Soy isoflavones inhibits the genotoxicity of benzo(a)pyrene in Swiss albino mice

Chemopreventive role of arabinogalactan against experimentally induced pulmonary carcinogenesis: a study in relation to its initiation phase

The aim of the present study is to divulge the chemopreventive potential of arabinogalactan (AG) on benzo(a)pyrene [B(a)P] induced initiation of lung carcinogenesis. AG is one of the naturally occurring bioactive polysaccharides which is widely found in medicinal plants. Male Balb/c mice were divided into four experimental groups. Group I served as control. Group II animals were injected with B(a)P (50 mg/kg b. wt. i.p.). Group III animals were administered with AG (7.5 mg/kg b.wt.) orally. Group IV animals received B(a)P and AG as in group II and group III, respectively. B(a)P treatment in mice resulted in imbalance of carcinogen metabolizing enzymes and respiratory marker enzymes at 2nd, 6th and 10th week of the experimental protocol. Also, it leads to the increased protein synthesis as depicted by increased argyrophilic nucleolar organizer regions (AgNOR) positive cells and altered histopathological features. Studies on bronchoalveolar lavage fluid (balf) of B(a)P exposed animals revealed increase in surface tension when compared with control counterparts. Apart from target tissue (lung), B(a)P also led to the clastogenic damage in other tissues (spleen and bone marrow) as depicted by increase in percentage of micronucleus cells at different time intervals. Treatment with AG efficiently counteracted all the above anomalies and restored cellular homeostasis. These observations suggest that AG has the potential to modulate B(a)P induced changes in the pulmonary tissue as well as other tissues which could have implications in delaying the initiation of carcinogenesis, however, further investigations are required to explore its complete mechanism of action.

Antioxidant potential of Rumex vesicarius L.: in vitro approach

OBJECTIVE

To assess in-vitro antioxidant activity of different fraction and perform high performance thin layer chromatography fingerprint analysis of most active fraction of Rumex vesicarius L. (R. vesicarius).

METHODS

In the present study, acetone, ethyl acetate, n-butanol, and methanol extracts of R. vesicarius were evaluated for radical scavenging activity by studying the inhibition of the level of lipid peroxidation induced by Fe(++)/ascorbate, DNA sugar damage, scavenging of hydrogen peroxide, diphenylphosphine DPPH radical scavenging activity, total phenolic content, total flavonoids content and total proanthocyanidin. High performance thin layer chromatography finger print profiling of R. vesicarius L. was also done.

RESULTS

Lipid peroxidation induced by the iron/ascorbate system, hydrogen peroxide, diphenylphosphine and DNA sugar damage were inhibited by the addition of different extract of R. vesicarius. Among them, methanolic extract showed maximum efficacy. The methanolic extract showed the highest total phenolic, total flavonoids and total proanthocyanidin contents.

CONCLUSIONS

The results suggest that the extracts can be a vital source of phytochemical antioxidants.

Effect of flavonoids and hyperthermal intraperitoneal chemotherapy on tumour growth and micronucleus induction in mouse tumour model

Hyperthermia enhanced the clastogenicity of alkylating agents. We investigated whether quercetin (QU; 3,3',4',5,7-pentahydroxy flavone) or naringenin (NAR) can sensitize Ehrlich ascites tumour (EAT) to cisplatin (CP) hyperthermal intraperitoneal chemotherapy treatment and whether these flavonoids in combination with CP can ameliorate CP-induced micronuclei (MNs) in peripheral blood reticulocytes of mice. QU or NAR were administered to mice 7 and 3 days before implantation of EAT cells, while CP (5 or 10 mg kg-1) was injected intraperitoneally to normothermic or hyperthermic-treated mice 3 days after implantation of EAT cells (2 106). Our study supports the claim that the QU or NAR in combined treatment with CP has the potential to inhibit tumour growth in both normothermic and hyperthermic conditions and attenuate number of MNs in the peripheral blood reticulocytes of mice at normothermic condition but enhanced the clastogenicity of CP agents in hyperthermal condition.

Alleviation of free radical mediated oxidative and genotoxic effects of cadmium by farnesol in Swiss albino mice

Farnesol is an isoprenoid found in essential oils of ambrette seeds, citronella and in various aromatic plants. Exposure to cadmium from various sources affects the renal system adversely and Cd is an established genotoxic agent. In the present study, we evaluated the antigenotoxic and antioxidant efficacy of farnesol against cadmium chloride (CdCl2)-induced renal oxidative stress and genotoxicity in Swiss albino mice. Single, intraperitoneal doses of CdCl2(5 mg/kg body weight) for 24 h resulted in a significant (P < 0.001) increase in chromosomal aberration and micronuclei formation. The oral administration of farnesol at two doses (1% and 2% per kg body weight) for seven consecutive days showed significant (P < 0.05) suppression of the genotoxic effects of CdCl2 in the modulator groups. To study the mechanism by which farnesol exerts its antigenotoxic potential, enzymes involved in metabolism and detoxification were estimated. CdCl2 intoxication adversely affected the renal antioxidant armory and increased TBARS formation and xanthine oxidase levels significantly (P < 0.001). Farnesol showed a significant (P < 0.001) recovery in antioxidant status viz, GSH content (and its dependent enzymes) and catalase activity. Farnesol pretreatment in CdCl2-intoxicated mice showed marked (P < 0.001) suppression of TBARS' formation and XO activity. Our results support the conclusion that the anticlastogenic effect of farnesol could be due to restoration of antioxidants and inhibition of oxidative damage.

Synthesis of PLGA nanoparticles of tea polyphenols and their strong in vivo protective effect against chemically induced DNA damage

In spite of proficient results of several phytochemicals in preclinical settings, the conversion rate from bench to bedside is not very encouraging. Many reasons are attributed to this limited success, including inefficient systemic delivery and bioavailability under in vivo conditions. To achieve improved efficacy, polyphenolic constituents of black (theaflavin [TF]) and green (epigallocatechin-3-gallate [EGCG]) tea in poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) were entrapped with entrapment efficacy of ~18% and 26%, respectively. Further, their preventive potential against 7,12-dimethylbenzanthracene (DMBA)-induced DNA damage in mouse skin using DNA alkaline unwinding assay was evaluated. Pretreatment (topically) of mouse skin with either TF or EGCG (100 μg/mouse) doses exhibits protection of 45.34% and 28.32%, respectively, against DMBA-induced DNA damage. However, pretreatment with TF-loaded PLGA-NPs protects against DNA damage 64.41% by 1/20th dose of bulk, 71.79% by 1/10th dose of bulk, and 72.46% by 1/5th dose of bulk. Similarly, 51.28% (1/20th of bulk), 57.63% (1/10th of bulk), and 63.14% (1/5th of bulk) prevention was noted using EGCG-loaded PLGA-NP doses. These results showed that tea polyphenol-loaded PLGA-NPs have ~30-fold dose-advantage than bulk TF or EGCG doses. Additionally, TF- or EGCG-loaded PLGA-NPs showed significant potential for induction of DNA repair genes (XRCC1, XRCC3, and ERCC3) and suppression of DNA damage responsive genes (p53, p21, MDM2, GADD45α, and COX-2) as compared with respective bulk TF or EGCG doses. Taken together, TF- or EGCG-loaded PLGA-NPs showed a superior ability to prevent DMBA-induced DNA damage at much lower concentrations, thus opening a new dimension in chemoprevention research.

Pluchea lanceolata protects against Benzo(a) pyrene induced renal toxicity and loss of DNA integrity

Evidence from epidemiological, experimental and clinical trial data indicates that a plant based diet can reduce the risk of chronic diseases and reduces toxic effects. In the present study, we report the antioxidant and anticlastogenic activity of Pluchea lanceolata (PL), an important medicinal plant, in both in vitro and in vivo model. Benzo(a)pyrene (B(a)P) administration leads to depletion of renal glutathione and its metabolizing enzymes. Pretreatment with PL (100 and 200 mg /kg b.wt) restored renal glutathione content and its dependent enzymes significantly (p<0.001) with simultaneous increase in catalase(CAT), quinone reductase(QR) in mouse kidney. Prophylactic administration of PL prior to B (a) P administration significantly decreased the malondialdehyde(MDA), H2O2 and xanthineoxidase (XO) levels at a significance of p<0.001, at both the doses. PL extract pretreated groups showed marked inhibition in B(a)P induced micronuclei formation in mouse bone marrow cells with simultaneous restoration of DNA integrity, viz. alkaline unwinding assay and DNA damage shown by gel-electrophoresis. HPTLC confirms the presence of quercetin in plant extract which could be responsible for PL protecting efficacy. In conclusion, the present findings strongly support the antioxidant efficacy of PL, possibly by modulation of antioxidant armory.

Allethrin-induced genotoxicity and oxidative stress in Swiss albino mice

Allethrin (C(19)H(26)O(3)) is non-cyano-containing pyrethroid insecticide that is used extensively for controlling flies and mosquitoes. Apart from its neurotoxic effects in non-target species, allethrin is reported to be mutagenic in bacterial systems. In this study, we observed oxidative damage-mediated genotoxicity caused by allethrin in Swiss albino mice. The genotoxic potential of allethrin was evaluated using chromosome aberrations (CAs) and a micronuclei (MN) induction assay as genetic end-points. The oral intubation of allethrin (25 and 50mg/kg b.wt.) significantly induces CAs and MN in mouse bone marrow cells. The DNA-damaging potential of allethrin was estimated in mouse liver using the DNA alkaline unwinding assay (DAUA) and by measuring the levels of 8-hydroxy-2'-deoxy-guanosine (8-OH-dG). Furthermore, a dose-dependent increase in reactive oxygen species (ROS) generation and lipid peroxidation (LPO), with a concurrent decrease in superoxide dismutase (SOD) and catalase, confirm its pro-oxidant potential. The DNA-damaging potential of allethrin was found to be mediated through the modulation of p53, p21, GADD45α and MDM-2. These results confirm the genotoxic and the pro-oxidant potential of allethrin in Swiss albino mice.

Glycyrrhizic acid: a phytochemical with a protective role against cisplatin-induced genotoxicity and nephrotoxicity

AIMS

Glycyrrhizic acid (GA) is a main sweetening component of licorice roots and has been found to be associated with multiple therapeutic properties. In this study, we used GA as a protective agent against the clastogenic and nephrotoxic effects of cisplatin (CP).

MAIN METHODS

Mice were given a prophylactic treatment of GA orally at doses of 75 and 150mg/kg body weight for seven consecutive days before the administration of a single intraperitoneal dose of CP at 7mg/kg body weight. The modulatory effects of GA on CP-induced nephrotoxicity and genotoxicity were investigated by assaying oxidative stress biomarkers, lipid peroxidation, serum kidney toxicity markers, DNA fragmentation, alkaline unwinding, and micronuclei and by histopathological examination of the kidneys.

KEY FINDINGS

A single intraperitoneal dose of cisplatin in mice enhanced renal lipid peroxidation, xanthine oxidase, and H(2)O(2) generation; depleted glutathione content, activities of the anti-oxidant enzymes glutathione peroxidase, glutathione reductase, catalase, glutathione-S-transferase and quinone reductase; induced DNA strand breaks and micronucleus formation (p<0.001); and majorly disrupted normal kidney architecture. Pretreatment with GA prevented oxidative stress by restoring the levels of antioxidant enzymes at both doses. A significant dose-dependent decrease in DNA fragmentation, micronucleus formation (p<0.05), and the kidney toxicity markers BUN (p<0.001), creatinine (p<0.01), and LDH (p<0.001) and restoration of normal kidney histology was observed.

SIGNIFICANCE

Our study supports the claim that the phytochemical GA has the potential to attenuate the side effects of anticancer drug overdose.

Antaxia-telangiectasia mutated gene polymorphisms and susceptibility to chromosomal damage among polycyclic aromatic hydrocarbons exposed workers

The aim was to explore the relationship between the ataxia-telangiectasia mutated (ATM) gene polymorphisms and susceptibility to cytokinesis-block micronucleus among workers exposed to polycyclic aromatic hydrocarbons (PAH). Blood and urine samples of 140 PAH-exposed workers and 66 non-PAH-exposed workers were collected. Seven tagging single nucleotide polymorphisms in ATM gene were selected by pariwise r(2) method and minor allele frequency cutoff of 0.05 from Chinese genotype data in HapMap project. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze the polymorphisms of ATM rs600931, rs652311, rs227060, rs227292, rs624366, rs189037 and rs228589. The results showed that ATM rs600931 AG and AG+AA genotypes exhibited significantly higher cytokinesis-block micronucleus (CBMN) frequency (11.14+/-6.91 per thousand and 10.57+/-6.82 per thousand) than did the GG genotype (7.66+/-5.69 per thousand, P=0.015 and 0.038, respectively). The subjects with rs189037 GA and GA+AA genotypes exhibited significantly higher CBMN frequency (10.99+/-6.90 per thousand and 10.51+/-6.76 per thousand) than that of the GG genotype (7.72+/-5.82 per thousand, P=0.018 and 0.035, respectively). The PAH-exposed workers with rs624366 GC and GC+CC genotypes exhibited significantly higher CBMN frequency (11.34+/-6.74 per thousand and 10.73+/-6.62 per thousand) than did the GG genotype (7.61+/-6.07 per thousand, P=0.001 and 0.003, respectively). rs227092 GT genotype exhibited significantly higher CBMN frequency (10.78+/-6.60 per thousand) than did the GG genotype (7.91+/-6.30 per thousand, P=0.025) among the PAH-exposed workers. The haplotype pairs GGGGTGC/AAACATT exhibited significantly higher CBMN frequency (12.05+/-7.40 per thousand) than did the GGGGTGC/GGGGTGC (7.51+/-6.19 per thousand, P=0.007) among the PAH-exposed group. In conclusion, it is suggested that the polymorphisms of ATM were associated with the CBMN frequencies among PAH-exposed workers.

Bromelain inhibits COX-2 expression by blocking the activation of MAPK regulated NF-kappa B against skin tumor-initiation triggering mitochondrial death pathway

Chemoprevention impels the pursuit for either single targeted or cocktail of multi-targeted agents. Bromelain, potential agent in this regard, is a pharmacologically active compound, present in stems and fruits of pineapple (Ananas cosmosus), endowed with anti-inflammatory, anti-invasive and anti-metastatic properties. Herein, we report the anti tumor-initiating effects of bromelain in 2-stage mouse skin tumorigenesis model. Pre-treatment of bromelain resulted in reduction in cumulative number of tumors (CNT) and average number of tumors per mouse. Preventive effect was also comprehended in terms of reduction in tumor volume up to a tune of approximately 65%. Components of the cell signaling pathways, connecting proteins involved in cell death were targeted. Bromelain treatment resulted in upregulation of p53 and Bax and subsequent activation of caspase 3 and caspase 9 with concomitant decrease in Bcl-2. A marked inhibition in cyclooxygenase-2 (Cox-2) expression and inactivation of nuclear factor-kappa B (NF-kappaB) was recorded, as phosphorylation and consequent degradation of I kappa B alpha was blocked by bromelain. Also, bromelain treatment curtailed extracellular signal regulated protein kinase (ERK1/2), p38 mitogen-activated protein kinase (MAPK) and Akt activity. The basis of anti tumor-initiating activity of bromelain was revealed by its time dependent reduction in DNA nick formation and increase in percentage prevention. Thus, modulation of inappropriate cell signaling cascades driven by bromelain is a coherent approach in achieving chemoprevention.

Past oral contraceptive use and current dietary soy isoflavones influence estrogen metabolism in postmenopausal monkeys (Macaca fascicularis)

Estrogen metabolism may play an important role in mammary carcinogenesis in postmenopausal women. We evaluated the effects of prior oral contraceptive (OC) treatment and current soy isoflavone consumption on endogenous estrogen metabolite concentration and biomarkers of tissue estrogen exposure in a monkey model. One hundred eighty-one female cynomolgus macaques were randomized to receive OC or placebo for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an isoflavone-depleted soy protein isolate (Soy-) diet, a diet containing soy protein isolate with a human equivalent of 129 mg isoflavone/d (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE+) at a human equivalent dose of 0.625 mg/d. Reverse-phase high-performance liquid chromatography directly coupled with tandem mass spectrometry was used to measure the concentrations of estrogen species in urine samples. Generally, prior OC treatment was associated with significantly reduced urinary estrogen metabolites (25-55% reduction; P<0.05 for each versus OC-). Animals that consumed isoflavones postmenopausally had increased urinary 2-hydroxyestrone and 16alpha-hydroxyestrone (50% and 56% increases, respectively), but reduced levels of 2-hydroxyestradiol, 2-methoxyestradiol, and 17-epiestriol (92%, 63%, and 66%, respectively), compared with animals fed a Soy- diet. Isoflavones did not have widespread effects on uterine or mammary proliferation biomarkers, whereas prior OC significantly reduced two of three proliferation end points in the endometrium. Premenopausal OCs may have long-term systemic effects on response to estrogen and its metabolism whereas postmenopausal dietary isoflavones may alter endogenous estrogen metabolism in a modest but selective manner.

Effects of prior oral contraceptive use and soy isoflavonoids on estrogen-metabolizing cytochrome P450 enzymes

Estrogen exposure and metabolism may play an important role in the development of estrogen-sensitive cancers in postmenopausal women. In this study we investigated whether past oral contraceptive (OC) administration or current dietary isoflavonoids (IF) affected expression and/or activity of steroid hormone-metabolizing cytochrome P450 (CYP) enzymes using complementary primate and cell culture models. One-hundred-eighty-one female cynomolgus macaques were randomized to receive OC or nothing for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an IF-depleted soy protein isolate (Soy-) diet, a Soy diet with IF (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE). Prior OC-treatment significantly reduced CYP gene expression in the mammary gland (< or =60% of OC-). Dietary IFs had no effect on CYP expression, while CEE-treatment decreased CYP1A1 and increased CYP3A4 mRNA in a tissue-specific manner. For in vitro studies, we measured effects of the isoflavonoids genistein, daidzein and equol on CYP activity using intact V79 cells stably transfected to express CYP1A1, CYP1B1, or CYP3A4. All three IFs significantly altered CYP activity in a dose-dependent and isoform-specific manner (20-95% inhibition versus controls). These results suggest potential mechanisms for prior OC and dietary IF effects on cancer risk in estrogen-responsive tissues.

Preventive effects of lupeol on DMBA induced DNA alkylation damage in mouse skin

Mutations that occur through DNA strand breaks are the precursors of the variety of genetic disorders including cancer. Life style and dietary habits are considered as major determinants in causation and prevention of genetic diseases. Epidemiological and laboratory studies suggest that plant derived compounds have the potential to prevent a number of genetic diseases. Therefore, use of nutraceuticals can be an important and convenient tool for chemoprevention. Polyphenolic phytochemicals such as epigallocatechin gallate flavonoids quercetin, genistein, curcumin and resveratrol constitute a class of nutraceuticals with notable efficacy in preclinical models of carcinogenesis. Lupeol, a pentacyclic triterpene present in mango, is a biologically active compound that has been reported to possess a number of pharmacological properties in the in vivo and in vitro studies. In the present study, we investigated the effects of lupeol on 7,12-dimethylbenz[a]anthracene (DMBA), induced DNA strand breaks in mouse skin, using an alkaline unwinding assay. Increasing doses of lupeol (50-200 microg/mouse) were given topically, prior or after the single topical application of DMBA (100 microg/mouse) with the sampling time of 24, 48, 72 and 96 h, respectively. Both pre and post treatment of lupeol showed significant (p<0.001) preventive effects in DMBA induced DNA strand breaks in dose and time dependent manner. The pre-treatment of lupeol at the dose of 200 microg/mouse showed 56.05% prevention, and post-treatment at the same dose showed 43.26% prevention, at 96 h time interval, against DMBA induced DNA strand breakage. The results suggest preventive effects of lupeol on DMBA induced DNA alkylation damage in Swiss albino mice.

Inhibitory effect of apigenin on benzo(a)pyrene-mediated genotoxicity in Swiss albino mice

Apigenin, a bioflavonoid, is abundantly present in fruits and vegetables and possesses potential chemopreventive properties against a wide variety of chronic diseases. In this study we investigated the anti-genotoxic effects of apigenin against a known genotoxicant, benzo(a)pyrene (B(a)P) (125 mg kg(-1) orally) toxicity in Swiss albino mice. B(a)P administration led to induction of cytochrome P-450 (CYP), aryl hydrocarbon hydroxylase (AHH) and DNA strand breaks (P < 0.001), which was suppressed by apigenin (2.5 and 5 mg kg(-1) orally) dose dependently (P < 0.001). B(a)P-induced depletion in the level of reduced glutathione (GSH), quinone reductase (QR) and glutathione-S-transferase (GST) was also shown to be restored by apigenin pre-treatment (P < 0.001). A simultaneous significant and dose-dependent reduction was noted in DNA strand breaks and in-vivo DNA damage (P < 0.001), which gives some insight into restoration of DNA integrity in modulator groups. These results strongly support the protective nature of apigenin against B(a)P-induced toxicity.