Effect of some hypoglycemic herbs on the activity of phase I and II drug-metabolizing enzymes in alloxan-induced diabetic rats

Department of Bioscience and Technology, Institute of Graduate Studies and Research, Alexandria University, Egypt. ssheweita@yahoo.com

Polycyclic aromatic hydrocarbons (PAHs) and N-nitrosamines (NNA) are mainly activated by cytochrome P450s, and their associated enzyme activities such as aryl hydrocarbon  (benzo(a)pyrene) hydroxylase (AHH), N-nitrosdimethylamineN-demethylase I (NDMA-dI),  NADPH-cytochrome C reductase, and detoxified by glutathione S-transferase (GST) and glutathione (GSH). The present study shows the influence of Cymbopogon proximus (Halfa barr), Zygophyllum coccineum L. (Kammun quaramany), Lupinus albus (Termis) as herbs capable of inducing hypoglycemia on the activity of the above mentioned enzymes in the liver of diabetic rats. Alloxan was administered as a single dose (120 mg/kg body weight) to induce diabetes and the herbs were administered to diabetic rats as repeated doses for 4 weeks. Alloxan-induced diabetes significantly increased the blood glucose level by 93% compared to the control level. On the other hand, repeated-dose treatments of diabetic rats with Cymbopogon proximus and Lupinus albus are more effective than Zygophyllum coccineum in restoring the elevated blood glucose level to the normal level. Alloxan treatment increased the hepatic activity of cytochrome P450, NADPH-cytochrome C reductase, AHH, NDMA-dI, GST and GSH by 112, 122, 82, 99, 64 and 26%, respectively. These herbs decreased the activity of above mentioned enzymes in the liver of diabetic rats compared to alloxan-treated rats. We conclude that alloxan increased the activity of cytochrome P450 system and that such herbs reduced these activities. The toxic effects of PAHs (e.g. benzo(a)pyrene) and NNA (e.g. N-nitrosdimethylamine) could be increased in the liver of diabetic rats through induction of their corresponding bioactivating enzymes. On the other hand, hypoglycemic herbs could alleviate the deleterious effects of these carcinogens in the liver of diabetic rats since these herbs reduced the hepatic content of cytochrome P450 and other associated enzyme activities compared to the diabetic group. Such alterations in the activity of phase I and II drug-metabolizing enzymes should be considered when therapeutic drugs are administered to diabetic patients since most of drugs are metabolized mainly by the cytochrome P450 system.

Biochemical study on the effects of some Egyptian herbs in alloxan-induced diabetic rats

Department of Biochemistry, Faculty of Science, Alexandria University, 21526, Alexandria, Egypt

The present study was carried out to investigate the effects of Lupinus albus, L. (Lupinus termis), family L. leguminosae, Cymbopogon proximus, (Halfa barr), family Gramineae, and Zygophyllum coccineum L. (Kammun quaramany), family L. Zygophyllacae on biochemical parameters in alloxan-induced diabetic rats. A dose of 1.5 ml of aqueous suspension of each herb/100 g body weight (equivalent to 75 mg/100 g b.wt.) was orally administered daily to alloxan-diabetic rats for 4 weeks. The levels of glucose, urea, creatinine and bilirubin were significantly (P<0.05) increased in plasma of alloxan-diabetic rats compared with the control group. In contrast, total protein and albumin were significantly decreased by 25 and 46%, respectively, versus control. Treatment of the diabetic rats with repeated doses of any one of the three herb suspensions could restore the changes of the above parameters to their normal levels after 4 weeks of treatment. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (AlP) activities were significantly (P<0.05) increased in the plasma of alloxan-diabetic rats. However, acetylcholinesterase activity was significantly (P<0.05) decreased in the plasma compared with the control group, whereas, such activity did not change in brain. The activities of AST, ALT and LDH were significantly (P<0.05) decreased in the liver of alloxan-diabetic rats by 58, 21 and 40%, respectively, and such activities increased in testes by 39, 26 and 26%, respectively, compared with the control group. Also, brain LDH was significantly (P<0.05) increased. Treatment of the diabetic rats with the aqueous suspension of the tested herbs restored the activities of the above enzymes to their normal level in plasma, liver and testes. The present results showed that the herb suspensions exerted antihyperglycemic effects and consequently may alleviate liver and renal damage caused by alloxan-induced diabetes.