Modulatory effects of Azadirachta indica leaf extract on cutaneous and hepatic biochemical status during promotion phase of DMBA/TPA-induced skin tumorigenesis in mice

摘要

The modulation in biochemical status of skin and hepatic tissue at the time point of commencement of promotion stageof skin carcinogenesis in mice and its intervention with aqueous Azadirachta indica leaf extract (AAILE) were investigated.7,12-Dimethylbenz(a)anthracene (DMBA, 500 nmol/100 ul of acetone) was applied topically for 2 weeks (twice weekly),followed by phorbol-12-myristate-13-acetate (TPA, 1.7 nmol/100 ul) twice weekly for 6 weeks on the depilated skin of miceand AAILE was administered orally at a dose level of 300 mg/kg body wt thrice a week for 10 weeks. DMBA/TPAtreatment upregulated the phase I enzymes in skin and hepatic tissue, as revealed by the increased cytochrome P450 (CYP)and cytochrome b5 (cyt b5) levels and aryl hydrocarbon hydroxylase (AHH) activity when compared to the control groupand differentially modulated the activities of phase II enzymes like glutathione-s-transferase (GST), DT-diaphorase (DTD)and uridine diphosphate glucuronosyltransferase (UDP-GT). AAILE treatment decreased the DMBA/TPA-induced increasein cutaneous CYP level and enhanced the DTD and UDP-GT activities when compared with DMBA/TPA group. In thehepatic tissue of AAILE + DMBA/TPA group, an increase in UDP-GT activity was observed when compared toDMBA/TPA group. DMBA/TPA treatment did not alter the skin lipid peroxidation (LPO) level when compared to controlgroup, however, in the animals that received AAILE treatment along with DMBA/TPA, a significant increase in LPO wasobserved when compared to control group. This was associated with a decrease in cutaneous reduced glutathione(GSH) level of AAILE + DMBA/TPA group. Enhanced LPO level was observed in the hepatic tissue of DMBA/TPA andAAILE + DMBA/TPA groups when compared to control group. However, no alteration was observed in their hepaticGSH levels. The micronuclei score in hepatic tissue did not exhibit significant inter-group differences. The results of thepresent study suggest that apart from skin, liver may be affected during DMBA/TPA-induced skin tumorigenesis. AAILEtreatment has the ability to modulate these changes potentially influencing the process of tumor formation. These findingsseem to be important to carcinogenesis and its intervention with anti-cancer agents.