The Hedyotic Diffusa Willd Injection Effect Against Ifosfamide Induced Toxicity By Interfere In Cytochrome P450

The purpose of the present work is to clartif the mechanism of hedyotic diffusa effect against ifosfamide-induced toxicity by interfere in cytochrome P450from three aspects as follows:The activity of CYP3A4and renal oxidative stress and histopatholation were inveastigated after ifosfamide co-administrated with hedyotis diffusa; The pharmacokinetics of ifosfamide in rat was evaluated after it combined with quercetin or oleanolic acid or ursolic acid, which are rich in hedyotis diffusa and have an anti-tumor effects; Oleanolic acid and ursolic acid were tested for metabolism pathways and their ability to modulate the activities of several cytochrome P450enzymes using human liver microsomes.Male SD rats were treated with saline, ifosfamide, hedyotis diffusa injection pius ifosfamide by the lateral tail vein for5days. The catalytic activity of CYP3A4was determined by measuring erythromycin N-demethlation. Renal tissue malondialdehyde(MDA) and glutathione(GSH) level, histopathology were evaluated; the aiti-tumor components,quercetin, oleanolic acid and ursolic acid, which are abundant in hedyotis diffusa and likely to inhibit CYP3A4, were partly administrated with ifosfamide. The analysis of ifosfamide in rats plasma were performed using LC-MS/MS. Pharmacokinetic parameters of k、t1/2、Tmax、AUC were analysized using non-compartmental model; Oleanolic acid or ursolic acid was incubated with eighit CYP probe substrate in human liver microsome, the inhibition ratio was calculated by comparing with CYP selective inhibitor. The metabolism enzymes of ursolic acid were identified on the basis of experiments including chemical inhibition in human liver microsomes and metabolism by human cDNA-expressed CYP enzymes. The results indicated that ifosfamide lightly induced the activity of CYP3A4, increased renal MDA and reduced GSH concentrations, and also caused renal injuries. The administration of hedyotis diffusa along with ifosfamide inhibited the activity of CYP3A4, counteracted the deleterrious effects of ifosfamide on renal MDA, GSH and morphological changes; It was suggested that oleanolic acid and ursolic acid could induce the biotransformation of ifosfamide by reducing its AUC to50%; The result indicated that oleanolic acid competitively inhibited CYP3A4-catalyzed midazolam hydroxylation. CYP3A4and CYP2C9were identified as the major enzymes which are responsible for the mebolism of ursolic acid.On the basis of these results, the mechanism of hedyotis diffusa effect aganist ifosfamide-induced toxicity could be presumed as follows: oleanolic acid, the component of hedyotis diffusa, inhibit the activity of CYP3A4, then decreases toxcity metabolities of CYP3A4-catalyzed ifosfamide, reduces the side-effect induced byifosfamide.