Interaction of novel thiocolchicine analogs with the tubulin isoforms from bovine brain

The antimitotic alkaloid colchicine binds to tubulin and inhibits microtubule assembly. Recently a new series of colchicine derivatives has been synthesized in which the seven-membered B-ring was shortened to a six-membered ring. In an effort to study the role of the B-ring substituents in this new series, we have studied the interaction of two compounds of this series, THC 5 and THC 18, with tubulin isoforms from bovine brain. We find that THC 18, which has a side chain with a pi-bonded SP2 conformation, binds differently to the tubulin isoforms, while THC 5 with a slightly different side chain does not. The results indicate that the conformation of the B-ring domain plays a major role in the differential interaction of a colchicine derivative with different tubulin isoforms. The results will be very important in designing potent antitumor derivatives of colchicine.

Synthesis and anticancer evaluation of certain alpha-methylene-gamma-(4-substituted phenyl)-gamma-butyrolactone bearing thymine, uracil, and 5-bromouracil

Certain alpha-methylene-gamma-(4-substituted phenyl)-gamma-butyrolactone bearing thymine, uracil, and 5-bromouracil were synthesized and evaluated for their anticancer activity. These compounds demonstrated a strong growth inhibitory activity against leukemia cell lines. The anticancer potency for the substituents of the lactone C(gamma)-phenyl is in an order of 4-Ph > 4-Cl, 4-Br > 4-Me, 4-NO2 > 4-F. For the pyrimidine portion, 5-bromouracil is more potent than uracil and thymine.

Substituted 7H-pyrido[4,3-c]carbazoles with potent anti-HIV activity

Several substituted 7H-pyrido[4,3-c]carbazoles were synthesized from the natural product mukonal and tested for inhibition of HIV replication in H9 lymphocytes. 5-Methoxy-7-methyl-7H-pyrido[4,3-c]carbazole (7) had an EC50 value of 0.0054 microgram/mL and the highest therapeutic index (TI = 503) in the series.

Calcium-dependent interaction of annexin I with annexin II and mapping of the interaction sites

Annexins are multifunctional intracellular proteins with Ca2+- and phospholipid-binding properties. Their structures consist of four conserved repeat domains that form the core and a diverse N-terminal tail, from which their functional differences may arise. We searched for cellular proteins that interact with the N-terminal tail plus domain I of annexin I (ANX1) by using the yeast two-hybrid method. Screening of a HeLa cell cDNA library yielded annexin II (ANX2) cDNA. The interaction between ANX1 and ANX2 also occurred in vitro in a Ca2+-dependent manner. Mapping of the interaction sites revealed that interaction between domain I of ANX1 and domain IV of ANX2 was stronger than the other combinations.

Decreased formation of ethoxyacetic acid from ethylene glycol monoethyl ether and reduced atrophy of testes in male rats upon combined administration with toluene and xylene

Male painters are commonly exposed to ethylene glycol monoethyl ether (EGE), a well known reproductive toxic agent causing testicular atrophy, in the form of solvent mixture containing toluene (TOL) and xylene (XYL). This study was carried out to determine the effect of exposing male rats to solvent mixture containing TOL and XYL on the EGE (200 mg/kg) on testicular atrophy and production of toxic metabolite, ethoxyacetic acid (EAA) from EGE. Compared to the extent of testes atrophy observed upon EGE administration alone, the combined administration of EGE (200 mg/kg) with TOL (250 mg/kg) and XYL (500 mg/kg) for 4 weeks has reduced the extent of testes atrophy by 25%. The combined administration delayed the time for appearance of the highest plasma concentration (t(max)) of EAA from 3 to 6 h and also decreased the highest concentration (Cmax) as well as the total amount of plasma EAA (AUC(0-18 h)) by 45 and 29%, respectively. This explained the diminished testicular atrophy in male rats observed when EGE was administered in a solvent mixture containing TOL and XYL. This study suggested that testicular toxicity observed in male painters caused by EGE may be decreased when they are exposed to EGE in the form of solvent mixture containing TOL and XYL.

Testicular catch-up growth after varicocele correction in adolescents

We evaluated retrospectively the outcome of artery-sparing (AS) versus non-artery-sparing (NAS) laparoscopic varicocelectomy and measured any reversal of testicular growth. Twenty patients (13 left and 7 bilateral varicoceles) were evaluated after surgery. A total of 27 varicocelectomies (20 AS and 7 NAS) were performed. The indication for surgery was smaller testicular size on the affected side in all patients and discomfort/pain in 3. The mean age was 12.9 years (range 8-15 years) at surgery. The testicular volumes were determined clinically and by color Doppler sonography (US). The follow-up time was 6-48 months after surgery. There were 4 recurrences out of 27 varicocelectomies (15%), of which 1 has been reoperated. Testicular volumes were equal in both groups after surgery, indicating catch-up growth except in the cases with minor recurrences (2 AS and 2 NAS varicocelectomies). In 12 testes, dilated veins in the pampiniform plexus were revealed by US. No severe intraoperative complications occurred. Three patients had a hydrocele after surgery (11%). These data show that there is testicular catch-up growth after varicocelectomy, but some questions remain unanswered: (1) should the remaining dilated veins detected by Doppler US be tackled; and (2) is an AS operation worthwhile?

Structures and stereochemistry of pseudolarolides K and L, novel triterpene dilactones from pseudolarix kaempferi

Pseudolarolides K(1) and L(2), two novel triterpenedilactones, were isolated from the seeds of Pseudolarix kaempferi, and their structures characterized from spectral data.

Structure-activity relationship study: short antimicrobial peptides

Many short antimicrobial peptides (< 18mer) have been identified for the development of therapeutic agents. However, Structure-activity relationship (SAR) studies about short antimicrobial peptides have not been extensively performed. To investigate the relationship between activity and structural parameters such as an alpha-helical structure, a net positive charge and a hydrophobicity, we synthesized and characterized diastereomers, scramble peptides and substituted peptides of the short antimicrobial peptide identified by combinatorial libraries. Circular dichroism (CD) spectra and in vitro activity indicated that an alpha-helical structure correlated with the antimicrobial activity and a beta-sheet structure also satisfied a structural requirement for antimicrobial activity. Most peptides consisting of L-amino acids lost antifungal activity in the presence of heat-inactivated serum, while active diastereomers and a scramble peptide with the beta-sheet structure retained antifungal activity in the same condition.

A new taxoid, 19-acetoxytaxagifine, from Taxus chinensis

A new taxane diterpene, 19-acetoxytaxagifine (1), was isolated from an ethanol extract of the aerial parts of Taxus chinensis. Its structure was determined on the basis of spectral evidence.

Successful treatment with ganciclovir for cytomegalovirus duodenitis following allogenic bone marrow transplantation

Cytomegalovirus(CMV) disease is a major cause of morbidity and mortality in immunocompromised patients. CMV enteritis should be considered when nausea and vomiting continue 3 to 4 weeks after bone marrow transplantation(BMT). The treatment of CMV enteritis is not well established. We report a CMV duodenitis patient following allogenic bone marrow transplantation. The patient had prolonged nausea and vomiting for 5 weeks after bone marrow transplantation and CMV duodenitis was diagnosed by the gastroduodenoscopic mucosal biopsy which showed cytomegalic cells. Ganciclovir treatment for 3 weeks resulted in the resolution of symptoms and promoted healing of the lesion. The patient was free of CMV infection until 288 days after allogenic BMT without maintenance ganciclovir treatment.

Novel anti-HIV lancilactone C and related triterpenes from Kadsura lancilimba

Three new triterpene lactones, lancilactones A (1), B (2), and C (3), together with the known kadsulactone A (4), were isolated from the stems and roots of Kadsura lancilimba. Their structures and stereochemistries were determined primarily from mass and NMR spectral data. Compound 3 inhibited HIV replication with an EC50 value of 1.4 microg/mL and a therapeutic index of greater than 71.4.

Novel cytotoxic diterpenes from the stem of Dysoxylum kuskusense

Three novel diterpenes, dysokusones A (1), B (2), and C (3), were isolated from the stem of Dysoxylum kuskusense as cytotoxic substances. The structures were established by spectroscopic examinations. Compounds 1, 2, and 3 were cytotoxic toward HL-60(TB) cells with EC50 values of 2.25, 6.35, and 2.37 microM, respectively. Compound 1 also displayed cytotoxicity against K-562 and NCI-H522 cells with EC50 values of 5.04 and 4.80 microM, respectively.

Low prevalence of activated protein C resistance and coagulation factor V Arg506 to Gln mutation among Korean patients with deep vein thrombosis

Activated protein C (APC) is a naturally occurring anticoagulant that interacts with factor V and VIII to inhibit the clotting cascade. The prevalence of APC resistance among Korean patients with deep vein thrombosis is ill defined. The aim of the present study was to investigate the prevalence of APC resistance and factor V Leiden mutation in Korean patients with deep vein thrombosis. The presence of factor V Leiden mutation was determined in 49 patients who visited Asan Medical Center. APC ratio was performed in 33 individuals from the above 49 patients. Three patients were excluded from the analysis because their baseline aPTT was prolonged. Resistance to APC was diagnosed when the APC ratio was below 2.55. APC resistance was documented in 8 individuals, representing 27% (8/30) of the patients on whom APC resistance test was performed. The 2 patients, who showed APC resistance, were positive for lupus anticoagulant. None of the 49 patients demonstrated factor V Leiden mutation. These findings indicate that factor V Leiden mutation is rare and APC resistance is less prevalent in Korean patients with deep vein thrombosis than in Caucasians. APC resistance not caused by factor V Leiden mutation may be a risk factor for deep vein thrombosis in this population.

Nitric oxide production after acute, unilateral hydrochloric acid-induced lung injury in a canine model

OBJECTIVE

To determine if acute unilateral lung injury induces only local or systemic inflammatory effects by measuring the production of nitric oxide (NO) and its metabolites (nitrites and nitrates) in the injured and the contralateral lung and the blood initially and 4 hrs after injury.

DESIGN

Unilateral hydrochloric acid instillation in split lung intubated subject studied over time.

SETTING

Animal physiology laboratory.

SUBJECTS

Five mongrel dogs.

INTERVENTIONS

Instillation of 10 mL of 0.1 N hydrochloric acid into one lung via a plastic catheter. Bronchoalveolar lavage (BAL) was done at 4 hrs.

MEASUREMENTS AND MAIN RESULTS

Unilateral acid instillation did not alter systemic blood pressure or cardiac output, nor did it induce arterial hypoxemia. The BAL nitrite and nitrate level on the side of injury was higher than the control side (3.6+/-1.36 vs. 1.5+/-1.58 mM, p < .05), and serum nitrites and nitrates levels also decreased from the levels before acid instillation levels (p < .05). Exhaled NO levels were measured only in three animals. The levels increased acutely on hydrochloric acid instillation from only the injured lung and returned to baseline over several minutes. However, the level of exhaled NO from the injured lung failed to increase 4 hrs after injury, despite the increase in BAL nitrites and nitrates.

CONCLUSIONS

Acute unilateral lung injury in the dog results in increased NO production that is compartmentalized to the injured lung. The increase in exhaled NO after injury is transient and does not allow one to monitor the progress of lung injury.

Synthesis and antiplatelet, antiinflammatory, and antiallergic activities of substituted 3-chloro-5,8-dimethoxy-1,4-naphthoquinone and related compounds

2-Amino (6), 2-alkylamino (7-8), 2-methoxy (9), 2-acetamido (10), and 5,8-diacetoxy (11) derivatives of the lead compound 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone (4) were synthesized, together with 6,7-dichloro-5,8dimethoxy-1,4-naphthoquinone (5), a positional isomer of 4. Antiplatelet, antiinflammatory, and antiallergic activities were evaluated, and most compounds were quite potent in all assays. Compounds 5 and 9-11 were especially active; however, 5 was ineffective against neutrophil superoxide formation, and 10 was ineffective against mast cell degranulation.

Helicobacter pylori reinfection rate and duodenal ulcer recurrence in Korea

In the short term, the eradication of Helicobacter pylori in patients with duodenal ulcer (DU) is deemed to be clearly effective; the long-term effectiveness apparently depends on the H. pylori reinfection rate. We conducted the present study to investigate the rates of H. pylori reinfection and DU recurrence in 45 patients previously cured of DU in whom H. pylori had been eradicated. These patients underwent gastroscopy and tests for H. pylori at least 1 year after eradication. In a control group comprising 31 patients with DU who were not treated with H. pylori eradication regimen, the DU recurrence rate was checked annually for 4 years. Twenty of 45 patients (44.4%) in whom the mean follow-up period was 3.5 years were again found to be H. pylori positive, and the reinfection rate was 12.8% per year. DU recurred in 8 of these 20 (40%) but not in any nonreinfected patients. In the control group, the DU recurrence rate was 61% within 1 year, 81% within 2 years, 84% within 3 years, and 90% within 4 years. The respective recurrence rates in the 45 patients in whom the bacteria had been eradicated were 0%, 4%, 13%, and 18%. The H. pylori reinfection rate was as high as 12.8% per year in Korea, but in that the DU recurrence rate is significantly lower (p < 0.01; odds ratio, 129.5) in the H. pylori-eradicated group than in the control group, the eradication of H. pylori in DU patients is effective over the long term (at least 4 years).

CDK4 down-regulation induced by paclitaxel is associated with G1 arrest in gastric cancer cells

Paclitaxel induces a cell cycle block at G2-M phase by preventing the depolymerization of microtubules and induces p53-independent apoptosis in many cancer cells. We observed that gastric cancer cells treated with paclitaxel have shown a cyclin-dependent kinase (CDK)4 down-regulation. This paclitaxel-induced CDK4 down-regulation resulted in a cell cycle arrest at G1-S phase. To confirm this observation, we prepared stable transfectants that overexpressed CDK4 and analyzed the cell cycle progression. Ectopic expression of CDK4 in SNU cells resulted in a release of paclitaxel-induced G1 arrest. The release of G1 arrest by enforced expression of CDK4 seems to make the cells more sensitive to paclitaxel-induced apoptosis. From this finding, we could then suggest that paclitaxel treatment induces both G1-S and G2-M blocks in the cell cycle progression of gastric cancer cells.

Community acquired fulminant Pseudomonas infection of the gastrointestinal tract in previously healthy infants

Three previously healthy infants presented with diarrhoea and pyrexia and deteriorated rapidly. Two patients had necrotizing bowel disease requiring aggressive surgical intervention. All survived. P. aeruginosa gastrointestinal infection in previously healthy children is an extremely rare condition with a high mortality. Ecthyma gangrenosum was present in over 60% of reported cases although often not recognized initially. A high index of clinical suspicion, including prompt recognition of ecthyma gangrenosum, is mandatory for an early diagnosis of P. aeruginosa gastrointestinal infection. Early diagnosis and treatment may improve the prognosis.

Synthesis and structure-function study about tenecin 1, an antibacterial protein from larvae of Tenebrio molitor

Tenecin 1, an inducible antibacterial protein secreted in the larvae of Tenebrio molitor, has a long N-terminal loop and common structural feature of insect defensin family corresponding to cysteine stabilized alpha/beta motif. To study the function of the N-terminal loop and disulfide bridges, N-terminal loop deleted tenecin 1, reduced tenecin 1 and tenecin 1 were chemically synthesized and their activities were measured. N-terminal loop deleted tenecin and reduced tenecin 1 did not show antibacterial activity. Circular dichroism (CD) spectroscopy data revealed that the alpha-helical content of tenecin 1 and the other proteins increased in the presence of 50% (v/v) trifluoroethanol (TFE) and the alpha-helical content of tenecin 1 was much higher than that of the other proteins in buffer with or without 50% (v/v) TFE. These results suggest that disulfide bridges are necessary for the activity structure and the N-terminal loop plays an important role in the increase of alpha-helix in the membrane mimetic environment and the activity.

Synthesis and cytotoxicity of 2-acetyl-4,8-dihydrobenzodithiophene-4, 8-dione derivatives

2-Acetyl-4,8-dihydrobenzo[1,2-b:4,5-b']dithiophene-4,8-dione (9) and 2-acetyl-4,8-dihydrobenzo[1,2-b:5,4-b']dithiophene-4,8-dione (19), together with 10 related mono- and disubstituted derivatives, were synthesized and evaluated in vitro by NCI against eight cancer types. All compounds showed significant activity against melanoma, HL-60 leukemia, NCI-H23 non-small-cell lung cancer, OVCAR-3 ovarian cancer, and MDA-MB-435 and MDA-N breast cancer cell lines. Compound 11, 2-(1'-acetoxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-b']dithiophene-4, 8-dione, showed the highest overall potency (mean GI50 = 40 nM).

Anti-AIDS agents. 34. Synthesis and structure-activity relationships of betulin derivatives as anti-HIV agents

Succinyl and 3'-substituted glutaryl betulin derivatives showed stronger anti-HIV activity and higher therapeutic index (TI) values than their dihydrobetulin counterparts, with ratios of 1.2:1 to 15:1 (cf. 7 and 15, 9 and 17, 10 and 18, 11 and 19, and 12 and 20). For various 3'-substituted glutaryl compounds, the order of anti-HIV effects, from strong to weak inhibition, was 3',3'-dimethyl, 3'-methyl, 3'-ethyl-3'-methyl, followed by 3',3'-tetramethylene glutaryl derivatives (10 > 9 > 11 > 12, 18 > 17 > 19 > 20). The most potent compound, 10, has two 3',3'-dimethylglutaryl groups and displays significant anti-HIV potency with an EC50 value of 0.000 66 microM and a TI of 21 515. Results for compounds (22 and 23) without a C-3 acyl group confirmed the importance of the C-3 acyl group to the anti-HIV effect. With 3',3'-tetramethylene glutaryl derivatives, triacyl 29 showed stronger inhibition than diacyl 12; in contrast, 3',3'-dimethylglutaryl compounds displayed opposite results. 3-Keto compounds (35 and 36) and 2,3-dihydro compounds (39 and 40) had EC50 values in the range of 4.3-10.0 microM, suggesting that A ring modification led to decreased potency. The reduced activity of amide (33 and 34), ester (41), and oxime (42) analogues suggested that the orientation and linkage of the C-3 acyl side chain play crucial roles in the potent anti-HIV activity. Finally, replacing the C-28 acyl group with a bulky non-carboxylic group produced a less potent compound (44). In the study of mechanism of action, our results indicated that fusion is not the primary target for the anti-HIV activity of 10. It appears to inhibit HIV replication at a late stage of the viral life cycle, i.e., after viral protein synthesis.

Antitumor agents. Part 186: Synthesis and biological evaluation of demethylcolchiceinamide analogues as cytotoxic DNA topoisomerase II inhibitors

Demethylation of colchiceinamide (2) and its analogues (3-10) afforded a novel class of mammalian DNA topoisomerase II inhibitors (2a-10a) without displaying tubulin inhibitory activity. All target compounds inhibited the catalytic activity of topoisomerase II at drug concentrations at 100 microM. An in vitro cytotoxicity assay indicated that compounds 3a and 8a were strong and tissue-selective cytotoxic agents against the MCF-7 breast cancer cell line (IC50 = 0.36 and 0.48 microgram/mL, respectively) and the CAKI-1 renal cancer cell line (IC50 = 0.72 and 0.96 microgram/mL, respectively).

Distributional patterns of phospholipase C isozymes in rat kidney

As the first step to investigate the physiological function of phospholipase C (PLC), we determined the distribution patterns of PLC isozymes in normal rat kidneys using Western blotting analysis and immunohistochemistry. Western blotting analysis was performed in four regions (cortex, outer stripe and inner stripe of the outer medulla, and the inner medulla). PLC-beta1 and beta3 were detected in the inner stripe of the outer medulla and the inner medulla. PLC-gamma1 was distributed homogeneously along the corticomedullary axis. PLC-gamma2 was observed in the medulla and PLC-delta1 showed a gradual increase from the cortex to the inner medulla. In contrast, no PLC-beta4 was detected in all regions. On immunohistochemistry, the immunoreactivities to PLC antibodies were observed as follows: PLC-beta1, from the thick ascending limb (TAL) to the inner medullary collecting tubule (IMCT); PLC-beta3, in the glomerulus (Glm), the ascending thin limb (ATL) and the collecting tubule; PLC-beta4, Glm, the proximal convoluted tubule (PCT), ATL, the distal convoluted tubule, the connecting tubule, and the collecting tubules; PLC-gamma1, PCT, TAL and IMCT; PLC-delta1, homogeneously from PCT to IMCT. PLC-beta3 immunoreactivities were detected in the nuclei of the TAL, ATL, outer medullary collecting tubule (OMCT) and IMCT. PLC-beta4 and gamma2 were observed in Glm, MTAL, ATL, OMCT and IMCT. These results suggest the intrarenal site-specific existence of PLC isozymes that may regulate kidney functions through the PLC-mediated signal transductions.

Crystal structure of the Ebola virus membrane fusion subunit, GP2, from the envelope glycoprotein ectodomain

We have determined the structure of GP2 from the Ebola virus membrane fusion glycoprotein by X-ray crystallography. The molecule contains a central triple-stranded coiled coil followed by a disulfide-bonded loop homologous to an immunosuppressive sequence in retroviral glycoproteins, which reverses the chain direction and connects to an alpha helix packed antiparallel to the core helices. The structure suggests that fusion peptides near the N termini form disulfide-bonded loops at one end of the molecule and that the C-terminal membrane anchors are at the same end. In this conformation, GP2 could both bridge two membranes and facilitate their apposition to initiate membrane fusion. We also find a heptad irregularity like that in low-pH-induced influenza HA2 and a solvent ion trapped in a coiled coil like that in retroviral TMs.