Benzo(a)pyrene (B(a)P), which is commonly used as an indicator species for polycyclic aromatic hydrocarbon (PAH) contamination, has a large number of hazardous consequences on human health. In the presence of the enzyme cytochrome-P-450 1A1 (CYP1A1), it undergoes metabolic activation to form reactive intermediates that are capable of inducing mutagenic, cytotoxic, teratogenic and carcinogenic effects in various species and tissues. Research within the last few years has shown that flavonoids exhibit chemopreventive effect against these toxins. In the present study, the protective effect of silymarin (a flavonoid) against B(a)P-induced toxicity was monitored in Wistar rats by evaluating the levels of hepatic phase I (CYP1A1), phase II enzymes (glutathione-S-transferase, epoxide hydroxylases, uridinediphosphate glucuronosyltransferases, NAD(P)H: quinone oxidoreductase 1, sulfotransferases), cellular antioxidant enzyme heme oxygenase and total glutathione. The results reveal that silymarin possesses substantial protective effect against B(a)P-induced damages by inhibiting phase I detoxification enzyme CYP1A1 and modulating phase II conjugating enzymes, which were confirmed by histopathological analysis. Overall, the inhibition of CYP1A1 and the modulation of phase II enzymes may provide, in part, the molecular basis for the effect of silymarin against B(a)P.
AlamJCookJL (2003) Transcriptional regulation of the heme oxygenase-1 gene via the stress response element pathway. Current Pharmaceutical Design9(30): 2499–2511.
2.
ArifJMShappellNSikkaHCKumarSGuptaRC (1999) 32P-Postlabeling analysis of lipophilic DNA adducts resulting from interaction with (+/−)-3-hydroxy-trans-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene. Chemico-biological Interactions118(2): 87–97.
3.
AsherGLotemJCohenBSachsLShaulY (2001) Regulation of p53 stability and p53-dependent apoptosis by NADH quinone oxidoreductase 1. Proceedings of the National Academy of Sciences98(3): 1188–1193.
BhatnagarTManojKMBarattiJC (2001) A spectrophotometric method to assay epoxide hydrolase activity. Journal of Biochemical Biophysical Methods50(1): 1–13.
6.
BonifazVShanYLambrechtRWDonohueSEMoschenrossDBonkovskyHL (2009) Effects of silymarin on hepatitis C virus and haem oxygenase-1 gene expression in human hepatoma cells. Liver International29(3): 366–373.
7.
BoyerTDVesseyDAHolcombCSaleyN (1984) Studies of the relationship between the catalytic activity and binding of non-substrate ligands by the glutathione S-transferases. The Biochemical Journal217(1): 179–185.
8.
CharalabopoulosKKarkabounasSCharalabopoulosAPapalimneouVIoachimEGiannakopoulosX (2003) Inhibition of benzo(a)pyrene-induced carcinogenesis by vitamin C alone and by vitamin C/vitamin E and selenium/glutathione. Biological Trace Element Research93(1): 201–211.
9.
ChenZZhangYYangJJinMWangXWShenZQ. (2011) Estrogen promotes benzo[a]pyrene-induced lung carcinogenesis through oxidative stress damage and cytochrome c-mediated caspase-3 activation pathways in female mice. Cancer Letters308(1): 14–22.
10.
ChengzhiCYanTShuqunCXuejunJYoubinQYinyinX. (2011) New candidate proteins for benzo(a)pyrene-induced spatial learning and memory deficits. The Journal of Toxicological Sciences36(2): 163–171.
11.
ChrungooVJReenRKSinghKSinghJ (1997) Effects of silymarin on UDP-glucuronic acid and glucuronidation activity in the rat isolated hepatocytes and liver in relation to D-galactosamine toxicity. Indian Journal of Experimental Biology35(3): 256–263.
12.
CrocenziFARomaMG (2006) Silymarin as a new hepatoprotective agent in experimental cholestasis: new possibilities for an ancient medication. Current Medicinal Chemistry13: 1055–1074.
13.
D’AndreaVPerezLMSanchez PozziEJ (2005) Inhibition of rat liver UDP-glucuronosyltransferase by silymarin and the metabolite silibinin-glucuronide. Life Sciences77(6): 683–692.
14.
DasAWangJHLienEJ (1994) Carcinogenicity, mutagenicity and cancer preventing activities of flavonoids: a structure-system-activity relationship (SSAR) analysis. Progress in Drug Research42: 133–166.
15.
De HaanLHBoerboomAMRietjensIMVan CapelleDDe RuijterAJJaiswalAK. (2002) A physiological threshold for protection against menadione toxicity by human NAD(P)H: quinone oxidoreductase (NQO1) in Chinese hamster ovary (CHO) cells. Biochemical Pharmacology64(11): 1597–1603.
16.
De JongWHKroeseEDVosJGVan LoverenH (1999) Detection of immunotoxicity of benzo[a]pyrene in a subacute toxicity study after oral exposure in rats. Toxicological Sciences50(2): 214–220.
17.
Dinkova-KostovaATTalalayP (2007) NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1), a multifunctional antioxidant enzyme and exceptionally versatile cytoprotector. Archives of Biochemistry and Biophysics501(1): 116–123.
18.
DongWTeraokaHKondoSHiragaT (2001) 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin induces apoptosis in the dorsal midbrain of zebrafish embryos by activation of arylhydrocarbon receptor. Neuroscience Letters303(3): 169–172.
19.
DvorakZKosinaPWalterovaDSimanekVBachledaPUlrichovaJ (2003) Primary cultures of human hepatocytes as a tool in cytotoxicity studies: cell protection against model toxins by flavonolignans obtained from Silybum marianum. Toxicology Letters137(3): 201–212.
20.
ElbekaiRHDukeJEl-KadiAO (2007) Ascorbic acid differentially modulates the induction of heme oxygenase-1, NAD(P)H: quinone oxidoreductase 1 and glutathione S-transferase Ya by As(3+), Cd(2+) and Cr(6+). Cancer Letters246(1–2): 54–62.
21.
EllmanGL (1959) Tissue sulfhydryl groups. Archives of Biochemistry and Biophysics82(1): 70–77.
22.
ElovaaraEMikkolaJStockmann-JuvalaHLuukkanenLKeski-HynnilaHKostiainenR. (2007) Polycyclic aromatic hydrocarbon (PAH) metabolizing enzyme activities in human lung, and their inducibility by exposure to naphthalene, phenanthrene, pyrene, chrysene, and benzo(a)pyrene as shown in the rat lung and liver. Archives of Toxicology81(3): 169–182.
23.
EndoKUnoSSekiTArigaTKusumiYMitsumataM. (2008) Inhibition of aryl hydrocarbon receptor transactivation and DNA adduct formation by CYP1 isoform-selective metabolic deactivation of benzo[a]pyrene. Toxicology and Applied Pharmacology230: 135–143.
FarombiEOSurhYJ (2006) Heme oxygenase-1 as a potential therapeutic target for hepatoprotection. Journal of Biochemistry and Molecular Biology39(5): 479–491.
26.
FerenciPDragosicsBDittrichHFrankHBendaLLochsH. (1989) Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. Journal of Hepatology9: 105–113.
27.
FraschiniFDemartiniGEspostiD (2002) Pharmacology of silymarin. Clinical Drug Investigation22: 51–65.
28.
GautierJCLecoeurSCosmeJPerretAUrbanPBeauneP. (1996) Contribution of human cytochrome P450 to benzo[a]pyrene and benzo[a]pyrene-7,8-dihydrodiol metabolism, as predicted from heterologous expression in yeast. Pharmacogenetics6(6): 489–499.
29.
GelboinHV (1980) Benzo[alpha]pyrene metabolism, activation and carcinogenesis: role and regulation of mixed-function oxidases and related enzymes. Physiological Reviews60(4): 1107–1166.
30.
GraslundAJernstromB (1989) DNA-carcinogen interaction: covalent DNA-adducts of benzo(a)pyrene 7,8-dihydrodiol 9,10-epoxides studied by biochemical and biophysical techniques. Quarterly Reviews of Biophysics22: 1–37.
31.
GuengerichFP (1988) Roles of cytochrome P-450 enzymes in chemical carcinogenesis and cancer chemotherapy. Cancer Research48(11): 2946–2954.
32.
GuengerichFP (1992) Metabolic activation of carcinogens. Pharmacology and Therapeutics54(1): 17–61.
33.
HabigWHJakobyWB (1981) Assays for differentiation of glutathione S-transferases. Methods Enzymology77: 398–405.
34.
HayesJDPulfordDJ (1995) The glutathione S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance. Critical Reviews in Biochemistry and Molecular Biology30(6): 445–600.
35.
JeonYJYoukESLeeSHSuhJNaYJKimHM (2002) Polychlorinated biphenyl-induced apoptosis of murine spleen cells is aryl hydrocarbon receptor independent but caspases dependent. Toxicology and Applied Pharmacology181: 69–78.
36.
KiruthigaPVPandianSKDeviKP (2010) Silymarin protects PBMC against B(a)P induced toxicity by replenishing redox status and modulating glutathione metabolizing enzymes: an in vitro study. Toxicology and Applied Pharmacology247: 116–128.
37.
KiruthigaPVShafreenRBPandianSKArunSGovinduSDeviKP (2007a) Protective effect of silymarin on erythrocyte haemolysate against benzo(a)pyrene and exogenous reactive oxygen species (H2O2) induced oxidative stress. Chemosphere68(8): 1511–1518.
38.
KiruthigaPVShafreenRBPandianSKDeviKP (2007b) Silymarin protection against major reactive oxygen species released by environmental toxins: exogenous H2O2 exposure in erythrocytes. Basic and Clinical Pharmacology and Toxicology100(6): 414–419.
39.
KlotzAVStegemanJJWalshC (1984) An alternative 7-ethoxyresorufin O-deethylase activity assay: a continuous visible spectrophotometric method for measurement of cytochrome P-450 monooxygenase activity. Analytical Biochemistry140(1): 138–145.
40.
Kojima-YuasaAUmedaKOhkitaTOpare KennedyDNishiguchiSMatsui-YuasaI (2005) Role of reactive oxygen species in zinc deficiency-induced hepatic stellate cell activation. Free Radical Biology and Medicine39(5): 631–640.
41.
KrenVWalterovaD (2005) Silybin and silymarin--new effects and applications. Biomedical Papers of the Medical Faculty of the University Palacky Olomouc Czechoslovakia149(1): 29–41.
42.
LandiLFiorentiniDGalliMCSegura-AguilarJBeyerRE (1997) DT-diaphorase maintains the reduced state of ubiquinones in lipid vesicles thereby promoting their antioxidant function. Free Radical Biology and Medicine22: 329–335.
43.
LeeuwenburghCJiLL (1995) Glutathione depletion in rested and exercised mice: biochemical consequence and adaptation. Archives of Biochemistry and Biophysics316(2): 941–949.
44.
LetteronPLabbeGDegottCBersonAFromentyBDelaforgeM. (1990) Mechanism for the protective effects of silymarin against carbon tetrachloride-induced lipid peroxidation and hepatotoxicity in mice. Evidence that silymarin acts both as an inhibitor of metabolic activation and as a chain-breaking antioxidant. Biochemical Pharmacology39(12): 2027–2034.
45.
LiuFLiuJChenQWangBCaoZ (2012) Pollution characteristics, ecological risk and sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediment from Tuhai-Majia River system, China. Procedia Environmental Sciences13: 1301–1314.
46.
LowryOHRosebroughNJFarrALRandallRJ (1951) Protein measurement with the Folin phenol reagent. Journal of Biological Chemistry193(1): 265–275.
47.
MannaSKMukhopadhyayAVanNTAggarwalBB (1999) Silymarin suppresses TNF-induced activation of NF-kappa B, c-Jun N-terminal kinase, and apoptosis. Journal of Immunolology163(12): 6800–6809.
48.
MarrazzoGBoscoPLa DeliaFScapagniniGDi GiacomoCMalaguarneraM. (2011) Neuroprotective effect of silibinin in diabetic mice. Neuroscience Letters504(3): 252–256.
49.
MartinSTBlackSD (1994) Detergent effects in rabbit liver microsomal UDP-glucuronosyltransferase studied by means of a continuous spectrophotometric assay with p-nitrophenol. Biochemical and Biophysical Research Communication200(2): 1093–1098.
50.
Mendoza-CozatlDLoza-TaveraHHernandez-NavarroAMoreno-SanchezR (2005) Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants. FEMS Microbiology Reviews29(4): 653–671.
51.
NabaviSMNabaviSFEslamiSMoghaddamAH (2012a) In vivo protective effects of quercetin against sodium fluoride-induced oxidative stress in the hepatic tissue. Food Chemistry132: 931–935.
52.
NabaviSMNabaviSFLatifiAMMoghaddamAHHellioC (2012b) Neuroprotective effects of silymarin on sodium fluoride-induced oxidative stress. Journal of Fluorine Chemistry142: 79–82.
53.
NebertDWRoeALDieterMZSolisWAYangYDaltonTP (2000) Role of the aromatic hydrocarbon receptor and [Ah] gene battery in the oxidative stress response, cell cycle control, and apoptosis. Biochemical Pharmacology59(1): 65–85.
54.
OztezcanSKirgizBUnlucerciYDogru-AbbasogluSBilgeHUysalM. (2004) Heme oxygenase induction protects liver against oxidative stress in x-irradiated aged rats. Biogerontology5(2): 99–105.
55.
PaeHOJeongGSJeongSOKimHSKimSAKimYC. (2007) Roles of heme oxygenase-1 in curcumin-induced growth inhibition in rat smooth muscle cells. Experimental and Molecular Medicine39(3): 267–277.
56.
PohlRJFoutsJR (1980) A rapid method for assaying the metabolism of 7-ethoxyresorufin by microsomal subcellular fractions. Analytical Biochemistry107(1): 150–155.
57.
ProcopioMLahmATramontanoABonatiLPiteaD (2002) A model for recognition of polychlorinated dibenzo-p-dioxins by the aryl hydrocarbon receptor. European Journal of Biochemistry269(1): 13–18.
58.
PushparajahDSUmachandranMPlantKEPlantNIoannidesC (2008) Up-regulation of the glutathione S-transferase system in human liver by polycyclic aromatic hydrocarbons; comparison with rat liver and lung. Mutagenesis23(4): 299–308.
59.
QamarWKhanRKhanAQRehmanMULateefATahirM. (2011) Alleviation of lung injury by glycyrrhizic acid in benzo(a)pyrene exposed rats: probable role of soluble epoxide hydrolase and thioredoxin reductase. Toxicology291(1–3): 25–31.
60.
RouachHFataccioliVGentilMFrenchSWMorimotoMNordmannR (1997) Effect of chronic ethanol feeding on lipid peroxidation and protein oxidation in relation to liver pathology. Hepatology25(2): 351–355.
61.
SangeethaNViswanathanPBalasubramanianTNaliniN (2012) Colon cancer chemopreventive efficacy of silibinin through perturbation of xenobiotic metabolizing enzymes in experimental rats. European Journal of Pharmacology674: 430–438.
62.
ShimadaTFujii-KuriyamaY (2004) Metabolic activation of polycyclic aromatic hydrocarbons to carcinogens by cytochromes P450 1A1 and 1B1. Cancer Science95(1): 1–6.
63.
ShouMGroganJMancewiczJAKrauszKWGonzalezFJGelboinHV. (1994) Activation of CYP3A4: evidence for the simultaneous binding of two substrates in a cytochrome P450 active site. Biochemistry33(21): 6450–6455.
64.
SiegelDBoltonEMBurrJALieblerDCRossD (1997) The reduction of alpha-tocopherolquinone by human NAD(P)H: quinone oxidoreductase: the role of alpha-tocopherolhydroquinone as a cellular antioxidant. Molecular Pharmacology52(2): 300–305.
65.
SteinkellnerHHoelzlCUhlMCavinCHaidingerGGsurA. (2005) Coffee consumption induces GSTP in plasma and protects lymphocytes against (+/−)-anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide induced DNA-damage: results of controlled human intervention trials. Mutatation Researh591(1–2): 264–275.
66.
StraifKBaanRGrosseYSecretanBEl GhissassiFCoglianoV (2005) Carcinogenicity of polycyclic aromatic hydrocarbons. The Lancet Oncology6(12): 931–932.
67.
SundbergKWiderstenMSeidelAMannervikBJernstromB (1997) Glutathione conjugation of bay- and fjord-region diol epoxides of polycyclic aromatic hydrocarbons by glutathione transferases M1-1 and P1-1. Chemical Research in Toxicology10(11): 1221–1227.
68.
SurhYJTannenbaumSR (1995) Sulfotransferase-mediated activation of 7,8,9,10-tetrahydro-7-ol, 7,8-dihydrodiol, and 7,8,9,10-tetraol derivatives of benzo[a]pyrene. Chemical Research in Toxicology8(5): 693–698.
69.
TalalayPDinkova-KostovaAT (2004) Role of nicotinamide quinone oxidoreductase 1 (NQO1) in protection against toxicity of electrophiles and reactive oxygen intermediates. Methods in Enzymology382: 355–364.
70.
TalalayPProchaskaHJSpencerSR (1990) Regulation of enzymes that detoxify the electrophilic forms of chemical carcinogens. Princess Takamatsu Symposia21: 177–187.
71.
TephlyTRBurchellB (1990) UDP-glucuronosyltransferases: a family of detoxifying enzymes. Trends in Pharmacological Sciences11(7): 276–279.
72.
TongZJamesMO (2000) Purification and characterization of hepatic and intestinal phenol sulfotransferase with high affinity for benzo[a]pyrene phenols from channel catfish, Ictalurus punctatus. Archives of Biochemistry and Biophysics376(2): 409–419.
73.
TsujiGTakaharaMUchiHTakeuchiSMitomaCMoroiY. (2011) An environmental contaminant, benzo(a)pyrene, induces oxidative stress-mediated interleukin-8 production in human keratinocytes via the aryl hydrocarbon receptor signaling pathway. Journal of Dermatological Science62(1): 42.
74.
TuncaRSozmenMCitilMKarapehlivanMErginsoySYaparK (2009) Pyridine induction of cytochrome P450 1A1, iNOS and metallothionein in Syrian hamsters and protective effects of silymarin. Experimental and Toxicologic Pathology61(3): 243–255.
75.
UnoSDaltonTPDerkenneSCurranCPMillerMLShertzerHG. (2004) Oral exposure to benzo[a]pyrene in the mouse: detoxication by inducible cytochrome P450 is more important than metabolic activation. Molecular Pharmacology65: 1225–1237.
76.
UnoSMakishimaM (2009) Benzo[a]pyrene toxicity and inflammatory disease. Current Rheumatology Reviews5(4): 266–271.
77.
ValenzuelaAGarridoA (1994) Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin. Biological Research27(2): 105–112.
78.
VenkataramananRRamachandranVKomoroskiBJZhangSSchiffPLStromSC (2000) Milk thistle, a herbal supplement, decreases the activity of CYP3A4 and uridine diphosphoglucuronosyl transferase in human hepatocyte cultures. Drug Metabolism and Disposition28(11): 1270–1273.
79.
Villa-CruzVDavilaJVianaMVazquez-DuhaltR (2009) Effect of broccoli (Brassica oleracea) and its phytochemical sulforaphane in balanced diets on the detoxification enzymes levels of tilapia (Oreochromis niloticus) exposed to a carcinogenic and mutagenic pollutant. Chemosphere74(9): 1145–1151.
80.
WangLQLehmlerHJRobertsonLWFalanyCNJamesMO (2005) In vitro inhibition of human hepatic and cDNA-expressed sulfotransferase activity with 3-hydroxybenzo[a]pyrene by polychlorobiphenylols. Environmental Health Perspectives113(6): 680–687.
81.
WellingtonKJarvisB (2001) Silymarin: a review of its clinical properties in the management of hepatic disorders. BioDrugs15(7): 465–489.
82.
WesterPMullerJSlobWMohnGDortantPKroeseE (2011) Carcinogenic activity of benzo[a]pyrene in a 2 year oral study in Wistar rats. Food and Chemical Toxicology50(3–4): 927–935.
83.
YehCTYenGC (2006) Involvement of p38 MAPK and Nrf2 in phenolic acid-induced P-form phenol sulfotransferase expression in human hepatoma HepG2 cells. Carcinogenesis27(5): 1008–1017.
84.
YoshiharaSMakishimaMSuzukiNOhtaS (2001) Metabolic activation of bisphenol A by rat liver S9 fraction. Toxicological Sciences62(2): 221–227.
85.
ZhaoJAgarwalR (1999) Tissue distribution of silibinin, the major active constituent of silymarin, in mice and its association with enhancement of phase II enzymes: implications in cancer chemoprevention. Carcinogenesis20(11): 2101–2108.
