Molecular action mechanisms of caramel color and interactions with turmeric in mouse gastric fundus

In this study, the effects of ammonium sulfite caramel color (E150d) on isolated mouse gastric fundus were investigated. In addition, the interaction of E150d with turmeric (Curcuma longa), an Ayurvedict drog, was analysed qualitatively and quantitatively. We used male mice (Swiss albino) in all experiments. After killing the mice by cervical dislocation gastric fundal tissues were isolated and placed in Tyrode's solution maintained at 37 oC and aerated with 95% O2 and 5%CO2. In qualitative experimental studies, isolated gastric fundal strips were prepared by longitudinally and mounted under 0.35 g tension. Experimental data were recorded by an isometric transducer. E150d (14mg/ml) caused reproducible relaxations in the isolated gastric fundal strips precontracted with carbachol (carbamylcholine cloride; 50 µM)). Ayurvedic drog turmeric (10 µL/ml) nonsignificantly increased the relaxations induced by E150d (14mg/ml). Nw-nitro-L-arginine (L-NOARG; 10 µM), an inhibitor of nitric oxide synthase, significantly inhibited the relaxations induced by E150d (14mg/ml) and turmeric (10 µl/ml) abolished the inhibitory action of L-NOARG and caused a significant increment on these relaxations. In contrast, ouabain (10 µM), an inhibitor of Na+/K+-ATPase, slightly inhibited the relaxations induced by E150d (14 mg/ml) and turmeric (10 µl/ml) nonsignificantly inhibited the effect of ouabain (10 µM) and slightly increased the relaxations induced by E150d (14mg/ml). In addition, tetraethylammonium (TEA; 50 µM), a potassium channel blocker, significantly inhibited the relaxations induced by E150d (14mg/ml). Turmeric (10µl/ml) nonsignificantly decreased the inhibitory effect of TEA and increased the relaxations induced by E150d (14mg/ml) in the related tissue. On the other hand, L-type calcium channel blocker verapamil (10 µM) or ryanodine receptor (intracellular calcium channel) blocker ruthenium red (10 µM) did not have a significant effect on relaxations induced by E150d (14mg/ml). And also, turmeric didn't affect the E150d relaxations exposed to verapamil or ruthenium red. In quantitative expereimental studies ELISA (Enzyme Linked Immunosorbent Assay) method was used. Isolated gastric fundal tissues of mice were separated into groups included control, turmeric (10 µl/ml), E150d (14mg/ml) and turmeric (10µl/ml)+E150d(14mg/ml) and incubated with related compounds in Tyrode solution maintained at 37 oC for 40 minutes. Then SOD, COX enzyme activities and nitrite concentrations of the groups separately and quantitatively analysed by using ELISA method. The principal of ELISA method is based on specific antigen-antibody reaction. E150d (14mg/ml) significantly increased SOD activity and turmeric (10 µl/ml) completely abolished the increment of SOD activity caused by E150d. Turmeric (10µl/ml), when used alone, did not significantly affect the nitrite level in the related tissue. In contrast E150d (14mg/ml) obviously decreased the nitrite level. But this reduction was not significant. Turmeric (10µl/ml) failed to abolish this reduction induced by E150d in the related tissue. On the other hand turmeric (10µl/ml), E150d (14mg/ml) or E150d(14mg/ml)+turmeric(10µl/ml) did not significantly affect the COX enzyme activity in the gastric fundal tissues. In conclusion, the experimental results show that nitrergic system and potassium channels may play a role on relaxations induced by E150d in the mouse gastric fundal strips. In addition E150d may increase SOD activity by means of generating superoxide anions in the related tissue. Furthermore, Ayurvedic drog turmeric may interact with E150d as an antioxidant agent and the harmful oxidative stress of E150d may be treated by turmeric.