Pharmacokinetics and pharmacodynamics of Rh2 and aPPD ginsenosides in prostate cancer: a drug interaction perspective.

Ginsenoside Rh2 and its aglycon (aPPD) are one of the major metabolites from Panax ginseng. Preclinical studies suggest that Rh2 and aPPD have antitumor effects in prostate cancer (PCa). Our aims in this review are (1) to describe the pharmacokinetic (PK) properties of Rh2 and aPPD ginsenosides; 2) to provide an overview of the preclinical findings on the use of Rh2 and aPPD in the treatment of PCa; and (3) to highlight the mechanisms of its PK and pharmacodynamic (PD) drug interactions. Increasing evidence points to the potential efficacy of Rh2 or aPPD for PCa treatment. Based on the laboratory studies, Rh2 or aPPD combinations revealed an additive or synergistic interaction or enhanced sensitivity of anticancer drugs toward PCa. This review reveals that enhanced anticancer activities were demonstrated in preclinical studies through interactions of Rh2 and/or aPPD with the proteins related to PK (e.g., cytochrome P450 enzymes, transporters) or PD of the other anticancer drugs or PCa signaling pathways. In conclusion, combining Rh2 or aPPD with anti-prostate cancer drugs leads to PK or PD interactions which could facilitate either therapeutically beneficial or toxic effects.

Enhanced the Bioavailability of Sterile 20(S)-Protopanaxadiol Nanocrystalline Suspension Coated by Bovine Serum Albumin for Intramuscular Injection: In Vitro and In Vivo Evaluation.

The aim of this study was to prepare a 20(S)-protopanaxadiol nanocrystalline suspension and enhance the bioavailability of 20(S)-protopanaxadiol by intramuscular injection. 20(S)-Protopanaxadiol nanocrystalline suspension was prepared using an anti-solvent combined with ultrasonic approach, in which meglumine and bovine serum albumin were screened as the optimized stabilizer and the coating agent during spray drying process, respectively. The optimal nanocrystallines were nearly spherical with a uniform particle size distribution, the mean particle size, polydispersity index, and drug loading of which were 151.20 ± 2.54 nm, 0.11 ± 0.01, and 47.15% (w/w), respectively. Sterile 20(S)-protopanaxadiol nanocrystalline suspension was obtained by passing through a 0.22-µm membrane, and the average filtration efficiency (FE%) was 99.96%. The cumulative release percentage of 20(S)-protopanaxadiol nanocrystalline suspension was 92.36% 20(S)-protopanaxadiol within 60 min in vitro, which was relatively rapid compared with that of the physical mixture for 12.51% and the 20(S)-protopanaxadiol bulk powder for 9.71% during the same time interval. The sterile 20(S)-protopanaxadiol nanocrystalline suspension caused minimal irritation responses by histological examination, indicating a good biocompatibility between the 20(S)-protopanaxadiol nanocrystalline suspension and muscle tissues. In pharmacokinetic study, the absolute bioavailability of 20(S)-protopanaxadiol nanocrystalline suspension for intramuscular injection and for oral gavage was 5.99 and 0.03, respectively. In summary, the 20(S)-protopanaxadiol nanocrystalline via intramuscular injection is an efficient drug delivery system to improve its bioavailability.

Pharmacokinetic interaction of calcitriol with 20(S)-protopanaxadiol in mice: Determined by LC/MS analysis.

The physiological and anti-cancer functions of vitamin D3 are accomplished primarily via 1α,25-dihydroxyvitamin D3 (calcitriol), whereas 20(S)-protopanaxadiol (aPPD) is a ginsenoside, which is isolated from Panax ginseng, with potential anti-cancer benefits. In the present study, we report a pharmacokinetic (PK) herb-nutrient interaction between calcitriol and aPPD in mice. A liquid chromatography mass spectrometry (LC/MS) method was developed using 4-phenyl-1,2,4-triazoline-3,5-dione derivatizing agent and we subsequently used the method to quantitate calcitriol in mouse serum. The limit of quantitation was 0.01 ng/ml which is approximately 100 fold lower than the previously reported assay from our laboratory. Calcitriol PK parameters were determined in non-tumor-bearing or C4-2 human prostate tumor-bearing nude mice following oral co-administration of calcitriol either alone or in combination with aPPD. Mice were pretreated with oral aPPD (70 mg/kg) or vehicle control twice daily for seven consecutive days, followed by a single oral dose of 4 µg/kg calcitriol alone or in combination with aPPD. Our PK results demonstrated that co-administration of calcitriol with aPPD (following pre-treatment with vehicle for seven days) resulted in a 35% increase in the area under the curve (AUC0-24 h) and a 41% increase in the maximum serum concentration (Cmax) compared to the calcitriol only group. aPPD therefore significantly increased calcitriol serum exposure. We also saw a reduction in the time required to reach Cmax. In contrast, calcitriol PK in mice co-administered with calcitriol and aPPD as well as those pretreated seven consecutive days with aPPD was no different than that determined for the mice that received vehicle for seven days as pre-treatment. Co-administration of calcitriol with aPPD therefore could increase health benefits of vitamin D3, however any increased risk of hypercalcemia, resulting from this combination approach, requires further investigation. Lastly, we surmise that a cytochrome P450 inhibition-based mechanism may contribute to the observed PK interaction.

Simultaneous determination of 20(S)-protopanaxadiol and its three metabolites in rat plasma by LC-MS/MS: application to their pharmacokinetic studies.

The aim of this study was to develop an LC-MS/MS method for simultaneous determination of 20(S) protopanaxadiol (PPD) and its three metabolites, PPD-glucuronide (M1), (20S,24S)-epoxy-dammarane-3,12,25-triol (M2) and (20S,24R)-epoxydammarane-3,12,25-triol (M3), in rat plasma. Precipitation with acetonitrile was employed for sample preparation and chromatographic separations were achieved on a C18 column. The sample was detected using triple quadrupole tandem mass spectrometer with selected reaction monitoring mode. The monitored precursor-to-product ion transitions were m/z 459.4 → 375.3 for PPD, m/z 635.4 → 113.0 for M1, m/z 477.4 → 441.4 for M2 and M3 and m/z 475.4 → 391.3 for IS. The developed assay was validated according to the guidelines of the US Food and Drug Administration. The calibration curves showed good linearity over the tested concentration ranges (r > 0.9993), with the LLOQ being 1 ng/mL for all analytes. The intra- and inter-day precisions (RSD) were < 9.51% while the accuracy (RE) ranged from -8.91 to 12.84%. The extraction recovery was >80% and no obvious matrix effect was detected. The analytes were stable in rat plasma with the RE ranging from -12.34 to 9.77%. The validated assay has been successfully applied to the pharmacokinetic study of PPD as well as its metabolites in rat plasma. According to the pharmacokinetic parameters, the in vivo exposures of M1, M2 and M3 were 11.91, 47.95 and 22.62% of that of PPD, respectively.

"Nano-Ginseng" for Enhanced Cytotoxicity AGAINST Cancer Cells.

Panax ginseng has high medicinal and health values. However, the various and complex components of ginseng may interact with each other, thus reducing and even reversing therapeutic effects. In this study, we designed and fabricated a novel "nano-ginseng" with definite ingredients, ginsenoside Rb1/protopanaxadiol nanoparticles (Rb1/PPD NPs), completely based on the protopanaxadiol-type extracts. The optimized nano-formulations demonstrated an appropriate size (~110 nm), high drug loading efficiency (~96.8%) and capacity (~27.9 wt %), long half-time in systemic circulation (nine-fold longer than free PPD), better antitumor effects in vitro and in vivo, higher accumulation at the tumor site and reduced damage to normal tissues. Importantly, this process of "nano-ginseng" production is a simple, scalable, green economy process.

A validated LC-MS/MS method for the simultaneous determination of 20-(S)-protopanaxatriol and its two active metabolites in rat plasma: Application to a pharmacokinetics study.

We present a validated liquid chromatography with tandem mass spectrometry method for simultaneous determination of 20-(S)-protopanaxatriol and its two oxidative stereoisomeric metabolites (20S,24S)-epoxy-dammarane-3,6,12,25-tetraol (M1) and (20S,24R)-epoxy-dammarane-3,6,12,25-tetraol (M2) in rat plasma. 20-(S)-Protopanaxatriol, M1, and M2 were extracted with methanol and separated on an ACQUITY HSS T3 column. The mass spectrometry detection was accomplished in selected reaction monitoring mode with precursor-to-product ion transitions of m/z 493.4→143.1 for M1 and M2, m/z 475.4→391.3 for 20-(S)-protopanaxatriol, and m/z 459.4→375.3 for 20-(S)-protopanaxadiol (internal standard). The method showed good linearity over the concentration ranges of 1-1000 ng/mL for 20-(S)-protopanaxatriol and 0.5-200 ng/mL for M1 and M2, with correlation coefficients of more than 0.995. The lower limits of quantification for 20-(S)-protopanaxatriol, M1, and M2 were 1, 0.5, 0.5 ng/mL, respectively. The intra- and interday precisions (RSD, %) were less than 10.41% while the accuracy (relative error, %) ranged from -3.14 to 8.73%. Under the current conditions, M1 and M2 were completely separated within 3 min. The validated assay was successfully applied to evaluating pharmacokinetic profiles of 20-(S)-protopanaxatriol, M1, and M2 in rat.

Simultaneous quantification of twenty-one ginsenosides and their three aglycones in rat plasma by a developed UFLC-MS/MS assay: Application to a pharmacokinetic study of red ginseng.

To track the pharmacokinetic features of red ginseng (RG), a rapid and sensitive ultra fast liquid chromatographic coupled with electrospray ionization triple quadrupole tandem mass spectrometry (UFLC-MS/MS) method was developed for simultaneous quantification of twenty-one ginsenosides and their three aglycones, including 18 prototype compounds (ginsenosides Rb1, Rb2, Rc, Rd, Re, Rg1, Rg5, Rh4, Rk1, Rk3, 20(S)-Rf, 20(S)-Rg2, 20(R)-Rg2, 20(S)-Rg3, 20(R)-Rg3, 20(S)-Rh1, 20(R)-Rh1, 20(S)-NG-R2), and 6 metabolites (ginsenosides 20(S)-Rh2 and Rh3, 20(S)-protopanaxadiol (PPD), 20(S)-protopanaxatriol (PPT), 20(R)-PPT, ginseng saponin compound K) of RG in rat plasma after oral administration of RG water extract at a single dose of 4g/kg body weight to rats. All analytes with internal standard (digoxin) were detected by multiple reaction monitoring in negative ionization mode and separated on an ACQUITY UPLC® BEH RP-C18 column (1.7µm, 100×2.1mm). This established method was well validated in terms of linearity, sensitivity, intra- and inter-day precisions, accuracy, recovery, matrix effect, stability, and had a lower limit of quantification at the concentration range of 0.12-8.12ng/mL for all of analytes. This UFLC-MS/MS approach was successfully applied to the pharmacokinetic study for RG water extract in rats. We firstly proposed that Rb1, Rb2, Rc, Rd, Rg1, Rg5, 20(S)-Rg3, 20(S)-Rh2, and 20(S)-PPD measured in rat plasma were suitable pharmacokinetic markers of RG extract in rats due to their high systemic exposure levels. Thus, this specific and reliable method will be useful for future applications to pharmacokinetic studies for various sources of ginsenoside samples and Panax herbs in vivo.

Potential accumulation of protopanaxadiol-type ginsenosides in six-months toxicokinetic study of SHENMAI injection in dogs.

SHENMAI injection (SMI), derived from famous Shen Mai San, is a herbal injection widely used in China. Ginsenosides are the major components of SMI. To monitor the exposure level of SMI during long-term treatment, a 6-month toxicokinetic experiment was performed. Twenty-four beagle dogs were dived into four groups (n = 6 in each group): a control group (0.9% NaCl solution) and three SMI groups (2, 6 or 3 mg/kg). The dogs were i.v. infused with vehicle or SMI daily for 180 d. Blood samples for analysis were collected at specific time points as follows: pre-dose (0 h); at 10, 30, and 60 min during infusion; and at 10, 30, 60, 90, 120, 240, and 300 min post-administration. Concentrations of ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, and Rg1 in the plasma were determined simultaneously by liquid chromatography-tandem mass spectrometry. Non-compartmental parameters were further calculated and analyzed. Significant differences were found between the kinetic behavior of 20(S)-protopanaxadiol-type (PPD-type) and 20(S)-protopanaxatriol-type (PPT-type) ginsenosides. Increasing in the exposure level of PPD-type ginsenosides was observed in dogs during the experiment. Therefore, PPD-type ginsenosides are closely related to the immunity modulation effect of SMI. Increased PPD-type ginsenoside exposure level may present potential toxicity and induce drug-drug interaction risks during SMI administration. As such, PPD-type ginsenoside accumulation must be carefully monitored in future SMI research.

Cytochromes P450 Inhibitory Excipient-Based Self-Microemulsions for the Improved Bioavailability of Protopanaxatriol and Protopanaxadiol: Preparation and Evaluation.

Protopanaxatriol and protopanaxadiol exhibit limited oral bioavailability due to the poor solubility and intestinal cytochromes P450-mediated metabolism. This study set out to develop a novel cytochromes P450 inhibitory excipient(s)-based self-microemulsion to encapsulate protopanaxatriol and protopanaxadiol so as to enhance the in vivo bioavailability by inhibiting intestinal metabolism. After screening the inhibitory effect of pharmaceutical excipients on the cytochromes P450-mediated metabolism, two self-microemulsions, SME-1 and SME-2, with similar physicochemical properties were prepared by using either active inhibitory excipients or corresponding inactive excipients. The results showed that no significant difference existed in the profiles of in vitro release, cellular uptake, and permeability in Caco-2 cells, and in vivo lymphatic transport between self-microemulsion-1 and self-microemulsion-2. The in vivo pharmacokinetic experiments indicated that self-microemulsion-1 conferred to significantly higher absolute bioavailability of protopanaxatriol (19.55 %) and protopanaxadiol (100.07 %) than those of the free drug (2.21 % and 23.70 %, respectively) or of self-microemulsion-2 (4.95 % and 45.35 %, respectively). The present work demonstrated that the presence of cytochromes P450 inhibitory excipients in self-microemulsion-1 tended to inhibit intestinal cytochromes P450-mediated metabolism and subsequently improved the oral bioavailability of protopanaxatriol and protopanaxadiol.

Evaluation and Comparison of the Inhibition Effect of Astragaloside IV and Aglycone Cycloastragenol on Various UDP-Glucuronosyltransferase (UGT) Isoforms.

As one of the main active ingredients from Radix Astragali (RA), orally dosed astragaloside IV (AST) is easily transformed to sapogenin-cycloastragenol (CAG) by deglycosylation in the gastrointestinal tract. Because the potential adverse effects of AST and CAG remain unclear, the present study in this article was carried out to investigate the inhibition effects of AST and CAG on UDP-glucuronosyltransferases (UGTs) to explore potential clinical toxicity. An in vitro UGTs incubation mixture was employed to study the inhibition of AST and CAG towards UGT isoforms. Concentrations of 100 µM for each compound were used to initially screen the inhibitory efficiency. Deglycosylation of AST to CAG could strongly increase the inhibitory effects towards almost all of the tested UGT isoforms, with an IC50 of 0.84 µM and 11.28 µM for UGT1A8 and UGT2B7, respectively. Ulteriorly, the inhibition type and kinetics of CAG towards UGT1A8 and UGT2B7 were evaluated depending on the initial screening results. Data fitting using Dixon and Lineweaver-Burk plots demonstrated that CAG competitively inhibited UGT1A8 and noncompetitively inhibited UGT2B7. From the second plot drawn with the slopes from the Lineweaver-Burk plot versus the concentrations of CAG, the inhibition constant (Ki) was calculated to be 0.034 µM and 20.98 µM for the inhibition of UGT1A8 and UGT2B7, respectively. Based on the [I]/Ki standard ([I]/Ki < 0.1, low possibility; 1 > [I]/Ki > 0.1, medium possibility; [I]/Ki > 1, high possibility), it was successfully predicted here that an in vivo herb-drug interaction between AST/CAG and drugs mainly undergoing UGT1A8- or UGT2B7-catalyzed metabolism might occur when the plasma concentration of CAG is above 0.034 µM and 20.98 µM, respectively.

Protopanaxadiol aglycone ginsenoside-polyethylene glycol conjugates: synthesis, physicochemical characterizations, and in vitro studies.

Ginsenosides are triterpenoid saponins, which is an active compound responsible for most of the pharmacological effects of ginseng (Panax ginseng Meyer). It is known to have numerous structural and pharmacological properties. However, aqueous solubility and delivery of ginsenosides in targeted region by avoiding undesirable toxicity to normal cell is also of prime importance. The aim of this study was to obtain amphiphilic ginsenoside derivatives in which hydrophilic polymers were conjugated to ginsenosides to enhance the water solubility and targeted delivery. To this end, the hydrophobic protopanaxadiol ginsenoside aglycone (aPPD) was covalently conjugated to the backbone of hydrophilic polyethylene glycol (PEG) through a pH sensitive ester linkage, which was confirmed by 1H NMR and FTIR. The resultant PPD is covalently conjugated to hydrophilic PEG through esterification (PEG-PPD) forming self-assembled spherical nanoparticles, whose average particle diameter was 189 nm as observed by FE-TEM and particle size analyzer respectively. In vitro release experiments revealed that the release rate of PPD was rapidly increased from the self-assembled nanoparticles under acidic conditions (pH 5.0) than in a physiological buffer (pH 7.4) condition. Furthermore, in vitro cytotoxicity assays revealed that PEG-PPD conjugates exhibited lower cytotoxicity in HT-29 cancer cells compared with PPD alone. Since the slow release of PPD from conjugates is triggered only by acidic environmental conditions, such as those found in extracellular solid tumor tissues, intracellular endosomes, and intracellular lysosomes, the conjugation of PPD may aid its selective delivery to these targets. Overall, results suggest that pH-dependent release of PPD, which expected in reduced cytotoxicity to non-targeted regions, may enhance the overall efficacy of PPD.

Formulation of 20(S)-protopanaxadiol nanocrystals to improve oral bioavailability and brain delivery.

The aim of this study was to fabricate 20(S)-protopanaxadiol (PPD) nanocrystals to improve PPD's oral bioavailability and brain delivery. PPD nanocrystals were fabricated using an anti-solvent precipitation approach where d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) was optimized as the stabilizer. The fabricated nanocrystals were nearly spherical with a particle size and drug loading of 90.44 ± 1.45 nm and 76.92%, respectively. They are in the crystalline state and stable at 4°C for at least 1 month. More than 90% of the PPD could be rapidly released from the nanocrystals, which was much faster than the physical mixture and PPD powder. PPD nanocrystals demonstrated comparable permeability to solution at 2.52 ± 0.44×10(-5)cm/s on MDCK monolayers. After oral administration of PPD nanocrystals to rats, PPD was absorbed quickly into the plasma and brain with significantly higher Cmax and AUC0-t compared to those of the physical mixture. However, no brain targeting was observed, as the ratios of the plasma AUC0-t to brain AUC0-t for the two groups were similar. In summary, PPD nanocrystals are a potential oral delivery system to improve PPD's poor bioavailability and its delivery into the brain for neurodegenerative disease and intracranial tumor therapies in the future.

Simultaneous determination of gypenoside LVI, gypenoside XLVI, 2α-OH-protopanaxadiol and their two metabolites in rat plasma by LC-MS/MS and its application to pharmacokinetic studies.

Gypenoside LVI and gypenoside XLVI are the major bioactive dammarane saponins from Gynostemma pentaphyllum. Gypenoside LVI, gypenoside XLVI, and their metabolite 2α-OH-protopanaxadiol (2α-OH-PPD) possess potent non-small cell lung carcinoma A549 cell inhibitory activity. A sensitive liquid chromatography tandem mass spectrometry method was developed and validated to study the pharmacokinetics of gypenoside LVI and XLVI, 2α-OH-PPD, metabolite 1 (M1), and metabolite 2 (M2) after administration of gypenosides or 2α-OH-PPD. Plasma samples from rats were protein precipitated with methanol. Analytes were detected by triple quadrupole MS/MS with an electrospray ionization source in the positive multiple reaction monitoring mode. The transition m/z 441.4→109.2 was selected to quantify gypenoside LVI and XLVI, and 2α-OH-PPD, because of the extensive conversion of the gypenosides to aglycone in the ionization source. M1 and M2 are isomers that shared the transition m/z 493.4→143.1. To avoid interference, the baseline separation of each analyte was performed on a SunFire C18 column with a gradient of acetonitrile (0.1% formic acid, v/v) and water (0.1% formic acid, v/v). The chromatographic run time was 10min. The linearity was validated over a plasma concentration range from 2.00 to 2000ng/mL for M1 and M2, and from 10.0 to 2000 for gypenosides LVI and XLVI, and 2α-OH-protopanaxadiol. The lower limits of quantification were 10.0, 10.0, 10.0, 2.00, and 2.00ng/mL for gypenoside LVI, gypenoside XLVI, 2α-OH-PPD, M1, and M2, respectively, with acceptable intra-/inter-day precision and accuracy. The extraction recovery rates were >86.9% for each compound. No apparent matrix effect or instability was observed during each step of the bioanalysis. After full validation, this method was proved to be simple, fast, and efficient in analyzing large batches of plasma samples for the analytes.

Self-microemulsifying Drug Delivery System Improved Oral Bioavailability of 20(S)-Protopanaxadiol: From Preparation to Evaluation.

20(S)-Protopanaxadiol (20(S)-PPD) is one type of sapogenin of protopanaxadiols and has a variety of pharmacological activities. In order to improve the dissolution of 20(S)-PPD as well as its oral bioavailability, a self-microemulsifying drug delivery system (SMEDDS) was utilized for 20(S)-PPD preparation. Following the preparation of the 20(S)-PPD SMEDDS, its dissolution, stability, and intestinal absorption in rats were studied, and the pharmacokinetics and optimal dosage after oral administration were evaluated. The dissolution tendency of the SMEDDS in phosphate buffered saline (PBS), 0.1 M HCl and distilled water was consistent. SMEDDS was stable under a condition of high temperature (40°C), high humidity or with strong light irradiation, or within 6 h in artificial digestive tracts. 20(S)-PPD SMEDDS was well-absorbed in all intestinal segments in rats. When the drug concentration was higher than 200 µg/mL or the perfusion flow was faster than 0.5 mL/min, passive diffusion of drug in the duodenum reached a saturated level. In addition, P-glycoprotein inhibitor did not affect the intestinal absorption of 20(S)-PPD SMEDDS. Pharmacokinetic study showed that Tmax in male rats was shortened significantly, while Cmax and area under the curve (AUC(0-t)) were remarkably increased. The relative oral bioavailability of 20(S)-PPD SMEDDS was increased approximately three fold compared with the 20(S)-PPD carboxy methyl cellulose (CMC). 20(S)-PPD SMEDDS (100 mg/mL) was administered by gastric infusion to both mice and rats for 14 d. SMEDDS improved the oral bioavailability of 20(S)-PPD and reduced the necessary drug dosage. 20(S)-PPD SMEDDS could become a promising clinical alternative as an anti-tumor or antidepressant drug.

Stereoselective formation and metabolism of 20(S)-protopanaxadiol ocotillol type epimers in vivo and in vitro.

(20S,24S)-epoxy-dammarane-3,12,25-triol (24S-epimer) and (20S,24R)-epoxy- dammarane-3,12,25-triol (24R-epimer), a pair of ocotillol type epimers, were identified as the main metabolites of 20(S)-protopanaxadiol (PPD). The aim of this study was to systematically investigate the formation and metabolism of this pair of epimers in vivo and in vitro and to elucidate the isoforms of cytochrome P450 enzymes responsible for the stereoselective metabolism of both epimers. The result showed that 24S-epimer was a more predominant ingredient in rat plasma after oral administration of PPD with higher area under the curve (AUC) values. Both the enzyme kinetic evaluations of the formation and elimination of 24S-epimer and 24R-epimer in rat liver microsomes (RLM) and human liver microsomes (HLM) indicated that 24S-epimer had a higher formation rate and a lower oxygenation metabolism rate than 24R-epimer, and the stereoselective differences were more obvious in HLM than in RLM. The chemical inhibition and recombinant human P450 isoforms assay showed that CYP3A4 was the predominant isoform responsible for the further metabolism of 24R-epimer in HLM. The biliary excretion ratio of the 24S-epimer glucuronide was more than 28-fold higher than that of 24R-epimer glucuronide after intravenous administration to rats, which also indicated 24S-epimer was more preferential to be metabolized as the glucuronide conjugate than 24R-epimer.

Self-microemulsifying drug-delivery system for improved oral bioavailability of 20(S)-25-methoxyl-dammarane-3ß, 12ß, 20-triol: preparation and evaluation.

The objective of this study was to develop a self-microemulsifying drug delivery system (SMEDDS) to enhance the oral bioavailability of the poorly water-soluble compound 20(S)-25-methoxydammarane-3ß;12ß;20-triol (25-OCH3-PPD). Optimized SMEDDS formulations for 25-OCH3-PPD contained Cremophor® EL (50%) as the surfactant, glycerin (20%) as the cosurfactant, and Labrafil® M1944 (30%) as the oil. The SMEDDS were characterized by morphological observation and mean droplet size. The pharmacokinetics and bioavailability of the 25-OCH3-PPD suspension and SMEDDS were evaluated and compared in rats. The plasma concentrations of 25-OCH3-PPD and its main metabolite, 25-OH-PPD, were determined by ultra performance liquid chromatography-tandem mass spectrometry. The relative bioavailability of SMEDDS was dramatically enhanced by an average of 9.8-fold compared with the suspension. Improved solubility and lymphatic transport may contribute to this enhanced bioavailability. Our studies highlight the promise of SMEDDS for the delivery of 25-OCH3-PPD via the oral route.

Identification of 20(S)-protopanaxatriol metabolites in rats by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry and nuclear magnetic resonance spectroscopy.

20(S)-Protopanaxatriol (PPT), one of the aglycones of ginsenosides, has been shown to exert cardioprotective effects against myocardial ischemic injury. However, studies on PPT metabolism have rarely been reported. This study is the first to investigate the in vivo metabolism of PPT following oral administration by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy. The structures of the metabolites were identified based on the characteristics of their MS data, MS(2) data, and chromatographic retention times. A total of 22 metabolites, including 17 phase I and 5 phase II metabolites, were found and tentatively identified by comparing their mass spectrometry profiles with those of PPT. Two new monooxygenation metabolites, (20S,24S)-epoxy-dammarane-3,6,12,25-tetraol and (20S,24R)-epoxy-dammarane-3,6,12,25-tetraol, were chemicallly synthesized and unambiguously characterized according to the NMR spectroscopic data. The metabolic pathways of PPT were proposed accordingly for the first time. Results revealed that oxidation of (1) double bonds at Δ((24,25)) to form 24,25-epoxides, followed by rearrangement to yield 20,24-oxide forms; and (2) vinyl-methyl at C-26/27 to form corresponding carboxylic acid were the predominant metabolic pathways. Phase II metabolic pathways were proven for the first time to consist of glucuronidation and cysteine conjugation. This study provides valuable and new information on the metabolism of PPT, which is indispensable for understanding the safety and efficacy of PPT, as well as its corresponding ginsenosides.

Identification of human cytochrome P450 enzymes involved in the hepatic and intestinal biotransformation of 20(S)-protopanaxadiol.

20(S)-Protopanaxadiol (aPPD), a ginseng sapogenin, has been shown to be a promising anti-cancer compound and anti-depressant agent. Although the bacterial biotransformation of ginsenosides has been studied thoroughly, few have reported on the cytochrome P450 (P450) mediated metabolism of aPPD. Taken orally, aPPD must first undergo absorption and metabolism in the intestine before further metabolism in the liver. The present study investigated the comparative biotransformation profile of aPPD in human intestinal microsomes (HIM) and human liver microsomes (HLM) and characterized the human P450 enzymes involved in aPPD metabolism. Three major monooxygenated metabolites and five minor dioxygenated metabolites were identified as the predominant products in aPPD incubations with HIM and HLM using liquid chromatography-mass spectrometry. Reaction phenotyping studies were performed with a panel of specific P450 chemical inhibitors, antibody inhibition and human recombinant P450 enzymes. Ketoconazole, a CYP3A inhibitor, blocked the formation of oxygenated metabolites of aPPD in both HIM and HLM in a concentration dependent manner. Among the human recombinant P450 enzymes assayed, CYP3A4 exhibited the highest activity towards aPPD oxidative metabolite formation, followed by CYP3A5. In summary, the results have shown that aPPD is extensively metabolized by HIM and the metabolite profile following in vitro incubations is similar in HIM and HLM. CYP3A4 and CYP3A5 isoforms are the predominant enzymes responsible for oxygenation of aPPD in HIM and HLM. The characterization of aPPD as a CYP3A substrate may facilitate better prediction of drug-herb interactions when aPPD is taken concomitantly with other therapeutic agents.

[Polybasic research on the biopharmaceutical characteristics of 20 (S)-protopanaxadiol].

In this study, the biopharmaceutical properties of 20 (S)-protopanaxadiol (PPD) were studied. Firstly, the equilibrium solubility and apparent oil/water partition coefficient of PPD were used to predict the absorption in vivo. Meanwhile the membrane permeability and absorption window were studied by Caco-2 cell model and single-pass intestinal perfusion model. Furthermore, the bioavailability and metabolism were combined to study the absorption properties and metabolic properties in vivo. All of them were used to provide theoretical and practical foundation for designing PPD preparation. The results showed that PPD is poorly water-soluble, and the equilibrium solubility in water is only 35.24 mg x L(-1). The oil-water partition coefficient is 46.21 (logP = 1.66). By Caco-2 cell model, the results showed PPD uptake in general, and it also has efflux. By in situ intestinal perfusion model, the results showed that the absorption of PPD in the intestine is good, and the effective permeability coefficient were duodenum > jejunum > ileum > colon. The oral bioavailability of PPD was 29.39%. It was not well. Metabolic studies showed PPD in vivo presented a wide spread metabolism. So the main factors that restricted oral bioavailability of PPD were the poor solubility and first-pass effect.

[Study on pharmacokinetics of 20 (S) -protopanaxadiol lipid cubic nanoparticles].

OBJECTIVE: To establish a high-performance liquid chromatographic/tandem mass spectrometry (HPLC-MS/MS) method for determining 20(S)-protopanaxadiol (PPD) in rat plasma, in order to analyze pharmacokinetic characteristics of PPD and PPD cubic nanoparticles. METHOD: Sprague-Dawley rats were administered orally with PPD and PPD cubic nanoparticles, respectively. Their blood samples were obtained from fossa orbitalis at regular time points. The mobile phase was 0.05% formic acidac etonitrile-0.05% formic acidac water (95:5). Electrospray ionization (ESI) was adopted for the quadrupole tandem mass spectrum. SCAN mode was used for the quantitative analysis, with m/z 460. 4/425.3 and m/z 622.9/318.3 (Rh2, interior label) as secondary fragment ions. The concentration of PPD in plasma was analyzed. The concentration-time curve was mapped. The data were calculated by DAS program. RESULT: The linearity of the PPD plasma concentration determination method ranged between 10-1 407 microg x L(-1), with the limit of quantification of 2.5 microg x L(-1). Both of the inter-day and intra-day precisions (RSD) were less than 13.25%, and the accuracy (relative error) was between +/- 8.50%. CONCLUSION: The method was so highly specific and sensitive with less plasma that it is suitable for pharmacokinetic studies. The prepared 20(S)-protopanaxadiol lipid cubic nanoparticles can enhance its absorption in vivo. Its relative bioavailability is 166% of the raw material.