Formulation of plumbagin loaded long circulating pegylated liposomes: in vivo evaluation in C57BL/6J mice bearing B16F1 melanoma.

CONTEXT AND OBJECTIVE: Plumbagin (2-methyl, 5-hydroxy, 1, 4-naphthoquinone), an anticancer agent is encapsulated either as conventional or long circulating liposomal formulations to enhance its biological half-life and antitumor efficacy. METHODS: The liposomes were prepared by thin film hydration method and in vitro characterization was carried out to examine the particle size, zeta potential, drug encapsulation efficiency and in vitro release. The optimized formulations were tested for pharmacokinetic and pharmacodynamic efficacy against mice bearing B16F1 melanoma. Also in vivo toxicity studies were carried out. RESULTS AND DISCUSSION: The optimum particle size and entrapment efficiency was observed at drug to lipid molar ratio of 1:20. The in-vitro release of plumbagin from the liposomal formulations in phosphate-buffered saline (pH 7.4) showed biphasic release with an initial burst release followed by sustained release phase. Elimination half life (T(½)) of pegylated, conventional and free plumbagin was 1305.76 ± 278.16, 346.87 ± 33.82 and 35.89 ± 7.95 min respectively. Further, plumbagin exhibited better antitumor efficacy in vivo when administered as long circulating liposomes with no signs of normal tissue toxicity. CONCLUSION: It can be concluded that the pegylated liposomes could provide a promising parenteral platform for plumbagin with enhanced plasma half-life and therapeutic efficacy.

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.

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.