Tumor growth inhibitory effect of juglone and its radiation sensitizing potential: in vivo and in vitro studies.

The present study aimed at evaluating the anticancer and radiosensitizing potential of juglone against a chemoresistant and radioresistant tumor (B16F1 melanoma) growing on C57BL/6J mice. Volume doubling time, growth delay, and median survival were used to assess the in vivo anticancer and radiosensitizing potential of juglone. In vitro radiosensitizing potential of juglone was studied using clonogenic, comet, and reactive oxygen species induction assays. Treatment of tumor-bearing mice with sublethal doses of juglone caused a dose-dependent inhibition of tumor growth as evident from the growth delay and median survival values. Comet assay using tumor tissue and blood showed differential toxicity of juglone, where higher levels of DNA damage was seen in tumor tissue compared with blood cells. Pretreatment of tumor-bearing mice with optimum dose of juglone before radiation resulted in significant tumor growth inhibition compared with radiation alone. From the clonogenic assay, the authors observed a sensitization enhancement ratio of 1.37 for the combination treatment compared with radiation alone. Furthermore, comet assay studies revealed the potential of juglone to enhance the radiation-induced DNA damage and cause a delay in its repair. Juglone pretreatment before radiation also resulted in a significant elevation in the intracellular reactive oxygen species levels compared with radiation alone. In conclusion, the results of this study show the potential of juglone to inhibit the growth of melanoma in vivo. The study also revealed the potential of juglone to augment the radiation-induced cell death of melanoma cells, which may be attributed to oxidative stress-mediated DNA damage and its delayed repair.

Evaluation of pharmacokinetic, biodistribution, pharmacodynamic, and toxicity profile of free juglone and its sterically stabilized liposomes.

The present study was aimed to formulate and compare the pharmacokinetic, biodistribution, pharmacodynamic, and toxicity profiles of free 5-hydroxy-1,4-naphthoquinone (juglone) with sterically stabilized liposomal form. The liposomes were optimized for size, zeta potential, entrapment efficiency (EE), and in vitro release properties. The optimized formulation had a mean size, zeta potential, and EE value of 137.1 nm, -43.1 mV, and 67.2%, respectively. In vitro release studies showed biphasic pattern with initial burst followed by sustained release over the study period, releasing about 61% after 24 h. In vitro cytotoxicity studies against melanoma cells indicated that liposomal juglone was more toxic than free juglone. Free juglone had short plasma half-life of about 2 h, whereas liposomal juglone exhibited significantly improved pharmacokinetics with a 12-fold increase in plasma half-life. Further, biodistribution studies indicated rapid renal elimination of free juglone, evidenced by its significant localization in kidneys. Conversely, the accumulation of liposomal juglone in kidneys reduced significantly with enhanced tumor localization, thereby resulting in enhanced antitumor activity. The histological studies revealed lower levels of nephrotoxicity for liposomal juglone compared with that of free juglone. To conclude, sterically stabilized liposomes could be a promising approach for the intravenous delivery of hydrophobic compounds such as juglone.

Antagonistic effects of Zingerone, a phenolic alkanone against radiation-induced cytotoxicity, genotoxicity, apoptosis and oxidative stress in Chinese hamster lung fibroblast cells growing in vitro.

Zingerone (ZO), a dietary phenolic compound was investigated for its ability to protect against radiation-induced oxidative stress and DNA damage in Chinese hamster fibroblast cells (V79). Cells treated with optimal dose of ZO (25 µg/ml), 1 h prior radiation exposure resulted in a significant (P<0.01) elevation of cell survival and decreased the genotoxicity (micronuclei and comet assays). Further, pretreatment with ZO significantly reduced radiation-induced oxidative stress as indicated by decreased reactive oxygen species levels and inhibition of mitochondrial depolarisation. The experiments conducted to evaluate the intracellular antioxidant activity in ZO-pretreated cells demonstrated a significant (P<0.01) increase in the various antioxidants like glutathione, gluthione-S-transferase, superoxide dismutase, catalase and a significant (P<0.01) decrease in malondialdehyde levels versus irradiation alone. Further, ZO scavenged various free radicals generated in vitro (OH·, O(2)·, DPPH·, ABTS·(+) and NO·) in a dose-dependent manner. The anti-apoptotic effect of ZO pretreatment was by the inhibition of the activation of capase-3, by upregulating Bcl-2 and down-regulating Bax proteins. Our study demonstrates the antagonistic effect of ZO against radiation-induced cytotoxicity. Further, ZO rendered anti-genotoxic, anti-apoptotic and anti-lipid peroxidative potency, plausibly ascribable to its antioxidant/free radical scavenging ability and also by the suppression of radiation-induced oxidative stress.

Antigenotoxic effect of mangiferin and changes in antioxidant enzyme levels of Swiss albino mice treated with cadmium chloride.

Cadmium is an environmental metal toxin implicated in human diseases. Mangiferin (MGN), a naturally occurring glucosylxanthone, is present in Mangifera indica. In this study, the protective role of MGN against cadmium chloride (CdCl(2))-induced genotoxicity was studied in Swiss albino mice. Mice were administered with single intra-peritoneal (i.p.) optimal dose of MGN (2.5 mg/kg b.wt.) before treatment with various concentrations of CdCl(2) (7, 8, 9, 10 and 11 mg/kg b.wt.). The LD( 50(30)) was found to be 8.5 mg/kg b.wt. for DDW + CdCl(2) group, while it was increased to 9.77 mg/kg after MGN treatment resulting in increase in the LD(50(30)) value by 1.26 mg, with a dose reduction factor (DRF) of 1.14. Treatment of mice to various doses of CdCl(2) resulted in a dose-dependent increase in the frequency of micronucleated polychromatic (MnPCE) and normochromatic erythrocytes (MnNCE), with corresponding decrease in the polychromatic / normochromatic erythrocyte ratio (PCE/NCE ratio) at various post-treatment times. MGN (2.5 mg/kg b.wt.) pretreatment significantly (p < .001) reduced the frequency of MnPCE, MnNCE and increased PCE/NCE ratio when compared with the DDW + CdCl(2) group at all post-treatment times indicating its antigenotoxic effect. Further, pretreatment of MGN declined the lipid peroxidation (LPx) content in liver, whereas significant increase was observed in hepatic Glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activity. Our study revealed that MGN has potent antigenotoxic effect against CdCl(2)-induced toxicity in mice, which may be due to the scavenging of free radicals and increased antioxidant status.

Juglone, a naphthoquinone from walnut, exerts cytotoxic and genotoxic effects against cultured melanoma tumor cells.

This study demonstrates cytotoxic and genotoxic potential of juglone, a chief constituent of walnut, and its underlying mechanisms against melanoma cells. MTT assay and clonogenic assay were used to study cytotoxicity, micronucleus assay to assess genotoxicity, glutathione (GSH) assay and 2',7'-dicholorofluorescein diacetate (DCFH-DA) assay to evaluate the oxidative stress induction. Apoptosis/necrosis induction was analysed by flow cytometry. We observed a concentration-dependent decrease in cell survival with a corresponding increase in the lactate dehydrogenase levels. A dose-dependent increase in the frequency of micronucleated binucleate cells indicated the potential of juglone to induce cytogenetic damage in melanoma tumor cells. Moreover, results of the micronuclei study indicated division delay in the proliferating cell population by showing decrease in the cytokinesis blocked proliferation index. Further, juglone-induced apoptosis and necrosis could be demonstrated by oligonucleosomal ladder formation, microscopic analysis, increase in the hypodiploid fraction (sub Go peak in DNA histogram), as well as an increased percentage of AnnexinV(+)/PI(+) cells detected by flow cytometry. A significant concentration-dependent decrease in the glutathione levels and increase in dichlorofluorescein (DCF) fluorescence after juglone treatment confirmed the ability of juglone to generate intracellular reactive oxygen species. The cytotoxic effect of juglone can be attributed to mechanisms including the induction of oxidative stress, cell membrane damage, and a clastogenic action leading to cell death by both apoptosis and necrosis.

Radiomodifying and anticlastogenic effect of Zingerone on Swiss albino mice exposed to whole body gamma radiation.

The radioprotective effect and antigenotoxic potential of phenolic alkanone, Zingerone (ZO) were investigated in Swiss albino mice exposed to gamma radiation. To study the optimum dose for radiation protection, mice were administered with ZO (10-100mg/kgb.wt.), once daily for five consecutive days. One hour after the last administration of ZO on the fifth day, animals were whole body exposed to 10 Gy gamma radiations. The radioprotective potential was assessed using animal survival at an optimal ZO dose of 20mg/kgb.wt., administered prior to 7-11 Gy. Further, the radioprotective potential of ZO was also analyzed by haemopoietic stem cell survival (CFU) assay, mouse bone marrow micronucleus test and histological observations of intestinal and bone marrow damage. Effect of ZO pretreatment on radiation-induced changes in glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPx) levels was also analyzed. ZO treatment resulted increase in the LD(50/30) by 1.8 Gy (dose reduction factor = 1.2). The number of spleen colonies after whole body irradiation of mice (4.5 or 7.5 Gy) was increased when ZO was administered 1h prior to irradiation. The histological observations indicated a decline in the villus height and crypt number with an increase in goblet and dead cell population in the irradiated group, which was normalized by pretreatment with ZO. A significant (p < 0.001) reduction in micronucleated polychromatic, normochromatic erythrocytes, increased PCE/NCE ratio, increase in the GSH, GST, SOD, CAT and decreased LPx levels were observed in ZO pretreated group when compared to the irradiated animals. Our findings demonstrate the potential of ZO in mitigating radiation-induced mortality and cytogenetic damage, which may be attributed to inhibition radiation-induced decline in the endogenous antioxidant levels and scavenging of radiation-induced free radicals.

Effect of silymarin on the oral bioavailability of ranitidine in healthy human volunteers.

The effect of silymarin pretreatment on the pharmacokinetics of ranitidine was investigated in 12 healthy male human volunteers aged 19-26 years. After an overnight fast, ranitidine 150 mg was administered to the volunteers either alone or after 7 days pretreatment with thrice daily dose of 140 mg silymarin. The wash-out period between each treatment was 7 days. Serum levels of ranitidine were determined by HPLC. Pharmacokinetic parameters were determined based on non-compartmental model analysis using the computer program KINETICA. There was no influence of silymarin on the pharmacokinetics of ranitidine. Concomitant administration of silymarin at this dosage did not alter ranitidine C(max) and AUC(0-infinity). There was a significant difference in area under the first moment curve (AUMC) and mean residence time. This result is useful in predicting the interaction of silymarin with other cytochrome 3A4 and P-glycoprotein substrates at normal dosage.