Gemcitabine-vitamin E conjugates: Synthesis, characterization, entrapment into nanoemulsions, and in-vitro deamination and antitumor activity.

Abu-Fayyad A, Nazzal S

Int J Pharm. 2017 Aug 7;528(1-2):463-470. doi: 10.1016/j.ijpharm.2017.06.031. Epub 2017 Jun 13.

Abstract

Gemcitabine is the first line therapy for pancreatic cancer. It is, however, extensively metabolized to the inactive form by deamination enzymatic reaction. Conjugation of gemcitabine with fatty acids on its 4-amino group was found to protect it from deamination deactivation reaction. The objective of the present study was to test the in-vitro anticancer activity of gemcitabine conjugated to the γ-tocotrienol isomer of vitamin E against pancreatic tumor cells. This objective was based on reported studies in which it was demonstrated that free tocotrienolisomers of vitamin E can potentiate the anticancer activity of gemcitabine. To accomplish this objective, a full synthesis scheme for gemcitabine conjugation to fatty acids (stearic and linoleic) and the tocopherol and tocotrienol isomers of vitamin E (α-T and γ-T3) was presented. The conjugates were characterized by ¹H NMR and mass spectrometry analysis and tested for their susceptibility to deamination. Also discussed is the impact of entrapping the conjugates into nanoemulsions on the physiochemical properties of the delivery system and the in vitro anticancer activity of gemcitabine against Bx-PC-3 and PNAC-1 pancreatic cancer cells. In-vitro enzymatic deamination study showed that the γ-T3 conjugate of gemcitabine was least affected by deamination deactivation reaction when compared with the free and conjugated gemcitabine in solution. Furthermore, in-vitro cytotoxicity study demonstrated that entrapment of gemcitabine-lipid conjugates into nanoemulsions significantly enhanced their anticancer activity when compared to the free drug. It was concluded that conjugation to the γ-T3 isomer is a viable option for gemcitabine delivery and is worthy of further investigation.

Kanchi MM, Shanmugam MK, Rane G, Sethi G, Kumar AP

Drug Discov Today. 2017 Aug 5. pii: S1359-6446(17)30137-X. doi: 10.1016/j.drudis.2017.08.001. [Epub ahead of print]

Abstract

Vitamin E family members: tocotrienols and tocopherols are widely known for their health benefits. Decades of research on tocotrienols have shown they have diverse biological activities such as antioxidant, anti-inflammatory, anticancer, neuroprotective and skin protection benefits, as well as improved cognition, bone health, longevity and reduction of cholesterol levels in plasma. Tocotrienols also modulate several intracellular molecular targets and, most importantly, have been shown to improve lipid profiles, reduce total cholesterol and reduce the volume of white matter lesions in human clinical trials. This review provides a comprehensive update on the little-known therapeutic potentials of tocotrienols, which tocopherols lack in a variety of inflammation-driven diseases.

Xu W, Mi Y, He P, He S, Niu L

Molecules. 2017 Aug 4;22(8). pii: E1299. doi: 10.3390/molecules22081299.

Abstract

γ-Tocotrienol, a kind of isoprenoid phytochemical, has antitumor activity. However, there is limited evidence that it has an effect on cervical cancer. In this study, the capacity to inhibit proliferation and induce apoptosis in human cervical cancer HeLa cells and the mechanism underlying these effects were examined. The results indicated that a γ-tocotrienol concentration over 30 μM inhibited the growth of HeLa cells with a 50% inhibitory concentration (IC₅₀) of 46.90 ± 3.50 μM at 24 h, and significantly down-regulated the expression of proliferative cell nuclear antigen (PCNA) and Ki-67. DNA flow cytometric analysis indicated that γ-tocotrienol arrested the cell cycle at G0/G1 phase and reduced the S phase in HeLa cells. γ-tocotrienol induced apoptosis of HeLa cells in a time- and dose-dependent manner. γ-tocotrienol-induced apoptosis in HeLa cells was accompanied by down-regulation of Bcl-2, up-regulation of Bax, release of cytochrome from mitochondria, activation of caspase-9 and caspase-3, and subsequent poly (ADP-ribose) polymerase (PARP) cleavage. These results suggested that γ-tocotrienol could significantly inhibit cell proliferation through G0/G1 cell cycle arrest, and induce apoptosis via the mitochondrial apoptotic pathway in human cervical cancer HeLa cells. Thus, our findings revealed that γ-tocotrienol may be considered as a potential agent for cervical cancer therapy.

Jang Y, Rao X, Jiang Q.

J Nutr Biochem. 2017 Aug;46:49-56. doi: 10.1016/j.jnutbio.2017.04.003. Epub 2017 Apr 12.

Abstract

Vitamin E gamma-tocotrienol (γTE) is known to have anticancer effects, but mechanisms underlying these actions are not clear. Here using liquid chromatography tandem mass spectrometry, we show that γTE induced marked changes of sphingolipids including rapid elevation of dihydrosphingosine and dihydroceramides (dhCers) in various types of cancer cells. The elevation of dihydrosphingolipids coincided with increased cellular stress, as indicated by JNK phosphorylation, and was prior to any sign of induction of apoptosis. Chemically blocking de novo synthesis of sphingolipids partially counteracted γTE-induced apoptosis and autophagy. Experiments using ¹³C₃, ¹⁵N-labeled l-serine together with enzyme assays indicate that γTE inhibited cellular dihydroceramide desaturase (DEGS) activity without affecting its protein expression or de novo synthesis of sphingolipids. Unlike the effect on dhCers, γTE decreased ceramides (Cers) after 8-h treatment but increased C_18:0-Cer and C_16:0-Cer after 16 and 24 h, respectively. The increase of Cers coincides with γTE-induced apoptosis and autophagy. Since γTE inhibits DEGS and decreases de novo Cer synthesis, elevation of Cers during prolonged γTE treatment is likely caused by sphingomeylinase-mediated hydrolysis of sphingomyelin. This idea is supported by the observation that an acid sphingomeylinase inhibitor partially reversed γTE-induced cell death. Our study demonstrates that γTE altered sphingolipid metabolism by inhibiting DEGS activity and possibly by activating SM hydrolysis during prolonged treatment in cancer cells.

Chen Y, Yin C, Yang Y, Fan Z, Shang J, Tan W.

J Electrocardiol. 2017 Jul - Aug;50(4):437-443. doi: 10.1016/j.jelectrocard.2017.03.007. Epub 2017 Mar 14.

Abstract

Ischemia/reperfusion (I/R) induces prolongation of QT interval and action potential duration (APD), which is a major cardiac electrical disorder in patients with arrhythmias. However, the mechanism of QT interval prolongation induced by I/R remains unclear. In the present study, we hypothesized that the rapid component of delayed rectifier potassium (I_Kr) channel plays an important role in I/R-induced QT interval prolongation. We observed a marked attenuation of I_Kr and a significant prolongation of action potential duration (APD) in a simulated I/R system with sodium dithionite (Na₂S₂O₄) in ventricular myocytes of guinea pigs. The I_Kr current density was inhibited by 64% and APD increased by 87% respectively. Moreover, the inhibition of I_Kr is primarily ascribed to overproduction of reactive oxygen species (ROS) by I/R, which can be partly reversed by antioxidant vitamin E (100μmol/L). The value of I_Kr tail current density increased from 0.516±0.040 pA/pF in I/R to 0.939±0.091 pA/pF when treated with vitamin E. Moreover, we also demonstrated that QTc interval was increased by I/R and reversed by Vitamin E in isolated guinea pig hearts. In conclusion, the inhibition of I_Kr is one of the underlying mechanisms of prolongation of QT interval and APD in I/R. Vitamin E might have a benefit in coronary reperfusion therapy.

Rýdlová M, Růnová K, Száková J, Fučíková A, Hakenová A, Mlejnek P, Zídek V, Tremlová J, Mestek O, Kaňa A, Zídková J, Melčová M, Truhlářová K, Tlustoš P.

Biomed Res Int. 2017;2017:6759810. doi: 10.1155/2017/6759810. Epub 2017 May 30.

Abstract

The response of nutrient status and biochemical processes in (i) Wistar and (ii) spontaneously hypertensive (SHR) rats upon dietary intake of selenium- (Se-) enriched defatted rapeseed (DRS) and/or vitamin E fortification was examined to assess the health benefit of DRS in animal nutrition. Twenty-four individuals of each type of rat were used: The control group was fed with an untreated diet (Diet A). In Diets B and C, soybean meal was replaced with defatted DRS, which comprised 14% of the total diet. The selenized DRS application resulted in ~3-fold increase of Se content in the diet. Diet C was also fortified with the addition of vitamin E, increasing the natural content by 30%. The Se content of the blood and kidneys tended to increase in the DRS groups, where the changes were significant (P < 0.05) only in the case of SHR rats. The iodine (I) content and the proportion of iodide in rat livers indicated a lower transformation rate of iodide into organoiodine compounds compared to the control. Slight and ambiguous alterations in the antioxidative response of the rat were observed in the DRS groups, but the addition of vitamin E to the diet helped to moderate these effects.

Chen Y, Yin C, Yang Y, Fan Z, Shang J, Tan W.

J Electrocardiol. 2017 Jul - Aug;50(4):437-443. doi: 10.1016/j.jelectrocard.2017.03.007. Epub 2017 Mar 14.

Abstract

Libinaki R, Vinh A, Tesanovic-Klajic S, Widdop RE, Gaspari TA.

Clin Exp Pharmacol Physiol. 2017 Jul 26. doi: 10.1111/1440-1681.12821. [Epub ahead of print]

Abstract

α-Tocopheryl phosphate (TP) is a naturally occurring form of Vitamin E found in the body. In the present study we compared the ability of an α-TP mixture (TPM) against a standard Vitamin E supplement, α-tocopherol acetate (TA) on the development of atherosclerotic lesions in ApoE-deficient mice. Mice were maintained on either a normal chow diet for 24 weeks (Normal Diet), versus a group in which the final 8 weeks of the 24 week period mice were placed on a high fat (21%), high cholesterol (0.15%) challenge diet (HFHC), to exacerbate atherosclerotic lesion development.. The difference in these two control groups established the extent of the diet induced atherosclerotic lesion development. Mice in the various treatment groups received either TA (300mg/kg chow) or TPM (6.7 to 200mg/kg chow) for 24 weeks, with TPM treatment resulting in dose-dependent significant reductions in atherosclerotic lesion formation and plasma levels of pro-inflammatory cytokines. TA-treated mice, with the tocopherol equivalent TPM dose (200mg/kg chow), showed no significant reduction in plasma lipid levels or evidence for aortic lesion regression. At this TPM equivalent TA dose, a 44% reduction in aortic lesion formation was observed. In addition, these TPM treated mice, also showed a marked reduction in aortic superoxide formation and decreased circulating plasma levels of known pro-inflammatory markers IL-6, MCP-1, IL-1β, IFN-γ and TNF-α. These findings indicate that TPM treatment slows progression of atherosclerotic lesions in ApoE-deficient mice with this effect potentially involving reduced oxidative stress and decreased inflammation.

Burbank AJ, Duran CG, Pan Y, Burns P, Jones S, Jiang Q, Yang C, Jenkins S, Wells H, Alexis N, Kesimer M, Bennett WD, Zhou H, Peden DB, Hernandez ML.

J Allergy Clin Immunol. 2017 Jul 20. pii: S0091-6749(17)31110-7. doi: 10.1016/j.jaci.2017.06.029. [Epub ahead of print]

Abstract

BACKGROUND:

We and others have shown that the gamma tocopherol (γT) isoform of vitamin E has multiple anti-inflammatory and antioxidant actions and that γT supplementation reduces eosinophilic and endotoxin (LPS)-induced neutrophilic airway inflammation in animal models and healthy human volunteers.

OBJECTIVE:

To determine if γT supplementation reduces eosinophilic airway inflammation and acute neutrophilic response to inhaled LPS challenge in volunteers with asthma.

METHODS:

Participants with mild asthma were enrolled in a double-blinded, placebo controlled crossover study to assess the effect of 1200 mg of γT daily for 14 days on sputum eosinophils, mucins and cytokines. We also assessed the effect on acute inflammatory response to inhaled LPS challenge following γT treatment, focusing on changes in sputum neutrophilia, mucins and cytokines. Mucociliary clearance was measured using gamma scintigraphy.

RESULTS:

Fifteen subjects with mild asthma completed both arms of the study. Compared to placebo, γT notably reduced pre-LPS challenge sputum eosinophils and mucins, including MUC5AC, and reduced LPS-induced airway neutrophil recruitment 6 and 24-hours after challenge. Mucociliary clearance was slowed 4-hours post-challenge in the placebo group but not in the γT treatment group. Total sputum mucins (but not MUC5AC) were reduced at 24-hours post-challenge during γT treatment compared to placebo.

CONCLUSION:

γT supplementation for 14 days reduced inflammatory features of asthma, including sputum eosinophils and mucins, as well as acute airway response to inhaled LPS challenge when compared to placebo. Larger scale clinical trials are needed to assess the efficacy of γT supplements as a complementary or steroid-sparing treatment for asthma.

Cha JY, Park JM, Lee HJ, Bae JS, Han YM, Oh BC, Ko KH, Hahm KB.

Curr Pharm Des. 2017 Jul 14. doi: 10.2174/1381612823666170714124824. [Epub ahead of print]

Abstract

Fat stress-induced liver disease is a hepatic manifestation of metabolic syndrome initiated by excess fat accumulation and encompasses a wide spectrum of diseases from non-alcoholic fatty liver disease to non-alcoholic steatohepatitis, a precursor lesion progressing to more aggressive liver cirrhosis and hepatocellular carcinoma. Although the incidence of these fat stress-induced liver diseases is rapidly increasing worldwide in parallel with the growing epidemics of obesity and metabolic diseases, its exact pathogenesis is not well defined. Although obesity, sedentary life-style, altered dietary pattern, insulin resistance, altered intestinal barrier function, inflammatory cytokines, and oxidative stress have been acknowledged as contributing factors because of the indefinite pathogenesis of metabolic diseases, the only reliable treatment is lifestyle intervention composed of restrictive diet and exercise. Additionally, some existing medications such as pioglitazone and antioxidants such as vitamin E were reported to be effective; in this review, several novel agents especifically targeting non-alcoholic fatty liver disease pathogenesis under clinical trial will be introduced. These include an NPC1L1 blocker (ezetimibe), which significantly improved histological and symptomatic scores associated with steatohepatitis and fibrosis; clofibrate, phentoxyfylline, ursodeoxycholic acid, and tocopherol, all of which are prescribed to relieve fat stress; and additional IgY targeted NPC1L1, tocotrienol, ursodeoxycholic acid, and -3 polyunsaturated fatty acids, which are actively under investigation to confirm the safety of long-term use.