Lysiphyllum strychnifolium (Craib) A. Schmitz Extracts Moderate the Expression of Drug-Metabolizing Enzymes: In Vivo Study to Clinical Propose.

Lysiphyllum strychnifolium (Craib) A. Schmitz (LS) has been traditionally used as a medicinal herb by folk healers in Thailand with rare evidence-based support. Hepatic cytochrome P450s (CYPs450) are well known as the drug-metabolizing enzymes that catalyze all drugs and toxicants. In this study, we investigated the mRNA levels of six clinically important CYPs450, i.e., CYP1A2, 3A2, 2C11, 2D1, 2D2, and 2E1, in rats given LS extracts. Seventy Wistar rats were randomized into seven groups (n = 10). Each group was given LS stem ethanol (SE) and leaf water (LW) extracts orally at doses of 300, 2000, and 5000 mg/kg body weight (mg/kg.bw) for twenty-eight consecutive days. After treatment, the expression of CYPs450 genes was measured using quantitative real-time PCR. The results revealed that SE and LW, which contained quercetin and gallic acid, promoted the upregulation of all CYPs450. Almost all CYPs450 genes were downregulated in all male LW-treated rats but upregulated in female-treated groups, suggesting that CYP gene expressions in LS-treated rats were influenced by gender. Moderate and high doses of the LS extracts had a tendency to induce six CYP450s' transcription levels in both rat genders. CYP2E1 gene showed a unique expression level in male rats receiving SE at a dose of 2000 mg/kg.bw, whereas a low dose of 300 mg/kg.bw was found in the LW-treated female group. As a result, our findings suggest that different doses of LS extracts can moderate the varying mRNA expression of clinically relevant CYP genes. In this study, we provide information about CYP induction and inhibition in vivo, which could be a desirable condition for furthering the practical use of LS extracts in humans.

Design, Synthesis, and Neuroprotective Activity of Phenoxyindole Derivatives on Antiamyloid Beta (Aß) Aggregation, Antiacetylcholinesterase, and Antioxidant Activities.

In this investigation, a number of phenoxyindole derivatives were designed, synthesized, and tested for their neuroprotective ability on SK-N-SH cells against Aß42-induced cell death and biologically specific activities involved in anti-Aß aggregation, anti-AChE, and antioxidant effects. The proposed compounds, except compounds 9 and 10, could protect SK-N-SH cells at the IC50 of anti-Aß aggregation with cell viability values ranging from 63.05% ± 2.70% to 87.90% ± 3.26%. Compounds 3, 5, and 8 demonstrated striking relationships between the %viability of SK-N-SH cells and IC50 values of anti-Aß aggregation and antioxidants. No significant potency of all synthesized compounds against AChE was found. Among them, compound 5 showed the strongest anti-Aß and antioxidant properties with IC50 values of 3.18 ± 0.87 and 28.18 ± 1.40 µM, respectively. The docking data on the monomeric Aß peptide of compound 5 demonstrated good binding at regions involved in the aggregation process, and the structural feature made it possible to be a superior radical scavenger. The most effective neuroprotectant belonged to compound 8, with a cell viability value of 87.90% ± 3.26%. Its unique mechanisms for enhancing the protective impact may serve additional purposes since it demonstrated mild biological-specific effects. In silico prediction of CNS penetration shows strong passive penetration ability across the blood-brain barrier from blood vessels to the CNS for compound 8. In light of our findings, compounds 5 and 8 appeared as potentially intriguing lead compounds for new therapeutic approaches to Alzheimer's disease. More in vivo testing will be revealed in due course.

Evaluation of the Intestinal Permeability of Rosmarinic Acid from Thunbergia laurifolia Leaf Water Extract in a Caco-2 Cell Model.

Thunbergia laurifolia (TL) has been traditionally used as an antidote and an antipyretic drug by folk healers for centuries in Thailand. Rosmarinic acid (RA) is major compound in TL extract and has attracted great interest due to its potential broad pharmacological effects. Herein, the permeability of RA was investigated in TL extract and as a pure compound in a Caco-2 cell model by using high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). The results reveal that the apparent permeability coefficient (Papp) values of RA in TL extracts and pure RA significantly increased after deconjugation by ß-glucuronidase/sulfatase enzymes. Our findings exhibit possible saturable biotransformation of RA and/or membrane transport while penetrated through Caco-2 cells. The cumulative amounts of RA as pure compounds and in TL extracts increased with the exposure time, and the efflux ratio (ER) was 0.27-1.14. RA in the TL extract has a similar absorption in the conjugated form and in the pure compound. The intestinal absorption of them is through passive diffusion. Therefore, our findings conclude that the intestinal transport of RA in TL extracts was mainly penetrated as conjugated forms with glucuronic acid and/or sulfate across Caco-2 cells and transported via passive diffusion.

The Effects of Andrographolide on the Enhancement of Chondrogenesis and Osteogenesis in Human Suprapatellar Fat Pad Derived Mesenchymal Stem Cells.

Andrographolide is a labdane diterpenoid herb, which is isolated from the leaves of Andrographis paniculata, and widely used for its potential medical properties. However, there are no reports on the effects of andrographolide on the human suprapatellar fat pad of osteoarthritis patients. In the present study, our goal was to evaluate the innovative effects of andrographolide on viability and Tri-lineage differentiation of human mesenchymal stem cells from suprapatellar fat pad tissues. The results revealed that andrographolide had no cytotoxic effects when the concentration was less than 12.5 µM. Interestingly, andrographolide had significantly enhanced, dose dependent, osteogenesis and chondrogenesis as evidenced by a significantly intensified stain for Alizarin Red S, Toluidine Blue and Alcian Blue. Moreover, andrographolide can upregulate the expression of genes related to osteogenic and chondrogenic differentiation, including Runx2, OPN, Sox9, and Aggrecan in mesenchymal stem cells from human suprapatellar fat pad tissues. In contrast, andrographolide suppressed adipogenic differentiation as evidenced by significantly diminished Oil Red O staining and expression levels for adipogenic-specific genes for PPAR-γ2 and LPL. These findings confirm that andrographolide can specifically enhance osteogenesis and chondrogenesis of mesenchymal stem cells from human suprapatellar fat pad tissues. It has potential as a therapeutic agent derived from natural sources for regenerative medicine.

The in vitro and in vivo study of novel formulation of andrographolide PLGA nanoparticle embedded into gelatin-based hydrogel to prolong delivery and extend residence time in joint.

Andrographolide (AG), a well-known traditional medicinal plant in Southeast Asia, is widely used for treatment of many chronic diseases. Interestingly, AG has been reported to have inhibitory effects on osteoclast function and anti-inflammatory properties. Because of these therapeutic properties, this study aimed to develop and optimize the formulation of AG using PLGA nanocarriers and gelatin-based hydrogel to prolong the retention time in the joint. We investigated the in vitro release pattern of the AG nanoparticles formulation which prepared by emulsion solvent evaporation method and embedded into gelatin-based hydrogel. The result showed that the AG loaded ester terminated end group PLGA polymer gradually released AG from the PLGA nanoparticles when compared with AG solution. Importantly, the combined use of gelatin-based hydrogel with AG from the PLGA nanoparticles significantly delayed the AG release more than 1 month. Furthermore, we selected the DiR fluorescence dye to represents AG and monitored the retention time by IVIS imaging. The optimal formulation was administered as intra-articular drug delivery systems in in vivo study. The results successfully displayed a long-term sustained release for implantation (≈2 months) and injection (≥2 months) providing a novel strategy for the local management of osteoarthritis disease.

The Intestinal Efflux Transporter Inhibition Activity of Xanthones from Mangosteen Pericarp: An In Silico, In Vitro and Ex Vivo Approach.

The capacity of α-mangostin (α-MG) and ß-mangostin (ß-MG) from mangosteen pericarp on P-glycoprotein (Pgp) in silico, in vitro, and ex vivo was investigated in this study. Screening with the ADMET Predictor™ program predicted the two compounds to be both a Pgp inhibitor and Pgp substrate. The compounds tended to interact with Pgp and inhibit Pgp ATPase activity. Additionally, bidirectional transport on Caco-2 cell monolayers demonstrated a significantly lower efflux ratio than that of the control (α-(44.68) and ß-(46.08) MG versus the control (66.26); p < 0.05) indicating an inhibitory effect on Pgp activity. Test compounds additionally revealed a downregulation of MDR1 mRNA expression. Moreover, an ex vivo absorptive transport in everted mouse ileum confirmed the previous results that α-MG had a Pgp affinity inhibitor, leading to an increase in absorption of the Pgp substrate in the serosal side. In conclusion, α- and ß-MG have the capability to inhibit Pgp and they also alter Pgp expression, which makes them possible candidates for reducing multidrug resistance. Additionally, they influence the bioavailability and transport of Pgp substrate drugs.

Modified tetra-oxygenated xanthones analogues as anti-MRSA and P. aeruginosa agent and their synergism with vancomycin.

Five isolated xanthones from the C. cochinchinense and G. mangostana were evaluated and tested for antibacterial activities. Isolated 4 and 5 exhibited potent anti-MRSA and P. aeruginosa activity, but showed poor pharmacokinetic properties via ADMET prediction. It led us to improve pharmacokinetic properties of 4 and 5 by partially modifying them in acidic condition yielding fourteen analogues. It was found that analogues 4b, 4d and 5b possessed proper pharmacokinetic properties, while only 4b exhibited the best anti-MRSA and P. aeruginosa activity. The SEM results indicated that 4b may interact with or damage the cell wall of MRSA and P. aeruginosa. Moreover, a combination of 4b and vancomycin exhibits synergistic effect against both MRSA and P. aeruginosa at MIC value of 4.98 (MIC = 18.75 µg/mL for 4b) and 9.52 µg/mL (MIC = 75 µg/mL for 4b), respectively.

Pharmacokinetic/Pharmacodynamic (PK/PD) Simulation for Dosage Optimization of Colistin Against Carbapenem-Resistant Klebsiella pneumoniae and Carbapenem-Resistant Escherichia coli.

The purpose was to explore the optimal dosage regimen of colistin using Monte Carlo simulations, for the treatment of carbapenem-resistant Klebsiella pneumoniae and carbapenem-resistant Escherichia coli based on PK/PD targets in critically ill patients. A total of 116 carbapenem-resistant K. pneumoniae and E. coli were obtained from various clinical specimens at Siriraj Hospital in Bangkok, Thailand. Minimum inhibitory concentrations (MICs) of colistin were determined by broth microdilution method. Monte Carlo simulation was used to calculate the cumulative fraction of response (CFR) for European Medicine Agency (EMA), US-Food and Drug Administration (FDA), Nation et al., Siriraj Hospital and our study regimens. The targeted CFR was 90%. For colistin-susceptible K. pneumoniae, all of the dosage regimens achieved ≥90% CFR in patients with creatinine clearance <80 mL/min except the FDA-approved regimens for patients with creatinine clearance 51-79 and 11-29 mL/min, respectively. While, patients with creatinine clearance ≥80 mL/min, CFR ≥90% was observed in Siriraj Hospital and our study regimen. For colistin-susceptible E. coli, all of the dosage regimens achieved ≥90% CFR regardless of renal function. In contrast, the currently approved regimens achieved CFR target in only 10-50% for colistin-resistant isolates subgroup. These results suggest that currently approved regimens still recommended for colistin-susceptible CRE. For colistin-resistant CRE, alternative approaches such as high dose or combination therapy should be considered.

Pharmacokinetics and Penetration of Sitafloxacin into Alveolar Epithelial Lining Fluid in Critically Ill Thai Patients with Pneumonia.

Sitafloxacin showed potent activity against various respiratory pathogens. Blood and bronchoalveolar lavage (BAL) fluid samples were obtained from 12 subjects after a single oral dose of sitafloxacin 200 mg. The mean ± SD (median) maximum ratio of epithelial lining fluid (ELF) to unbound plasma concentration was 1.02 ± 0.58 (1.33). The penetration ratios based on the mean and median area under the curve from 0 to 8 h (AUC0-8) were 0.85 and 0.79 µg · h/ml, respectively. Sitafloxacin penetrates well into ELF in critically ill Thai patients with pneumonia. (This study has been registered in the Thai Clinical Trials Registry [TCTR] under registration no. TCTR20170222001.).

Chitosan-based nanoparticles with damnacanthal suppress CRM1 expression.

Cancer is one of the leading causes of mortality worldwide. Phytochemicals may be promising anticancer agents given their various chemical structures and diverse biological activities. Damnacanthal (DAM) is a major bioactive component of Noni, which has been investigated previously as a cancer-preventive or chemotherapeutic agent. DAM has also been reported to exhibit anti-proliferative activity in several cancer types. In the present study, it was identified that DAM downregulates chromosome maintenance protein 1 (CRM1) expression in human cancer cells. The application of chitosan-based nanoparticles (NPs) with DAM also induced CRM1 downregulation, which suggests that chitosan-based NPs may be effective vehicles for delivery of phytochemicals such as DAM. It was also identified that DAM increased the levels of the tumor suppressor non-steroidal anti-inflammatory drugs-activated gene 1 in the nucleus, thereby leading to enhanced anticancer effects. The results of the present study indicate that DAM and its nanoformulation may be a candidate anticancer drug.

Comparative Fasting Bioavailability of 2 Cilostazol Formulations in Healthy Thai Volunteers: An Open-Label, Single-Dose, Randomized, 2-Way Crossover Study.

OBJECTIVE: To evaluate the bioequivalence of50 mg cilostazol tablets manufactured locally (Citazol®) and originally (Pletaal®) in healthy Thai volunteers. MATERIAL AND METHOD: An open-label, single dose, randomized, two-period, two-sequence, crossover study in 30 healthy volunteers. Each volunteer received a 50 mg cilostazol tablet of bothformulations with a washoutperiodofat least 14 days. Blood samples were obtained atpre-dose and over 48 hours after dosing. Cilostazolplasma concentrations were quantified by using liquid chromatography with tandem mass spectrometry (LC-MS/MS). RESULTS: The 30 volunteers completed the entire study. The geometric mean ratios (GAM) (test/reference) between the two formulations of cilostazol were 112.38% (101.70%-124.19%) for Cmax; 103.66% (96.06%-111.86%) for AUC0-48; and 95.14% (86.12%-105.12%)forAUC0-∞. There was no statistical difference ofthe Tmax between the twoformulations (p>0.05). No serious adverse events related to the studied drugs were found. CONCLUSION: No significant difference in the analyzed pharmacokineticparameters was found between the twoformulations of 50 mg cilostazol tablets. Therefore, it can be concluded that these two cilostazol tablet formulations were considered bioequivalent.

Pharmacokinetics of mitragynine in man.

BACKGROUND: Kratom, known botanically as Mitragyna speciosa (Korth.), is an indigenous tree in Southeast Asia. Kratom is currently easily available worldwide via special shops and the Internet to use as a drug of abuse, opioid alternative, or pain killer. So far, the pharmacokinetics of this plant has been studied only in animals, and there is no such study in humans. The major abundant active alkaloid in Kratom, mitragynine, is one of the promising new chemical substances to be developed as a new drug. The aim of this study was to examine the pharmacokinetics of mitragynine and assess the linearity in pharmacokinetics in chronic users. METHODS: Since Kratom is illegal in Thailand, studies in healthy subjects would be unethical. We therefore conducted a prospective study by enrolling ten chronic, regular, healthy users. We adjusted the steady state in each subject by giving a known amount of Kratom tea for 7 days before commencement of the experiment. We admitted and gave different oral doses to subjects to confirm linearity in pharmacokinetics. The mitragynine blood concentrations at 17 times points and the urine concentrations during the 24-hour period were collected and measured by liquid chromatography-tandem mass spectrometry method. RESULTS: Ten male subjects completed the study without adverse reactions. The median duration of abuse was 1.75 years. We analyzed one subject separately due to the abnormal behavior of blood concentration. From data of nine subjects, the pharmacokinetic parameters established were time to reach the maximum plasma concentration (0.83±0.35 hour), terminal half-life (23.24±16.07 hours), and the apparent volume of distribution (38.04±24.32 L/kg). The urine excretion of unchanged form was 0.14%. The pharmacokinetics were observed to be oral two-compartment model. CONCLUSION: This was the first pharmacokinetic study in humans, which demonstrated linearity and was consistent with the oral two-compartment model with a terminal half-life of about 1 day. The pharmacokinetic linearity and parameters reported are necessary pharmacological information of Kratom, and there is a possibility for it to be developed medically as a pain killer or better opioid substitute in the future.

Development of phyllanthin-loaded self-microemulsifying drug delivery system for oral bioavailability enhancement.

Phyllanthin, a poorly water-soluble herbal active component from Phyllanthus amarus, exhibited a low oral bioavailability. This study aims at formulating self-microemulsifying drug delivery systems (SMEDDS) containing phyllanthin and evaluating their in-vitro and in-vivo performances. Excipient screening was carried out to select oil, surfactant and co-surfactant. Formulation development was based on pseudo-ternary phase diagrams and characteristics of resultant microemulsions. Influences of dilution, pH of media and phyllanthin content on droplet size of the resultant emulsions were studied. The optimized phyllanthin-loaded SMEDDS formulation (phy-SMEDDS) and the resultant microemulsions were characterized by viscosity, self-emulsification performance, stability, morphology, droplet size, polydispersity index and zeta potential. In-vitro dissolution and oral bioavailability in rats of phy-SMEDDS were studied and compared with those of plain phyllanthin. Phy-SMEDDS consisted of phyllanthin/Capryol 90/Cremophor RH 40/Transcutol P (1.38:39.45:44.38:14.79) in % w/w. Phy-SMEDDS could be emulsified completely within 6 min and formed fine microemulsions, with average droplet range of 27-42 nm. Phy-SMEDDS was robust to dilution and pH of dilution media while the resultant emulsion showed no phase separation or drug precipitation after 8 h dilution. The release of phyllanthin from phy-SMEDDS capsule was significantly faster than that of plain phyllanthin capsule irrespective of pH of dissolution media. Phy-SMEDDS was found to be stable for at least 6 months under accelerated condition. Oral absorption of phyllanthin in rats was significantly enhanced by SMEDDS as compared with plain phyllanthin. Our study indicated that SMEDDS for oral delivery of phyllanthin could be an option to enhance its bioavailability.

In vitro-in vivo correlation study for the dermatopharmacokinetics of terbinafine hydrochloride topical cream.

BACKGROUND: To investigate the relationship between dermatopharmacokinetic (DPK) tape stripping from in vitro and in vivo using 1% terbinafine hydrochloride topical cream as the model formulation. METHODOLOGY: In vitro and in vivo tape strippings were conducted on separated pig ear skin used as a biological membrane for franz diffusion cell testing and the non-hairy skin area at the ventral forearms of healthy volunteers, respectively. Terbinafine (1%) topical cream was applied to the skin for 0.5, 2, and 4 h. The drug profiles of terbinafine across the stratum corneum were determined immediately (time 0 h), and at 0.5, 1, 2, and 4 h after removing the formulation. The amounts of terbinafine were analyzed by a validated high-performance liquid chromatography-ultraviolet method. The area under the curve (AUC) and the maximum amounts of terbinafine absorption (Q(max)) were obtained from pharmacokinetic software. Partition coefficient (K(SC/veh)) and diffusion parameter (D/L²) were derived from the Fick's second law equation. During the schedule time of 8 h, the deviations of in vitro and in vivo data were 6.61 and 30.46% for AUC and Q(max), respectively. There was insignificant difference of the K(SC/veh) and the D/L² between excised pig ear and human skin. In addition, K(SC/veh) and D/L² at T(max) of 2 h were used to predict the AUC presented the value of 4.7481 %h whereas the true value calculated from pharmacokinetic software provided the value of 5.9311 %h differing from each other in approximate of 20%. CONCLUSIONS: In vitro tape stripping using the separated pig ear skin as a viable membrane of the franz diffusion cell testing demonstrates the potential to represent in vivo tape stripping in human for topical bioavailability/bioequivalence study of terbinafine hydrochloride 1% topical cream.

Dermal pharmacokinetics of Terpinen-4-ol following topical administration of Zingiber cassumunar (plai) oil.

The purpose of this study was to investigate dermal pharmacokinetics of terpinen-4-ol in rats following topical administration of plai oil derived from the rhizomes of Zingiber cassumunar Roxb. Unbound terpinen-4-ol concentrations in dermal tissue were measured by microdialysis. The dermal pharmacokinetic study of terpinen-4-ol was performed under non-occlusive conditions. The oil was topically applied at a dose of 2, 4, and 8 mg/cm2 plai oil corresponding to the amount of 1.0, 1.9, and 3.8 mg/cm2 terpinen-4-ol, respectively. Following topical application of the oil, terpinen-4-ol rapidly distributed into the dermis and demonstrated linear pharmacokinetics with no changes in the dose-normalized area under the concentration-time curves across the investigated dosage range. The mean percentages of free terpinen-4-ol distributed in the dermis per amount of administered were 0.39 ± 0.06 %, 0.41 ± 0.08 %, and 0.30 ± 0.03 % for 2, 4, and 8 mg/cm2 doses, respectively. The dermal pharmacokinetics of terpinen-4-ol could provide information for its further formulation development and therapy schedules.

Bioequivalence study of 10 mg ramipril tablets in healthy Thai volunteers.

OBJECTIVE: To determine the bioequivalence of 10 mg dose of ramipril tablets between the test product (Ramtace 10 mg, Unison Laboratories, Thailand) and the reference product (Tritace 10 mg, Aventis Pharma SPA, Italy). MATERIAL AND METHOD: The present study was carried out with a single dose, 2-treatment, 2-period, 2-sequence randomized crossover design under fasting condition with a minimum of 14 days washout period in 24 healthy Thai male and female volunteers. Plasma samples for determination of ramipril and ramiprilat were obtained pre-dose and at frequent intervals for up to 72 h post dose. Ramipril and ramiprilat plasma concentrations were quantified by a validated method employing high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All ofthe pharmacokinetic parameters were investigated using non-compartmental analysis. RESULTS: The result demonstrated the 90% confidence interval (90%CI) of the geometric mean ratio (test/reference) of C max, AUC(0-72) and AUC(0-infinity) of ramipril were 97.26% (84.50%-111.93%), 100.70% (89.47%-113.34%) and 100.29% (88.90% 113.15%), respectively. For ramiprilat, the 90% CI for C max, AUC(0-72), and AUC(0-infinity) were 108.87% (103.00%-115.07%), 104.93% (100.50%-109.55%) and 103.30% (98.03%-108.85%), respectively. CONCLUSION: the 90% confidence intervals for log-transformed geometric mean test/reference formulation ratios of primary parameters were entirely within 80.00%-125.00%. Thus, it can be concluded that the test formulation was bioequivalent to the reference formulation.

Bioequivalence study of 50 mg sertraline tablets in healthy Thai volunteers.

OBJECTIVE: To determine the bioavailability of 50 mg sertraline tablets between the test product (Zotaline, M&H Manufacturing Co., Ltd, Thailand) and the reference product (Zoloft, Pfizer Australia Pty Ltd, Australia). MATERIAL AND METHOD: An open-labeled, single dose, 2-treatment, 2-period, 2-sequence, randomized crossover study under fasting conditions with 14 days washout period was conducted in 24 healthy Thai volunteers. Blood samples were collected before dosing and at frequent intervals for up to 96 h post dose. Analysis of sertraline concentrations was performed using a validated liquid chromatography with tandem mass spectrometry (LC-MS/MS) method. RESULTS: Twenty-four volunteers completed both treatment periods. Pharmacokinetic parameters were determined using the non-compartment model. The 90 percent confidence intervals of the geometric mean ratios (test/reference) of C(max) 104.47% (96.64%-112.93%), AUC(0-96) 108.06% (100.71%-115.94%) and AUC(0-infinity) 108.39% (100.93%-116.40%) fell within the equivalence range (80%-125%). There was no significant difference of the T(max) parameter between the two formulations (p > 0.05). No serious adverse events related to the study drugs were found. CONCLUSION: The two formulations of sertraline tablets were bio-equivalent in Thai healthy volunteers.

Bioequivalence study of 500 mg glucosamine sulfate in Thai healthy volunteers.

BACKGROUND AND OBJECTIVE: Glucosamine sulfate is widely used to relieve symptoms from osteoarthritis. The present study was conducted in order to determine pharmacokinetic and assess the in-vivo bioequivalence of two different hard capsule formulations of glucosamine sulfate when administered as equal dose of 500 mg. The two formulations contained different salt form where reference product is NaCl and test product is KCl. MATERIAL AND METHOD: A randomized, single dose, two-treatment, two-period, two-sequence crossover study was conducted. Twenty-four healthy volunteers were recruited at Siriraj Clinical Research Unit. Each subject received a dose of 500 mg glucosamine sulfate of both formulations with at least one-week washout period. Blood samples were collected over 24 h after the oral administration. The plasma fractions were analyzed for glucosamine using a liquid chromatography-mass spectrometry (LC-MS/MS). RESULTS: Twenty-four volunteers were enrolled in the present study Pharmacokinetic parameters were determined using the non-compartment model. The 90% confidence intervals of the mean ratios (test/reference) of C(max) (93.69%; ranged from 86.68%-113.32%) and AUC(0-t), (97.73; ranged from 87.38%-112.62%) fell within the acceptable range (80-125%) for bioequivalent eligibility. Both preparations were well tolerated and had a few non-serious adverse events. CONCLUSION: The glucosamine sulfate containing KCl (test product) is bioequivalent to glucosamine sulfate containing NaCl (reference product) in terms of rate and extent of absorption.

Elucidation of the natural artemisinin decomposition route upon iron interaction: a fine electronic redistribution promotes reactivity.

The conformational analysis of artemisinin by molecular dynamics and quantum chemistry calculations revealed the existence of seven energy minima with specific interconversion pathways. Among the seven conformers, only , and were able to undergo bond rearrangements upon Fe(2+) interaction. These rearrangements were due to a peculiar puckering of the trioxane ring that brings its three oxygen atoms in an ideal geometrical position for interacting with Fe(2+) ions, promoting an electronic redistribution in the molecule. A rapid molecule rearrangement led to a stable energy minimum structure with an additional ring that is similar to a plant metabolite. Our results suggest an alternative pathway for generating toxic radical chemical species for the malaria parasite, where artemisinin is not toxic by itself but rather is an intermediate for molecular partners that generate radical structures deleterious for the parasite proteins, after electron transfers from the Fe(2+)/artemisinin complex.