Perilla ketone: a potent lung toxin from the mint plant, Perilla frutescens Britton.

Perilla ketone, from the essential oil of Perilla frutescens, is a potent pulmonary edemagenic agent for laboratory animals and livestock. This finding would account for reported effects of the plant on grazing cattle. The use of perilla in oriental foods and medicinal preparations suggests possible hazards to human health as well.

Inhibition of separated forms of cyclic nucleotide phosphodiesterase from pig coronary arteries by 1,3-disubstituted and 1,3,8-trisubstituted xanthines.

A series of xanthines with varied substituents in the 1, 3, and 8 positions were prepared in an attempt to understand the structure--activity relationship for alkylxanthines as inhibitors of two different forms of cyclic nucleotide phosphodiesterase. Polar substituents on the 1 or 3 position of the xanthine reduced the potency of the xanthines to inhibit both the calmodulin-sensitive and the "cyclic AMP specific" forms of phosphodiesterase. Polar substituents on the 8 position of the xanthine, other than a carboxylic acid, increased the potency to inhibit the calmodulin-sensitive form of phosphodiesterase, if they were capable of donating electrons to the xanthine nucleus. On the other hand, any substituent in the 8 position larger than H reduced the potency of the xanthines to inhibit the cyclic AMP specific form of phosphodiesterase. Topographical maps of the active sites of the two forms of phosphodiesterase are presented in summary.

Inhibition of separated forms of phosphodiesterases from pig coronary arteries by uracils and by 7-substituted derivatives of 1-methyl-3-isobutylxanthine.

A series of 7-substituted 1-methyl-3-isobutylxanthines was designed in an attempt to increade the specificity of the 1-methyl-3-isobutylxanthine (MIX) structure for one of the two cyclic nucleotide phosphodiesterase peaks isolated by DEAE-cellulose chromatography of the soluble fraction of the intima + media layer of pig coronary arteries. A series of 1,3-dialkyluracils was of low potency as inhibitors of either peak I or peak II. The 7-substituted xanthines were prepared by alkylation of MIX with the corresponding alkyl or aralkyl halide in DMF containing K2CO3. These compounds were, in general, much less potent inhibitors of peak II activity than was MIX, but some of them retained the potency of MIX as inhibitors of peak I and, therefore, were relatively specific for inhibition of peak I. 7-Bzl-MIX was the most selective compound tested; it was a potent inhibitor of peak I activity but was much less effective as an inhibitor of peak II activity. Substitution of either electron-withdrawing (nitro) or electron-donating (methoxy) groups on the 7-benzyl moiety reduced the effectiveness of the 7-benzyl compounds as inhibitors of peak I. Chlorobenzyl substitution increased the potency slightly over the benzyl but not the selectivity between peaks.

Accurate, wide-range, automated, high-performance liquid chromatographic method for the estimation of octanol/water partition coefficients II: Equilibrium in partition coefficient measurements, additivity of substituent constants, and correlation of biological data.

Occasionally, results from the highly reproducible automated log P(o/w) measurement (ALPM) differ from those determined by shake-flask methods. Several specific examples affording different values are presented. One source of these differences may be curvilinearity in plots of log (t - t0) versus percent methanol, which complicate accurate intercept determinations and, thus, estimates of log P(o/w). Other sources of these differences are presented and discussed, although their cause remains unclear. Equilibrium ALPM log P(o/w) measurements of various phenyl-, methyl-, fluoro-, chloro-, and bromobenzenes, suggest substituent constants are not strictly additive. Moreover, the higher values indicate that calculated values may not be accurate for those compounds having multiple substituents or high log P(o/w) values. ALPM gives better predictability of the in vivo concentration process of 8 or 12 toxicants in fish than the shake-flask method, another HPLC method, or even calculated log P(o/w) values. However, it equally correlates the binding to bovine serum albumin by 34 chemicals as predicted by a combination of shake-flask and calculated log P(o/w) values reported elsewhere.

Accurate, wide-range, automated, high-performance liquid chromatographic method for the estimation of octanol/water partition coefficients I: Effect of chromatographic conditions and procedure variables on accuracy and reproducibility of the method.

A high-performance liquid-chromatographic (HPLC) procedure is reported for estimation of the logarithm of the octanol/water partition coefficient, log P(o/w). This automated log P(o/w) measurement (ALPM) circumvents many inherent difficulties with the shake-flask method, yet gives high reproducibility and excellent overall correlation with shake-flask results. Partition coefficients for numerous structurally diverse chemicals, ranging from approximately 0 to approximately 8 log P(o/w) units, can be determined; however, values for zwitterionic compounds cannot be obtained. Additional advantages of ALPM include lower cost and greater safety when compared with other HPLC or shake-flask procedures. Chromatographic conditions (i.e., flow rate and temperature) and variables (i.e., column length and solvent composition) affecting this method are discussed in detail. ALPM may also find application in quality control of HPLC columns, qualitative-quantitative analysis, and in computer-controlled method development and analysis.

Preparation and Baeyer-Villiger Reaction of certain 2-carbalkoxycyclopropyl methyl ketones.

Treatment of mixed anhydrides derived from cis- and trans-2-carbobenzyloxycyclopropanecarboxylic acids and ethyl chloroformate with ethoxymagnesio di-tert-butyl malonate and subsequent treatment of the resulting adducts with p-toluenesulfonic acid afforded cis- and trans-benzyl-2-acetylcyclopropanecarboxylates in good to excellent yields, with retention of the original stereochemistry of the systems. These methyl ketones and an open chain congener, benzyl levulinate, were inert toward m-chloroperbenzoic acid. The cis-isomer and benzyl levulinate underwent normal Baeyer-Villiger reactions mediated by trifluoroperacetic acid, forming moderate yields of the acetate ester insertion products.

The effects of selected bulky substituents on the pulmonary toxicity of 3-furyl ketones in mice.

Preliminary studies examined the toxicity of a series of simple alkyl 3-furyl ketone congeners of perilla ketone, 1-(3-furyl)-4-methylpentan-1-one (1), in mice, but little was known about how aromatic or bulky side chains might affect toxicity. Therefore, 3-furylphenyl ketone (2) 3-furylphenethyl ketone (3) and 1-3-furyl-4, 4-dimethylpentan-1-one (4) were synthesized to examine this problem. The 48-h LD50 (i.p.) in Notre Dame Swiss mice for each analog was greater than that of the parent toxicant, perilla ketone (1, 30 +/- 5; 2, 173 +/- 4; 3, 150 +/- 11; 4, 79 +/- 5 mumol/kg). Absorption and distribution of these compounds should be similar based on their lipophilicities. Preliminary evidence suggested that the reduced toxicities of 2, 3 and 4 compared with 1 cannot be explained on the basis of 13C-NMR (electron density) characteristics. Instead, the reduced potency likely is the result of steric hindrance of bioactivation by the bulky side chain substituents and(or) alternative metabolism on the phenyl ring rather than the furan ring of 2 and 3.

Arsenic-sulfur amino acid interactions in the chick.

Experiments were conducted with growing crossbred chicks to determine the reasons why cysteine exacerbates roxarsone (3-nitro-4-hydroxyphenylarsonic acid) toxicity. A fortified corn-soybean meal diet that met or exceeded all nutrient requirements of the young chick was fed. While cysteine enhanced roxarsone toxicity, it had little effect on the toxicity of the inorganic arsenicals As2O3 and As2O5. The toxicity of another pentavalent organic arsenical, phenylarsonic acid, was also exacerbated by cysteine. In contrast, the growth-depression resulting from feeding the trivalent form of phenylarsonic acid, i.e., phenylarsine oxide, was not affected by dietary addition of cysteine. Supplementation of the diet with cystine, methionine or K2SO4 did not exacerbate roxarsone toxicity. Reduced glutathione (GSH), however, slightly increased the gain/feed depression resulting from feeding 300 mg roxarsone/kg diet. When injected ip 1) roxarsone and cysteine, or 2) roxarsone and ascorbic acid killed 100 or 60% of the birds, respectively, within 48 h postinjection. Few (6.7%) deaths resulted from ip injections of the same level of roxarsone alone. Therefore, the potentiation of toxicity requires pentavalent organic arsenicals and compounds that can act as reducing agents. We concluded that cysteine exacerbates roxarsone toxicity by reducing it to the more toxic trivalent state.

Species susceptibility to the pulmonary toxicity of 3-furyl isoamyl ketone (perilla ketone): in vivo support for involvement of the lung monooxygenase system.

To explore a possible relationship between metabolism and lethality, the acute toxicity of naturally occurring perilla ketone (PK), 1-(3-furyl)-4-methyl-pentan-1-one, was examined in the uninduced mouse, hamster, rabbit, dog and pig. The LD50 (+/- SE), determined using intraperitoneal (ip) injection, for the mouse and hamster were low at 5.0 +/- .3 and 13.7 +/- .9 mg/kg, respectively. The rabbit died from an ip dosage of near 14 mg/kg and estimated ip LD50 dosages were quite high for the dog and pig, being 106 +/- 25 mg/kg and over 158 mg/kg, respectively. Dogs and the pig that died from ip injections of PK displayed varying degrees of midzonal and centrilobular liver damage and dogs also had elevated serum alkaline phosphatase and glutamic-pyruvic transaminase activities. In contrast, rodents and rabbits display only pulmonary toxicity from this agent. Cytochromes P-450 and b5 concentrations and NADPH-cytochrome c reductase activity were determined for the lung, liver and kidney of mice, hamsters, rabbits, dogs, swine, sheep and cattle. High correlation between lethality and enzyme concentration further supports the hypothesis that enzymatic bioactivation of PK is required for toxicity in all species.

Biological activity of phenolic compounds. Hepatic cytochrome P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats fed phenolic monomers, polymers, and glycosides.

Eight experiments were conducted to determine effects of a phenolic polymer (Kraft wood lignin, Indulin), phenolic glycosides (cane molasses and wood molasses), and phenolic monomers (vanillin, vanillic acid, ferulic acid, and p-coumaric acid) on liver cytochromes P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats. Chicks fed 6.0% lignin had a higher (P less than 0.01) cytochromes P-450 content than did chicks fed 0% fiber, 6.0% wood cellulose (Solka Floc), or 6.0% arenaceous flour. NADPH cytochrome c reductase activity was not affected by treatment. Chicks fed 12.0% wood molasses had a higher (P less than 0.06) cytochromes P-450 level than did chicks fed 0% fiber or 6.0% wood molasses. Cane molasses incorporated at both 6.0 and 12.0% of the diet induced (P less than 0.05) cytochromes P-450 content over those of control-fed birds. Chicks fed 6.0% lignin, with or without antibiotic (bacitracin:neomycin sulfate, 2:1), had a higher (P less than 0.01) cytochromes P-450 level than did chicks fed control diets, with or without antibiotic. Additionally, chicks fed 6.0% lignin had lower (P less than 0.01) intestinal diaminopimelic acid (DAP) levels than did chicks fed 0% fiber. Rats fed 0% fiber, 6.0% wood cellulose, 6.0% arenaceous flour, or 6.0% lignin exhibited no difference in cytochrome level or activity among treatments. Chicks fed 0.5% vanillin, 0.5% vanillic acid, 0.5% ferulic acid, or 0.5% p-coumaric acid had comparable cytochromes level and activity compared with chicks fed no phenolics. Chicks fed 0.5% p-coumaric acid had lower (P less than 0.05) rates of gain than did chicks fed control or other phenolic-containing diets. Rats fed these phenolics had similar cytochromes P-450 content among treatments.