Biotransformation of Piceatannol, a Dietary Resveratrol Derivative: Promises to Human Health.

SCOPE: To evaluate the health-promoting potentials of piceatannol (PIC), a dietary resveratrol derivative, its biotransformation is examined. METHODS AND RESULTS: The biotransformation is tested in human/rat hepatic microsomes and cytosols; its pharmacokinetic profiles are assessed in rats. Although limited phase I metabolism exists in microsomes, PIC is rapidly converted to two pharmacologically active metabolites, namely rhapontigenin (RHA) and isorhapontigenin (ISO) in cytosols. Such biotransformation is completely blocked by entacapone, a well-known catechol-O-methyltransferase (COMT) inhibitor, demonstrating that the O-methylation is mediated by COMT. Moreover, PIC is identified as a substrate inhibitor of COMT, suggesting its potential benefits in Alzheimer's disease. Due to extensive phase II metabolism including glucuronidation, sulfation, and O-methylation, PIC displays rapid clearance and at least 4.02% ± 0.61% and 17.70% ± 0.91% of PIC is converted to RHA and ISO, respectively, in rats after intravenous administration. Similarly, PIC serves as an effective precursor of ISO upon oral administration. CONCLUSION: Since PIC and its metabolites possess pleiotropic health-promoting activities, it has emerged as a promising nutraceutical candidate for further development. This study also reinforces the importance of in vivo testing in nutritional researches as the active metabolite(s) may be absent from the in vitro system.

Comparison assessment between SIM and MRM mode in the analysis of 3-MCPD ester, 2-MCPD ester and glycidyl ester.

The detection of 3- and 2-MCPD ester and glycidyl ester was transformed from selected ion monitoring (SIM) mode to multiple reaction monitoring (MRM) mode by gas chromatography triple quadrupole spectrometry. The derivatization process was adapted from AOCS method Cd 29a-13. The results showed that the coefficient of determination (R2) of all detected compounds obtained from both detection mode was comparable, which falls between 0.997 and 0.999. The limit of detection and quantification (LOD and LOQ) were improved in MRM mode as compared to SIM mode. In MRM mode, the LOD of 3- and 2-MCPD ester was achieved 0.01 mg/kg while the LOQ was 0.05 mg/kg. Besides, LOD and LOQ of glycidyl ester were 0.024 and 0.06 mg/kg respectively. A blank spiked with MCPD esters (0.03, 0.10 and 0.50 mg/kg) and GE (0.06, 0.24 and 1.20 mg/kg) were chosen for repeatability and recovery tests. MRM mode showed better repeatability in area ratio and recovery with relative standard deviation (RSD %) < 5% for 2-, 3-MCPD ester at 0.5 mg/kg and GE at 1.2 mg/kg. Quantification of 22 food samples from different category were performed by repeated injections in both detection modes. Briefly, the contaminants from crude palm oil, mustard and olive oil were present in minute amount which below the LOD or LOQ in both detection modes. Sample from chocolate and infant formula products showed certain level of MCPD esters and GE, and their detection was more precisely quantitated based on MRM mode. Besides, margarine products showed a higher level of contaminations due to the high fat content in these products. MRM mode detection was proven to provide precise data with low RSD % in different food matrices. MRM mode detection was robust and selective for MCPD esters and GE analyses, it should be applied to determine the concentration of MCPD esters and GE contaminations in food.

Isorhapontigenin, a bioavailable dietary polyphenol, suppresses airway epithelial cell inflammation through a corticosteroid-independent mechanism.

BACKGROUND AND PURPOSE: Chronic obstructive pulmonary disease (COPD) is a corticosteroid-resistant airway inflammatory condition. Resveratrol exhibits anti-inflammatory activities in COPD but has weak potency and poor pharmacokinetics. This study aimed to evaluate the potential of isorhapontigenin, another dietary polyphenol, as a novel anti-inflammatory agent for COPD by examining its effects in vitro and pharmacokinetics in vivo. EXPERIMENTAL APPROACH: Primary human airway epithelial cells derived from healthy and COPD subjects, and A549 epithelial cells were incubated with isorhapontigenin or resveratrol and stimulated with IL-1ß in the presence or absence of cigarette smoke extract. Effects of isorhapontigenin and resveratrol on the release of IL-6 and chemokine (C-X-C motif) ligand 8 (CXCL8), and the activation of NF-κB, activator protein-1 (AP-1), MAPKs and PI3K/Akt/FoxO3A pathways were determined and compared with those of dexamethasone. The pharmacokinetic profiles of isorhapontigenin, after i.v. or oral administration, were assessed in Sprague-Dawley rats. KEY RESULTS: Isorhapontigenin concentration-dependently inhibited IL-6 and CXCL8 release, with IC50 values at least twofold lower than those of resveratrol. These were associated with reduced activation of NF-κB and AP-1 and, notably, the PI3K/Akt/FoxO3A pathway, that was relatively insensitive to dexamethasone. In vivo, isorhapontigenin was rapidly absorbed with abundant plasma levels after oral dosing. Its oral bioavailability was approximately 50% higher than resveratrol. CONCLUSIONS AND IMPLICATIONS: Isorhapontigenin, an orally bioavailable dietary polyphenol, displayed superior anti-inflammatory effects compared with resveratrol. Furthermore, it suppressed the PI3K/Akt pathway that is insensitive to corticosteroids. These favourable efficacy and pharmacokinetic properties support its further development as a novel anti-inflammatory agent for COPD.

Determination of pinostilbene in rat plasma by LC-MS/MS: Application to a pharmacokinetic study.

Pinostilbene (3-methoxyresveratrol or trans-3,4'-dihydroxy-5-methoxystilbene) is a naturally occurring monomethylether analogue of resveratrol (trans-3,5,4'-trihydroxystilbene) that exhibits various pharmacological activities. To further examine its medicinal potential, a sensitive LC-MS/MS method was developed and validated for the determination of pinostilbene in rat plasma. Heavy Isotope labelled resveratrol was used as an internal standard. The ESI was operated in its negative ion mode while pinostilbene and resveratrol were measured by multiple reaction monitoring (MRM) using precursor-to-product ion transitions of m/z 241→181 and m/z 233→191, respectively. This LC-MS/MS method had excellent selectivity, sensitivity (LLOQ=1ng/ml), accuracy (both intra- and interday analytical recovery within 100±15%) and precision (both intra- and interday RSD < 15%). The matrix effect was insignificant. The pharmacokinetics of pinostilbene was subsequently profiled in Sprague-Dawley rats. Upon intravenous administration (5 or 10mg/kg), pinostilbene displayed rapid clearance (Cl=129±42 or 107±31ml/min/kg) and extremely short mean transit time (MTT=6.24±0.41 or 8.52±1.38min). After oral dosing (50mg/kg), the bioavailability of pinostilbene was limited but highly erratic (F=1.87±2.67%). Pharmacokinetic comparison among pinostilbene, resveratrol and some resveratrol analogues suggested that stilbenes with meta-hydroxyl group(s) may be associated with metabolic instability and subsequently suffer from rapid clearance and low oral bioavailability. The information obtained from this study will facilitate further exploration on pinostilbene as well as other resveratrol analogues.

Analysis of trans-2,6-difluoro-4'-(N,N-dimethylamino)stilbene (DFS) in biological samples by liquid chromatography-tandem mass spectrometry: metabolite identification and pharmacokinetics.

The metabolism of a promising antineoplastic agent, trans-2,6-difluoro-4'-(N,N-dimethylamino)stilbene (DFS), was studied in mouse, rat, and human liver microsomes using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the multiple reaction monitoring-information-dependent acquisition-enhanced product ion scan (MRM-IDA-EPI) method. Ten putative metabolites were identified and the structures of four metabolites were confirmed using authentic standards. Since trans-2,6-difluoro-4'-(N-methylamino)stilbene (DMDFS, M1) was present in all species as metabolite and displayed in vitro growth inhibition superior to DFS, its pharmacokinetic profiles were examined in Sprague-Dawley rats using DFS as a comparator. A reliable LC-MS/MS multiple reaction monitoring (MRM) method was subsequently developed and validated for the simultaneous quantification of both DFS and DMDFS in rat plasma for this purpose. Upon intravenous administration (4 mg/kg), DFS had a moderate clearance (Cl = 62.7 ± 23.2 mL/min/kg), terminal elimination half-life (t 1/2 λZ = 299 ± 73 min), and mean transit time (MTT = 123 ± 14 min) with demethylation metabolism accounting for about 10 % of its total clearance. DMDFS possessed an intravenous pharmacokinetic profile similar to DFS. During oral dosing (10 mg/kg) where both DFS and DMDFS were absorbed rapidly, the oral bioavailability of DFS was approximately 2-fold greater than that of DMDFS (DFS: F = 42.1 ± 12.8 %; DMDFS: F = 18.7 ± 3.9 %). Interestingly, the DMDFS exposure after oral dosing of DFS (10 mg/kg) was comparable to that after oral administration of DMDFS (10 mg/kg) alone. As DFS displayed potent anticancer activities and excellent pharmacokinetic profiles, it appears to be a favorable candidate for further pharmaceutical development.

Determination of naturally occurring resveratrol analog trans-4,4'-dihydroxystilbene in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study.

trans-4,4'-Dihydroxystilbene (DHS) is a naturally occurring resveratrol analog that displayed promising anti-cancer activities in pre-clinical studies. To further probe its therapeutic potential, a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the measurement of DHS in rat plasma using electrospray ionization and multiple reaction monitoring in its negative ion mode. This analytical method demonstrated excellent linearity (R(2) > 0.99), selectivity, sensitivity (with a lower limit of quantification of 2.0 ng/mL), accuracy (both intra- and inter-day analytical recovery within 100 ± 15%) and precision (both intra- and inter-day relative standard deviation within 10%). The pharmacokinetic profiles of DHS were subsequently assessed in Sprague-Dawley rats. Following intravenous injection (4 mg/kg), DHS had a moderate apparent volume of distribution of the central compartment (V(c) = 887 ± 297 mL/kg), clearance (Cl = 44.7 ± 5.1 mL/min/kg) and a relatively short mean transit time (MTT = 24.1 ± 8.8 min). When it was given as an oral suspension (10 mg/kg), DHS was absorbed slowly (t max 180 or 300 min) with very limited plasma exposure and absolute oral bioavailability (F = 2.22 ± 0.72%). On the other hand, when DHS was fully solubilized by hydroxypropyl-ß-cyclodextrin, it was absorbed rapidly (t(max) 30 or 45 min) with more than 15-fold increase in maximal plasma concentration (C(max)), plasma exposure (AUC(0→last)) and bioavailability (F = 36.3 ± 4.8%). Statistical comparison provided clear evidence that DHS was better than resveratrol from the perspective of pharmacokinetics. In conclusion, further explorations of DHS as an anti-cancer agent are warranted.

Quantification of the resveratrol analogs trans-2,3-dimethoxy-stilbene and trans-3,4-dimethoxystilbene in rat plasma: application to pre-clinical pharmacokinetic studies.

trans-2,3-Dimethoxystilbene (2,3-DMS) and trans-3,4-dimethoxystilbene (3,4-DMS) are two synthetic resveratrol (trans-3,5,4'-trihydroxystilbene) analogs. In this study, a simple HPLC method was developed and validated to determine 2,3-DMS and 3,4-DMS in rat plasma. Chromatographic separation was obtained with a reversed-phase HPLC column through a 12.5-min gradient delivery of a mixture of acetonitrile and water at the flow rate of 1.5 mL/min at 50 °C. The lower limit of quantification was 10 ng/mL. After successful validation, the pharmacokinetic profiles of 2,3-DMS and 3,4-DMS were subsequently studied in Sprague-Dawley rats. Upon single intravenous administration (4 mg/kg), 2,3-DMS had a medium volume of distribution of the central compartment (Vc = 2.71 ± 0.51 L/kg), quite rapid clearance (Cl = 52.0 ± 7.0 mL/min/kg), moderate mean transit time (MTT0→last = 131.0 ± 4.5 min) but a fairly long terminal elimination half-life (t1/2 λZ = 288.9 ± 92.9 min). Interestingly, 3,4-DMS displayed a pharmacokinetic profile apparently distinct from 2,3-DMS and it had more extensive distribution (Vc = 5.58 ± 1.73 L/kg), faster clearance (Cl = 143.4 ± 40.5 mL/min/kg) and shorter residence (MTT0→last = 61.4 ± 27.1 min). Following single oral administration (10 mg/kg), 2,3-DMS had low and erratic plasma exposure (Cmax = 37.5 ± 23.7 ng/mL) and poor oral bioavailability (2.22% ± 2.13%) while the oral bioavailability of 3,4-DMS was even poorer than 2,3-DMS. Clearly, the location of the methoxy groups had a significant impact on the pharmacokinetics of resveratrol analogs. This study provided useful information for the design of resveratrol derivatives in future study.

Quantification of pinosylvin in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pre-clinical pharmacokinetic study.

Pinosylvin (trans-3,5-dihydroxystilbene), a naturally occurring analogue of resveratrol (trans-3,5,4'-trihydoxystilbene), exhibited various beneficial pharmacological activities in pre-clinical studies. To further probe its potential medicinal application, a sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for the quantification of pinosylvin in rat plasma. A simple protein precipitation procedure was used for plasma cleanup before analysis by LC-MS/MS with electrospray ionisation and multiple reaction monitoring in its negative ion mode. This LC-MS/MS method demonstrated good selectivity, accuracy (intra- and inter-day analytical recovery within 100±7.7%), precision (intra- and inter-day coefficient of variation<12.0%) and sensitivity (lower limit of detection=1.0ng/mL), with excellent linearity (R(2)>0.99) over the range of 1-1000ng/mL. The pharmacokinetic profiles of pinosylvin were subsequently assessed in Sprague-Dawley rats. Following intravenous administration (5 or 10mg/kg), plasma levels of pinosylvin declined rapidly with a short half-life (t1/2<10min). Upon oral administration at 15mg/kg, pinosylvin could not be quantified in plasma (<1ng/mL) while dose-escalation to 50mg/kg led to a low and erratic plasma exposure with very poor estimated oral bioavailability (F<1%). The short half-life and limited systemic exposure of pinosylvin prompt caution in its therapeutic application and it warrants exploration in developing pinosylvin pro-drug.

Pharmacokinetics of pterostilbene in Sprague-Dawley rats: the impacts of aqueous solubility, fasting, dose escalation, and dosing route on bioavailability.

SCOPE: Pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene, PTS) possesses various health-promoting effects. This study aimed to investigate the impacts of aqueous solubility, fasting, dose escalation, and dosing route on its bioavailability in Sprague-Dawley rats. METHODS AND RESULTS: Upon intravenous administration (2.5 mg/kg), PTS had rapid clearance (Cl = 68.2 ± 9.8 mL/min/kg) and moderate terminal elimination half-life (t(1/2λz) = 93.9 ± 22.3 min). Dose-escalation led to about twofold decline in clearance at the dose of 25 mg/kg (Cl = 36.4±7.8 mL/min/kg). When given in oral suspension (15 mg/kg), PTS had relatively low bioavailability (F = 15.9 ± 7.8%) while fasting substantially attenuated its bioavailability (F< 5.5 %). However, when dosed in a solution formulated with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) (15 mg/kg), PTS possessed good bioavailability (F = 59.2 ± 19.6%). Dose escalation resulted in about twofold increase in bioavailability at the dose of 60 mg/kg. Sublingual delivery (2.5 mg/kg) led to rapid absorption and moderate bioavailability (F = 25.8 ± 13.1%). Statistical comparison clearly indicated that the pharmacokinetics of PTS was more favorable than resveratrol. CONCLUSION: Aqueous solubility was identified as a barrier to its oral bioavailability while solubilizing PTS with HP-ß-CD substantially increased its bioavailability; dose manipulation was a practical strategy to enhance its bioavailability and systemic exposure; and its delivery through oral mucosa was feasible. As PTS possessed superior pharmacokinetics, it is a favorable candidate for further development.