Inhibition of growth ofPhytophthora parasitica var.nicotianae by aromatic acids and coumarins in a laboratory bioassay.

Hydroxy-, dihydroxy-, trihydroxy-, methoxy-, dimethoxy-, hydroxy-+methoxy-, amino-, chloro-, and nitro-substituted benzoic, phenylacetic, phenylpropanoic, and phenylpropenoic (cinnamic) acids were evaluated for activity against the growth ofPhytophthora parasitica var.Nicotianae, Races 0 and 1, in a laboratory bioassay. Several substituted coumarins were also tested. In general, for Race 0, the phenylpropenoic acids were more active (on a millimolar basis), than the corresponding benzoic, phenylacetic, or phenylpropionic acids (9 of 14 series). Among the most active acids wereo-hydroxycinnamic and the chloro- and methoxycinnamic acids. The activities of unsubstituted benzoic and phenylpropionic acids were comparable to the most active compounds tested. Monohydroxyaromatic acids were more active than most dihydroxy acids of the same chain length. Dihydro-3,4-dihydroxycinnamic acid was slightly more active than the corresponding cinnamic acid, while the reverse was true for the mono-p-hydroxycinnamic acid versusp-hydroxyphenylpropionic acid. Coumarin was more active than its hydroxy, methyl, hydroxymethyl, or methoxy derivatives. In general, Race 1 was even more significantly affected by the aromatic acids. Glycosylated coumarins were inactive in the bioassay, compared to their aglycones.

The application of solid phase extraction to the analysis of tobacco-specific nitrosamines.

A new isolation and separation method has been developed for the alkaloid-related nitrosamines in tobacco, called tobacco-specific nitrosamines (TSNA). The improved isolation procedure involves the extraction by sonication of TSNA from cured tobacco with toluene and an aqueous citrate buffer solution, while purification is achieved by solid phase extraction on small silica cartridges. Interfering extract materials are eluted from the silica cartridges with the toluene and a chloroform-methylene chloride solvent, while subsequent elution with chloroform yields the TSNA in a purified fraction. Gas chromatographic analyses on an SE-54-coated glass capillary column and detection by a nitrogen-phosphorous detector produce very good data on the four TSNAs, which include N-nitrosanatabine (NATB), N-nitrosoanabasine (NAB), 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (called NNK), and N-nitrosonornicotine (NNN). The method is shown to be quantitative, reproducible, and applicable to the determination of TSNA in various tobacco samples, such as stems and lamina of cured tobacco leaves, as well as to smokeless tobacco.

A study on the mutagenicity of tobacco smoke from low-tar cigarettes.

A series of 16 low-tar cigarettes, yielding from 1 to 10 mg of tar, were smoked on a modified cigarette smoking machine that collected both mainstream (MS, inhaled) smoke and sidestream (SS, between puffs) smoke. The SS smoke is the major contributor to environmental tobacco smoke. The collected MS and SS smoke condensates were evaluated for mutagenicity by the Ames test and compared with MS and SS smoke condensates from a high-tar cigarette. Both MS and SS condensates of low-tar cigarettes (LTCs) were tested with the Salmonella strains TA1538 and TA100. Except for three cigarettes, the MS smoke mutagenicities of the LTC smoke condensates were significantly reduced (about 30%) when compared with a control, high-tar (23-mg) cigarette. Opposite results were obtained for the SS smoke condensates, which were more mutagenic (about 20%) than the SS smoke condensate of the high-tar cigarette. Thus, LTC mainstream smoke may be less hazardous to the LTC smoker, whereas LTC sidestream may emit more mutagenic compounds into environmental tobacco smoke, which, through passive inhalation, could affect both smokers and nonsmokers.

The contribution of low tar cigarettes to environmental tobacco smoke.

A series of low tar cigarettes (LTC) were smoked and the quantities of condensable mainstream (inhaled) and sidestream (between puffs) smoke compounds were determined and compared to those produced by a high tar, nonfilter cigarette. It was found that the LTC produced large quantities of sidestream smoke condensates, about equal to the high tar cigarette, and contained very high levels of toxic or cocarcinogenic phenols. On an equal weight basis, the LTC emitted more of these hazardous compounds into sidestream and environmental tobacco smoke. Higher smoke yields of a flavor additive and a sugar degradation product indicated addition of such compounds during the manufacture of LTC. It was concluded that, compared to a high tar cigarette, smoking LTC may be better for the smoker, but not for the nearby nonsmoker. Information should be developed to allow smokers to choose LTC that produce lower levels of hazardous compounds in their environmentally emitted sidestream smoke.

Selenium-mediated reduction in the mutagenicity of cigarette smoke.

Cigarette smoke contains carcinogens and mutagens and affects the health of smokers. Recently, increased research has proven the potentially protective activity of selenium (Se) against heavy metal toxicity, cancer, and other health disorders. Accordingly, we have proposed the fortification of tobacco with Se to develop safer cigarettes. As a start in evaluating any biological effects of added Se, we have determined the mutagenicity of inhaled, mainstream (MS) cigarette smoke condensate (CSC), with and without Se, in the preincubation assay of the Ames test. Initially, it was shown that Se, as sodium selenite, was not mutagenic at high concentrations (up to 80 micrograms/plate) with strains TA1538 and TA1978. Subsequently, the effects of different levels of Se, added to MS CSC, were examined with TA98, TA100, and TA1538. On the average, addition of 10 micrograms Se produced mutagenicity reductions of about 50%. Higher levels of added Se yielded further reductions. Cigarette sidestream (SS) smoke, collected between puffs, was also tested. Again, Se added to SS-CSC gave similar reductions, confirming its antimutagenic effect for both mainstream and sidestream smoke.

Increasing selenium in cigarettes and smoke: transfer to smoke.

The selenium content of some American tobaccos and cigarettes was determined. The quantities of added selenium that were transferred from cigarettes to inhaled, mainstream smoke were examined for several commercial and experimental cigarettes of different tar levels. For high-tar cigarettes, as much as 10% of added selenium was found in mainstream smoke, while low-tar cigarettes delivered about 3% of added selenium. Transfer rates of selenium to mainstream smoke are reported for various levels of fortification (0-25 micrograms/cigarette) and the rationale for selenium fortification is discussed. Based on highly favorable reports in the literature on the antitumor activity of selenium, the fortification of tobacco with selenium may become a viable way of producing a safer tobacco product. It is proposed that such selenium-fortified smoking products be developed and evaluated extensively.

Effects of varied smoking machine parameters on deliveries of total particulate matter and selected smoke constituents from an ultra low-tar cigarette.

A typical ultra low-tar cigarette was mechanically smoked under varying conditions designed to simulate potential changes in human smoking behavior. Determination of the yields of total particulate matter and analyses of individual smoke components, including nicotine, phenolics, acids, and the humectant, glycerol, demonstrated significant changes in smoke composition as related to intensity and frequency of inhalation. Physical obstruction of tipping paper ventilation, by negating the effects of air dilution of smoke, resulted in increased smoke deliveries similar to those observed when puffing volume and frequency were increased.

Tumor-promoting activity of certain extracts of tobacco.

Tumor-promoting activities of extracts of fluecured and cigarette tobacco were evaluated. Initially, fluecured tobacco was extracted consecutively with hexane, chloroform, acetone, ethyl alcohol, methyl alcohol, and water; and the extracts were tested for tumor-promoting activity on mouse skin. The hexane and chloroform extracts were fractionated on silicic acid, and the fractions were devoid of tumorigenic activity. The acetone and alcohol extracts showed marginal activity. Subsequently, chloroform-extracted cigarette tobacco was extracted with water, and the aqueous extract was partitioned by solvent precipitation methods. Bioassay results showed tumor-promoting activity for the aqueous extract, with tumors in 38% of the animals. The aqueous extract appeared about five times as active as smoke condensate derived from an equal weight of tobacco.

Mouse skin tumorigenesis and induction of aryl hydrocarbon hydroxylase by tobacco smoke fractions.

Ten fractions separated from the neutral portion of cigarette smoke condensate (CSC) were tested on mouse skin for tumor-initiating activity and for their capacity to induce the enzyme aryl hydrocarbon hydroxylase (AHH). Tumor-initiating activity was confined primarily to the fraction containing more than 90% of the polynuclear aromatic hydrocarbons (PAH) in CSC. One other PAH-containing fraction was active. The combined initiating effect of these fractions was comparable to that of a 40-ppm solution of benzo[a]pyrene (BP), which is about 40 times the BP content of CSC. Some of the neutral fractions that have been demonstrated to cause tumor promotion in mice pretreated with 7,12-dimethylbenz-[aA1ANTHRACENE sere inactive as tumor initiators. The fractions that contained aromatic hydrocarbons induced mouse skin AHH levels twofold to sixfold after a single topical application. AHH-inducing activity was not, however, a reliable indicator of the carcinogenic potential of a fraction.