Safety assessment of 2-ethyl-3,(5 or 6) dimethylpyrazine as a food ingredient.

2-Ethyl-3,(5 or 6)-dimethylpyrazine (CAS No. 27043-05-6), a heterocyclic, nitrogen-containing compound, is used in the food industry as a flavor ingredient for its characteristic roasted odor and flavor, reminiscent of roasted cocoa or nuts. Pyrazines, including 2-ethyl-3,(5 or 6)-dimethylpyrazine, are widely distributed in foods and because of their natural unavoidable occurrence in cooked food; therefore, pyrazine compounds, including 2-ethyl-3,(5 or 6)-dimethylpyrazine, are commonly consumed in the daily diet. 2-Ethyl-3,(5 or 6)-dimethylpyrazine is oxidized in rats almost exclusively via its aliphatic side-chain to carboxylic acid derivatives. The LD(50) of 2-ethyl-3,(5 or 6)-dimethylpyrazine in rats was reported as 460 mg/kg and it is reported to be irritating to the skin, eyes and the upper respiratory tract. Two 90-day rat feeding studies have been conducted on 2-ethyl-3,(5 or 6)-dimethylpyrazine, with the one reporting a no effect level of 12.5mg/kg/day (both sexes) and a second study reporting a NOAEL of 2-ethyl-3,(5 or 6)-dimethylpyrazine 17 and 18 mg/kg/day for male and female rats, respectively. Although no genotoxicity studies were found on 2-ethyl-3,(5 or 6)-dimethylpyrazine, structurally similar pyrazine derivatives were reported as clastogenic in mammalian cells and non-mutagenic in bacterial assays. The relevance of the positive results in assays with Saccharomyces cerevisiae and Chinese hamster ovary cells in vitro is unclear. The data and information available, including a prolonged history of safe use, indicate that at the current level of intake, the food flavoring use of 2-ethyl-3,(5 or 6)-dimethylpyrazine is safe.

Humoral pathway for local transfer of the priming pheromone androstenol from the nasal cavity to the brain and hypophysis in anaesthetized gilts.

It is generally accepted that pheromones act by stimulating of the dendritic receptors of the olfactory neurones massed in the olfactory epithelium. This study was designed to ascertain whether it is possible for the boar pheromone androstenol (5alpha-androst-16-en-3-ol) to be transported from the nasal cavity of anaesthetized gilts to the brain and hypophysis via local transfer from the blood in the perihypophyseal vascular complex. The experiment was performed on days 18-21 of the porcine oestrous cycle (crossbred gilts, n = 6). Tritiated androstenol (3H-A; total amount 10(8) d.p.m. (758 ng)) was applied for 1 min onto the respiratory part of the nasal mucosa, 4-6 cm from the opening of the nares. Arterial blood samples from the aorta and from the carotid rete were collected every 2 min during the 60 min period following administration of the steroid. Total radioactive venous effluent from the head was removed and an adequate volume of homologous blood was transfused into the heart through the carotid external vein. At the end of the experiment gilts were killed and tissue samples of the hypophysis and some brain structures were collected to measure radioactivity. In addition, corresponding control tissues were collected from three untreated gilts and from three heads of gilts 60 min after 3H-A was applied post mortem into the nasal cavity. The concentration of 3H-A was significantly higher (P < 0.0001) in the arterial blood of the carotid rete than that of aorta. The mean rate of 3H-A counter current transfer from venous to arterial blood in the perihypophyseal vascular complex, expressed as the ratio of the 3H-A concentration in arterial blood of the carotid rete to the 3H-A concentration in blood sampled simultaneously from the aorta, was 1.96 +/- 0.1. The concentration of 3H-A in plasma from the venous effluent from the head ranged from 1.3 to 1.8 pg x ml(-1). During the 60 min period of the experiment, 0.68% of the total applied dose of 3H-A was resorbed from the nasal cavity into the venous blood. Moreover, we found that 3H-A was present in the olfactory bulb (P <0.01), amygdala, septum, hypothalamus, adenohypophysis, neurohypophysis (P > 0.05) and perihypophyseal vascular complex (P < 0.01). These results demonstrate that, in anaesthetized gilts, the boar pheromone androstenol may be resorbed from the nasal mucosa, transferred in the perihypophyseal vascular complex into arterial blood supplying the brain and hypophysis, and then arrested in the hypophysis and certain brain structures. We suggest that in addition to the standard neural pathway for signalling pheromones, another pathway exists whereby androstenol, as a priming pheromone, may be resorbed from the nasal cavity into the bloodstream and then pass locally from the perihypophyseal vascular complex into the arterial blood supplying the brain and hypophysis, thus avoiding the first passage metabolism in the liver.

Humoral pathway for transfer of the boar pheromone, androstenol, from the nasal mucosa to the brain and hypophysis of gilts.

Signaling and priming pheromones play an important role in intraspecies behavioral and sexual interactions and in the control of reproduction. It is generally accepted that pheromones act by stimulating the dendritic receptors in the mucus-imbedded cilia of olfactory neurons massed in the olfactory epithelium. The boar pheromone androstenol, known to induce sexual behavior in pigs, is 1 of 2 pheromones that have been chemically defined, tritiated and thus made available for use in studies. In Experiment 1, sexually mature cyclic gilts at Days 16 to 21 of the estrous cycle were humanely killed and the heads separated from the bodies. The heads were attached to a perfusion system using heated, oxygenated, heparinized, autologous blood. A total amount of 10(8) dpm (758 ng) of 3H-5 alpha-androstenol (3HA) was either infused into the angularis oculi veins that drain the nasal cavities (n = 7) over a 5-min period or applied through intranasal catheters onto the mucose surface (n = 16) for 2 min. In both groups frequent blood samples were collected from the carotid rete and from venous effluent. Concentration of 3HA in the arterial blood of the carotid rete after direct (into angularis oculi veins) or indirect (onto the nasal mucosa) administration of 3HA into veins draining the nasal cavities was significantly higher than background radioactivity before 3HA administration (P < 0.0001 and P < 0.05, respectively). The 3HA was selectively accumulated (compared with the respective control tissue) in the neurohypophysis (P < 0.001), adenohypophysis (P < 0.01), ventromedial hypothalamus (P < 0.05), corpus mammillare (P < 0.01), and perihypophyseal vascular complex (P < 0.001). In a second in vitro experiment, active uptake of 3HA into the nasal mucosa of the proximal, respiratory segment of the nasal cavity was observed. These results demonstrate a humoral pathway for the transfer of pheromones from the nasal cavity to the hypophysis and brain. Androstenol was taken up by the respiratory part of the nasal mucosa, resorbed into blood, transported to the cavernous sinus and transferred into the arterial blood of the carotid rete (supplying the hypophysis and brain), and then selectively accumulated in the hypophysis and certain brain structures.