery ranged from 91.2% to 112.1% for all analytes. The pharmacokinetic study showed that TMCA, PMCA and TF could be rapidly absorbed into the circulation and reached their peak concentrations at about 9.1, 9.0 and 24.0min, respectively. TF had a lower oral bioavailability (2.0%) than TMCA (90.1%) and PMCA (96.5%), but it remained in the body much longer (t1/2, λz, 4.8h, oral dose) than TMCA (0.6h) and PMCA (0.9h).

CONCLUSIONS

A sensitive LC-MS/MS method was developed and applied to a pharmacokinetic study of TMCA, PMCA and TF of PSH in rats. The three components are proved to be bio-available active components of PSH and might display their in vivo pharmacological activities at different levels and different time periods after oral administration.

Identification and characterization of potent CYP2D6 inhibitors in lotus leaves

ETHNOPHARMACOLOGICAL RELEVANCE

The herb of lotus (Nelumbo nucifera) leaves is a commonly used traditional Chinese herbal medicine that is utilized for the treatment of sunstroke, to assuage thirst, and to cure both diarrhea and fever in China. Modern pharmacological studies have demonstrated that the herb exhibits various pharmacological effects, such as anti-hyperlipidemia, anti-obesity, anti-oxidant, anti-HIV, anti-microbial, and anti-hypoglycemic activities. Currently, the herb is becoming more popular in China as a "tea drink" or as a main ingredient of some herbal formulations, which implies that the herb and/or its products are now more likely to be concurrently administered with conventional medicines for losing body weight and reducing blood lipids. However, its potential inhibitory effect on human cytochrome P450 (CYP) has not been systemically investigated to date. The present study was performed to assess the potential inhibitory effects of lotus leaf alcoholic extract (LAE), its major fractions, and its main compounds on five CYP isoenzymes (CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) in vitro.

MATERIAL AND METHODS

Five probe substrates were incubated with human liver microsomes in the presence or absence of the LAE, the alkaloid fraction (AF), the flavonoid fraction (FF), or the individual aporphine alkaloids, namely, nuciferine (NF), N-nornuciferine (N-NF), and 2-hydroxy-1-methoxyaporphine (HMA). After the incubation, the relative metabolites of the substrates were analyzed using LC-MS/MS.

RESULTS

The results showed that the LAE strongly inhibited CYP2D6 with an IC50 value of 12.05µg/mL and weakly inhibited other isoenzymes. In addition, FF was found to weakly inhibit CYP2D6, whereas AF exerted a markedly higher inhibitory effect on CYP2D6 activity with an IC50 value of 0.96µg/mL. The three aporphine alkaloids isolated from the AF (NF, N-NF, and HMA) significantly inhibited CYP2D6 with IC50 values of 3.78, 3.76, and 3.15µM, respectively. Their Lineweaver-Burk plots and Dixon plots showed that NF, N-NF, and HMA competitively inhibited CYP2D6 activity with Ki values of 1.88, 2.34, and 1.56µM, respectively.

CONCLUSION

The study revealed that the alkaloid compounds in lotus leaves exert a potent inhibitory effect on CYP2D6 isoenzyme. The possible drug interactions of the leaves and their preparations with conventional medicines should thus be taken into account.

Pharmacokinetic mechanism of enhancement by Radix Pueraria flavonoids on the hyperglycemic effects of Cortex Mori extract in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus, characterized by abnormal blood glucose evaluation, is a serious chronic disease. In the treatment of the disease, α-glycosidase inhibitors play an important role for controlling the postprandial blood glucose level. Cortex Mori, a traditional Chinese herbal medicine, has a long history of use for the treatment of headaches, cough, edema and diabetes. Modern pharmacological studies have shown that the herb has beneficial effects on the suppression of postprandial blood glucose levels by inhibiting α-glycosidase activity in the small intestine. 1-Deoxynojirimycin (DNJ), the main active ingredient of this herb, is recognized as a potent α-glycosidase inhibitor. Our previous studies have shown that the hypoglycemic effect of Cortex Mori extract (CME) was significantly improved when giving CME in combination with Radix Pueraria flavonoids (RPF). In the present study, the pharmacokinetics and intestinal permeability of DNJ were comparatively investigated in rats after being given orally or by intestinal perfusion with CME alone or in CME-RPF pairs, to explore the mechanism of this synergistic effect.

MATERIALS AND METHODS

The role of RPF on the plasma and urine concentrations of DNJ from CME orally administered was investigated. Four groups of rats received a single oral dose of either CME or CME-RPF, at DNJ equivalent doses of 20 and 40mg/kg, respectively. After dosing, plasma and urine were collected and assayed by LC/MS/MS. In addition, another two groups of rats were used for small intestinal perfusion with CME or CME-RPF at DNJ concentration of 10µM.

RESULTS

Compared to the data when dosing with CME alone, the Cmax of DNJ were decreased from 5.78 to 2.94µg/ml (p<0.05) and 10.66 to 5.35µg/ml (p<0.01); Tmax were delayed from 0.40 to 0.55h and 0.35 to 0.50h (p<0.05); and MRT were significantly prolonged from 1.14 to 1.72h (p<0.05) and 0.95 to 1.62h (p<0.01), after dosing with CME-RPF at DNJ doses of 20 and 40mg/kg, respectively. In addition, the urinary recovery of DNJ over the first 4h after dosing significantly decreased from 48.76% to 33.86%. Effective permeability (Peff) of DNJ was decreased from 7.53×10(-3) to 3.09×10(-3)cm/s (p<0.05) when RPF was added to CME, when it was evaluated using the rat intestinal perfusion model.

CONCLUSIONS

All the above results demonstrate that RPF was able to suspend and delay the absorption of DNJ, but did not affect the total amount of DNJ in the body. The resulting higher concentration of DNJ in the small intestine produced a relatively stronger effect of depressing the elevation of the postprandial blood glucose level. These findings support the important role of RPF in the application of CME on blood glucose control.

The effects of all-trans-retinoic acid on cell cycle and alkaline phosphatase activity in pancreatic cancer cells

Pancreatic cancer is one of the tumors with the highest mortality, poorly responding to available chemotherapeutic agents. The objective of this study was to study the anticancer effects of all-trans retinoid acid, a functional form of vitamin A, on pancreatic cancer cells. Human pancreatic cancer MiaPaCa-2 cells were treated with 1, 5, 10, 20, 30, 40 and 50 microM ATRA for 1, 2, 3, 4, 5 or 6 d, respectively. Cell growth was determined by MTT viability assay. The cell cycle distribution and the alkaline phosphatase (ALP) activity were analyzed by flow cytometry and chemical analyzer, respectively. The results show that ATRA significantly inhibited the growth of MiaPaCa-2 cells at 40 and 50 microM. ATRA arrested pancreatic cancer cells at G0/G1 phase. The sub-G1 peak and DNA fragmentation were observed. There were time and dose dependent increases in alkaline phosphatase activity (ALP), an indicator of cell differentiation, upon treatment with ATRA when compared to controls. In conclusion, ATRA has an inhibitory effect on the cell growth of MiaPaCa-2, and its tumor suppressive effect is by means of cell cycle arrest and apoptosis induction.

Suppression of telomerase activity and arrest at G1 phase in human cervical cancer HeLa cells by all-trans retinoic acid

Of all neoplasms found in women, cervical cancer has the third highest incidence and causes the fourth most deaths. All-trans retinoic acid (ATRA) may be with chemopreventive potential on cervical cancer, but the mechanisms underlying is not clear. To investigate the mechanisms, human cervical cancer HeLa cells were treated with ATRA for 1, 2, 3, or 4 days in vitro. We found that ATRA inhibited the growth of HeLa cells in a dose-dependent manner at the concentrations from 0.3 to 9.6 mumol/L. Flow cytometric analysis showed that HeLa cells were arrested at G0/G1 phase by ATRA, and the aneuploidy was found when cells were treated for 4 days, which is the first report that ATRA causes aneuploid cycle in HeLa cells. The expression of human telomerase catalytic subunit messenger RNA was decreased remarkably by ATRA. These findings suggested that the inhibition of telomerase activity and arrest of cells at G0/G1 phase might be the key steps through which ATRA inhibits the proliferation of HeLa cells. Our results provide a possible mechanistic explanation for the growth inhibitory effect of ATRA on HeLa cells. Therefore, retinoids may have therapeutic potential to complement current treatments of cervical cancers.

Effect of daidzein on cell growth, cell cycle, and telomerase activity of human cervical cancer in vitro

Phytoestrogens are some plant compounds exhibiting estrogen-like activities. However, some studies have shown that they also affect the growth of some nonhormone-dependent diseases. In this study, daidzein--one of the most common phytoestrogens--was used to investigate its effects on human cervical cancer cells HeLa in vitro. First, the cell growth was measured by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Then, the distributions of cell cycle and apoptosis were analyzed with the help of flow cytometry. Finally, the telomerase activity was detected by using real-time quantitative reverse transcription-polymerase chain reaction. The results showed that at the concentrations from 6.25 to 100 micro mol/l, daidzein inhibited the growth of HeLa cells. Flow cytometric analysis showed that cancer cells were arrested at G(0)/G(1) or G(2)/M phase with daidzein. The inductive effects of apoptosis were more obviously observed in low-concentration groups. After HeLa cells were treated with daidzein, the expression of human telomerase catalytic subunit mRNA decreased. These meant that daidzein affected human nonhormone-dependent cervical cancer cells in several ways, including cell growth, cell cycle, and telomerase activity in vitro.

Biphasic effect of daidzein on cell growth of human colon cancer cells

Colorectal cancer is one of the most common cancers in the world, poorly responding to available chemotherapeutic agents. To investigate whether natural molecules can inhibit colon cancer progression, we investigated a principle phytoestrogen found in soybean known as daidzein, and determined its effects on the human colon cancer cell line LoVo. LoVo cells were treated with 0.1, 1, 5, 10, 50 and 100 microM daidzein for 2, 3, 4 or 5 d. The results indicated that daidzein stimulated the growth of LoVo cells at 0.1 and 1 microM whereas at higher concentrations (10, 50 and 100 microM) cell growth was inhibited in a dose-dependent manner. Treatment of daidzein at 10, 50 and 100 microM resulted in cell cycle arrest at G0/G1 phase, DNA fragmentation and increases in caspase-3 activity. There were no changes in alkaline phosphatase activity (ALP), an indicator of cell differentiation, upon treatment with daidzein when compared to controls. These results indicate that daidzein has a biphasic effect on LoVo cell growth and its tumor suppressive effect is by means of cell cycle arrest and apoptosis but not through cell differentiation.