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Differences between human, rat and guinea pig hepatocyte cultures. A comparative study of their rates of beta-oxidation and esterification of palmitate and their sensitivity to R-etomoxir.

Rat hepatocyte cultures have higher rates of beta-oxidation of palmitate and lower rates of esterification to glycerolipid than human or guinea pig hepatocytes. The R-enantiomer of etomoxir (sodium 2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate), a hypoglycaemic compound and inhibitor of carnitine palmitoyltransferase I, inhibited palmitate beta-oxidation in all three species, but the sensitivity to inhibition was highest in human hepatocytes and lowest in rat hepatocytes. The concentration causing half-maximal inhibition was approximately: 0.1 microM in human; 1 microM in guinea pig and 10 microM in rat hepatocytes. In human and in guinea pig hepatocytes the inhibition of beta-oxidation by R-etomoxir was associated with an increase in the esterification of palmitate but in rat hepatocytes R-etomoxir lowered the total rate of palmitate metabolism. The S-enantiomer of etomoxir had no significant effect on beta-oxidation or esterification of palmitate in any of the three species. It is concluded that there are significant differences between human, rat and guinea pig hepatocytes, not only in the relative partitioning of palmitate between beta-oxidation and esterification, but also in the sensitivity to an inhibitor of carnitine palmitoyltransferase I.

Animals↗

The electrophilic, mutagenic and tumorigenic activities of phenyl and 4-nitrophenyl vinyl ethers and their epoxide metabolites.

The metabolism and mutagenicity of phenyl and 4-nitrophenyl vinyl ethers (PVE and NPVE) and their epoxide metabolites, phenoxyoxirane (PO) and 2'-(4-nitro-phenoxy)oxirane (NPO), were studied including reactions with DNA and tests for carcinogenicity. PVE and NPVE were epoxidized in dry acetone by dimethyldioxirane to give high yields (95%) of the pure epoxides. The epoxides are unstable in aqueous media and in 0.1 N phosphate buffer, pH 7.4, at 37 degrees C; they had half-lives of 2.7 min (PO) and 4.4 min (NPO). These times were reduced to 1.9 min (PO) and 2.5 min (NPO) in the presence of isotonic (154 mM) chloride ion. In neutral phosphate buffer these epoxides hydrolyze to form glycolaldehyde and the corresponding phenols; in the presence of chloride ion, chloroacetaldehyde and several unknown compounds are also formed. Glycolaldehyde was also found as a hydrolysis product of the presumed epoxides generated in the hepatic microsomal oxidation of PVE and NPVE. PO and NPO reacted with DNA to form adducts that depurinated in weak acid to form 7-(2'-oxoethyl)guanine and N(2),3-ethenoguanine. PO was weakly mutagenic in Salmonella typhimurium TA1535 while NPO was much more mutagenic under the same conditions. PO and NPO were found to have mutagenic half-lives that matched their chemical half-lives. PO and NPO were found to be tumorigenic in the skin of mice after single or five initiating doses followed by multiple doses of phorbol ester (TPA). NPO was a stronger tumor initiator than PO. NPO had appreciable activity as an initiator of hepatoma formation in infant male B6C3F1 mice. Thus PO and NPO are electrophilic, mutagenic and tumorigenic metabolites of their corresponding phenyl vinyl ethers.

Animals↗

Cyclopropyl oxiranes: reversible inhibitors of cytosolic and microsomal epoxide hydrolases.

A series of aryl- and alkyl-substituted cyclopropyl oxiranes were synthesized as potential suicide inhibitors of mouse liver epoxide hydrolase (EH). The inhibitory potency of each compound and its corresponding alkene precursor was determined with mouse liver EHs using [3H]-cis-stilbene oxide as substrate for microsomal EH (mEH) and for glutathione-S-transferase, and using [3H]-trans-stilbene oxide for cytosolic EH (cEH). The cyclopropyl oxiranes all showed low (26-60% at 5 X 10(-4) M) inhibition of glutathione transferase and moderate inhibition (I50 = 5 X 10(-4) to 6 X 10(-6) M) for cEH and mEH. cis-Phenylcyclopropyl oxirane had an I50 for mEH near that for a commonly used inhibitor, 1,1,1-trichloropropene oxide. Inhibition appeared competitive and reversible, and the cyclopropyl oxiranes appeared to function as alternate substrates. Absence of irreversible inhibition is evidence against a strongly electrophilic epoxide-opening mechanism involving a cyclopropyl carbinyl-homoallyl cation rearrangement. Instead, a concerted mechanism is favored, in which electrophilic opening and hydroxide attack occur in a concerted fashion.

Animals↗

Inhibition of type II collagen-induced arthritis in rats by triptolide.

The effects of purified triptolide, a diterpenoid triepoxide compound derived from the Chinese traditional anti-rheumatic medicinal plant extract, Tripterygium wilfordii Hook f (TWHf), were determined in type II collagen-induced arthritis (CIA) in rats. Lewis rats were immunized with bovine type II collagen and treated with purified triptolide 0.1 mg/kg/day or control (vehicle for triptolide) by daily gavage feedings for 28 days. Triptolide was well-tolerated with no evidence of toxicity. Treatment with triptolide resulted in significant delay in time to onset of arthritis (P = 0.039), as well as significantly decreased arthritis incidence (P = 0.024), clinical arthritis severity score (P < 0.0001), histopathological arthritis severity score (P < 0.0001), and in vivo cell-mediated immunity to collagen (P = 0.0004). Triptolide appeared to be a potent immunomodulatory inhibitor of CIA in rats and this may account for the previously observed anti-rheumatic properties of crude extracts of TWHf, although more extensive studies will be needed to confirm these effects.

Animals↗

New natural epothilones from Sorangium cellulosum, strains So ce90/B2 and So ce90/D13: isolation, structure elucidation, and SAR studies.

In addition to epothilones A (1) and B (2), 37 natural epothilone variants and epothilone-related compounds were isolated from the culture broth of a 700 L fermentation of Sorangium cellulosum, strain So ce90/B2. Of these, only the 12,13-desoxyepothilones, epothilone C (14) and D (15), were produced in significant amounts (3-6 mg/L); the 21-hydroxy derivatives and epothilones E (3) and F (4), in low and variable amounts due to further degradation by the producing organism. Most of the other epothilone variants were produced only in 1-100 microg/L amounts. The new compounds are very similar in structure to the parent compounds 1, 2 and 14, 15 and are presumably the result of the imperfect selectivity of the biosynthetic enzymes for acetate and propionate. Further, epothilones containing an oxazole moiety (10-13) in the side chain instead of a thiazole as well as ring-expanded 18-membered macrolides, epothilones I (30-35), and a ring contracted 14-membered macrolide, epothilone K (36), were found as very minor metabolites. The mutant strain, So ce90/D13, instead of macrolactones, produced short-chain carboxylic acids 40, 41, and 42 bearing the characteristic thiazole side chain. The structures of the new epothilones were elucidated on the basis of comprehensive NMR and MS data. The new epothilone variants were tested in a cytotoxicity assay with mouse fibroblasts (cell line L929), and structure-activity relationships were established. Several new natural epothilones showed activity comparable to 1 and 2, but in no case exceeded that of 2.

Animals↗

Inhibitory role of gibberellins in theobroxide-induced flowering of Pharbitis nil.

Theobroxide, a novel active compound isolated from a fungus, has been reported previously to induce potato tuberization and flower bud formation in Pharbitis nil under non-inductive long-day conditions. Up to date, the action mechanism of theobroxide on flower-bud induction of P. nil, however, is still unknown. In the present study, we observed a reduction of the stem length, along with the induction of flower buds, in theobroxide-treated and short-day-grown P. nil plants. Also, the results showed that flower bud formation was delayed markedly in P. nil seedlings with removal of cotyledons or exposure to night break. The suppression effect of night-break and cotyledon-removal, however, was abolished completely by spraying theobroxide. Endogenous gibberellin(1/3) contents in P. nil plants treated with theobroxide or grown under short-day conditions were relatively lower, suggesting that gibberellins probably are negatively involved in theobroxide- and short-day-induced flower-bud formation of P. nil.

Cotyledon↗

Synthesis and tumor-initiating activity in mouse skin of dibenzo[a,l]pyrene syn- and anti-fjord-region diolepoxides.

Dibenzo[a,l]pyrene (DB[a,l]P) is the most potent carcinogen among polycyclic aromatic hydrocarbons. Because the fjord-region diolepoxide (DE) pathway is one of the mechanisms of activation, (+/)-trans-DB[a,l]P-11,12-dihydrodiol, (+/-)-anti-DB[a,l]PDE and (+/-)-syn-DB[a,l]PDE were synthesized. The key intermediate for these syntheses, 12-methoxy-DB[a,l]P, was successfully obtained by cyclization of 6-(3-methoxybenzyl)benzanthrone with methanesulfonic acid, which in turn was prepared by 1,4 conjugate addition of 3-methoxybenzyl magnesium bromide to benzanthrone. The presence of the DB[a,l]P nucleus in the dihydrodiolepoxides and diolepoxides was proven by conversion of 12-methoxyDB[a,l]P into the parent compound in several steps. The tumor-initiating activity of the two diolepoxides in mouse skin was compared to that of DB[a,l]P-11,12-dihydrodiol and the parent DB[a,l]P. Groups of 24 8 week old female SENCAR mice were topically initiated with 12, 4 or 1.33 nmol of compound in 100 microliters of acetone. Starting 1 week later, promotion with 12-O-tetradecanoylphorbol-13-acetate (1.62 nmol in 100 microliters acetone) was begun and continued twice weekly for 30 weeks. At the 12, 4 and 1.33 nmol doses, anti-DB[a,l]PDE induced 2.0, 0.7 and 0.7 tumors per mouse (t/m) respectively, whereas syn-DB[a,l]PDE induced 1.8, 1.5 and 1.8 t/m. At the same three doses, DB[a,l]P-11,12-dihydrodiol induced 4.6, 4.3 and 2.8 t/m, and DB[a,l]P resulted in 9.3, 7.1 and 5.2 t/m. These results confirm that DB[a,l]P is more potent than its 11,12-dihydrodiol and show that the two diolepoxides are less tumorigenic than their precursors. At the medium and low doses, syn-DB[a,l]PDE is more tumorigenic than its congener anti-DB[a,l]PDE.

Animals↗

Development of a small-caliber vascular graft with antithrombogenicity induced by extreme hydrophilicity.

A small-caliber vascular graft with an excellent patency rate, which has satisfactory antithrombogenicity due to high hydrophilicity, has been developed. It is hemostatic at the anastomotic site and has an affinity for endothelial-like cells, smooth musclelike cells, and fibroblasts. Fresh carotid artery with an ID of 2.5 to 3.0 mm was obtained from a dog and sonicated to induce destruction of the cell components. It was then cross-linked with a hydrophilic polyepoxy compound. As controls, glutaraldehyde (GA) treated grafts were prepared. Twenty-one dogs were used, 14 for the new graft and the other 7 as controls. A segment of the graft, 6 cm in length, was implanted into the carotid artery. Sodium heparin was given during surgery, but no anticoagulant was used thereafter. The compliance of the new graft was similar to that of the native artery. No excessive bleeding was noticed at the anastomotic sites. The patency rate was 70.8% during the longest observation period of 145 days, but was only 10% in the controls. Microscopic observation revealed that by the seventh day after implantation, endothelial-like cells had appeared near the anastomotic lines on the inner surface of the new graft; smooth musclelike cells were observed on the 38th day after implantation. From these results, there is a good possibility that this new graft, with its many advantages, may be used clinically.

Animals↗

Reduction of the antigenicity and immunogenicity of xenografts by a new cross-linking reagent.

To overcome the disadvantages of glutaraldehyde (GA), new cross-linking reagents, polyepoxy compounds (PC), were introduced and their effects on the antigenicity and immunogenicity of biomaterials were investigated. In the qualitative study, antigenicity of type I collagen in bovine arteries treated with GA or glycerol polyglycidyl ether (GPE), a kind of PC, was detected using a fluorescent antibody technique. To evaluate the immunogenicity quantitatively, DDY mice were twice immunized with homogenates of GA, GPE, or untreated dog arteries. Using their sera collected 10 and 90 days after the last immunization as primary antibodies, the dogs' peripheral lymphocytes were stained with FITC labeled anti-mouse IgG antibodies against shared antigens on arteries and lymphocytes. Percentages of stained lymphocytes were then analyzed with flow cytofluorometry. In both qualitative and quantitative studies, extremely low antigenicity and immunogenicity were shown in GA or GPE treated arteries. It is therefore suggested that GPE is an ideal cross-linking reagent for vascular and valvular xenografts and is applicable to clinical use.

Animals↗

Mutagenic and cell-transforming activities of triol-epoxides as compared to other chrysene metabolites.

The syn- and anti-isomers of the bay-region diol-epoxides of chrysene and of 3-hydroxychrysene and their metabolic precursors have been investigated for mutagenicity in Salmonella typhimurium (reversion to histidine prototrophy) and V79 Chinese hamster cells (acquirement of resistance to 6-thioguanine) and for transforming activity in M2 mouse prostate cells. Other known and potential chrysene metabolites have been included in mutagenicity experiments. Direct mutagenic activity in S. typhimurium TA 100 exhibited, in order of potency, anti-triol-epoxide greater than syn-triol-epoxide greater than anti-diol-epoxide greater than syn-diol-epoxide greater than chrysene 5,6-oxide much greater than chrysene-1,2-quinone, chrysene-3,4-quinone, and chrysene 5,6-quinone. Chrysene, the six isomeric chrysenols, and the trans-dihydrodiols [trans-1,2-dihydroxy-1,2-dihydrochrysene (chrysene-1,2-diol), trans-3,4-dihydroxy-3,4-dihydrochrysene, trans-5,6-dihydroxy-5,6-dihydrochrysene, and 9-hydroxy-trans-1,2-dihydroxy-1,2-dihydrochrysene (9-hydroxychrysene-1,2-diol)] were inactive per se but were activated to mutagens in the presence of reduced nicotinamide adenine dinucleotide phosphate-fortified postmitochondrial fraction (S9 mix) of liver homogenate from Arochlor 1254-treated rats. Chrysene, 3-hydroxychrysene, chrysene-1,2-diol, and 9-hydroxychrysene-1,2-diol were activated efficiently; the other compounds were activated weakly. In S. typhimurium TA 98, the mutagenic activities of the chrysene derivatives were weak in comparison with those in the strain TA 100. trans-3,4-Dihydroxy-3,4-dihydrochrysene (in the presence of S9 mix) was the most efficacious mutagen in strain TA 98. The relative mutagenic potencies of the directly active compounds differed from the results obtained in strain TA 100, in that in strain TA 98 the anti-diol-epoxide was more mutagenic than the triol-epoxides and chrysene 5,6-oxide was more mutagenic than syn-diol-epoxide and syn-triol-epoxide. In V79 cells, the order of mutagenic potency was: anti-triol-epoxide greater than anti-diol-epoxide greater than syn-triol-epoxide greater than syn-diol-epoxide greater than chyrsene 5,6-oxide greater than chrysene-1,2-diol (in the presence of S9 mix) greater than 9-hydroxychrysene-1,2-diol (in the presence of S9 mix) greater trans-3,4-dihydroxy-3,4-dihydrochrysene in the presence of S9 mix). Chrysene, 3-hydroxychrysene, 5-hydroxychrysene, and 6-hydroxychrysene showed no mutagenic effects in V79 cells, either in the presence or absence of S9 mix.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Metabolism of styrene oxide in the rat and guinea pig.

The metabolism of styrene oxide has been studied in the rat and guinea pig, with emphasis upon bivalent sulfur metabolites. Methylthio analogs of phenylethylene glycol, with the methylthio group in both possible positions, were found as urinary metabolites in both species. These compounds were present in more than trace amounts. The excretion of 2-hydroxy-1-methylthio-1-phenylethane amounted to about 7% of the administered dose in the guinea pig, and about 2% in the rat, in o-24 hr urine samples. The positional isomer 1-hydroxy-2-methylthio-1-phenylethane was excreted in lesser amounts in both species. Acidic urinary metabolites derived from glutathione conjugates are species dependent. In this study, the only products observed in the rat were the mercapturic acids expected as a result of reaction of the oxide with glutathione. In the guinea pig, the major bivalent sulfur acids were the corresponding mercaptoacetic acids. Other related metabolites included a mercaptolactic and a mercaptopyruvic acid, together with one of the mercapturic acids. These metabolites result from partial acetylation or acetylation/deacetylation of cysteine or cysteinylglycine adducts. The hitherto unobserved dihydrodiol formed via an arene oxide was found as a minor metabolite for both styrene and styrene oxide.

Animals↗

Evaluation of different injection techniques in the gas chromatographic determination of thermolabile trace impurities in a drug substance.

Thermodegradation of labile compounds in the hot injection port of a gas chromatograph causes many problems and can lead to ambiguous, poorly reproducible results. Splitless injection used in trace analysis in order to achieve a lower detection limit may even enhance the difficulties due to the longer residence time of the volatized sample in the injection port. Different techniques were tested to avoid thermodegradation of an epoxide and its corresponding chlorohydrin in a drug substance: variation of the injector temperature, high inlet flow rate during injection by electronic pressure programming, and cool on-column injection. The results showed that on-column injection was superior to splitless injection. The chlorohydrin formed epoxide by release of HCl upon splitless injection. A more detailed investigation of the factors that affect epoxide formation indicates that active sites within the injector are responsible for the degradation and that the reaction is temperature dependent. However, results equivalent to those obtained by on-column injection were obtained for splitless injection when inert materials were used in the injector.

Chlorohydrins↗

Identification of novel 7,12-dimethylbenz[a]anthracene adducts in cellular ribonucleic acid.

The interaction of guanosine with 7,12-dimethylbenz[a]anthracene (DMBA) 5,6-oxide under alkaline conditions resulted in the formation of six derivatives. These six compounds were cochromatographed with nucleosides obtained by hydrolysis of RNA isolated from rat liver cells treated with [3H]DMBA. The cochromatography showed that three of these adducts were formed in cellular RNA. The three products constituted less than 5% of the total nucleoside-DMBA adducts as shown by chromatography on Sephadex LH-20 and high-pressure liquid chromatography. In one of them, the 2'-hydroxy group of the ribose moiety of guanosine was linked to the C-5, and in the second, to the C-6 position of the DMBA 5,6-oxide residue. In the third derivative, the C-8 position of guanosine was linked to the C-5 of the DMBA 5,6-oxide moiety. These results show, for the first time, modifications of the ribose moiety and of the guanine residue at the C-8 position in the cellular RNA by a metabolite of a polycyclic hydrocarbon.

9,10-Dimethyl-1,2-benzanthracene↗

Some properties of vicinal diol-epoxides derived from benzo(a)anthracene and benzo(a)pyrene.

The alkylating properties of pairs of syn- and anti-isomers of 2 diol-epoxides derived from benzo(a)pyrene (BP) and of 1 derived from benz(a)anthracene (BA) have been investigated. Of the anti-diol-epoxides, anti-BP 7,8-diol-9,10-oxide was the most reactive compound towards DNA, towards sodium p-nitrothiophenolate in a non-aqueous solvent system, and towards 4-(p-nitrobenzyl)pyridine in aqueous solution; anti-BP 9,10,-diol-7,8-oxide was of intermediate reactivity and anti-BA 8,9-diol-10,11-oxide was least reactive. The syn-diol-epoxides gave unsatisfactory results with DNA and 4-(p-nitrobenzyl)pyridine because of their rapid solvolysis in aqueous solution, but with sodium p-nitrothiophenolate showed the order of reactivity syn-BP 7,8-diol-9,10-oxide greater than syn-BA 8,9-diol-10,11-oxide greater than syn-BP 9,10-diol-7,8-oxide. The products of the reaction between diol-epoxides and nucleic acids were examined by Sephadex LH-20 chromatography followed by high-pressure liquid chromatography (HPLC) and the diol-epoxides were shown to react principally with the guanosine and adenosine moieties of RNA.

Alkylating Agents↗

Effects of 2[5(4-chlorphenyl)pentyl]oxirane-2-carboxylate on fatty acid synthesis and fatty acid oxidation in isolated rat hepatocytes.

The effects of the hypoketonaemic and hypoglycaemic compound 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA) on fatty acid synthesis and fatty acid oxidation in rat hepatocytes were examined. Two microM-POCA caused a small stimulation of fatty acid synthesis which might be due to an increased flux through pyruvate dehydrogenase. Ten to one hundred microM-POCA inhibited (40-70%) fatty acid synthesis. At low concentrations (less than or equal to 5 microM) POCA was a more powerful inhibitor of fatty acid oxidation than of synthesis, but at higher concentrations (10-100 microM) the inhibition of synthesis and oxidation was similar. One hundred microM POCA-CoA inhibited acetyl-CoA carboxylase by about 22% and 100 microM-palmitoyl-CoA by about 33%. Since POCA was a more potent inhibitor of fatty acid synthesis than palmitate, but POCA-CoA did not inhibit acetyl-CoA carboxylase more strongly than palmitoyl-CoA, it is suggested that POCA-CoA may inhibit fatty acid synthase directly.

Acetyl-CoA Carboxylase↗

Subcellular distribution of epothilones in human tumor cells.

Epothilones are a new class of natural and potent antineoplastic agents that stabilize microtubules. Although 12,13-epoxide derivatives are potent antiproliferative agents, the activities of the corresponding 12,13-olefin analogs are significantly decreased. These data were confirmed for two new analogs, 6-propyl-EpoB (pEB) and 6-propyl-EpoD (pED), in comparison with the natural compounds EpoB/EpoD, by using human A431, MCF7, and MDR1-overexpressing NCI/Adr cells. By using tritiated pEB/pED, compound uptake, release, and nuclear accumulation were investigated in A431 and NCI/Adr cells. In these cells, epothilones can principally be recognized and exported by Verapamil-sensitive efflux pumps, which are not identical to MDR1. The degree of export depends on the structure, olefin vs. epoxide-analog, and also on the intracellular drug concentration. The accumulation of pED used at 3.5 or 70 nM, respectively, was increased in the presence of 10 microM Verapamil in both cell lines 2- to 8-fold. In contrast, the intracellular levels of pEB were affected by Verapamil only at 3.5 nM pEB in NCI/Adr (2-fold) and not in A431 cells. In addition, strong nuclear accumulation was observed for pEB (40-50%) but not paclitaxel or pED (5-15%) in both cell lines. Our study suggests that differences in growth inhibitory efficacy between epoxide and olefin analogs may be based on different mechanisms of drug accumulation and subcellular distribution.

Antineoplastic Agents, Phytogenic↗

Development of a competitive immunoassay for the determination of N-(2-hydroxypropyl)valine adducts in human haemoglobin and its application in biological monitoring.

Propylene oxide (PO) is an important industrial compound and a directly acting mutagen. Human exposure to PO can be monitored by the determination of haemoglobin adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxypropyl)valine in whole haemoglobin was developed and its potential usefulness as a tool for biologically monitoring occupational exposure was demonstrated. Analytical reliability was confirmed in a comparative study with GC-MS (range 3.7-992 nmol g-1 haemoglobin (Hb), correlation coefficient 0.99, n=10). The assay has been configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay employs a whole blood matrix and has a working range of 2-250 pmol g-1 Hb. It does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results in potentially exposed workers indicate the assay's high potential usefulness in routine occupational biomonitoring of exposure to PO.

Animals↗

Cycloepoxydon, 1-hydroxy-2-hydroxymethyl-3-pent-1-enylbenzene and 1-hydroxy-2-hydroxymethyl-3-pent-1,3-dienylbenzene, new inhibitors of eukaryotic signal transduction.

In a screening for new inhibitors of NF-KB and AP-1 mediated signal transduction pathways in COS-7 cells using secreted alkaline phosphatase (SEAP) as a reporter gene three novel compounds, cycloepoxydon (1), 1-hydroxy-2-hydroxymethyl-3-pent-1-enylbenzene (2) and 1-hydroxymethyl-3-pent-1,3-dienylbenzene (3) were isolated from fermentations of the deuteromycete strain 45-93. Cycloepoxydon inhibits the TPA-induced NF-KB and AP-1 mediated SEAP expression with an IC50 of 1-2 micrograms/ml (4.2-8.4 microns) and 3-5 micrograms/ml (12.6-21 microns) respectively. 1-Hydroxy-2-hydroxymethyl-3-pent-1-enylbenzene (2) inhibits the TPA-induced NF-KB and AP-1 mediated SEAP expression with an IC50 of 7 micrograms/ml (36.4 microns) and 5 micrograms/ml (26 microns). 3 showed only a weak inhibition of the AP-1 and no influence on NF-KB dependent reporter gene expression. In COS-7 and HeLa S3 cells electrophoretic mobility shift assays showed that cycloepoxydon strongly reduced the TPA and TNF- alpha mediated binding of NF-KB to a high affinity consensus sequence which was due to the inhibition of phosphorylation of the protein IKB.

Alkenes↗