Determinations of morin, quercetin and their conjugate metabolites in serum

Determination of Morin in Maclura cochinchinensis Heartwood by HPLC

The HPLC-DAD method was developed to determine morin content in Maclura cochinchinensis Corner heartwood extract. The chromatographic separation was performed using a Hypersil BDS C18 column, isocratic solvent system of 0.5% acetic acid in water:acetonitrile (80:20) with 1.0 mL/min flow rate and detected at 355 nm. The standard curve of morin was linear in the range of 7-905 μg/mL. The method was precise with intra-day relative standard deviation (RSD) of lower than 1% and 2.06% for inter-day RSD. The method accuracy represented by percent recover was 99.58%. The highly efficient HPLC system developed from this study could detect morin contents in M. cochinchinensis heartwood samples collected from various locations in Thailand in the range of 0.74-1.57% w/w. This developed method provided a useful standardization procedure of M. cochincihinesis materials for further application in pharmacy and other commercial developments.

Preparation, characterization, and in vivo evaluation of a self-nanoemulsifying drug delivery system (SNEDDS) loaded with morin-phospholipid complex

Background

As a poorly water-soluble drug, the oral application of morin is limited by its low oral bioavailability. In this study, a new self-nanoemulsifying drug delivery system (SNEDDS), based on the phospholipid complex technique, was developed to improve the oral bioavailability of morin.

Methods

Morin-phospholipid complex (MPC) was prepared by a solvent evaporation method and characterized by infrared spectroscopy and X-ray diffraction. After formation of MPC, it was found that the liposolubility of morin was significantly increased, as verified through solubility studies. An orthogonal design was employed to screen the blank SNEDDS, using emulsifying rate and particle size as evaluation indices. Ternary phase diagrams were then constructed to investigate the effects of drug loading on the self-emulsifying performance of the optimized blank SNEDDS. Subsequently, in vivo pharmacokinetic parameters of the morin-phospholipid complex self-nanoemulsifying drug delivery system (MPC-SNEDDS) were investigated in Wistar rats (200 mg/kg of morin by oral administration).

Results

The optimum formulation was composed of Labrafil^® M 1944 CS, Cremophor^® RH 40, and Transcutol^® P (3:5:3, w/w), which gave a mean particle size of approximately 140 nm. Oral delivery of the MPC-SNEDDS exhibited a significantly greater C_max (28.60 μg/mL) than the morin suspension (5.53 μg/mL) or MPC suspension (23.74 μg/mL) (all P < 0.05). T_max was prolonged from 0.48 to 0.77 hours and to 1 hour for MPC and MPC-SNEDDS, respectively. In addition, the relative oral bioavailability of morin formulated in the MPC-SNEDDS was 6.23-fold higher than that of the morin suspension, and was significantly higher than that of the MPC suspension (P < 0.05).

Conclusion

The study demonstrated that a SNEDDS combined with the phospholipid complex technique was a promising strategy to enhance the oral bioavailability of morin.

Tissue distribution and elimination of estrogenic and anti-inflammatory catechol metabolites from sesaminol triglucoside in rats

Sesaminol triglucoside (STG) is the main sesame (Sesamum indicum L.) lignan. Like many other plant lignans, STG can be converted to the mammalian lignans by intestinal microbiota. The objectives of the present study were to investigate the distribution of STG metabolite in rats, and the effects of STG and its metabolite on in vitro inflammation and estrogenic activities. STG was metabolized via intestinal microflora to a biologically active catechol moiety which would then be absorbed into the body in rats. After oral administration of STG to Sprague-Dawley rats, the concentrations of major STG metabolites in rectum, cecum, colon, and small intestines are higher than those in liver, lung, kidney, and heart. Its concentration in brain is low but detectable. The present study demonstrates that STG may be metabolized to form the catechol metabolites first by intestinal microflora and then incorporated via intestine absorption into the cardiovascular system and transported to other tissues. Results showed that the catechol metabolites were found to be able to penetrate the tail end of intestines (large intestine) and go through urinary excretion. STG metabolites significantly reduced the production of IL-6 and TNF-alpha in RAW264.7 murine macrophages stimulated with lipopolysaccharide. The estrogenic activities of STG metabolites were also established by ligand-dependent transcriptional activation through estrogen receptors. This study clearly shows that STG has anti-inflammatory and estrogenic activities via metabolism of intestinal microflora.

Effects of morin on the pharmacokinetics of nicardipine after oral and intravenous administration of nicardipine in rats

This study investigated the effects of orally administered morin, an inhibitor of cytochrome P450 3A (CYP3A) and P-glycoprotein (P-gp), on the pharmacokinetics of orally and intravenously administered nicardipine in rats. Nicardipine is reportedly a substrate for CYP3A4 and P-gp. Nicardipine was administered orally (12 mgkg−1) with or without orally administered morin (1.5, 7.5 and 15 mgkg−1), and intravenously (4 mgkg−1) with or without orally administered morin (7.5 and 15 mgkg−1). In the presence of morin, the pharmacokinetic parameters of nicardipine were significantly altered in the oral group but not in the intravenous group, suggesting that CYP3A-mediated metabolism of nicardipine in the liver is not significantly inhibited by morin. The presence of 7.5 and 15 mgkg−1 of morin significantly increased (P&lt; 0.01, 67.8–112%) the area under the plasma concentration-time curve and the peak plasma concentration (P&lt; 0.01, 53.5–93.1%) of orally administered nicardipine. The presence of 7.5 and 15 mgkg−1 of morin significantly decreased (P &lt; 0.01, 40.4–52.8%) the total body clearance of orally administered nicardipine compared with the control group. The enhanced oral bioavailability of nicardipine suggests that intestinal-mediated CYP3A4 metabolism and P-gp-mediated efflux of nicardipine are inhibited by morin. Based on these results, concomitant use of morin or morin-containing dietary supplements with nicardipine may require close monitoring for potential drug interactions.

Bioavailability and tissue distribution of sesamol in rat

Sesamol, generally regarded as the main antioxidative component in sesame oil, can be generated from sesamolin by roasting sesame seed or bleaching sesame oil. This paper reports the bioavailability of sesamol in Sprague-Dawley (SD) rats. Biological fluid was sampled following a dose of sesamol of 50 mg/kg by gastric gavage (p.o.) or by intravenous injection. The pharmacokinetic data of sesamol were calculated by noncompartmental model. The tissue distribution of sesamol (p.o., 100 mg/kg) in SD rats was also investigated. The concentration changes of sesamol were determined in various tissues and plasma within a 24 h period after oral administration of sesamol. The results showed that the oral bioavailability of sesamol was 35.5 +/- 8.5%. Sesamol was found to be able to penetrate the blood-brain barrier and go through hepatobiliary excretion. Sesamol conjugated metabolites were widely distributed in SD rat tissues, with the highest concentrations in the liver and kidneys and the lowest in the brain. It is postulated that sesamol is incorporated into the liver first and then transported to the other tissues (lung, kidneys, and brain). The major metabolites of sesamol distributed in the lung and kidney were glucuronide and sulfate.

Effects of morin on the pharmacokinetics of etoposide in rats

This study investigated the effects of orally administered morin, an inhibitor of CYP isozyme and P-glycoprotein (P-gp), on the pharmacokinetics of intravenous and orally administered etoposide in rats. It was reported that etoposide is a substrate for P-gp and metabolized mainly via CYP3A4 and to a lesser degree via CYP1A2 and 2E1. Etoposide was administered through intravenous (2 mg/kg) or oral (6 mg/kg) routes to rats with or without orally administered morin (5 or 15 mg/kg), which was administered 30 min before etoposide. The pharmacokinetic parameters of etoposide intravenously administered were not significantly different from other groups, suggesting that CYP 3A-mediated metabolism and the P-gp mediated efflux of etoposide in the liver and kidney seemed not to be markedly inhibited by orally administered morin. However, orally administered morin (15 mg/kg) significantly increased the AUC (45.8%), C(max) (32.0%) and the absolute bioavailability (35.9%) of orally administered etoposide compared with the control, which could be mainly due to inhibition of CYP isoenzyme and P-gp in the intestine by morin. The dosage regimen of etoposide should be taken into consideration for toxic reactions when combined with morin or dietary supplements containing morin in patients.

Marked decrease of cyclosporin bioavailability caused by coadministration of ginkgo and onion in rats

Quercetin was reported to modulate CYP isoenzymes and P-glycoprotein (Pgp), a drug efflux transporter. Our previous study reported that quercetin significantly decreased the bioavailability of cyclosporin, a substrate for CYP3A4 and Pgp, in rats and pigs. Ginkgo and onion contain quercetin and its glycosides as St. John's Wort. The coadministration of cyclosporin with ginkgo or onion may be subject to clinically relevant interactions as St. John's Wort. Therefore, this study aimed to investigate the influences of ginkgo and onion on the absorption and disposition of cyclosporin in rats. Cyclosporin was administered orally and intravenously to rats with and without an oral dose of ginkgo or onion in crossover designs. Blood samples were collected via cardiopuncture and blood cyclosporin concentration was assayed by a specific monoclonal fluorescence polarization immunoassay. Everted gut sac was used to investigate the effects of ginkgo and onion on the function of intestinal Pgp. Oral coadministration of ginkgo and onion significantly decreased the Cmax of cyclosporin by 62% and 60%, and reduced the AUC0-t by 51% and 68%, respectively, whereas no influence was observed when cyclosporin was given intravenously. This indicates that the interactions between cyclosporin and ginkgo or onion occurred mainly at the absorption site. In conclusion, ginkgo and onion markedly decreased the oral bioavailability of cyclosporin. We suggest that concurrent intake of quercetin-rich herbs or foods with cyclosporin are better avoided in order to ensure the efficacy of cyclosporin.

Morin sulphates/glucuronides enhance macrophage function in microgravity culture system

BACKGROUND

The immune system changes significantly in astronauts during and after space flight. Although the mechanism has not been defined, it is reasonable to begin developing effective countermeasures to the physiological consequences of spaceflight, especially immunosuppression. Many studies have been published about the effect of flavonoids on immune modulation. Thus, the aim of this study was to develop whether flavonoids could be the effective countermeasures to the immunosuppression caused by microgravity.

MATERIALS AND METHODS

We used a rotating wall vessel 3D (three-dimensional) culture system which recreates some of the culture conditions that occur during microgravity to study the effects of microgravity on the function of macrophages and assess the modulating effects of flavonoids on microgravity-induced macrophage dysfunction.

RESULTS

We demonstrated 65% and 80% reduction in mitogen-induced nitric oxide and cytokine production of 3D-cultured macrophages, compared to conventional two-dimensional (2D)-cultured cells. Moreover, the microgravity-induced macrophage dysfunction was not restored by transferring cells from 3D to 2D culture. However, the addition of morin sulphates/glucuronides in 3D culture compensated for the loss of macrophage function.

CONCLUSION

The result presented here suggests for the first time that an immune-modulatory strategy using flavonoid supplements such as morin would benefit the health of astronauts.

Morin sulfates/glucuronides exert anti-inflammatory activity on activated macrophages and decreased the incidence of septic shock

Morin is a flavonoid present in fruits and Chinese herbs. Based on in vitro studies, morin has been reported to show various beneficial biological activities. However, there is growing evidence that conjugative metabolism is central to the biological fate of flavonoids. Therefore, the biological effects of morin could be primarily determined by its conjugated metabolites. In this study, the effects of morin and its sulfates/glucuronides on the production of nitric oxide (NO) and cytokines from lipopolysaccharide (LPS)-activated macrophages were individually investigated and compared. The results indicated that the 50% NO production was inhibited from LPS-activated RAW 264.7 cells by 1.25 mM morin and 1.25 microM morin sulfates/glucuronides. Meanwhile, the 50% inhibition concentration (IC50) values of morin and morin sulfates/glucuronides in activated peritoneal macrophages were 1.5 mM morin and 1.5 microM morin sulfates/glucuronides, respectively. In addition, 30% of the tumor necrosis factor-alpha (TNF-alpha) and 35% of the interleukin (IL)-12 productions from activated macrophages were inhibited by 2-2.5 mM morin and 2-2.5 microM morin sulfates/glucuronides, respectively. Furthermore, phagocyte activities in the peripheral blood of those for mice dosed with morin for two months were about 65-70% of controls. Lower NO production and reduced macrophage phagocytic activities corresponded to LPS-resistant state. These findings indicated that morin may exhibit anti-inflammatory activity and reduced the incidence of experimental septic shock through decreasing the functions of macrophages and may regulate immune response through modulating the cytokine profiles. Therefore, morin could be a promising therapeutic candidate for inflammatory disease due to the strong activity of its metabolites.

Profound difference in pharmacokinetics between morin and its isomer quercetin in rats

Morin and quercetin are isomeric antioxidant flavonols widely distributed in plant foods and herbs. The pharmacokinetics of both flavonols at two doses were investigated and compared in rats. Parent forms and their glucuronides and sulfates in serum were determined by HPLC before and after enzymatic hydrolysis, respectively. After oral dosing of morin, both the parent form, morin, and its glucuronides and sulfates were present in the bloodstream. The conjugated metabolites predominated at the dose of 25 mg kg(-1), whereas the parent form was predominant at the dose of 50 mg kg(-1). Moreover, the AUC of morin parent form increased by a factor of 37 when the dose doubled, indicating that morin showed nonlinear pharmacokinetics. On the other hand, quercetin presented only as glucuronides and sulfates in the blood, indicating negligible bioavailability of quercetin, and the metabolites showed linear pharmacokinetics at the two doses studied. When considering the total AUC of parent form with conjugated metabolites, the extent of absorption of morin was 3 fold that of quercetin at the dose of 50 mg kg(-1). The results indicated that the difference in hydroxylation pattern on B-ring of flavonol markedly affected their fates in rats.

Urinary pharmacokinetics of baicalein, wogonin and their glycosides after oral administration of Scutellariae Radix in humans

Baicalin, baicalein, wogonoside and wogonin are flavone constituents of Scutellariae Radix with various beneficial biological activities. The purpose of this study was to investigate the urinary pharmacokinetics of these flavones after oral administration of Scutellariae Radix commercial powder. Ten healthy male volunteers received a dose of 5.2 g commercial powder (comparable to 9 g crude drug), respectively. The concentrations of baicalin, baicalein and wogonin in the commercial powder as well as their metabolites in urine were assayed by HPLC method. The glucuronides and sulfates of baicalein and wogonin in urine were hydrolyzed with beta-glucuronidase and sulfatase, respectively. Our results showed that the mean cumulated renal excretion of baicalein glucuronides and sulfates were 43.1+/-4.5 micromol (2.9% of dose) and 64.8+/-6.3 micromol (4.3% of dose), respectively, whereas wogonin glucuronides and sulfates were 21.6+/-2.0 micromol (5.9% of dose) and 20.7+/-1.7 micromol (5.7% of dose), respectively. The result indicated that the renal excretion of conjugated metabolites of wogonin (11.6% of dose) were higher than that of baicalein (7.2% of dose). The baicalein sulfates was predominant than the corresponding glucuronides, whereas wogonin sulfates was comparable to the corresponding glucuronides.