Catechol and alkylcatechols are known co-carcinogens present in cigarette smoke. Hydroquinone, although nongenotoxic, can form a metabolite with nephrotoxic properties and is a potential human carcinogen. The formation of dihydroxybenzenes during smoking originates with the pyrolysis of several precursors from tobacco. These include cellulose, chlorogenic acid, rutin, etc. The present study attempts to quantitate the contribution of chlorogenic acid and rutin to the formation of dihydroxybenzenes and of some alkyldihydroxybenzenes. Also it estimates the contribution to the formation of dihydroxybenzenes from other potential precursors including glucose, fructose, sucrose, cellulose, pectin, starch, and lignin. The study was done in three parts: 1. pyrolytic evaluation of the amount of dihydroxybenzenes in smoke generated from isolated potential precursors; 2. analysis of smoke from cigarettes made from a variety of tobaccos (14 single grades) and two blended cigarettes, followed by correlations of dihydroxybenzenes yield with the tobacco content of various suspected precursors; 3. addition of chlorogenic acid or rutin to several tobaccos followed by the smoking of the spiked cigarettes and measurement of dihydroxybenzenes yield increase. The study shows that for a variety of singlegrade cigarettes and for two blended cigarettes (one being the 2R4F Kentucky reference), the contribution of chlorogenic acid and of rutin to the formation of catechol and hydroquinone in smoke depends on the blend. For the 2R4F cigarette, the contribution from chlorogenic acid is 8.7% for catechol, and 7.7% for hydroquinone (for ISO smoking protocol). For the same cigarette, the contribution from rutin is 3.7% for catechol and 5.1% for hydroquinone. The results of the study are in agreement with a previously reported finding indicating that chlorogenic acid contributes about 13% to the catechol formation in smoke for the 1R1 Kentucky reference cigarette. The study results suggest that other components in tobacco, besides chlorogenic acid, rutin, glucose, fructose, sucrose, cellulose, pectin, starch, and lignin are major contributors to the formation of catechol and hydroquinone in cigarette smoke.

SUMMARYQuinic acid [D(-)-quinic acid, (1S, 3R,4S,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid], and inositol [myoinositol, (1R,2R,3S,4S,5R,6S-cyclohexane-1,2,3,4,5,6-hexol or cis-1,2,3,5-trans-4,6-cyclohexane-hexol] are oxygenated compounds well known as tobacco constituents. Although mentioned in the literature as constituents of tobacco leaf as early as 1930, very little information is offered regarding the quantitation of quinic acid and inositol, up to the present day. This study describes a simple procedure for the analysis of quinic acid and myo-inositol in tobacco and reports the levels of these two analytes in various single grade and blended tobaccos from commercial and Kentucky reference cigarettes. The procedure is based on an original LC/MS/MS analysis of the tobacco extract. This method and its validation are described in this paper. A wide range of levels of the analytes was observed from sample to sample. Burley samples were in general low in both quinic acid and inositol compared to flue-cured tobaccos. The levels of myo-inositol detected in the analyzed samples were consistent with previously reported results for flue-cured tobaccos, but significantly lower than those reported for Burley. Besides myo-inositol, a number of naturally occurring stereoisomers of inositol are known. These include scyllo-, muco-, D-chiro-and neo-inositol. Other isomers are possible, including L-chiro-, allo-, epiand cis-inositol, but they are less common. No previous study has been reported regarding the evaluation of these compounds in tobacco, and the present study indicated that only myo-inositol and D(-)-quinic acid are found in tobacco. [Beitr. Tabakforsch. Int. 25 (2012) 2,3,4,5,6-hexol ou cis-1,2,3,5-trans-4,6-cyclohexanehexol] sont des composés oxygénés bien connus comme constituants du tabac. Bien qu'ils aient été mentionnés dès 1930 comme constituants de la feuille de tabac dans la littérature spécialisée, il n'existe jusqu'à présent que très peu d'informations concernant la

Formation of dihydroxybenzenes in cigarette smoke is a subject of considerable interest because some dihydroxybenzenes are co-carcinogens, (e.g., catechol and certain alkylcatechols), and others such as hydroquinone can form metabolites that have toxic or carcinogenic properties. This present study describes the contribution of tobacco quinic acid (or (1S,3R,4S,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid) and myo-inositol (or (1R,2R,3S,4S,5R,6S)-cyclohexane-1,2,3,4,5,6-hexol) to the formation of dihydroxybenzenes in cigarette smoke. The study is a continuation of a previous one showing the contribution of chlorogenic acid and rutin as precursors for these compounds (6). The yields of dihydroxybenzenes formed by pyrolysis of quinic acid and myo-inositol are relatively high and both quinic acid and myo-inositol can be present in some tobacco types at levels as high as 1% by weight. The level of these compounds makes them potentially important contributors to the formation of dihydroxybenzenes in cigarette smoke. Similar to the previous study on other dihydroxybenzene precursors from tobacco, this present study was done in three parts: 1) pyrolytic evaluation of the amount of dihydroxybenzenes in smoke generated from isolated quinic acid and myoinositol; 2) analysis of smoke from cigarettes made from a variety of tobaccos (14 single grades) and two blended cigarettes, followed by correlations of dihydroxybenzene yields from these cigarettes with the level of quinic acid and myo-inositol in the tobaccos; 3) addition of quinic acid or myo-inositol to several tobaccos followed by the smoking of the spiked cigarettes and measurement of the dihydroxybenzenes yield increase. The study performed on a variety of single-grade tobacco cigarettes and for two blended-tobacco cigarettes (one being the 2R4F Kentucky reference) shows that the contribution of quinic acid and of inositol to the formation of catechol and hydroquinone in smoke depends on the blend, as previously shown for chlorogenic acid and rutin. The study results suggest that quinic acid and myo-inositol may be major contributors to the formation of dihydroxybenzenes in cigarette smoke. Although the calculations do not provide precise numbers for the contribution of quinic acid and inositol to the formation of dihydroxybenzenes, these results suggest that the contribution could be as high as 50 to 60% of the level of dihydroxybenzenes.