Microbial transformation of beta-sitosterol and stigmasterol into 26-oxygenated derivatives

The genetically modified Mycobacterium sp. BCS 396 strain has been used to transform sterols with stigmastane side chain in order to obtain 26-oxidized metabolites. beta-Sitosterol (I) was transformed to 4-stigmasten-3-one (II), 26-hydroxy-4-stigmasten-3-one (III), and 3-oxo-4-stigmasten-26-oic acid (IV), while stigmasterol (V) was converted to 4,22-stigmastadien-3-one (VI), 6 beta-hydroxy-4,22-stigmastadien-3-one (VII), 26-hydroxy-4,22-stigmastadien-3-one (VIII), 3-oxo-4,22-stigmastadien-26-oic acid methyl ester (IX), and 3-oxo-1,4,22-stigmastatrien-26-oic acid methyl ester (X) with that strain. In both beta-sitosterol and stigmasterol, 26-oxidation generates the R-configuration on C-25.     

Synthesis and structure-activity relationships of cephalosporins, 2-isocephems, and 2-oxaisocephems with C-3' or C-7 catechol or related aromatics

A series of cephalosporins, 2-isocephems, and 2-oxaisocephems with C-3' catechol-containing (pyridinium-4-thio)methyl groups and 2-isocephems with C-7 catechol related aromatics have been prepared and evaluated for antimicrobial activity. It turns out that these compounds have highly potent activity against Gram-negative bacteria, especially resistant pathogens such as Pseudomonas aeruginosa. The most active compound of the series was (6S,7S)-7-[2-(2-aminothiazol-4-yl)-2-[(Z)-[(1,5-dihydroxy-4-pyr idon-2-yl) methoxy]imino]acetamido]-3-[[[(4-methyl-5-carboxymethyl)thiazol-2- yl] thio]methyl]-8-oxo-1-aza-4-thiabicyclo [4.2.0] oct-2-ene-2-carboxylic acid which exhibited potent in vitro activity against clinically isolated P, aeruginosa and Acinetobacter baumanii which is also resistant to many anti-infectives, and good in vivo efficacy against clinically isolated P aeruginosa.     

Studies on alpha-sialylation using sialyl donors with an auxiliary 3-thiophenyl group

Reaction of the methyl ester of 2-chloro-3-S-phenyl-3-thiosialic acid (4) with sodium thiomethoxide in acetonitrile at 0 degrees C affords the methyl ester of 2-S-methyl-3-S-phenyl-2,3-di-thio-alpha-sialic acid (6a) in quantitative yield. Sialylation of tetrahydropyran-2-methanol (7) and 2-(trimethylsilyl)ethyl 2,2'3,6,6'-penta-O-benzyl-alpha-lactoside (8) with 6a in the presence of phenylsulfenyl triflate (PST) as promotor in CH3 CN at -40 degrees C gives alpha-sialosides 9 and 10 in good yield and excellent stereoselectivity. No beta-sialosides are formed in either case. Acetylation of product 10, and the subsequent reductive removal of the 3-thiophenyl group using Ph3SnH, affords 12--protected GM3 trisaccharide--in 82% yield after two steps. Sialylation of acceptor 8 with chloride 4 using silver triflate as promotor afforded 10 in 48% yield after two days at -15 degrees C in THF. A possible mechanism of sialylation with 6a that involves intermediate alpha- and beta-nitrilium ions is discussed.     

A GC-MS study of three major acidic metabolites of delta 1-tetrahydrocannabinol

The major urinary metabolite of delta 1-tetrahydrocannabinol (delta 1-THC) (1), delta 1-THC-7-oic acid (2), has been extensively studied for several purposes, including testing in the workplace for drug abuse. Immunoassays in combination with more specific methods such as gas chromatography-mass spectrometry (GC-MS), are commonly used for verification of positive results in the screening. Two additional and recently synthesized acidic metabolites of 1, 4",5"-bisnor-delta 1-THC-7,3"-dioic acid (3) and 4"-hydroxy-delta 1-THC-7-oic acid (4), were studied to widen the scientific basis in the analysis. Five different derivatives were examined using GC-MS. In addition, a new deuterated internal standard for 2, [2H10]-2, was evaluated. According to our results, suitable derivatives of 2, 3, and 4, according to chromatographic properties, are the methyl ester/silyl ether (procedure a), the methyl ester/trifluoroacetate (procedure b), or the silyl ester/silyl ether (procedure c). The estimated recoveries of [2H5]-3 and [2H6]-4 using liquid-liquid extraction were 24% and 50%, respectively. The properties of [2H10]-2 as internal standard were equivalent to those of [2H9]-2 and, under the conditions used, did not appear to give rise to a significantly higher chromatographic resolution from that of 2. However, [2H10]-2 produces ions at different mass numbers, which makes it useful as a complement to the existing deuterated internal standards of 2.     

An economic synthesis of 1,2,3,4-tetra-O-acetyl-5-thio-D-xylopyranose and its transformation into 4-substituted-phenyl 1,5-dithio-D- xylopyranosides possessing antithrombotic activity

D-Xylose was converted via 1,2-O-isopropylidene-alpha-D-xylofuranose (4) into 3-O-benzoyl-5-S-benzoyl-1,2-O-isopropylidene-alpha-D-xylofuranose which, after methanolysis, acetylation and subsequent acetolysis afforded 1,2,3,4-tetra-O-acetyl-5-thio-alpha-D-xylopyranose (14) in an overall yield of 36%. Reaction of 4 with thionyl chloride gave a mixture of the diastereomeric cyclic sulfites, the structures of which were established by X-ray crystallography. Their oxidation with sodium periodate afforded the corresponding cyclic sulfate 23. Treatment of 23 with potassium thioacetate gave the potassium salt of 5-S-acetyl-1,2-O-isopropylidene-alpha-D-xylofuranose 3-O-sulfonic acid (26) which, after methanolysis, acetylation and subsequent acetolysis afforded 14 in an overall yield of 56%. Treatment of 4 with sulfuryl chloride gave a mixture containing 5-chloro-3-O-chlorosulfonyl-5-deoxy-1,2-O-isopropylidene-alpha-D- xylofuranose, 3,7,9,11-tetraoxa-4-thia-10-dimethyl-tricyclo[6,3,0, 0(2,6)]undecane S-dioxide and 23 in a 2:3:7 ratio. Tetraacetate 14 was converted into the alpha-1-bromide 18 as well as into the alpha-1-O-trichloroacetimidate 17. These three compounds were used as donors for the glycosylation with 4-cyanothiophenol, affording the 4-cyanophenyl 2,3,4-tri-O-acetyl-1,5-dithio-alpha- (29) and beta-D-xylopyranoside (30) in different ratios, depending on the reaction conditions. When donor 18 was used in the presence of potassium carbonate, besides 29 and 30 two aryl C-glycosylated-thioglycosides, i.e. 4-cyano-2-(2,3,4-tri-O-acetyl-5-thio-beta-D-xylopyranosyl)phenyl 2,3,4-tri-O-acetyl-1,5-dithio-alpha- and beta-D-xylopyranoside (32 and 33) as well as 4-cyano-2-(2,3,4-tri-O-acetyl-5-thio-beta-D-xylopyranosyl)phenyl disulfide 34 could be isolated as byproducts. Deacetylation of 30 with sodium methoxide in methanol afforded, besides 4-cyano-phenyl 1,5-dithio-beta-D-xylopyranoside (1), the corresponding 4-[(methoxy)(imino)methyl]phenyl glycoside 2. The 4-cyano group of 1 was converted into the 4-aminothiocarbonyl, the 4-(methyl-thio)(imino)methyl, the 4-amidino and the 4-(imino)(hydrazino)methyl group. All of these glycosides showed a significant antithrombotic activity on rats.     

alpha-Methylene-gamma-butyrolactones: synthesis and vasorelaxing activity assay of coumarin, naphthalene, and quinoline derivatives

Certain alpha-methylene-gamma-butyrolactone derivatives of coumarin, naphthalene, and quinoline were synthesized and evaluated for vasorelaxing effects on isolated rat thoracic aorta. The 7-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2H- 1- benzopyran-2-ones, which have an aliphatic methyl substituent at the lactone C2, were more active than their C2-phenyl counterparts against high-K+ (80 mM) medium, Ca2+ (1.9 mM)-induced vasoconstriction and the norepinephrine (NE, 3 microM)-induced phasic and tonic constrictions (2a vs. 2b; 2c vs. 2d; 2e vs. 2f; 2g vs. 2h). Although 3-chloro-7-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2- furanyl)methoxy]-4-methyl-2H-1-benzopyran-2-one (2g) demonstrated the most potent inhibitory activities on the NE-induced phasic and tonic constrictions at concentrations of as low as 10 micrograms/ml, it possesses both affinity for NE-receptor and intrinsic activity to trigger the vasoconstriction. However, 8-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2- furanyl)methoxy]quinoline (10a) and other quinoline derivatives (11a, 12a) are pure irreversible non-competitive blockers of NE-receptor with no intrinsic activity. The aromatic ring played an important role in the vasorelaxing effects of alpha-methylene-gamma-butyrolactones; naphthalene was inactive, quinolines exhibited only affinity to the alpha-receptor, and coumarins possessed both affinity and intrinsic activity.     

Synthesis and pharmacological activities of ethyl 5-cyano-1,6-dihydro-6-oxo-2-(2,3,4-pyridyl)-3-pyridinecarboxylates and derivatives

The synthesis of ethyl esters of 5-cyano-1,6-dihydro-6-oxo-3-pyridinecarboxylic acids carrying as 2-substituent the 2-,3- or 4-pyridyl group is described. By alkaline hydrolysis followed by acidification, these esters gave the corresponding carboxylic acids, which were decarboxylated to 1,2-dihydro-2-oxo-6-(2,3,4-pyridyl)-3-pyridinecarbonitriles. As milrinone analogues, the above compounds were tested on contractile activity and frequency rate of spontaneously beating atria from reserpine-treated guinea-pigs. Ethyl 5-cyano-1,6-dihydro-6-oxo-2-(2-pyridyl)-3-pyridinecarboxylate showed an appreciable positive inotropic activity, although inferior to that of milrinone; moreover, some other compounds bearing the above 2-substitution pattern showed interesting antiinflammatory, analgesic and hypotensive activity.     

Triterpenoid saponins from Gypsophila oldhamiana

Three new triterpenoid saponins were isolated from the roots of Gypsophila oldhamiana. Their structures were elucidated, using a combination of homonuclear and heteronuclear 2D nmr and fabms, as 3-0-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranolyl-(1-->3)] -beta-D-glucuronopyranosyl quillaic acid methyl ester [1], 3-0-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-beta- D-glucuronopyranosyl gypsogenin methyl ester [2], and 3-0-beta-D-galactopyranolsyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3) ]-beta-D-glucuronopyranosyl quillaic acid 28-[0-beta-D-fucopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->3)]-alpha-L- rhamnopyranosyl] ester.     

Synthesis and structure-activity relationships of dual histamine H2 and gastrin receptor antagonists with decreased hydrophobicity

In order to study structure-activity relationships of the previously reported dual histamine H2 and gastrin receptor antagonists and also to improve their low oral absorbability, we tried two chemical modifications. One tried to decrease the high hydrophobicity of the parent hybrid compounds to an appropriate level by incorporating a hydrophilic group into the molecule and the other by replacing the more hydrophobic groups with less hydrophobic ones. The former compounds (type I) involved hybrid compounds with a hydroxyl group at a position of a spacer, a piperidine moiety of H2A, or a phenyl ring at the C5 of the benzodiazepine skeleton as well as those with a free carboxyl group in the piperidine moiety of H2A. The latter (type II) involved hybrid compounds with the C5-phenyl group replaced with either a methyl group or hydrogen atom. Among them, only a type I compound, ([2-[3-(3-piperidin-1-ylmethylphenoxy)propylcarbamoyl] ethylcarbamoyl]methyl)carbamic acid 3-[3-[5-(3-hydroxyphenyl)-1-methyl-2-oxo-2,3-dihydro-1H-1,4-benzodiaz epin-3-yl]ureido]benzyl ester (18), showed potent dual histamine H2 and gastrin receptor antagonistic activity, whereas others resulted in a significant decrease of histamine H2 receptor antagonistic activity. The in vivo gastric acid antisecretory activity of 18 evaluated by Schild's rat method, however, did not suggest any notable improvement in oral absorbability.     

Synthesis and biological activity of 4-amino-7-oxo-substituted analogues of 5-deaza-5,6,7,8-tetrahydrofolic acid and 5,10-dideaza-5, 6,7,8-tetrahydrofolic acid

The 4-amino-7-oxo-substituted analogues of 5-deaza-5,6,7, 8-tetrahydrofolic acid (5-DATHF) and 5,10-dideaza-5,6,7, 8-tetrahydrofolic acid (DDATHF) were synthesized as potential antifolates. Treatment of the alpha,beta-unsaturated esters 11a-c, obtained in one synthetic step from commercially available para-substituted methyl benzoates (9a-c) and methyl 2-(bromomethyl)acrylate (10), with malononitrile in NaOMe/MeOH afforded the corresponding pyridones 12a-c. Formation of the pyrido[2,3-d]pyrimidines 13a-c was accomplished upon treatment of 12a-c with guanidine in methanol. After the hydrolysis of the ester group present in 13a-c, the resulting carboxylic acids 14a-c were treated with diethyl cyanophosphonate in Et3N/DMF and coupled with L-glutamic acid dimethyl ester to give 15a-c. Finally, the basic hydrolysis of 15a-c yielded the desired 4-amino-7-oxo-substituted analogues 16a-c in 20-27% overall yield. Compounds 16a-c were tested in vitro against CCRF-CEM leukemia cells. The results obtained indicated that our 4-amino-7-oxo analogues are completely devoid of any activity, the IC50 being higher than 20 microg/mL for all cases except 14c for which a value of 6.7 microg/mL was obtained. These results seem to indicate that 16a-c are inactive precisely due to the presence of the carbonyl group in position C7, the distinctive feature of our synthetic methodology.     

Ketomethylenebestatin: synthesis and aminopeptidase inhibition

The synthesis of (6R,5S,2RS)-6-amino-5-hydroxy-2-isobutyl-4-oxo-7- phenylheptanoic acid (9), a carbaanalogue of the aminopeptidase (AP) inhibitor bestatin (1) is described. This synthesis was carried out by a malonic ester alkylation with the suitably protected halomethyl ketone of (2S,3R)-AHPBA*), followed by a second alkylation with isobutyl bromide of the resulting 4-ketodiester, and subsequent decarboxylation and deprotection. The inhibitory potencies of the 1:1 diastereomeric mixture 9 against AP-B, AP-M and Leu-AP were approximately 10-fold lower than those of bestatin.     

Demonstration of neuraminidase activity in human blood serum and human milk using a modified, radioactively labelled alpha1-glycoprotein as substrate

N-Acetylneuramini acid of alpha1-glycoprotein was oxidized with a small molar excess of periodate and reduced with tritium-labelled borohydride. By this method about 50% of the N-acetylneuraminic acid was converted to its radioactively labelled C8-analog and 25% to its C7-analog. Using this modified alpha1-glycoprotein as substrate, minimum neuraminidase concentrations of 10(-18) units/ml, related to the activity of neuraminidase from Vibrio cholerae, could be determined. Neuraminidase activity was demonstrated in 95% of the sera or blood plasma samples from a series of 417 healthy or ill human individuals and in milk samples from 5 different donors. The neuraminidase in both serum and milk had optimal activity at pH 5.5. On an average, 10(-10) neuraminidase units were found in 1 ml serum and 10(-8) units in 1 ml milk. Although the neuraminidase activities in the sera varied, a correlation with definite pathological states is not yet possible. N-Acetylneuraminate pyruvate-lyase activity could not be detected in human serum.     

Synthesis and antibacterial activity of a new series of tetracyclic pyridone carboxylic acids

A novel tetracyclic pyridone carboxylic acid with a thiazolidine ring, 1,2-dihydro-9,1-(epoxymethano)-7-fluoro-8-(4-methyl-1-piperazinyl)-5-oxo -5H- thiazolo[3,2-a]quinoline-4-carboxylic acid (4a), and variants with a nitrogen atom (4b) or carbonyl group (4c) in the place of the 10-position oxygen atom of 4a were prepared and tested for antibacterial activity and inhibitory activity on DNA gyrase from Escherichia coli KL-16. The in vitro antibacterial potency with regard to the 10-position atom was found to be of the following order; O > NCH3 = C = O. The IC50 values for DNA gyrase inhibition activity for the 4a, 4b, and 4c compounds were 0.33, 0.53, and 0.67 g/mL, respectively. The activity of 4a, in which the C-3 methyl group and C-5 of ofloxacin (2a) were connected with a sulfur atom to restrict the conformation of 2a, was more potent than that of 2a against both Gram-positive and -negative bacteria, except for Pseudomonas aeruginosa. Compared to the tetracyclic pyridone carboxylic acid 1a, which has a flat thiazole ring, compound 4a showed comparable or slightly more potent activity against both Gram-positive and -negative bacteria, except for P. aeruginosa.     

Nonpeptide angiotensin II receptor antagonists. Synthesis and biological activity of potential prodrugs of benzimidazole-7-carboxylic acids

In order to improve the oral bioavailability (BA) of 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimid azole - 7-carboxylic acid (3: CV-11194) and 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4- yl]methyl]-1H-benzimidazole-7-carboxylic acid (4: CV-11974), novel angiotensin II (AII) receptor antagonists, chemical modification to yield prodrugs has been examined. After selective tritylation of the tetrazole rings in 3 and 4, treatment of N-tritylated benzimidazole-7-carboxylic acids (6, 7) with a variety of alkyl halides, followed by deprotection with hydrochloric acid, afforded esters of 3 and 4. Mainly 1-(acyloxy)alkyl esters and 1-[(alkoxycarbonyl)oxy]alkyl esters, double ester derivatives, were synthesized. Their inhibitory effect on AII-induced pressor response in rats and oral BA were investigated. (Pivaloyloxy)methyl and (+/-)-1-[[(cyclohexyloxy)-carbonyl]oxy]ethyl esters of 3 and 4 showed marked increases in oral bioavailability which significantly potentiated the inhibitory effect of the parent compounds on AII-induced pressor response. Among them, (+/-)-1-[[(cyclohexyloxy)carbonyl]oxy]ethyl 2- ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimida zole- 7-carboxylate (10s, TCV-116) was selected as a candidate for clinical evaluation.     

Geranylgeranyl pyrophosphate synthase encoded by the newly isolated gene GGPS6 from Arabidopsis thaliana is localized in mitochondria

A number of new 1,4-benzodiazepin-2-one-based gastrin/CCK-B receptor antagonists related to the archetypal analogue L-365,260, and more closely to the recently reported compound YM022, have been synthesized and evaluated for biological activity. The compounds were screened for their ability to inhibit the binding of [125I]CCK-8 to gastrin/CCK-B receptors prepared from rat brains and that of [3H]L-364,718 to CCK-A receptors from rat pancreas, and were shown to be potent and selective ligands for the gastrin/CCK-B receptor. Functional studies in vivo demonstrated the compounds to be antagonists of the receptor as evidenced by their ability to inhibit pentagastrin-induced gastric acid secretion in anesthetized rats. More extensive evaluation in vivo included determination of ED50 values in the rat acid secretion model for selected compounds and an examination of the effect of these compounds on pentagastrin-induced gastric acid secretion in Heidenhain pouch dogs following oral and intravenous administration. Two compounds, i.e. (3R)-N-[1-[(tert-butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5-(2-pyri dyl) -1H-1,4-benzodiazepin-3-yl]-N'-[3-(methylamino)phenyl]urea, 15c (YF476), and (3R)-N-[1-[(tert-Butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5- (2-pyridyl)-1H-1,4-benzodiazepin-3-yl]-N'-[3-(dimethylamino)phenyl ]urea hydrochloride, 15d, showed potent dose-dependent effects in both models with the former showing excellent oral bioavailability and an ED50 of 21nmol/kg po in dogs. 15c is currently under clinical investigation for the treatment of gastro-oesophagal reflux disease (GORD).     

Measures of activity and damage in rheumatoid arthritis: depiction of changes and prediction of mortality over five years

We devised a simple and effective purification for the microdetermination of thromboxane B3 (TXB3), a hydrolysis product of TXA3- [18O2]TXB3 was synthesized by the repeated base-catalyzed hydrolysis of methyl ester derivatives in [18O]water, to obtain an internal standard (IS) for the gas chromatography/selected ion monitoring (GC/SIM) of TXB3. The methyl ester (ME)-methoxime (MO)-dimethylisopropylsilyl (DMIPS) ether derivative was prepared, then GC/SIM was carried out by monitoring the ion at m/z 668 for TXB3 and that at m/z 672 for IS. A good linear response over the range of 10 pg approximately 10 ng was demonstrated. We were able to detect the levels of TXB3 in the medium of human erythroleukemia (HEL) cell cultured with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). This method can be used to determine 3-series thromboxane in biological samples.     

A tale of novel intoxication: seven cases of gamma-hydroxybutyric acid overdose

The chemical behaviours of 4-methyl-2-oxo-2H-benzopyran-7-yl oxoacetyl hydrazine (2) towards some different reagents such as anhydride compounds, aromatic aldehydes, carbon disulphide, and nitrous acid yielded the corresponding pathalazine derivatives (3, 4, 5), hydrazone derivative (6), 1,3,4-oxadiazole derivative (7, 8, 9) and acid azide (10) respectively. Treatment of 10 with absolute alcohols, amines and ethyl amino acid ester gave the corresponding carbamate derivative (11), substituted urea derivative (12) and ethyl substituted alkyl acetate (13) respectively. The biological activity of some synthesized compounds was evaluated.     

Action of DNA-gyrase inhibiting derivatives of 4-oxo-1, 4-dihydro-3-pyridinecarboxylic acid against Trypanosoma brucei

Ten derivatives of 4-oxo-1,4-dihydro-3-pyridinecarboxylic acid as DNA-gyrase inhibitors were evaluated in vitro and in vivo against Trypanosoma brucei brucei IPP. Two compounds were were active at 100 microM in vitro after 1 h incubation time. After 24 h incubation, 8 compounds were active and the most interesting compound, 1-(4-hydroxy-2-methyl-phenyl)-6-[2-(4,5-dichloro-phenyl)-ethenyl] -4-oxo-1, 4-dihydropyridine-3-carboxylic acid (compound No. 8) was trypanocidal at 10 microM. The trypanocidal effects were not noted in vivo after subcutaneous treatment administered as a single dose of 50 mumols/kg. The in vitro trypanocidal effect is correlated with the DNA-gyrase inhibition.     

Impaired duodenal bicarbonate secretion in diabetic rats. Salutary effect of nitric oxide synthase inhibitor

We previously reported the impaired HCO3- secretion and the increased mucosal susceptibility to acid in the duodenum of streptozotocin (STZ)-induced diabetic rats. In this study, we investigated the salutary effect of the NO synthase inhibitor L-NAME (NG-nitro-L-arginine methyl ester) on these changes and compared it with those of insulin. Animals were injected streptozotocin (STZ: 70 mg/kg, ip) and used after 1, 3-4, and 5-6 weeks of diabetes with blood glucose levels of > 300 mg/dL. Under urethane anesthesia the HCO3- secretion was measured in the proximal duodenal loop using a pH-stat method and by adding 10 mM HCl. L-NAME (20 mg/kg x 2) or insulin (4 units/rat) was administered sc for 4-5 weeks, starting 1 week after STZ treatment. The duodenal HCO3- secretory responses to various stimuli such as mucosal acidification (10 mM HCl for 10 min), 16,16-dimethyl prostaglandin E2 (dmPGE2: 10 micrograms/kg, i.v.), and vagal stimulation (0.5 mA, 2 ms, 3 Hz) were significantly decreased in STZ-treated rats, depending on the duration of diabetes. Repeated administration of L-NAME, starting from 1 week after STZ treatment, significantly reduced blood glucose levels toward normal values and restored the HCO3- responses to various stimuli in STZ rats, the effects being similar to those observed after supplementation of insulin. Diabetic rats developed duodenal lesions after perfusion of the duodenum with 150 mM HCl for 4 h, but this ulcerogenic response was significantly inhibited by the repeated treatment with L-NAME as well as insulin. We conclude that L-NAME is effective in ameliorating hyperglycemic conditions in STZ-diabetic rats, similar to insulin, and restores the impaired HCO3- secretion and the increased mucosal susceptibility to acid in diabetic rat duodenums.     

Visoltricin, a novel biologically active compound produced by Fusarium tricinctum

The major compound responsible for toxicity to Artemia salina of some Fusarium tricinctum strains has been isolated, and its structure has been elucidated by spectroscopical methods, i.e. UV, IR, MS, 1H-NMR and 13C-NMR. The novel compound, trivially named visoltricin, is the first imidazole derivative produced by Fusarium spp., and its structure has been established as the methyl ester of 3-[1-methyl-4-(3-methyl-2-butenyl)-imidazol-5yl]-2-propenoic acid (molecular formula C13H18N2O2; MW = 234.297). Visoltricin was toxic to A. salina larvae (LD50 = 8.5 x 10(-7) M), and inhibited the growth of six human tumour cell lines (out of 60 lines tested) at concentrations lower than 10(-5) M. Tested on rabbit eye it showed an interesting miotic activity similar to that of pilocarpine, a miotic agent largely used in the therapy of glaucoma. This biological activity could be explained in part by the anticholinesterase properties shown by visoltricin towards both human serum and pure enzymes (EC 3.1.1.7 and EC 3.1.1.8). Kinetics studies showed for visoltricin a mixed-type and reversible inhibition of the EC 3.1.1.7 enzyme with the competitive inhibition constant (Ki) = 1.9 x 10(-4) M.