Observing Confined Local Oxygen-induced Reversible Thiol/Disulfide Cycle with a Protein Nanopore.

Disulfide bonds play an important role in thiol-based redox regulation. However, owing to the lack of analytical tools, little is known about how local O2 mediates the reversible thiol/disulfide cycle under protein confinement. In this study, a protein-nanopore inside a glove box is used to control local O2 for single-molecule reaction, as well as a single-molecule sensor for real-time monitoring of the reversible thiol/disulfide cycle. The results demonstrate that the local O2 molecules in protein nanopores could facilitate the redox cycle of disulfide formation and cleavage by promoting a higher fraction of effective reactant collisions owing to nanoconfinement. Further kinetic calculations indicate that the negatively charged residues near reactive sites facilitate proton-involved oxygen-induced disulfide cleavage under protein confinement. The unexpectedly strong oxidation ability of confined local O2 may play an essential role in cellular redox signaling and enzyme reactions.

Profiling single-molecule reaction kinetics under nanopore confinement.

The study of a single-molecule reaction under nanoconfinement is beneficial for understanding the reactive intermediates and reaction pathways. However, the kinetics model of the single-molecule reaction under confinement remains elusive. Herein we engineered an aerolysin nanopore reactor to elaborate the single-molecule reaction kinetics under nanoconfinement. By identifying the bond-forming and non-bond-forming events directly, a four-state kinetics model is proposed for the first time. Our results demonstrated that the single-molecule reaction kinetics inside a nanopore depends on the frequency of individual reactants captured and the fraction of effective collision inside the nanopore confined space. This insight will guide the design of confined nanopore reactors for resolving the single-molecule chemistry, and shed light on the mechanistic understanding of dynamic covalent chemistry inside confined systems such as supramolecular cages, coordination cages, and micelles.

Morphological and Molecular Phylogenetic Data of the Chinese Medicinal Fungus Cordyceps liangshanensis Reveal Its New Systematic Position in the Family Ophiocordycipitaceae.

A cordycipitoid fungus infecting Hepialidae sp. in Nepal was supposed to be identical to Cordyceps liangshanensis, originally described from southwestern China, and thus, transferred to the genus Metacordyceps or Papiliomyces in previous studies. However, our multi-gene (nrSSU-nrLSU-tef-1α-rpb1-rpb2) phylogenetic and morphological studies based on the type specimen and additional collections of C. liangshanensis revealed that the fungus belongs to the genus Ophiocordyceps (Ophiocordycipitaceae). Therefore, a new combination O. liangshanensis was made, and a detailed description of this species was provided.

Inositol polyphosphate multikinase IPMK-1 regulates development through IP3/calcium signaling in Caenorhabditis elegans.

Inositol polyphosphate multikinase (IPMK) is a conserved protein that initiates the production of inositol phosphate intracellular messengers and is critical for regulating a variety of cellular processes. Here, we report that the C. elegans IPMK-1, which is homologous to the mammalian inositol polyphosphate multikinase, plays a crucial role in regulating rhythmic behavior and development. The deletion mutant ipmk-1(tm2687) displays a long defecation cycle period and retarded postembryonic growth. The expression of functional ipmk-1::GFP was detected in the pharyngeal muscles, amphid sheath cells, the intestine, excretory (canal) cells, proximal gonad, and spermatheca. The expression of IPMK-1 in the intestine was sufficient for the wild-type phenotype. The IP3-kinase activity of IPMK-1 is required for defecation rhythms and postembryonic development. The defective phenotypes of ipmk-1(tm2687) could be rescued by a loss-of-function mutation in type I inositol 5-phosphatase homolog (IPP-5) and improved by a supplemental Ca2+ in the medium. Our work demonstrates that IPMK-1 and the signaling molecule inositol triphosphate (IP3) pathway modulate rhythmic behaviors and development by dynamically regulating the concentration of intracellular Ca2+ in C. elegans. Advances in understanding the molecular regulation of Ca2+ homeostasis and regulation of organism development may lead to therapeutic strategies that modulate Ca2+ signaling to enhance function and counteract disease processes. Unraveling the physiological role of IPMK and the underlying functional mechanism in C. elegans would contribute to understanding the role of IPMK in other species, especially in mammals, and benefit further research on the involvement of IPMK in disease.

Secoisolariciresinol Diglucoside Delays the Progression of Aging-Related Diseases and Extends the Lifespan of Caenorhabditis elegans via DAF-16 and HSF-1.

Secoisolariciresinol diglucoside (SDG) is a phytoestrogen and rich in food flaxseed, sunflower seeds, and sesame seeds. Among the beneficial pharmacological activities of SDG on health, many are age related, such as anticancer, antidiabetes, antioxidant, and neuroprotective effects. Thus, we investigated if SDG had an effect on antiaging in Caenorhabditis elegans (C. elegans). Our results showed that SDG could extend the lifespan of C. elegans by up to 22.0%, delay age-related decline of body movement, reduce the lethality of heat and oxidative stress, alleviate dopamine neurodegeneration induced by 6-hydroxydopamine (6-OHDA), and decrease the toxicity of Aß protein in C. elegans. SDG could increase the expression of the downstream genes of DAF-16, DAF-12, NHR-80, and HSF-1 at mRNA level. SDG could not extend the lifespan of mutants from genes daf-16, hsf-1, nhr-80, daf-12, glp-1, eat-2, and aak-2. The above results suggested that SDG might enhance the stress resistance, delay the progression of aging-related diseases, and extend the lifespan of C. elegans via DAF-16 and HSF-1.

Tectochrysin increases stress resistance and extends the lifespan of Caenorhabditis elegans via FOXO/DAF-16.

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Tectochrysin is a flavonoid compound and rich in a traditional Chinese Medicine Alpinia oxyphylla Miq., which has antioxidant, anti-inflammatory, anti-cancer, anti-bacterial, anti-diarrhea, hepatoprotective, and neuro-protective effects. Therefore, we tested if tectochrysin had an effect on aging in Caenorhabditis elegans (C. elegans). Our results showed that tectochrysin could extend the lifespan of C. elegans by up to 21.0%, delay the age-related decline of body movement, improve high temperature-stress resistance and anti-infection capacity, and protected worms against Aß1-42-induced toxicity. Tectochrysin could not extend the lifespan of the mutants from genes daf-2, daf-16, eat-2, aak-2, skn-1, and hsf-1. Tectochrysin could increase the expression of DAF-16 regulated genes. The extension of lifespan by tectochrysin requires FOXO/DAF-16 and HSF-1. Overall, our findings suggest that tectochrysin may have a potential effect on extending lifespan and age-related diseases.

The Effects of Age and Reproduction on the Lipidome of Caenorhabditis elegans.

Aging is a complex life process, and a unified view is that metabolism plays key roles in all biological processes. Here, we determined the lipidomic profile of Caenorhabditis elegans (C. elegans) using ultraperformance liquid chromatography high-resolution mass spectrometry (UPLC-HRMS). Using a nontargeted approach, we detected approximately 3000 species. Analysis of the lipid metabolic profiles at young adult and ten-day-old ages among wild-type N2, glp-1 defective mutant, and double mutant daf-16;glp-1 uncovered significant age-related differences in the total amount of phosphatidylcholines (PC), sphingomyelins (SM), ceramides (Cer), diglycerides (DG), and triglycerides (TG). In addition, the age-associated lipid profiles were characterized by ratio of polyunsaturated (PUFA) over monounsaturated (MUFA) lipid species. Lipid metabolism modulation plays an important role in reproduction-regulated aging; to identify the variations of lipid metabolites during germ line loss-induced longevity, we investigated the lipidomic profiles of long-lived glp-1/notch receptor mutants, which have reproductive deficiency when grown at nonpermissive temperature. The results showed that there was some age-related lipid variation, including TG 40:2, TG 40:1, and TG 41:1, which contributed to the long-life phenotype. The longevity of glp-1 mutant was daf-16-dependent; the lipidome analysis of daf-16;glp-1 double mutant revealed that the changes of some metabolites in the glp-1 mutant were daf-16-dependent, while other metabolites displayed more complex epistatic patterns. We first conducted a comprehensive lipidome analysis to provide novel insights into the relationships between longevity and lipid metabolism regulated by germ line signals in C. elegans.

[Simultaneous determination of thirteen components in Tong'an injection by LC-MS/MS].

The aim of this study was to develop a simple, sensitive ultra performance liquid chromatography mass spectrometry (UPLC-MS/MS) method for the determination of syringaresinol, N-trans-feruloyltyramine, chelerythrine chloride, sinomenine, coptisine chloride, sanguinarine, chelidonine, magnolflorine, allocryptopine, protopine, farrerol, stylopine and dihydrosanguin-arine in Tong'an injection (TAI), which could be used for the quality control of TAI. The UPLC analysis was performed on Agilent Zorbax SB-Aq column (2.1 mm×150 mm,3.5 µm), with 0.1% formic acid solution (A) -acetonitrile (B) as the mobile phase for gradient elution (0.01-2 min, 5%B; 2-8 min, 5%-30%B; 8-11 min, 30%-95%B; 11-13 min, 95%B; 13-13.1 min, 95%-5%B; 13.1-14 min, 5%B). The flow rate was 0.5 mL•min⁻¹, and the column temperature was 25 ℃; multiple reaction monitoring (MRM) was performed in electrospray ion source positive ion mode for quantitative determination. The calibration curves for the above thirteen compounds showed good linear relationship in corresponding mass concentration range (r>0.999 0). The average recovery rate of the compounds ranged from 95.70% to 104.8%, with RSD of less than 1.9%. The contents of thirteen active components in 10 batches of TAI were 0.021 2-0.029 0, 0.001 7-0.002 3, 0.000 9-0.001 3, 5.952-6.205 2, 0.195 4-0.240 5, 0.002 0-0.002 9, 0.693-0.798 2, 0.069 3-0.078 2, 0.089 29-0.102 9, 0.386 5-0.420 1, 0.014 3-0.015 9, 0.755 3-0.842 1, and 0.008 2-0.011 2 g•L⁻¹ respectively. Methodology validation proved that this method was simple, rapid, sensitive and accurate, which can be used to provide reference for the comprehensive evaluation of TAI quality. The determination results of 10 batches of TAI showed the content of each batch had no significant difference. The results may provide a basis for the quality control of TAI.

Otophylloside B Protects Against Aß Toxicity in Caenorhabditis elegans Models of Alzheimer's Disease.

Alzheimer's disease (AD) is a major public health concern worldwide and the few drugs currently available only treat the symptoms. Hence, there is a strong need to find more effective anti-AD agents. Cynanchum otophyllum is a traditional Chinese medicine for treating epilepsy, and otophylloside B (Ot B), isolated from C. otophyllum, is the essential active component. Having previously identified anti-aging effects of Ot B, we evaluated Ot B for AD prevention in C. elegans models of AD and found that Ot B extended lifespan, increased heat stress-resistance, delayed body paralysis, and increased the chemotaxis response. Collectively, these results indicated that Ot B protects against Aß toxicity. Further mechanistic studies revealed that Ot B decreased Aß deposition by decreasing the expression of Aß at the mRNA level. Genetic analyses showed that Ot B mediated its effects by increasing the activity of heat shock transcription factor (HSF) by upregulating the expression of hsf-1 and its target genes, hsp-12.6, hsp-16.2 and hsp-70. Ot B also increased the expression of sod-3 by partially activating DAF-16, while SKN-1 was not essential in Ot B-mediated protection against Aß toxicity.

Method to evaluate the quality of herbal medicines based on the dynamic changes of chemical compounds and pharmacological activity.

Quality control has been one of the key scientific issues in the modernization of traditional Chinese medicine. This study explored a novel method for quality evaluation of herbal medicines. High-performance liquid chromatography fingerprints and the osteoblast proliferation activity of 18 batches of Achyranthes bidentata, which were prepared with salt, were determined to establish a chromatographic database and an activity database. Correlation analyses of these databases were performed using partial least squares to obtain regression coefficients (positive and negative correlation coefficients). Then, the sums of the products of the positive and negative correlation peak areas and the corresponding coefficients, respectively, were calculated for each sample. The absolute value of the ratios of the sums of the positive and negative products were calculated, our studies showed that this ratio was significantly correlated with the proliferation activity, particularly when the activity was in the best and worst ranges. Therefore, we developed a parameter that was used to evaluate the quality of samples osteoblast proliferation activity. The quality of another ten batches of samples was assessed to verify this method. The results indicated that this method can be used for quality evaluation of herbal medicines according to the dynamic changes in the chemical compounds and activity.

Timosaponin B-II Ameliorates Palmitate-Induced Insulin Resistance and Inflammation via IRS-1/PI3K/Akt and IKK/NF-[Formula: see text]B Pathways.

This study aimed to investigate the effect of timosaponin B-II (TB-II) on palmitate (PA)-induced insulin resistance and inflammation in HepG2 cells, and probe the potential mechanisms. TB-II, a main ingredient of the traditional Chinese medicine Anemarrhena asphodeloides Bunge, notably ameliorated PA-induced insulin resistance and inflammation, and significantly improved cell viability, decreased PA-induced production of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]) and interleukin-6 (IL-6) levels. Further, TB-II treatment notably decreased malondialdehyde (MDA) and lactate dehydrogenase (LDH) levels, and improved superoxide dismutase (SOD) and nitric oxide (NO). TB-II also reduced HepG2 cells apoptosis. Insulin receptor substrate-1 (IRS1)/phosphatidylinositol 3-kinase (PI3K)/Akt and inhibitor of nuclear factor [Formula: see text]-B kinase (IKK)/NF-[Formula: see text]B pathways-related proteins, and IKK[Formula: see text], p65 phosphorylation, serine phosphorylation of insulin receptor substrate-1 (IRS-1) at S307, tyrosine phosphorylation of IRS-1, and Akt activation were determined by Western blot. Compared to model group, TB-II significantly downregulated the expression of p-NF-[Formula: see text]Bp65, p-IKK[Formula: see text], p-IRS-1, p-PI3K and p-Akt. TB-II is a promising potential agent for the management of palmitate-induced insulin resistance and inflammation, which might be via IR/IRS-1/PI3K/Akt and IKK/NF-[Formula: see text]B pathways.

Timosaponin B-II ameliorates diabetic nephropathy via TXNIP, mTOR, and NF-κB signaling pathways in alloxan-induced mice.

BACKGROUND: Many synthesized drugs with clinical severe side effects have been used for diabetic nephropathy (DN) treatment. Therefore, it is urgent and necessary to identify natural and safe agents to remedy DN. Timosaponin B-II (TB-II), a major steroidal saponin constituent in Anemarrhena asphodeloides Bunge, exhibits various activities, including anti-inflammatory and hypoglycemic functions. However, the anti-DN effects and potential mechanism(s) of TB-II have not been previously reported. PURPOSE: To investigate the effect of TB-II on DN in alloxan-induced diabetic mice. METHODS: TB-II was isolated and purified from A. asphodeloides Bunge using macroporous adsorption resin and preparative high-performance liquid chromatography. The effect of TB-II on DN was evaluated in alloxan-induced diabetic mice using an assay kit and immunohistochemical determination in vivo. The expression of mammalian target of rapamycin (mTOR), thioredoxin-interacting protein (TXNIP), and nuclear transcription factor-κB (NF-κB) signaling pathways was also measured using Western blot analysis. RESULTS: TB-II significantly decreased the blood glucose levels and ameliorated renal histopathological injury in alloxan-induced diabetic mice. In addition, TB-II remarkably decreased the levels of renal function biochemical factors, such as kidney index, blood urea nitrogen, serum creatinine, urinary uric acid, urine creatinine, and urine protein, and it reduced lipid metabolism levels of total cholesterol and triglycerides and the levels of inflammatory cytokines interleukin-6 and tumor necrosis factor-α in alloxan-induced mice. Furthermore, TB-II inhibited the expression of mTOR, TXNIP, and NF-κB. CONCLUSION: The results revealed that TB-II plays an important role in DN via TXNIP, mTOR, and NF-κB signaling pathways. Overall, TB-II exhibited a prominently ameliorative effect on alloxan-induced DN.

Novel Application of Natural Anisole Compounds as Enhancers for Transdermal Delivery of Ligustrazine.

To improve the transdermal delivery of ligustrazine, Foeniculum vulgare food origin anisole compounds were employed as promoters. Transdermal fluxes of ligustrazine were determined by Franz-type diffusion cells. Fourier transform-infrared (FT-IR) spectra were used to detect the biophysical changes of the stratum corneum and to explore the mechanism of permeation enhancement. A scanning electron microscope (SEM) was used to monitor the morphological changes of the skin. Among the three anisoles, anisic acid increased the penetration flux of ligustrazine significantly. The ligustrazine flux with anisic acid (11.9 µg/cm(2)/h) was higher than that any other group (p < 0.05). Spectra observations revealed that these anisole enhancers were able to disturb and extract the stratum corneum lipids. In addition, apparent density was used to describe the desquamation extent of the scutella. Multiple mechanisms are involved in the permeation enhancement of ligustrazine, including disturbing and extracting stratum corneum lipid, forming a competitive hydrogen bond. All data suggested that anisole compounds could be a group of safe and active penetration enhancers for transdermal delivery of ligustrazine.

[Determination of residual organic solvents and macroporous resin residues in Akebia saponin D].

According to ICH, Chinese Pharmacopoeia and supplementary requirements on the separation and purification of herbal extract with macroporous adsorption resin by SFDA, hexane, acetidine, ethanol, benzene, methyl-benzene, o-xylene, m-xylene, p-xylene, styrene, diethyl-benzene and divinyl-benzene of residual organic solvents and macroporous resin residues in Akebia saponin D were determined by headspace capillary GC. Eleven residues in Akebia saponin D were completely separated on DB-wax column, with FID detector, high purity nitrogen as the carry gases. The calibration curves were in good linearity (0.999 2-0.999 7). The reproducibility was good (RSD < 10%). The average recoveries were 80.0% -110%. The detection limit of each component was far lower than the limit concentration. The method is simple, reproducible, and can be used to determine the residual organic solvents and macroporous resin residues in Akebia saponin D.

Enhancement of absorption and bioavailability of echinacoside by verapamil or clove oil.

PURPOSE: This present study investigated the absorption kinetics of echinacoside (ECH) in situ and in vitro and its oral bioavailability in rats. Additional aim was to find an agent(s) to promote ECH absorption and oral bioavailability among two efflux proteins and three absorption promoters. METHODS: ECH absorption behaviors were investigated by everted gut sac model in vitro and single-pass intestinal perfusion model in situ. Pharmacokinetics study was performed to investigate the influences of verapamil and clove oil on ECH bioavailability in vivo. All samples were measured at different time intervals by high performance liquid chromatography. RESULTS: The results showed that the effective permeability coefficient (P eff) and apparent permeability coefficient of ECH were 0.83×10(-6)-3.23×10(-6) cm/s and 2.99×10(-6)-9.86×10(-6) cm/s, respectively. The P eff among duodenum, jejunum, and ileum were not statistically different, but they were higher than colon (P<0.01), which demonstrated that intestinal ECH absorption was poor and site dependent. Additionally, verapamil and clove oil significantly increased the jejunal P eff of ECH both in situ and in vitro. Moreover, the bioavailability of ECH in combination with verapamil and clove oil were increased by 1.37-fold (P<0.05) and 2.36-fold (P<0.001), respectively, when compared to ECH group. Overall, verapamil and clove oil facilitated ECH absorption and oral bioavailability. CONCLUSION: The absorption and bioavailability of ECH were enhanced by verapamil and clove oil, respectively, both in vitro and in vivo. Consequently, the combination of verapamil and clove oil with ECH will be a promising and effective approach to promote intestinal absorption and oral bioavailability of ECH.

The Lifespan-Promoting Effect of Otophylloside B in Caenorhabditis elegans.

Aging is the major risk factor for many human diseases and degeneration. Thus, clinically effective medicine could delay the process of aging and aging-related diseases are desperately wanted. In traditional Chinese medicine (TCM), some were claimed to slow down aging. Qingyangshen (Cynanchum otophyllum schneid) is such a TCM. Here, we assayed the longevity effect of compound Otophylloside B (Ot B), a C-21 steroidal glycoside isolated from Qingyangshen, in Caenorhabditis elegans, which is a popular model for aging research. Our results showed that Ot B could modestly extend the lifespan of C. elegans, delay the age-related decline of body movement and improve the stress resistance. Further investigating the molecular mechanism of lifespan extension effect revealed that Ot B could activate the FOXO transcription factor DAF-16. Ot B could not further extend the lifespan of long-lived mutant of insulin/IGF-1-like receptor (daf-2). In addition, Ot B also requires SIR-2.1 and CLK-1 which is an enzyme in ubiquinone synthesis, for lifespan extension.

Microcrystalline preparation of akebia saponin D for its bioavailability enhancement in rats.

Akebia Saponin D (ASD) or asperosaponin VI is the most abundant constituent of the rhizome of Dipsacus asper, which has been used for the treatment of lower back pain, traumatic hematoma and bone fractures. In recent years, it was reported that ASD was a potential treatment strategy for Alzheimer's disease (AD). However, the low bioavailability of ASD limited its clinical utility. Microcrystalline preparation is one of the effective methods to improve drug absorption. The drugs prepared by different methods can present different solid forms (polymorphs), and different polymorphs have significantly different bioavailabilities. The objective of this study was to prepare ASD polymorphs using the different preparation processes and to evaluate their physicochemical properties and oral absorption. ASD-2 obtained by the antisolvent process was simpler and had higher recovery (78.5%) than that of ASD-1 by a two-step macroporous resin column separation (56.5%). The ASD polymorphs were characterized using differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The results revealed that ASD-2 existed in microcrystalline form, while ASD-1 was amorphous. Furthermore, the equilibrium solubility, dissolution in aqueous solution and pharmacokinetic parameters of the samples were determined. ASD-2 showed lower aqueous solubility than that of ASD-1 (p < 0.01). In addition, ASD-2 showed lower dissolution with only 65% of the drug released while ASD-1 had a higher dissolution with 99% of drug released at the end of the 180 min testing period. Although ASD-1 significantly increased solubility and dissolution, the AUC 0-20h of ASD-2 was 4.3 times that of the amorphous ASD-1 in vivo. Data suggest that the microcrystalline preparation of ASD-2 is not only reasonable in economy and suitable for large-scale preparation, but also a promising method to enhance bioavailability of ASD.

Study on the anti-gout activity of chlorogenic acid: improvement on hyperuricemia and gouty inflammation.

Gout is a metabolic disorder associated with hyperuricemia resulting in the deposition of monosodium urate (MSU) crystals in joints and tissues. Lowering serum uric acid (Sur) levels and anti-inflammation are highly essential in treating gout. Chlorogenic acid (CA), as one of the most abundant polyphenols in the Chinese medicines, has been rarely reported to have an anti-gout effect. The model of potassium oxonate (PO)-induced hyperuricemia in mice and MSU crystal-induced inflammation in rats has been established in this study. The potential beneficial effects and mechanisms of CA on hyperuricemia and gouty arthritis were elucidated. The results demonstrated that CA significantly decreased the Sur level by inhibiting the xanthine oxidase (XOD) activity but not increasing the urinary uric acid (Uur) level. In addition, CA also exhibited the effect of suppressing paw swelling. Further investigation indicated that CA improved the symptoms of inflammation induced by MSU crystals by inhibiting the production of proinflammatory cytokines including interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The present study suggests that CA may have a considerable potential for development as an anti-gouty arthritis agent for clinical application.

Absorption characteristics of the total alkaloids from Mahonia bealei in an in situ single-pass intestinal perfusion assay.

AIM: To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis (TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. METHOD: The absorption behavior was investigated in an in situ single-pass intestinal perfusion (SPIP) assay in rats. RESULTS: The intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds (jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids (borneol or camphor) was higher than by the monocyclic monoterpenes (menthol or menthone), and promotion by compounds with a hydroxyl group (borneol or menthol) was higher than those with a carbonyl group (camphor or menthone). The apparent permeability coefficient (Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant (Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. CONCLUSION: The intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein (P-gp) and organic cation transporters (OCT), rather than multidrug resistance protein (MRP) and breast cancer resistance protein (BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively.

Intestinal absorptive transport of Genkwanin from Flos genkwa using a single-pass intestinal perfusion rat model.

To investigate the absorptive transport behavior of genkwanin and the beneficial effects of monoterpene enhancers with different functional groups, the single-pass intestinal perfusion (SPIP) of rats was used. The results showed that genkwanin was segmentally-dependent and the best absorptive site was the duodenum. The effective permeability coefficient (P eff ) was 1.97 × 10(-4) cm/s and the absorption rate constant (Ka) was 0.62 × 10(-2) s(-1). Transepithelial transportation descended with increasing concentrations of genkwanin. This was a 1.4-fold increase in P eff by probenecid, whereas a 1.4-fold or 1.6-fold decrease was observed by verapamil and pantoprazole, respectively. Furthermore, among the absorption enhancers, the enhancement with carbonyl (camphor and menthone) was higher than that with hydroxyl (borneol and menthol). The concentration-independent permeability and enhancement by coperfusion of probenecid indicated that genkwanin was transported by both passive diffusion and multidrug resistance protein (MDR)-mediated efflux mechanisms.