Computational identification of novel signature of T2DM-induced nephropathy and therapeutic bioactive compounds from Azanza garckeana

OBJECTIVES

Diabetic nephropathy (DN) is one of the most prevalent secondary complications associated with diabetes mellitus. Decades of research have implicated multiple pathways in the etiology and pathophysiology of diabetic nephropathy. There has been no reliable predictive biomarkers for the onset or progression of DN and no successful treatments are available.

METHODS

In the present study, we explored the datasets of RNA sequencing data from patients with Type II diabetes mellitus (T2DM)-induced nephropathy to identify a novel gene signature. We explored the target bioactive compounds identified from Azanza garckeana, a medicinal plant commonly used by the traditional treatment of diabetes nephropathy.

RESULTS

Our analysis identified lymphotoxin beta (LTB), SRY-box transcription factor 4 (SOX4), SOX9, and WAP four-disulfide core domain protein 2 (WFDC2) as novel signatures of T2DM-induced nephropathy. Additional analysis revealed the pathological involvement of the signature in cell-cell adhesion, immune, and inflammatory responses during diabetic nephropathy. Molecular docking and dynamic simulation at 100 ns conducted studies revealed that among the three compounds, Terpinen-4-ol exhibited higher binding efficacies (binding energies (ΔG) = -3.9~5.5 kcal/mol) against the targets. The targets, SOX4, and SOX9 demonstrated higher druggability towards the three compounds. WFDC2 was the least attractive target for the compounds.

CONCLUSION

The present study was relevant in the diagnosis, prognosis, and treatment follow up of patients with diabetes induced nephropathy. The study provided an insight into the therapeutic application of the bioactive principles from Azanza garckeana. Continued follow-up invitro validations study are ongoing in our laboratory.

Therapeutic potential of EGFR/mTOR/Nf-kb targeting small molecule for the treatment of non-small cell lung cancer

Despite the therapeutic advancement with chemotherapy and targeted therapy against non-small-cell lung cancer (NSCLC), most patients ultimately develop resistance to these drugs, exhibiting disease progression, metastasis, and worse prognosis. There is, therefore, a need for the development of novel multi-targeted therapies that can offer a high therapeutic index with lesser chances of drug resistance against NSCLC. In the present study, we evaluated the therapeutic potential of a novel multi-target small molecule NLOC-015A for targeted treatment of NSCLC. Our in vitro studies revealed that NLOC-015A exhibited a broad spectrum of anticancer activities against lung cancer cell line. NLOC-015A decreased the viability of H1975 and H1299 cells with respective IC₅₀ values of 2.07±0.19 and 1.90±0.23 µm. In addition, NLOC-015A attenuated the oncogenic properties (colony formation, migratory ability, and spheroid formation) with concomitant downregulation of expression levels of epidermal growth factor receptor (EGFR)/mammalian target of rapamycin (mTOR)/AKT, nuclear factor (NF)-κB, signaling network. In addition, the stemness inhibitory effect of NLOC0-15A was accompanied by decreased expression levels of aldehyde dehydrogenase (ALDH), MYC Proto-Oncogene (C-Myc), and (sex-determining region Y)-box 2 (SOX2) in both H1975 and H1299 cell lines. Furthermore, NLOC-015A suppressed the tumor burden and increased the body weight and survival of H1975 xenograft-bearing mice. Treatment with NLOC-015A also attenuated biochemical and hematological alterations in the tumor bearing mice. Interestingly, NLOC-015A synergistically enhanced the in vitro efficacy, and therapeutic outcome of osimertinib in vivo. In addition, the toxicity of osimertinib was significantly attenuated by combination with NLOC-015A. Altogether, our findings suggested that combining osimertinib with NLOC-015 appears to be a promising way to improve osimertinib's efficacy and achieve better therapeutic results against NSCLC. We therefore suggest that NLOC-015A might represent a new candidate for treating NSCLC via acting as a multitarget inhibitor of EGFR/mTOR/NF-Κb signaling networks and efficiently compromising the oncogenic phenotype of NSCLC.

In silico repurposing of midostaurin as a therapeutic candidate for head and neck cancer via targeting SPARC/MMP9/CD44 Cancer-Associated Fibroblasts (CAFs) oncogenic signature

Head and neck squamous carcinoma (HNSCC) affects more than half a million individuals and ranks the ninth leading cause of death globally each year. Many patients develop treatment resistance leading to poor clinical outcomes. The poor treatment responses are in part due to the heterogeneity of HNSCC tumor and tumor microenvironment (TME). The interaction of tumor cells with their TME has been studied vigorously in recent years because of their pivotal roles in tumorigenesis and determining the treatment response. Cancer-associated fibroblasts (CAFs) are one of the most abundant tumor-infiltrating cells, which have been shown to associate with the aggressive behavior of HNSCC. Hence, targeting and disrupting the tumor-CAFs interactions represents a rational therapeutic approach. To develop targeted therapeutic drugs against CAFs, the identification of CAF-associated gene signature is essential. Here, we analyzed multiple sequencing databases including microarrays and single-cell RNA-sequencing databases and identified SPARC/MMP9/CD44 as HNSCC targetable gene signatures encompassing cancer-associated fibroblasts (CAFs). We found SPARC/MMP9CD44 signature was highly expressed in HNSC tissues compared to adjacent normal tissues. Increased SPARC/MMP9/CD44 signature levels strongly correlated with tumor-infiltrating CAFs, suggesting the functional importance of this signature for HNSCC-CAFs interaction and progression. Subsequently, we utilized a genomics approach and identified midostaurin as the top-ranking drug candidate for targeting SPARC/MMP9/CD44 signature. For validation, we performed molecular docking of midostaurin in complex with SPARC/MMP9/CD44 and demonstrated midostaurin's high binding affinities compared to their respective standard inhibitors. In summary, our study provided a rapid genomics approach for identifying targetable gene signature and drug candidate for HNSCC.

Deciphering the immuno-pathological role of FLT, and evaluation of a novel dual inhibitor of topoisomerases and mutant-FLT3 for treating leukemia

Acute myeloid leukemia (AML) is a type of leukemia with an aggressive phenotype, that commonly occurs in adults and with disappointing treatment outcomes. Genetic alterations were implicated in the etiology of cancers and form the basis for defining patient prognoses and guiding targeted therapies. In the present study, we leveraged bulk and single-cell RNA sequencing datasets from AML patients to determine the clinical significance of Fms-related receptor tyrosine kinase 3 (FLT3) alterations on the T-cell phenotype and immune response of AML patients. Subsequently, we evaluated the therapeutic potential of Lwk-n019, a novel small-molecule derivative of thiochromeno[2,3-c]quinolin-12-one. Our results suggested that FLT3 plays an important role in the progression, aggressive phenotype, and worse immune response of patients. An FLT3 mutation was associated with dysfunctional T-cell phenotypes, and high risk and shorter survival of AML patients. Our findings further suggested that the aggressiveness of AML and the prognostic role of FLT3 are associated with the co-occurrence of NPM1 and DNMT3A mutations. Lwk-n019 demonstrated dose-dependent anticancer activities against various leukemia cancer cell lines. Lwk-n019 demonstrated highly selective kinase inhibitory activities against the wild-type FLT3 (D835V) and mutant FLT3 (internal tandem duplication (ITD), D835V) with >95% and 99% inhibitory levels, respectively. Moreover, the compound demonstrated the best binding constant (Kd value) of 0.77 µM against FLT3 (ITD, 835V). In addition, Lwk-n019 significantly inhibited the activities of both the topoisomerase I (TOPI) and TOPII enzymes, with higher TOPI inhibitory activity than camptothecin, a clinical inhibitor. While the jejunum, duodenum, cecum, and colon were prime sites of absorption, Lwk-n019 achieved maximum concentration (Cmax), Vd, blood/plasma ratio, time to maximum concentration (Tmax), area under the receiver operating concentration curve (AUC)_(0-24), and AUC_(0-∞) values of 0.665 µg/mL, 5.21 Vc, L/kg, 1.5 h, 6634.7, and 6909.2, respectively. In conclusion, Lwk-n019 demonstrated anticancer activities via multi-target inhibition of TOPs and kinases with high inhibition preference for mutant ITD-FLT3. The present pioneer study provides a basis for advanced optimization of drug potency, selectivity, specificity, and other properties desired of anticancer drug leads. Studies are ongoing to determine the full therapeutic properties of Lwk-n019 and the detailed mechanisms of FLT3 in TOP inhibition.

Erratum: A preclinical report of a cobimetinib-inspired novel anticancer small-molecule scaffold of isoflavones, NSC777213, for targeting PI3K/AKT/mTOR/MEK in multiple cancers

[This corrects the article on p. 2590 in vol. 11, PMID: 34249417.].

A preclinical report of a cobimetinib-inspired novel anticancer small-molecule scaffold of isoflavones, NSC777213, for targeting PI3K/AKT/mTOR/MEK in multiple cancers

The phosphatidylinositol 3-kinase (PI3K)/protein kinase B/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) signaling pathways are critical for normal human physiology, and any alteration in their regulation leads to several human cancers. These pathways are well interconnected and share a survival mechanism for escaping the depressant effect of antagonists. Therefore, novel small molecules capable of targeting both pathways with minimal or no toxicity are better alternatives to current drugs, which are disadvantaged by their accompanying resistance and toxicity. In this study, we demonstrate that the PI3K/AKT/mTOR/MEK is a crucial oncoimmune signature in multiple cancers. Moreover, we describe NSC777213, a novel isoflavone core and cobimetinib-inspired small molecule, which exhibit both antiproliferative activities against all panels of NCI60 human tumor cell lines (except COLO205 and HT29) and a selective cytotoxic preference for melanoma, non-small-cell lung cancer (NSCLC), brain, renal, and ovarian cancer cell lines. Notably, for NSC777213 treatment, chemoresistant ovarian cancer cell lines, including SK-OV-3, OVCAR-3, OVCAR-4, and NCI/ADR-RES, exhibited a higher antiproliferative sensitivity (total growth inhibition (TGI) = 7.62-31.50 µM) than did the parental cell lines OVCAR-8 and IGROV1 (TGI > 100 µM). NSC777213 had a mechanistic correlation with clinical inhibitors of PI3K/AKT/mTOR/MEK. NSC777213 demonstrates robust binding interactions and higher affinities for AKT and mTOR than did isoflavone, and also demonstrate a higher affinity for human MEK-1 kinase than some MEK inhibitors under clinical developments. In addition, treatment of U251 and U87MG cells with NSC777213 significantly downregulated the expression levels of the total and phosphorylated forms of PI3K/AKT/mTOR/MEK. Our study suggests that NSC777213 is a promising PI3K/AKT/mTOR/MEK inhibitor for further preclinical and clinical evaluation as a chemotherapeutic agent, particularly for the treatment of NSCLC, melanoma, and brain, renal, and ovarian cancers.

Erratum: Preclinical investigation of ovatodiolide as a potential inhibitor of colon cancer stem cells via downregulating sphere-derived exosomal β-catenin/STAT3/miR-1246 cargoes

[This corrects the article on p. 2337 in vol. 10, PMID: 32905416.].

Preclinical investigation of ovatodiolide as a potential inhibitor of colon cancer stem cells via downregulating sphere-derived exosomal β-catenin/STAT3/miR-1246 cargoes

Patients with advanced-stage colon cancer often exhibit resistance against treatment and distant metastasis, both key contributors to poor prognosis. Emerging evidence indicates that cancer stem cells (CSCs), characterized by the enhanced ability to self-renew, resist therapeutics, and promote metastasis, represents a clinical challenge to target. Alternative therapeutic approaches are urgently required. Here, we explored the feasibility of disrupting the intracellular communications between CSCs and the tumor microenvironment by way of exosomes. First, we demonstrated that exosomes secreted by colon tumorspheres (Exo^sp) promoted 5-FU resistance, migration, and tumorsphere formation. Exo^sp also increased the generation of cancer-associated fibroblasts and M2 polarized macrophages in vitro. Oncogenic molecules, including IL-6, p-STAT3, TGF-β1, and β-catenin, were identified as the cargoes of Exo^sp. Furthermore, the public database revealed the high abundance of miR-1246 in serum exosomes from colon cancer patients, and we verified in the Exo^sp from HCT116 and HT29 cells. Therapeutically, we demonstrated the ovatodiolide treatment reduced exosomal cargoes from tumorspheres (Exo^sp_OV). Exo^sp_OV were significantly less capable of promoting 5-FU resistance, migration, and tumorsphere formation when co-cultured with HCT116 and HT29 cells. Notably, Exo^sp_OV was less CAF- and M2 TAM-transformative. Computational docking analysis revealed that OV could bind and significantly reduced β-catenin activity. Finally, mouse xenograft data indicated that ovatodiolide suppressed tumor growth via down-regulating IL-6, STAT3, β-catenin expression, and serum exosomal miR-1246. In conclusion, our findings provided preclinical supports for ovatodiolide as a colon CSC inhibitor by reducing β-catenin/STAT3/miR-1246 signaling conveyed by CSC derived exosomes.

The identification and validation of Trichosstatin A as a potential inhibitor of colon tumorigenesis and colon cancer stem-like cells

Colon cancer is one of the most prevalent cancer types in developed countries. Metastasis and drug resistance are two contributing factors to the high mortality rate. Accumulating evidence suggest that cancer stem-like cells (CSCs) represents as a major contributor to these malignant features. Here, we identified and isolated colon cancer stem-like cells using side-population (SP) method from human colon cancer cell lines. SP colon cells demonstrate cancer stem-like cell properties including enhanced sphere-forming ability and resistance towards fluorouracil (5-FU). The CSC properties were associated with the increased expression level of major oncogenic and stem cell markers including β-catenin, NF-kB, Akt/mTOR, KRAS and c-Myc. Trichostatin A (TSA), an antifungal antibiotic also a HDAC inhibitor, was found to function not only to decrease the expression of oncogenic markers but also the colon CSC properties. Importantly, TSA and 5-FU combined treatment synergistically suppressed colon cancer viability. Finally, in vivo results demonstrated that TSA alone and in combination with 5-FU effectively suppressed colon tumorigenesis. Collectively, this study provides preclinical evidence that TSA may function as a potential colon cancer therapeutic agent by targeting CSC and overcoming 5-FU resistance.

Cyproheptadine use in hepatocellular carcinoma

This study was conducted to compare the effectiveness of Cyproheptadine (CY) use in patients with different stages of HCC who received different therapeutic modalities; such a comparison has not been conducted by previous large, prospective, randomized studies. We conducted a cohort study using the Taiwan Cancer Registry Database for analysis. We included patients diagnosed as having HCC from January 1, 2002, to December 31, 2011. The patient cohort comprised those who received different treatments, and we compared patients who received CY with those who did not. In total, 70,885 patients were included, and the mean follow-up duration was 1.95 years. The adjusted hazard ratio (aHR) of all-cause deaths significantly decreased in all stages in the patients who received palliative treatments with CY use compared with those who received palliative treatments without CY use (all P < 0.0001 and aHR = 0.76, 0.80, 0.66, and 0.66 for stages I, II, III, and IV, respectively). Among the patients who received no treatment, CY use alone reduced the risk of all-cause deaths in stages I-IV (all P < 0.0001 and aHR = 0.61, 0.57, 0.54, and 0.52 for stages I, II, III, and IV, respectively). Among the patients with clinical stage I-II HCC (as determined by the American Joint Committee on Cancer) who received curative treatments, CY use did not reduce all-cause deaths. CY use might improve survival in patients with HCC receiving palliative treatments or no treatment regardless of clinical stages.

Folate deficient tumor microenvironment promotes epithelial-to-mesenchymal transition and cancer stem-like phenotypes

Clinically, serum level of folate has been negatively correlated to the stage and progression of liver cancer. Nevertheless, the functional consequence of folate deficiency (FD) in malignancy has not been fully investigated. Human hepatocellular carcinoma (HCC) cells (as study model) and other cancer types such as lung and glioma were cultured under folate deficient (FD) and folate complete (FD) conditions. Molecular characterization including intracellular ROS/RNS (reactive oxygen/nitrogen species), viability, colony formation, cancer stem-like cell (CSC) phenotype analyses were performed. In vivo tumorigenesis under FD and FC conditions were also examined. FD induced a significant increase in ROS and RNS, suppressing proliferative ability but inducing metastatic potential. Mesenchymal markers such as Snail, ZEB2, and Vimentin were significantly up-regulated while E-cadherin down-regulated. Importantly, CSC markers such as Oct4, β-catenin, CD133 were induced while PRRX1 decreased under FD condition. Furthermore, FD-conditioned HCC cells showed a decreased miR-22 level, leading to the increased expression of its target genes including HDAC4, ZEB2 and Oct4. Finally, xenograft mouse model demonstrated that FD diet promoted tumorigenesis and metastasis as compared to their FC counterparts. Our data provides rationales for the consideration of folate supplement as a metastasis preventive measure.

Abstract 222: Anticancer effects of Withaferin A on UP-LN1 carcinoma cells through the inhibition of STAT3 phosphorylation and IFN-γ-mediated induction of metastatic cancer stem cells

Cancer stem cells (CSCs) have been defined as a subpopulation of cancer cells with the ability of self-renewal, giving rise to different progenies, and transition between epithelial and mesenchymal status in response to the tumor microenvironment. Due to the lack of an appropriate cell model, our understanding of CSC biology remains poor and the development of CSC antagonists is challenging. We herein used the UP-LN1 cell line as a CSC model which was derived from a gastrointestinal tumor-to-lymph node metastasis lesion. UP-LN1 cells constitute two major components, the floating (F) and adherent (A) cells. F cells were identified as the primary niche of CSCs, and could be serially subcultured while maintaining their stem-like properties including high self-renewal potential, formation of suspended grape-like aggregates and/or spheres, resistance to multiple drugs and NK/LAK effectors, as well as an increased CDY1 (a novel iPS probe) dye retention. Using this cell model, we demonstrated that Withaferin A (WA) dramatically reduced the proliferation of F cells and their ability to form aggregates in vitro. WA also dose-dependently reduced the side population cells. Mechanistically, WA treatment resulted in the down-regulation of two axes, CXCR4 and STAT3, both instrumental in the acquisition of metastatic ability and the development/maintenance of CSCs. We validated the in vitro results using non-invasive imaging technique in a xenograft mouse model. WA-treated animals demonstrated a marked decrease in tumor burden and metastasis, indicating that WA is potentially an effective agent for targeting CSCs.

Citation Format: Chi-Tai Yeh, Alexander TH Wu, Hung-Chang Chen, Cheng-Keng Chuang, See-Tong Pang, Shuen-Kuei Liao. Anticancer effects of Withaferin A on UP-LN1 carcinoma cells through the inhibition of STAT3 phosphorylation and IFN-γ-mediated induction of metastatic cancer stem cells . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 222. doi:10.1158/1538-7445.AM2013-222

Abstract 229: Pterostilbene suppresses the generation of breast cancer stem cells within tumor microenvironment and metastasis via modulating NF-κB/microRNA448 circuit

Tumor microenvironment plays a key role in promoting epithelial-to-mesenchymal transition (EMT), a cellular step for cancer cells to gain metastatic ability and is also associated to the generation of cancer stem cells (CSCs). Agents capable of modulating the tumor microenvironment could be more efficient in managing tumor progression. Pterostilbene, a natural stilbene isolated from blueberries have been suggested for its anti-cancer effects. Here, we explored the potential microenvironment modulating effects of pterostilbene in a M2-polarized macrophages (M2 TAMs) and breast cancer cell co-culture system. We first demonstrated that co-culturing with M2 TAMs increased the percentage of CD44+/CD24- CSC population and migratory/invasive abilities. We then showed that pterostilbene treatment dose-dependently overcame M2 TAM-induced enrichment of CSCs and metastatic potential of breast cancer cells. Mechanistically, pterostilbene suppressed NFκB, Twist1, Vimentin and increased E-cadherin expression. Importantly, pterostilbene-mediated NFκB downregulation was correlated to an increased amount of microRNA448. Finally, using non-invasive bioluminescence technique we demonstrated that pterostilbene treatment significantly suppressed M2 TAM co-cultured MDA-MB-231 tumorigenesis and metastasis. Thus, pterostilbene could be a potential anti-CSC agent for clinical development.

Citation Format: Chi-Tai Yeh, Jeng-Fong Chiou, Chih-Hsiung Wu, Alexander TH Wu. Pterostilbene suppresses the generation of breast cancer stem cells within tumor microenvironment and metastasis via modulating NF-κB/microRNA448 circuit. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 229. doi:10.1158/1538-7445.AM2013-229

Effects of calcium entry blocker (nicardipine) tocolysis in rhesus macaques: fetal plasma concentrations and cardiorespiratory changes

Tocolytic doses of nicardipine, a dihydropyridine calcium entry blocker, were administered to chronically catheterized rhesus monkeys between days 128 and 132 of gestation. During periods of spontaneous uterine contractility, a 500 micrograms nicardipine bolus was injected intravenously, and this was followed by continuous infusion (6 micrograms/kg/min) to the mother for 1 hour. Uterine activity (amniotic fluid pressure) and maternal heart rate and blood pressure were monitored continuously. Paired maternal and fetal blood samples were drawn at frequent intervals to monitor pH, PO2, PCO2, and plasma nicardipine concentrations. Peak maternal nicardipine concentrations ranged from 175 to 865 ng/ml while peak fetal levels ranged from 7 to 35 ng/ml. Fetal heart rate and blood pressure were unaffected. However, fetuses became acidotic (pH 7.26 +/- 0.01 versus 7.33 +/- 0.01) and hypoxemic (PO2 16.0 +/- 3.2 versus 24.5 +/- 2.0 mm Hg) after maternal nicardipine treatment (p less than 0.01). Despite the fact that maternal nicardipine treatment exerted a significant tocolytic effect, the undesirable fetal side effects are of concern and deserve further investigation.

Ketorolac tromethamine absorption, distribution, metabolism, excretion, and pharmacokinetics in animals and humans

Ketorolac tromethamine (KT), a potent non-narcotic analgesic, with cyclooxygenase inhibitory activity, was administered (14C-labeled and unlabeled) intravenously (iv), orally (po), and intramuscularly (im) in solution to humans, cynomolgus monkeys, rabbits, rats, and mice. KT was absorbed rapidly (Tmax less than 1.0 hr) and efficiently (greater than 87%) following po and im doses in all species. The plasma half-life of ketorolac (K) ranged from 1.1 hr (rabbits) to 6.0 hr (humans). The protein binding of K ranged from 72.0% (mouse) to 99.2% (humans). Linear pharmacokinetics of K was observed in the mouse after single oral doses of KT ranging from 0.25 to 16 mg/kg. Radioactivity was excreted predominantly into urine, ranging from 78.9% (mouse) to 102% (monkey) following iv doses. The dose was excreted into urine primarily as K conjugates, K, and p-hydroxy-K in humans. The monkey was similar to humans with respect to kinetics, but did not form the p-hydroxy metabolite. The rabbit was unusual in that it exhibited substantial presystemic metabolism (50%). The rat excreted a much higher percentage of radioactivity into the feces and formed an additional unidentified metabolite. The most comparable species with respect to humans metabolically was the mouse. The metabolism and excretion of K was similar following iv, po, and im doses within each species studied.

Capillary column gas chromatographic method using electron-capture detection for the simultaneous determination of nicardipine and its pyridine metabolite II in plasma

A rapid, specific and direct method based on capillary column gas chromatography with electron-capture detection is described for the simultaneous determination of nicardipine, a new calcium antagonist, and its pyridine metabolite II in human plasma. In this method, the nicardipine, its pyridine metabolite II and internal standard are extracted from the plasma and then partially purified by acid-base partitioning prior to the final injection onto the capillary column gas chromatograph for quantification by means of an electron-capture detector. The quantification limit of the method is 1 ng/ml of plasma for both nicardipine and its pyridine metabolite II. The coefficients of variation for nicardipine and the pyridine metabolite II at concentrations of 1-50 ng/ml are less than 7% and less than 9% (n = 4), respectively. The method has been validated against a previously developed high-performance liquid chromatographic method (sensitivity 5 ng/ml).

A high-performance liquid chromatographic method for the simultaneous determination of nicardipine and its pyridine metabolite II in plasma

A rapid and specific method in which reverse-phase high-performance liquid chromatography (HPLC) with UV detection was used for the simultaneous determination of nicardipine and its pyridine metabolite II in human plasma is described. Nicardipine, its pyridine metabolite II, and the internal standard were extracted from plasma and partially purified by acid-base partitioning. Final purification and quantitation were achieved by HPLC by using a reverse-phase column and a UV detector (254 nm). The extraction efficiencies for nicardipine and its pyridine metabolite II from 1 mL of plasma were 77.4 and 81.1%, respectively. The sensitivity of the assay was 5 ng/mL for both nicardipine and its pyridine metabolite II, and the linear concentration range of the assay was 5-150 ng/mL for both compounds. The low coefficients of variation (less than or equal to 5%) for samples spiked with nicardipine and its pyridine metabolite II in this concentration range demonstrate good reliability and reproducibility of the assay. The HPLC procedure has been validated by comparison with a GC-electron-capture detection (ECD) procedure, which gives the combined concentration of nicardipine-its pyridine metabolite II (total) and with an HPLC/GC-ECD procedure, which gives the concentration of its pyridine metabolite II. All three methods, which were developed in our laboratory, were used to analyze nicardipine and its pyridine metabolite II in specimens of plasma from subjects treated with nicardipine hydrochloride. Good correlations were found for concentrations of nicardipine, its pyridine metabolite II, and nicardipine plus the metabolite determined by these three procedures. The HPLC procedure is suitable for use in pharmacokinetic studies following administration of nicardipine hydrochloride to humans.

Transformation of arachidonate into 6-oxoprostaglandin F1 alpha, thromboxane B2 and prostaglandin E2 by sheep lung microsomal fraction

In the presence of haemoglobin and isoproterenol, the microsomal fraction of sheep lung catalysed the conversion of arachidonate predominantly into thromboxane B2 and to a lesser extent into 6-oxoprostaglandin F1alpha. Very little prostaglandin E2 and prostaglandin F2alpha were formed. If reduced glutathione was added in combination with haemoglobin and isoproterenol, the synthesis of prostaglandin E2 was favoured over that of thromboxane B2 and 6-oxoprostaglandin F1alpha. The identities of these products were confirmed by t.l.c. and by combined g.l.c.-mass spectrometry. These results indicate that microsomal fraction of sheep lung possesses active prostaglandin synthase, prostacyclin synthase and thromboxane synthase activities.

Hydroxylated metabolies of R,S-1-(tetrahydro-2-furanyl)-5-fluorouracil (Ftorafur) in rats and rabbits

Two hydroxylated metabolies (M1 and M2) have been isolated from rabbit urine after administration of Ftorafur (FT). The structures of 3'-OH-FT and 4'-OH-FT were assigned to M1 and M2, respectively. A reverse-phase high performance liquid chromatography assay was developed for jeasuring FT, M1, M2, and 5-fluorouracil (FU) plasma levels. M1, M2, and FU were present in rabbit and rat plasma in greatly varying concentrations after FT administration. Pharmacokinetic studies suggest that FU formation proceeds via metabolic intermediate(s) and that the extent of FT activation is variable. A horse liver thymidine phosphorylase ,reparation capable of catalyzing the conversion of beta-ribo-2'-deoxy-5-fluorouracil to FU was inactive against FT and M1. However, 20% of M2 was converted to FU by this enzume, which suggests that the urinary metabolite M2 consisted of a mixture of enantiomers with 20% present in the natural beta-D configuration. The stereochemistry of M1 remains unknown. Hydroxylation of FT to beta-D-4'-OH-FT and subsequent cleavage to FU by thymidine phosphorylase represents one possible activation mechanism of FT to FU. ,owever, lack of correlation between plasma levels of M2 and FU indicates that this mode of metabolic activation may account for only part of the overall activation of FT in vivo.

Determination of ftorafur and 5-fluorouracil levels in plasma and urine

A gas chromatographic method was developed for ftorafur (Ft) detection in plasma and urine with a sensitivity of 1 mug/ml. Specific determination of its metabolite 5-fluorouracil (FU) with a sensitivity of 1 ng/ml was achieved by column chromatographic separation from Ft and subsequent gas chromatography-mass spectrometry of bis-silyl-FU in the selected ion mode (GC-MS-SIM) using bis-15N-FU as internal standard. Intravenous injections of 2-14C-Ft and 2',5'-14C-Ft were given to rats and rabbits respectively, and plasma and urine were analyzed for Ft, and 14C activity. Unchanged Ft accounted for most of the 14C activity in plasma, while FU concentrations were below 0.15% and 0.4% relative to Ft concentrations in the rabbit and the rat, respectively. 30-60% of the urinary 14C activity was unchanged Ft and less than 0.2% FU. The significance or low FU levels is discussed in view of the hypothesis that Ft acts as a transport form of its metabolite FU.