The maintenance of an appropriate serum concentration of a drug is known to be important for its pharmacological effects and the prevention of unexpected adverse effects. Functional alterations of drug transporters and drug-metabolizing enzymes may influence the serum concentration of drugs through changes in its pharmacokinetics and pharmacodynamics (PK/PD). There are many drug transporters expressed in the brain, liver, kidneys, and intestine including ATP-binding cassette (ABC) transporters and solute carriers (SLCs), which contribute to the systemic distribution of various drugs. Furthermore, the expression and function of P-glycoprotein (P-gp), one of the ABC transporters, is altered by environmental factors such as lifestyle and disease. In this review, we have focused on the influence of functional alterations in the intestinal P-gp on the PK/PD of drugs administered via the oral route under diabetic conditions. Altered expression patterns of intestinal P-gp observed under diabetic conditions exhibit pathological stage-dependency. Furthermore, many factors, such as serum glucose, insulin, nitric oxide, and cytokines, influence expression of intestinal P-gp. Finally, to design appropriate and individually targeted pharmacotherapy, it is necessary to consider the influence of alterations in the intestinal P-gp as well as drug metabolizing enzymes under diabetic conditions based on experimental results obtained from fundamental animal research.
Traumatic events in early life are implicated in an increased risk of psychiatric diseases, such as depression and anxiety disorders. Serotonin is thought to play a central role in stress-induced psychiatric diseases. Serotonergic systems, including neural organization and receptor function, could dramatically change with each developmental stage. Here, we reviewed the persistent influence of early life stress on emotional regulation, focusing on the serotonergic system in rats. An aversive stimulus, foot shock (FS), during the early postnatal period (2–3 weeks after birth) produced behavioral, neuroanatomical and electrophysiological changes accompanied by serotonergic dysfunction, especially functional impairment of the serotonin (5-hydroxytryptamine; 5-HT)1A receptor in the cortico-limbic area. These findings suggest that normalization of the cortico-limbic serotonergic function has therapeutic potential for early stress-induced emotional disturbance.
The serotonergic nervous system plays crucial roles in regulating psycho-emotional, cognitive, sensori-motor and autonomic functions. It is now known that multiple serotonin (5-hydroxytryptamine; 5-HT) receptors regulate extrapyramidal motor functions, which are implicated in pathogenesis and/or treatment of various neurological disorders (e.g., Parkinson’s disease and drug-induced extrapyramidal motor deficits). Specifically, antagonism of 5-HT2A/2C receptors alleviates antipsychotic-induced extrapyramidal side effects (EPS) by relieving the 5-HT2A/2C receptor-mediated inhibition of nigral dopaminergic neuron activity and striatal dopamine release. Indeed, many of the second generation antipsychotics (e.g., risperidone, perospirone and olanzapine) commonly possess potent 5-HT2A/2C blocking actions which contribute to their atypical antipsychotic property. In addition, activation of 5-HT1A receptors also improves antipsychotic-induced EPS and motor disabilities in animal models of Parkinson’s disease. Microinjection studies revealed that stimulation of postsynaptic 5-HT1A receptors in the striatum or motor cortex plays an important role in the antiparkinsonian actions. Furthermore, recent studies demonstrated that antagonism of 5-HT3 and 5-HT6 receptors alleviates extrapyramidal motor disorders while 5-HT4, 5-HT5, and 5-HT7 receptors are mostly inactive. These results encourage drug discovery research into new 5-HT receptor ligands that could improve current therapies for extrapyramidal motor disorders.
Anorexia is an important issue in the management of elderly patients with cancer because it contributes to the development of malnutrition, increases morbidity and mortality, and negatively affects patients’ quality of life. This review summarizes the potential mechanisms of the development of anorexia in three animal models that mimic the situations commonly seen in elderly patients receiving chemotherapy. Cisplatin-induced anorexia is attributable to a decrease in peripheral and central ghrelin secretion caused by the stimulation of serotonin (5-hydroxytryptamine; 5-HT)2B and 5-HT2C receptors via 5-HT secretion. Age-associated anorexia is caused by an increase in plasma leptin, which results from disturbed reactivity of ghrelin in the hypothalamus and regulation of ghrelin secretion. Environmental change causes the activation of central 5-HT1B and 5-HT2C receptors and the melanocortin-4 receptor system, resulting in a decrease in circulating ghrelin levels which lowers food intake. New therapeutic approaches based on these pathophysiological mechanisms are warranted for the treatment of anorexia in cancer patients, especially elderly ones.
Serotonin (5-hydroxytryptamine; 5-HT), a well-characterized neurotransmitter in the central nervous system, plays a crucial role in regulating mood, body temperature, sleep, appetite, and metabolism. Serotonin is synthesized in the serotonergic neuron of the central nervous system; however, approximately 90% of serotonin is synthesized and localized in the gastrointestinal (GI) tract, especially in the enterochromaffin (EC) cells. In the GI tract, serotonin mediates control over a variety of physiological functions such as contraction/relaxation of smooth muscle, and peristaltic and secretory reflexes, directly or indirectly through intrinsic primary afferent neurons. The receptors mediating the action of serotonin are mainly classified into 7 major groups known as the 5-HT1 to 5-HT7 receptors. The 5-HT3 receptor is distinguished from among the other 5-HT receptor subtypes because it is only a ligand-gated ion channel, whereas the other subtypes serve as G protein-coupled receptors. The 5-HT3 receptor, which is generally considered to be localized in the central and peripheral nervous systems, is involved in processes associated with emotion, cognition, memory, pain perception, and GI functions including secretion and motility. Recently, an increasing number of findings have provided evidence of the important role of the 5-HT3 receptor in the regulation of inflammatory and immune responses. In fact, several 5-HT3 receptor antagonists have been reported to ameliorate intestinal inflammation. Therefore, this review focuses on the role of 5-HT3 receptors in the pathogenesis of intestinal inflammation.
5-Hydroxytryptamine (5-HT) is involved in regulation of both physiological and pathophysiological conditions in tissues throughout the body. 5-HT induces vascular smooth muscle constriction in most vessels. The vasoconstrictive effects of 5-HT are mediated by 5-HT1B and 5-HT2A receptors located on the membrane of smooth muscle cells, except in the intracranial arteries which constrict only through 5-HT1B receptors. 5-HT also acts as vasodilator because it releases nitric oxide from endothelial cells. This response is dominantly mediated by 5-HT1B receptors but not by 5-HT2A receptors. In this review, we focus on the action of 5-HT via G protein-coupled 5-HT receptors involved in some vascular-related pathophysiological responses. Furthermore, we describe the possibilities of 5-HT receptors as targets for drug therapy against saphenous vein grafts diseases (especially in patients with diabetes mellitus), migraine and pulmonary arterial hypertension.
5-Hydroxytryptamine (5-HT) in the bloodstream is largely contained in platelets and circulates throughout the entire vascular system. 5-HT released from activated platelets dramatically changes the function of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). In VSMCs, 5-HT induces proliferation and migration via 5-HT2A receptors. These effects are further enhanced by vasoactive substances such as thromboxane A2 and angiotensin II. 5-HT2A receptor activation in VSMCs also causes both enhancement of prostaglandin I2 production by inducing cyclooxygenase-2 and reduction of nitric oxide (NO) by suppressing inducible NO synthase. Evidence showing that 5-HT in ECs plays a principal role in angiogenesis now exists. Stimulation of 5-HT1 and/or 5-HT2 receptors has been implicated in the angiogenic effect of 5-HT. The extracellular signal-regulated kinase and endothelial NO synthase (eNOS) activation-dependent pathways are involved in the mechanisms. Moreover, 5-HT4 receptors in ECs have been shown to also regulate angiogenesis. Recent reports show sarpogrelate, a selective antagonist of the 5-HT2A receptor, indirectly enhances the function of 5-HT1B receptors in ECs via inhibition of 5-HT2A receptors in VSMCs or platelets. This indirect action of 5-HT1B receptors in ECs may increase NO production derived from eNOS and a vasodilator response. Furthermore, sarpogrelate and other 5-HT2A receptor antagonists have been shown to reduce the constitutive activity of 5-HT2A receptors. It is believed that increasing evidence on the role of 5-HT receptors will contribute to the expansion of the clinical application of existing therapeutic drugs such as sarpogrelate, and to the development of new 5-HT receptor-related drugs for treating cardiovascular diseases.
The present paper proposes a new approach for fitting the plasma effect-site equilibrium rate constant (Ke0) of propofol to satisfy the condition that the effect-site concentration (Ce) is equal at the time of loss of consciousness (LOC) and recovery of consciousness (ROC). Forty patients receiving intravenous anesthesia were divided into 4 groups and injected propofol 1.4, 1.6, 1.8, or 2 mg/kg at 1200 mL/h. Durations from the start of injection to LOC and to ROC were recorded. LOC and ROC were defined as an observer’s assessment of alertness and sedation scale change from 3 to 2 and from 2 to 3, respectively. Software utilizing bisection method iteration algorithms was built. Then, Ke0 satisfying the CeLOC=CeROC condition was estimated. The accuracy of the Ke0 estimated by our method was compared with the Diprifusor TCI Pump built-in Ke0 (0.26 min−1), and the Orchestra Workstation built-in Ke0 (1.21 min−1) in another group of 21 patients who were injected propofol 1.4 to 2 mg/kg. Our results show that the population Ke0 of propofol was 0.53±0.18 min−1. The regression equation for adjustment by dose (mg/kg) and age was Ke0=1.42–0.30×dose–0.0074×age. Only Ke0 adjusted by dose and age achieved the level of accuracy required for clinical applications. We conclude that the Ke0 estimated based on clinical signs and the two-point fitting method significantly improved the ability of CeLOC to predict CeROC. However, only the Ke0 adjusted by dose and age and not a fixed Ke0 value can meet clinical requirements of accuracy.
Peroxisome proliferator-activated receptor γ (PPARγ) plays indispensable roles in adipogenesis, which is frequently impaired under pathological conditions such as non-alcoholic steatohepatitis (NASH). Thus, a potent PPARγ antagonist, T0070907 is known as a useful tool for understanding such pathological conditions, while T007097 was also suggested to have PPARγ-independent actions. In the present study, we found that T0070907 inhibited adipogenesis concomitantly with the induction of rapid apoptosis of immature adipocytes within 2 h, whereas another PPARγ antagonist, SR-202 did not show such cytotoxicity. However, T0070907 did not affect the viabilities of pre-adipocytes, mature adipocytes, and NIH-3T3 fibroblasts. The cytotoxic effect of T0070907 was not inhibited by GW1929, a PPARγ agonist, but was inhibited by α-tocopherol, which was previously shown to provide clinical benefit to NASH patients. Interestingly, treatment with high amounts of α-tocopherol alone slightly increased the cellular lipid content in mature adipocytes, but did not affect PPARγ-dependent luciferase reporter expression in COS-7 cells. Moreover, other lipophilic antioxidants, such as tocotrienols, tert-butylhydroquinone, and butylated hydroxyanisole, also inhibited T0070907-induced apoptosis like α-tocopherol. Consequently, it is suggested that T0070907 efficiently inhibits adipogenesis, not only via PPARγ-dependent manner, but also through the induction of apoptosis specifically against immature adipocytes via oxidative stress in a PPARγ-independent manner.
Protein kinase C (PKC) modulators are very attractive therapeutic targets in cancer. Since most cancer cells display increased glycolysis, elucidations of the effects of PKC activation on glycolysis is necessary for the development of effective medicine. In the present study, to clarify the role of PKC in the regulation of glycolysis, we examined the effect of phorbol 12-myristate 13-acetate (PMA), a PKC activator, on the expression and activity of glucose and lactic acid metabolism-related genes in human rhabdomyosarcoma cells (RD cells). In parallel to increases in glucose uptake and mRNA levels of glucose transporters (GLUTs) induced by PMA treatment for 6 h, the hexokinase (HK) mRNA level and activity were also significantly increased in RD cells. On the other hand, a significant increase in lactate dehydrogenase (LDH) mRNA level and activity was seen when the cells were incubated with PMA for 24 h, but not for 6 or 12 h, and was associated with lactic acid production. These effects by PMA treatment were markedly suppressed by Bisindolylmaleimide (BIM), a PKC inhibitor. Furthermore, chetomin, a hypoxia-inducible factor 1 (HIF-1) inhibitor, completely abrogated the increment of LDH mRNA level and activity as well as monocarboxylate transporter (MCT) 4, a lactic acid efflux transporter. In conclusion, we found that HK and LDH activity induced by PKC activation was associated with the glucose uptake and lactic acid level and that LDH and MCT4 are modulated by a common factor, HIF-1.
We examined the antifungal activity of various synthetic triamines on several fungi. Among various triamines having a general structure H2N(CH2)aNH(CH2)bNH2 (a=2–5, b=3–8), some triamines (a=4 or 5) showed inhibitory effect on the growth of Candida albicans and C. tropicalis. Determination of the minimum inhibitory concentrations (MICs) of these triamines on C. albicans showed that triamine 4–8 (a=4, b=8) and triamine 5–8 had strong antifungal activity. Further analysis revealed that the antifungal effect of triamine 4–8 was fungistatic and the antifungal effect was diminished by the addition of spermidine, a physiological triamine, to the medium. These results suggested that triamine 4–8 is antagonistic to spermidine and the antifungal activity is due to the suppression of the action of intrinsic polyamines. On the agar medium, C. albicans formed microcolonies even in the presence of triamine 4–8 by long cultivation. We then observed the form of C. albicans using microscope and found that the cells cultivated with triamine 4–8 were round, similar to the yeast form, while most of the cells on the agar medium without triamine 4–8 were hyphal form. Subsequently, we investigated the synergistic effect of two compounds with triamine 4–8, cyclohexylamine and dl-α-difluoromethylornithine which are inhibitors of enzymes involving in the biosynthesis of physiological polyamines such as spermidine. The results showed that the antifungal activity of triamine 4–8 increased by the addition of these enzyme inhibitors.
A triterpene saponin, glucoglycyrrhizin, was isolated from a glycyrrhizin-deficient strain 83-555 of Glycyrrhiza uralensis (Leguminosae), and the structure was determined by chemical and spectral data to be 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucuronopyranosyl]-glycyrrhetinic acid. Since this saponin has a 2′-O-β-D-glucopyranosyl moiety instead of the 2′-O-β-D-glucuronopyranosyl moiety of glycyrrhizin, the glucuronidation of 3-O-β-D-glucuronopyranosyl-glycyrrhetinic acid leading to glycyrrhizin is inhibited in this strain. All 4 offspring of the 83-555 strain produced glucoglycyrrhizin. Interestingly, 2 of the offspring produced both glycyrrhizin and glucoglycyrrhizin, and sequence analysis of the pkr gene suggested that these 2 offspring were hybrids of 83-555 strain and glycyrrhizin-producing strains.
Genetically modified (GM) chickens carrying the human erythropoietin (hEpo) gene have been developed to produce recombinant hEpo protein in eggs. However, such animals have not been approved as food sources in Japan. We developed a method for detecting the hEpo gene in chicken meat using a real-time polymerase chain reaction (real-time PCR). The hEpo gene was clearly detected in genomic DNA extracted from magnum and heart of a chimeric chicken containing the hEpo gene. A plasmid containing the hEpo gene was used as a standard reference molecule as well. The results clearly showed that our method was capable of detecting the hEpo gene contained in the plasmid in the presence of genomic DNA extracted from a raw chicken meat sample. We successfully used this method to test six samples of raw chicken meat and six samples of chicken meat in processed foods. This method will be useful for monitoring chicken meat that might have originated from GM chickens carrying the hEpo gene to assure food safety.
The myogenic differentiation of C2C12 myoblast cells is induced by the novel androgen receptor (AR) partial agonist, (17α,20E)-17,20-[(1-methoxyethylidene)bis-(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11), as well as by dihydrotestosterone (DHT). YK11 is a selective androgen receptor modulator (SARM), which activates AR without the N/C interaction. In this study, we further investigated the mechanism by which YK11 induces myogenic differentiation of C2C12 cells. The induction of key myogenic regulatory factors (MRFs), such as myogenic differentiation factor (MyoD), myogenic factor 5 (Myf5) and myogenin, was more significant in the presence of YK11 than in the presence of DHT. YK11 treatment of C2C12 cells, but not DHT, induced the expression of follistatin (Fst), and the YK11-mediated myogenic differentiation was reversed by anti-Fst antibody. These results suggest that the induction of Fst is important for the anabolic effect of YK11.
Diarylureas and diarylamides derivatives are reported to have antitumor activity. Encouraged by the interesting antiproliferative activity of diarylurea and diarylamide derivatives, we synthesized a new series of diarylureas and diarylamides containing pyrrolo[3,2-c]pyridine scaffold. In this study, we demonstrate that a N-(3-(4-benzamido-1H-pyrrolo[3,2-c]pyridin-1-yl)phenyl)-4-morpholino-3-(trifluoromethyl)benzamide, KIST101029, inhibits neoplastic cell transformation induced by insulin-like growth factor 1 (IGF-1) in mouse epidermal JB6 Cl41 cells. The KIST101029 compound inhibited mitogen-activated protein kinase/extracellular signal-regulated kinase kinases (MEK), c-jun N-terminal kinases (JNK), and mechanistic target of rapamycin (mTOR) signaling pathways induced by IGF-1 in JB6 Cl41 cells, resulting in the inhibition of c-fos and c-jun transcriptional activity. In addition, the KIST101029 inhibited the associated activator protein-1 (AP-1) transactivation activity and cell transformation induced by IGF-1 in JB6 Cl41 cells. Consistent with these observations, in vivo chorioallantoic membrane assay also showed that the KIST101029 inhibited IGF-1-induced tumorigenicity of JB6 Cl41 cells. Importantly, KIST101029 suppressed the colony formation of A375 cells in soft agar. Taken together, these results indicate that a KIST101029 might exert chemopreventive effects through the inhibition of phosphorylation of MAPK and mTOR signaling pathway.
Benzylacetone is released by heated agarwood, when inhaled it has a potent effect on reducing the locomotor activity of mice. This study investigated the relationships between the sedative activities of benzylacetone and its derivatives as well as the chemical structures of these compounds by comparing their activities in mice treated with a series of compounds. It was demonstrated that benzylacetone-like compounds had sedative activities and their intensities varied depending on the functional group in the carbon chain, the substituent in the benzene ring, and their combinations. A quantitative structure–activity relationship study was carried out using a series of 17 benzylacetone derivatives to determine the structural features with significant for the sedative activity.
Candida albicans is the most common fungal pathogen. Galleria mellonella is widely used as an infection model host. Nevertheless, the G. mellonella–C. albicans infection model had not been optimized for drug evaluation before this study. In this work, we revealed that 5×105 colony forming unit (CFU)/larva was a suitable inoculum to optimize the G. mellonella–C. albicans infection model in order to evaluate antifungal agents. Using our optimized model, the antifungal effect of fluconazole, amphotericin B and flucytosine, and the synergy between amphotericin B and flucytosine were successfully verified. Thus, this study provides a rapid, inexpensive and reliable way to evaluate antifungals in vivo.
Disintegration time is an important characteristic of orally disintegrating tablets (ODTs), and evaluation of disintegration time is a key step in formulation development, manufacturing, and clinical practice. In this study, we aimed to clarify the clinical disintegration time of ODTs that are currently used clinically, and to evaluate its correlation with the in vitro disintegration time of ODTs which was measured using Tricorptester, a newly developed disintegration testing apparatus. The clinical disintegration time of 17 ODT products was measured in healthy volunteers (n=9–10; age range, 21–28 years). A randomized single-blind trial was performed; each tablet was placed on the tongues of the participants, and it disintegrated in their oral cavities. No significant difference was observed in the clinical disintegration time of each ODT among the 3 groups to which the subjects were randomly assigned. The clinical disintegration time of the 17 ODT products was between 17.6 s and 33.8 s. The in vitro disintegration time of 26 clinically used ODT products measured using Tricorptester ranged between 4.40 s and 30.4 s. A significant positive correlation was observed between in vitro and clinical disintegration times (r=0.79; p<0.001). This study shows that all the tested products, which are clinically available in Japan, showed good disintegration and that the disintegration time varied according to the product. In addition, the in vitro disintegration time of ODTs measured using Tricorptester is a good reflection of the disintegration time in the oral cavity.
Azithromycin (AZM), a 15-membered ring macrolide antimicrobial agent, has an antibacterial spectrum that includes intracellular parasitic pathogens that survive or intracellularly multiply in alveolar macrophages (AMs). The subcellular distribution of AZM in AMs was evaluated in vitro in comparison with clarithromycin (CAM). AZM and CAM (50 µM) were applied to the NR8383 cells, used as an in vitro model of AMs, followed by incubation at 37°C or 4°C. The total amount of AZM in cells and subcellular distribution (cell fractionation) was determined after incubation. High level of AZM accumulation was observed in the NR8383 cells at 37°C, and the equilibrium intracellular to extracellular concentration ratio (I/E ratio) was approximately 680, which was remarkably higher than that of CAM (equilibrium I/E ratio=28). The intracellular accumulation of AZM and CAM was temperature dependent. In addition, AZM distributed to the granules fraction including organelles and soluble fraction including cytosol in the NR8383 cells, whereas CAM mainly distributed in soluble fraction. The amount of AZM in the granules fraction was markedly reduced in the presence of ammonium chloride for increase in intracellular pH. These results indicate that AZM is distributed in acidic compartment in AMs. This study suggests that high AZM accumulation in the NR8383 cells is due to the trapping and/or binding in acidic organelles, such as lysosomes.
This study examines the ability of vitamin E to inhibit hyperoxia-induced loss of soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins in the neuronal cytoplasm. Here, the effects of vitamin E on hyperoxia-induced changes in the expressions of N-ethylmaleimide-sensitive factor (NSF) and soluble NSF-attachment protein α (α-SNAP) in the rat brain were analyzed. When rats were subjected to hyperoxia, the expression of both SNARE proteins was markedly decreased compared to normal rats. Vitamin E significantly inhibited the decrease in the expression of NSF in rats subjected to hyperoxia. Rats showed the tendency to improve the loss of α-SNAP by vitamin E-supplementation, although it was not statistically significant. On the other hand, vitamin E deficient rats showed marked loss of these proteins in the brain in the absence of oxidative stress. These results suggest that hyperoxia induces a loss of SNARE proteins, which are involved in membrane docking between synaptic vesicles and pre-synaptic membranes, and that vitamin E prevents the oxidative damage of SNARE proteins. Consequently, it is implied that vitamin E inhibits impaired neurotransmission caused by oxidative stress through the prevention of oxidative damage to SNARE proteins by probably its antioxidant effect.
Okadaic acid is a C38 fatty acid derivative that is known to specifically inhibit the activity of protein phosphatase 2A (PP2A). Previously, we reported that inhibition of PP2A by okadaic acid elicited extracellular signal-regulated kinase (ERK) activation, and that PP2A may be involved in melanogenesis. However, the effects of okadaic acid on melanogenesis have not been completely evaluated. In the present study, we investigated the molecular mechanisms involved in okadaic acid modulation of melanin synthesis in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment with okadaic acid inhibited melanin production in a dose-dependent manner. Moreover, okadaic acid led to a decrease in tyrosinase protein levels without altering mRNA expression. Therefore, we investigated whether the decreased level of tyrosinase by okadaic acid was related to proteasomal degradation of tyrosinase. We found that MG132, a proteasome inhibitor, almost completely abolished both the downregulation of tyrosinase levels and the inhibition of melanin synthesis by okadaic acid. Taken together, our data indicate that okadaic acid inhibits melanin synthesis via proteasomal degradation of tyrosinase.
Drugs containing the carboxylic functional group can be metabolized to form acylglucuronides believed to cause idiosyncratic drug toxicity when the acylglucuronide is unstable. Recent studies have shown that the half-life of an acylglucuronide in phosphate buffer is the best means for classifying acylglucuronides into safe, warning, and withdrawn drugs. However, it is difficult to halt the late stage development of new chemical entities due to the instability of their acylglucuronides. We report an optimized in vitro method for determining the half-lives of acylglucuronides in simple phosphate buffer without the need for authentic standards. The experiment was divided into two incubations. In the first incubation, acylglucuronide was synthesized by human liver microsomes, and in the second incubation, the degradation rate of acylglucuronide in phosphate buffer was determined. The degradation rate constants of acylglucuronides were determined from changes in the LC-MS/MS peak area and the half-lives were calculated. We evaluated the half-lives of 10 drugs: 3 safe drugs (telmisartan, gemfibrozil and flufenamic acid) and 7 withdrawn or warning drugs (zomepirac, diclofenac, furosemide, ibuprofen, S-naproxen, probenecid and tolmetin). The half-lives of the 3 safe drugs were 10.6 h or longer, whereas the half-lives of the 7 withdrawn or warning drugs were 4.0 h or shorter. Although authentic acylglucuronide standards were not used, we obtained half-lives of acylglucuronides in phosphate buffer similar to those reported previously. Using this method, the risk of reactivity caused by acylglucuronides can be evaluated in the early stages of drug discovery.
In this study, we examined the substrate specificity and inhibitor sensitivity of rabbit 20α-hydroxysteroid dehydrogenase (AKR1C5), which plays a role in the termination of pregnancy by progesterone inactivation. AKR1C5 moderately reduced the 3-keto group of only 5α-dihydrosteroids with 17β- or 20α/β-hydroxy group among 3-ketosteroids. In contrast, the enzyme reversibly and efficiently catalyzed the reduction of various 17- and 20-ketosteroids, including estrogen precursors (dehydroepiandrosterone, estrone and 5α-androstan-3β-ol-17-one) and tocolytic 5β-pregnane-3,20-dione. In addition to the progesterone inactivation, the formation of estrogens and metabolism of the tocolytic steroid by AKR1C5 may be related to its role in rabbit parturition. AKR1C5 also reduced various non-steroidal carbonyl compounds, including isatin, an antagonist of the C-type natriuretic peptide receptor, and 4-oxo-2-nonenal, suggesting its roles in controlling the bioactive isatin and detoxification of cytotoxic aldehydes. AKR1C5 was potently and competitively inhibited by flavonoids such as kaempferol and quercetin, suggesting that its activity is affected by ingested flavonoids.
Lignans of Forsythia spp. are essential components of various Chinese medicines and health diets. However, the seasonal alteration in lignan amounts and the gene expression profile of lignan-biosynthetic enzymes has yet to be investigated. In this study, we have assessed seasonal alteration in amounts of major lignans, such as pinoresinol, matairesinol, and arctigenin, and examined the gene expression profile of pinoresinol/lariciresinol reductase (PLR), pinoresinol-glucosylating enzyme (UGT71A18), and secoisolariciresinol dehydrogenase (SIRD) in the leaf of Forsythia suspense from April to November. All of the lignans in the leaf continuously increased from April to June, reached the maximal level in June, and then decreased. Ninety percent of pinoresinol and matairesinol was converted into glucosides, while approximately 50% of arctigenin was aglycone. PLR was stably expressed from April to August, whereas the PLR expression was not detected from September to November. In contrast, the UGT71A18 expression was found from August to November, but not from April to July. The SIRD expression was prominent from April to May, not detected in June to July, and then increased again from September to November. These expression profiles of the lignan-synthetic enzymes are largely compatible with the alteration in lignan contents. Furthermore, such seasonal lignan profiles are in good agreement with the fact that the Forsythia leaves for Chinese medicinal tea are harvested in June. This is the first report on seasonal alteration in lignans and the relevant biosynthetic enzyme genes in the leaf of Forsythia species.