Protective role of AKBA against benzo(a)pyrene-induced lung carcinogenesis by modulating biotransformation enzymes and oxidative stress.

The present study was designed to explore the chemopreventive potential of 3-acetyl-11-keto-ß-boswellic acid (AKBA) during the initiation and promotion stage of lung carcinogenesis induced by benzo(a)pyrene (BaP) in female Sprague Dawley rats. BaP was administered at a dose level of 50 mg/kg b.wt. twice a week orally in olive oil for 4 weeks. AKBA administration was started 4 weeks before BaP treatment and continued for another 8 weeks at a dose level of 50 mg/kg b.wt. orally in olive oil three times a week. BaP treatment showed significantly increased in the activities of Phase I biotransformation enzymes (Cytochrome P450 , b5 , and aryl hydrocarbon hydrolase) and inhibited the activity of Phase II enzyme (glutathione-S-transferase). Also, a significant elevation in oxidative stress biomarkers lipid peroxidation, reactive oxygen species, and protein carbonyl content concentration. Further, an appreciable decrease was observed in the activities of endogenous antioxidant enzymes superoxide dismutase, CAT, GPx, GR, and a decline in nonenzymatic GSH levels. As a result of BaP induced oxidative stress, alteration in erythrocytes morphology was observed. Fourier transform infrared spectroscopy spectrum of lung tissue showed structural changes due to BaP exposure. Moreover, levels of tumor biomarkers such as total sialic acid, carcinoembryonic antigen, and alkaline phosphatase were significantly elevated following BaP treatment which was substantiated by alterations noticed in the histoarchitecture of lung tissue. Interestingly, AKBA administration to BaP treated rats appreciably alleviated the changes inflicted by BaP on various biochemical indices and histoarchitecture of lungs. Therefore, the study clearly revealed that AKBA by containing oxidative stress shall prove to be quite effective in providing chemoprevention against BaP induced lung carcinogenesis.

Effect of Zinc on Hepatic and Renal Tissues of Chronically Arsenic Exposed Rats: A Biochemical and Histopathological Study.

Consumption of arsenic-contaminated drinking water has become major global health concern. One of the major mechanism responsible for the toxicity of arsenicals is the generation of oxidative stress. Zinc, a nutritional antioxidant, plays key role in maintaining various cellular pathways. The present study was aimed at elucidating the effects of zinc supplementation on hepatic and renal tissue damage caused by arsenic exposure to rats. Rats were randomly divided into four experimental groups: control; As administered; Zn supplemented; combined zinc; and arsenic supplemented. Arsenic exposure resulted in significantly elevated accumulation of arsenic in the liver and kidney tissue. In the liver, exposure to arsenic reduced the levels of reduced glutathione (GSH), total glutathione (TG), redox ratio, and the activity of superoxide dismutase (SOD), whereas lipid peroxidation (LPO), inflammation markers, and nitric oxide (NO) levels were elevated with no significant change in catalase (CAT) activity. Arsenic exposure also enhanced the serum levels of liver functional indices and histological abnormalities in liver sections. In the kidney, a significant increase in NO levels and decrease in SOD activity was observed, with no significant changes in the rest of the parameters. The administration of zinc- to arsenic-intoxicated animals significantly improved their hepatic function parameters, arsenic burden, and histological changes which were associated with the restoration of enzymatic and non-enzymatic antioxidant defense system as compared to their intoxicated counterparts. In the kidney also, the NO levels and SOD activity were restored. This data reveals that zinc is effective in ameliorating the toxic effects inflicted by chronic arsenic toxicity.

Acetyl-11-keto-ß-boswellic acid modulates membrane dynamics in benzo(a)pyrene-induced lung carcinogenesis.

Membrane fluidity is the most important physiochemical property of cell membranes and governs its functional attributes. The current investigations were undertaken to understand the potential role of acetyl-11-keto-ß-boswellic acid (AKBA), if any, on regulation of membrane dynamics under conditions of benzo(a)pyrene (BaP)-induced lung carcinogenesis in female rats. The animals were divided into five groups which included (I) Normal control, (II) Vehicle treated (olive oil), (III) BaP treated, (IV) AKBA treated and (V) BaP + AKBA treated. BaP was administered at a dose level of 50 mg/kg b.wt. in olive oil orally twice a week for 4 weeks. AKBA was given at a dose level of 50 mg/kg b.wt. in olive oil orally thrice a week for 24 weeks. In addition, AKBA was also administered at a similar dose to BaP-treated animals 4 weeks prior to BaP administration and continued for another 20 weeks. The lipid profile and membrane dynamics were analysed in lung tissue. Total lipids, phospholipids content, membrane fluidity, polarization and order of membrane were significantly (p ≤ 0.001) increased in BaP-exposed animals. However, significant decrease was observed in glycolipids, cholesterol, microviscosity and anisotropy levels compared with normal control animals. Appreciable improvements in above indices were recorded when AKBA was administered to BaP-treated animals. Moreover, the structural variations observed in Fourier-transform infrared spectroscopy spectrum were also normalized in BaP-treated rats with AKBA supplementation. This suggests that the AKBA has a potential role in improving membrane fluidity and associated lipid content in BaP-induced lung carcinogenesis.

Radiomodulatory effects of Aloe vera on hepatic and renal tissues of X-ray irradiated mice.

The present study was aimed to explore the protective role of Aloe vera gel extract against hepatic and renal damage caused by X-ray exposure to mice. Male balb/c mice were divided into four groups: control, Aloe vera gel extract [AV] (50 mg/ kg b.w on alternate days for 30 days), X-ray (2 Gy) and AV + X-ray. X-ray irradiation enhanced the serum levels of liver function indices and chromosomal abnormalities in liver. Kidney function markers were found to be deranged and were accompanied by reduced glomerular filtration rate indicating renal dysfunction. Irradiation caused histopathological and biochemical alterations in both tissues which was associated with enhanced reactive oxygen species (ROS), lipid peroxidation (LPO) levels, lactate dehydrogenase (LDH) activity and enhanced apoptosis as revealed by TUNEL assay and DNA fragmentation. The administration of Aloe vera gel extract to X-ray exposed animals significantly improved their hepatic and renal function parameters which were associated with a reduction in ROS/LPO levels, LDH activity and chromosomal abnormalities as compared to their irradiated counterparts. In vitro assays revealed effective radical scavenging ability of Aloe vera gel extract, which may be linked to its potential in exhibiting antioxidant effects in in vivo conditions. This data suggested that Aloe vera may serve to boost the antioxidant system, thus providing protection against hepatic and renal damage caused by X-ray.

Quantum mechanical treatment of As3+-thiol model compounds: implication for the core structure of As(III)-metallothionein.

Exposure to inorganic arsenic (As) is one of the major health concerns in several regions around the world. Binding of As(III) with thiols is central to the mechanisms related to its toxicity, detoxification, and therapeutic effects. Due to its high thiol content, metallothionein (MT) is presumed to play an important role in case of arsenic toxicity. Consequences of these As-thiol interactions are not yet clear due to various difficulties in the characterization of arsenic bound proteins by spectroscopic techniques. Computational modeling can be a reliable approach in predicting the molecular structures of such complexes. This paper presents the results of a systematic study on different As(III)-thiol model compounds conducted by both ab initio and DFT methods with different Gaussian type basis sets. Proficiency of these theoretical methods has been evaluated in terms of bond lengths, bond angles, free energy, partial atomic charges, computational cost, and comparison with the experimental data. It has been demonstrated that the DFT-B3LYP/6-311+G(3df) functional offers better accuracy in predicting the structure and the UV absorption spectra of As(III)-thiol complexes. The results of the present study also helps in defining the boundaries for the core of arsenic bound MT so that quantum mechanical/molecular mechanical (QM/MM) methods can be employed to predict the structural and functional aspects of the protein. Graphical Abstract Optimized structural parameters of As3+-thiol model compounds.

Pro-Oxidant Role of Silibinin in DMBA/TPA Induced Skin Cancer: 1H NMR Metabolomic and Biochemical Study.

Silibinin, a major bioactive flavonolignan in Silybum marianum, has received considerable attention in view of its anticarcinogenic activity. The present study examines its anticancer potential against 7, 12-dimethylbenz(a)anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) induced skin cancer. Male LACA mice were randomly segregated into 4 groups: Control, DMBA/TPA, Silibinin and Silibinin+DMBA/TPA. Tumors in DMBA/TPA and Silibinin+DMBA/TPA groups were histologically graded as squamous cell carcinoma. In the Silibinin+DMBA/TPA group, significant reduction in tumor incidence (23%), tumor volume (64.4%), and tumor burden (84.8%) was observed when compared to the DMBA/TPA group. The underlying protective mechanism of Silibinin action was studied at pre-initiation (2 weeks), post-initiation (10 weeks) and promotion (22 weeks) stages of the skin carcinogenesis. The antioxidant nature of Silibinin was evident at the end of 2 weeks of its treatment. However, towards the end of 10 and 22 weeks, elevated lipid peroxidation (LPO) levels indicate the pro-oxidative nature of Silibinin in the cancerous tissue. TUNEL assay revealed enhanced apoptosis in the Silibinin+DMBA/TPA group with respect to the DMBA/TPA group. Therefore, it may be suggested that raised LPO could be responsible for triggering apoptosis in the Silibinin+DMBA/TPA group. 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used to determine the metabolic profile of the skin /skin tumors. Dimethylamine (DMA), glycerophosphocholine (GPC), glucose, lactic acid, taurine and guanine were identified as the major contributors for separation between the groups from the Principal Component Analysis (PCA) of the metabolite data. Enhanced DMA levels with no alteration in GPC, glucose and lactate levels reflect altered choline metabolism with no marked Warburg effect in skin tumors. However, elevated guanine levels with potent suppression of taurine and glucose levels in the Silibinin+DMBA/TPA group are suggestive of the pro-oxidative nature of Silibinin in regressing tumors. Thus, supporting the theory of augmented LPO levels resulting in increased apoptosis in the skin tumors treated with Silibinin.

Protective Effects of Zinc Against Acute Arsenic Toxicity by Regulating Antioxidant Defense System and Cumulative Metallothionein Expression.

Arsenic (As), a toxic metalloid, is one of the major global concerns. The toxicity resulting from As exposure is linked to the generation of reactive oxygen intermediates during their redox cycling and metabolic activation processes that cause lipid peroxidation (LPO). Zinc (Zn), a redox-inactive metal, helps to maintain cellular functions because of its prominent role in antioxidant network through multiple mechanisms. The present study, therefore, explores the effectiveness of administered Zn to combat against acute As toxicity by analysis of antioxidant defense status, alkaline phosphatase (ALP) activity, histological profile, MT expression, and elemental status in rat liver. To achieve this goal, four experimental groups, one control and three receiving different metal supplementations, were chosen (group 1, control; group 2, Zn supplemented; group 3, As substituted; group 4, Zn + As supplemented). The levels of reduced glutathione (GSH) and activities of glutathione reductase (GR) and ALP were lowered, whereas LPO levels and activity of superoxide dismutase (SOD) were elevated with no significant change in catalase (CAT) activity. Histopathological changes were also observed in the As substituted group in comparison to the control. Particle-induced X-ray emission (PIXE) analysis showed decrease in Fe and S concentration in rat liver after As intoxication, whereas As was below detection limit, i.e., <1 ppm. Zn administration almost restored the antioxidants, ALP activity, histopathological changes, and elemental status. A cumulative increase in MT expression was found with the combined treatment of Zn and As. Also, Zn alone caused no significant change in the antioxidant defense system. It can be concluded that restoration of antioxidant activity and increased MT expression are the two independent protective mechanisms of Zn to reduce acute As toxicity.

Decreased white matter integrity in fronto-occipital fasciculus bundles: relation to visual information processing in alcohol-dependent subjects.

Chronic alcohol abuse is characterized by impaired cognitive abilities with a more severe deficit in visual than in verbal functions. Neuropathologically, it is associated with widespread brain structural compromise marked by gray matter shrinkage, ventricular enlargement, and white matter degradation. The present study sought to increase current understanding of the impairment of visual processing abilities in alcohol-dependent subjects, and its correlation with white matter microstructural alterations, using diffusion tensor imaging (DTI). To that end, a DTI study was carried out on 35 alcohol-dependent subjects and 30 healthy male control subjects. Neuropsychological tests were assessed for visual processing skills and deficits were reported as raw dysfunction scores (rDyS). Reduced FA (fractional anisotropy) and increased MD (mean diffusivity) were observed bilaterally in inferior and superior fronto-occipital fasciculus (FOF) fiber bundles. A significant inverse correlation in rDyS and FA values was observed in these fiber tracts whereas a positive correlation of these scores was found with the MD values. Our results suggest that FOF fiber bundles linking the frontal lobe to occipital lobe might be related to visual processing skills. This is the first report of an alteration of the white matter microstructure of FOF fiber bundles that might have functional consequences for visual processing in alcohol-dependent subjects who exhibit no neurological complications.

Zinc as a nutritional approach to bone loss prevention in an ovariectomized rat model.

OBJECTIVE: In this study, we have investigated the role of zinc supplementation (a nutritional antioxidant) in an ovariectomized osteopenic rat model. METHODS: Forty-eight female Wistar rats were assigned to four groups: control, zinc, ovariectomy (OVX), and OVX + zinc. Analysis was performed to compare the study groups on bone metabolism markers, bone antioxidant enzymes, and zinc and copper levels in serum and bone tissues. Electron microscopy was also performed to assess morphological changes. RESULTS: Estradiol levels decreased and tartarate-resistant acid phosphatase 5b levels increased in the OVX group. In the OVX + zinc group, these levels were regulated; however, estradiol levels were still significantly lower than those in controls. The OVX group showed significantly higher urinary excretion of hydroxyproline, which recovered upon zinc supplementation but was higher than normal levels. The activities of catalase and superoxide dismutase decreased in ovariectomized animals and up-regulated upon zinc supplementation. Zinc supplementation in the OVX group revoked reduced glutathione levels and elevated malondialdehyde levels. Reduction in zinc and copper levels was observed in the bone tissues and serum of the OVX group. Zinc administration restored these levels to normal. Electron microscopic studies revealed a looser structure and resorbed areas in ovariectomized rat cortical bone. Zinc administration restored bone tissue morphology. CONCLUSIONS: These findings suggest that changes in cortical bone attributed to estrogen deficiency are arrested by zinc supplementation, which can be a sustainable approach to improving bone health.

Altered uptake and biological half-lives of 65Zn on arsenic exposure--modulation by zinc treatment.

The present study revealed the effects of zinc on the biokinetics of (65)Zn in rats following arsenic intoxication. The animals were segregated into four groups: group I--untreated controls, group II--arsenic treated (100 ppm as NaAsO(2) in drinking water), group III--zinc treated (227 mg ZnSO(4) per liter drinking water), and group IV--arsenic + zinc treated. Each rat was injected intraperitoneally with 1.85 MBq radioactivity of (65)Zn following 3 months of different treatments, and the radioactivity was determined using a suitably shielded scintillation counter. Arsenic treatment showed a significant increase in the fast component (Tb(1)) of the biological half-life of (65)Zn in liver, which remained unaltered in the whole body. Furthermore, arsenic treatment decreased significantly the slow component (Tb(2)) in the whole body, which remained unchanged in the liver. However, zinc supplementation to arsenic-treated rats normalized Tb(1) in the liver, but caused no change in Tb(2) in the whole body. Furthermore, the uptake values of (65)Zn were significantly increased in the liver, brain, kidney, and intestine following arsenic treatment, and the values in the liver and brain were decreased by zinc. Hence, zinc plays a significant role in regulating the biokinetics of (65)Zn in the liver and the whole body of arsenic-intoxicated rats.