The effect of dietary guar gum on the activities of some key enzymes of carbohydrate and lipid metabolism in mouse liver

1. The effects of a 100 g/kg substitution of guar gum on the body-weight gain, food consumption and faecal dry weight of mice fed on a high-sucrose diet and on the activities of hepatic glucose-6-phosphate dehydrogenase (EC 1 . 1 . 1 .49), 6-phosphogluconate dehydrogenase (EC 1 . I . 1 .44), malate dehydrogenase (oxaloacetatedecarboxylating) (NADP+) (EC I . 1 . 1 .40), ATP-citrate (pro-3S)-lyase (EC 4 . I .3.8), 6-phosphofructokinase (EC 2.7. 1 . 1 I), pyruvate kinase (EC 2 .7 .1 .40) and fructose-1,Qbisphosphatase (EC 3.1 .3.11) were studied. 2. Guar gum had no effect on body-weight gain or food consumption but increased faecal dry weight. 3. Guargumincreasedtheactivitiesofglucose-6-phosphatedehydrogenase,malatedehydrogenase(oxaloacetatedecarboxylating) (NADP+) and 6-phosphofructokinase expressed on a wet-liver-weight basis. 4. Guar gum increased the activities of glucose-6-phosphate dehydrogenase, malate dehydrogenase (oxaloacetatedecarboxylating)(NADP+), ATP-citrate (pro-3S)-lyase and 6-phosphofructokinase expressed on a liver-protein basis. 5. Guar gum increased the activities of glucose-6-phosphate dehydrogenase and malate dehydrogenase (oxaloacetate-decarboxylating)(NADP+) expressed on a body-weight basis. 6. These results suggest that guar gum increases the flux through some pathways of hepatic lipogenesis when mice are fed on high-sucrose diets.