ABSTRACT
trans-Dehydrocrotonin (t-DCTN), the diterpenoid from Croton cajucara Bentham, exhibits hypoglycemic and hypolipidemic activities, but in high doses is associated with a discrete hepatotoxicity. In the search for measures to mitigate this, pretreatment with the antioxidants N-acetylcysteine and vitamin E has been examined. Mice that received a high dose t-DCTN (100 mg/kg) manifested hepatic damage, as evidenced by significant elevations in serum ALT and AST, and hepatic GSH, and histological alterations, which could be obliterated by pretreatment with vitamin E, but not with N-acetylcysteine, possibly by creating an effective antioxidant balance.
Subject(s)
Acetylcysteine/pharmacology , Antioxidants/pharmacology , Chemical and Drug Induced Liver Injury/prevention & control , Diterpenes, Clerodane/toxicity , Vitamin E/pharmacology , Alanine Transaminase/blood , Animals , Aspartate Aminotransferases/blood , Catalase/blood , Chemical and Drug Induced Liver Injury/blood , Chemical and Drug Induced Liver Injury/enzymology , Diterpenes, Clerodane/antagonists & inhibitors , Drug Interactions , Glutathione/analysis , Histocytochemistry , Male , Mice , Thiobarbituric Acid Reactive Substances/analysisABSTRACT
This study was aimed to clarify the mechanisms of gastroprotection by centipedic acid (CPA), a natural diterpene from Egletes viscosa LESS. (Asteraceae) using ethanol-induced gastric mucosal damage in mice and gastric secretion in 4-h pylorus-ligated rats as model systems. In mice, intragastrically administered CPA (25, 50, 100 mg/kg) greatly reduced the mucosal lesions induced by 96% ethanol (0.2 ml, p.o.) by 18, 53, and 79%, respectively, whereas N-acetylcysteine (NAC, 300 mg/kg, i.p.), the reference compound produced a 50% inhibition. In 4-h pylorus-ligated rats, CPA (50 mg/kg) applied intraduodenally decreased both gastric secretory volume and total acidity. Similar to NAC, the plant diterpene effectively prevented the ethanol associated decrease in non-proteic sulfhydryls (NP-SH) and the elevated thiobarbituric acid-reactive substances (TBARS) in gastric tissue, suggesting that these compounds exert an antioxidant effect. Pretreatment of mice with indomethacin, the cyclooxygenase inhibitor but not with capsazepine, the transient receptor potential vanilloid-1 (TRPV1)-receptor antagonist greatly suppressed the gastroprotective effect of CPA. Furthermore, CPA gastroprotection was significantly attenuated in mice pretreated with L-NAME or glibenclamide the respective inhibitors of nitric oxide synthase and K(+)(ATP) channel activation. These data suggest that CPA affords gastroprotection by different and complementary mechanisms, which include a sparing effect on NP-SH reserve, and roles for endogenous prostaglandins, nitric oxide, and TRPV1-receptor and K(+)(ATP) channel activation.
