The therapeutic potential of tocotrienol, an extract of vitamin E with anti-cancer properties, is hampered by its failure to specifically reach tumors after intravenous administration, without secondary effects on normal tissues. We hypothesize that the encapsulation of tocotrienol-rich fraction (TRF) within vesicles bearing transferrin, whose receptors are overexpressed on many cancer cells, could result in a selective delivery to tumors after intravenous administration. The objectives of this study are therefore to prepare and characterize transferrin-targeted vesicles encapsulating TRF, and to evaluate their therapeutic efficacy in vitro and in vivo. The entrapment of TRF in transferrin-bearing vesicles led to a 3-fold higher TRF uptake and more than 100-fold improved cytotoxicity in A431 (epidermoid carcinoma), T98G (glioblastoma) and A2780 (ovarian carcinoma) cell lines compared to TRF solution. The intravenous administration of TRF encapsulated in transferrin-bearing vesicles led to tumor regression and improvement of animal survival in a murine xenograft model, contrary to that observed with controls. The treatment was well tolerated by the animals. This work corresponds to the first preparation of a tumor-targeted delivery system able to encapsulate tocotrienol. Our findings show that TRF encapsulated in transferrin-bearing vesicles is a highly promising therapeutic system, leading to tumor regression after intravenous administration without visible toxicity.
Publications
Modulation of melanin synthesis and its gene expression in skin melanocytes by palm tocotrienol rich fraction
Suzana Makpol, Nur Nadia Mohd Arifin, Zahariah Ismail, Chua Kien Hui, Yasmin Anum Mohd Yusof and Wan Zurinah Wan Ngah
African Journal of Biochemistry Research Vol.3 (12), pp. 385-392, December, 2009
Melanin is the pigment that determines skin color. Melanin synthesis is catalysed by the enzyme tyrosinase and is controlled by TYR, TYRP1 and TYRP2 genes. The objective of this study was to evaluate the anti pigmentation property of palm tocotrienol rich fraction by determining melanin synthesis and expression of genes involved in its regulation in skin melanocytes. Palm tocotrienol rich fraction (TRF) which contains 75% a-tocotrienol and 25% tocopherol was used to inhibit melanin synthesis which was determined by determining melanin level and tyrosinase enzyme activity. Expression of TYR, TYRP1 and TYRP2 genes was determined by quantitative real time reverse transcriptase polymerase chain reaction (real time RT-PCR). Primary culture of skin melanocytes was divided into two groups; untreated control and cells that were treated with 500 μg/ml tocotrienol rich fraction for 24 h. Our results showed that there was a reduction in tyrosinase activity and melanin content in melanocytes treated with tocotrienol rich fraction compared to control (p < 0.05). Expression of TYRP2 gene in melanocytes treated with tocotrienol rich fraction was also decreased (p < 0.05) compared to control. In conclusion, palm tocotrienol rich fraction has an anti pigmentation property that inhibit melanin synthesis by inhibiting tyrosinase activity and down regulating TYRP2 gene expression.
The effects of palm oil tocotrienol-rich fraction supplementation on biochemical parameters, oxidative stress and the vascular wall of streptozotocin-induced diabetic rats
Budin SB, Othman F, Louis SR, Bakar MA, Das S, Mohamed J.
Clinics (Sao Paulo). 2009;64(3):235-44.
Objective:This study examined the effects of palm oil tocotrienol-rich fractions on streptozotocin-induced diabetic rats.
Methods: Animals were divided into three groups: (i) normal non-diabetic (NDM), (ii) diabetic treated (tocotrienol-rich fractions – TRF) and (iii)diabetic untreated (non-TRF). The treatment group received oral administration of tocotrienol-rich fractions (200 mg/kg body weight) daily for eight weeks. The normal non-diabetic and the diabetic untreated groups were fed standard rat feed. Blood glucose and lipid profiles, oxidative stressmarkers and morphological changes of the thoracic aorta were evaluated.
Results: Tocotrienol-rich fractions treatment reduced serum glucose and glycated hemoglobin concentrations. The tocotrienol-rich fractions group also showed significantly lower levels of plasma total cholesterol, low-density lipoprotein cholesterol, and triglyceride, as compared to the untreated group. The tocotrienol-rich fractions group had higher levels of high-density lipoprotein cholesterol, as compared to the untreated group. Superoxide dismutase activity and levels of vitamin C in plasma were increased in tocotrienol-rich fractions-treated rats. The levels of plasma and aorta malondealdehyde + 4-hydroxynonenal (MDA + 4-HNE) and oxidative DNA damage were significant following tocotrienol-rich fractions treatment. Electron microscopic examination showed that the normal morphology of the thoracic aorta was disrupted in STZ-diabetic rats. Tocotrienol-richfractions supplementation resulted in a protective effect on the vessel wall.
Conclusion: These results show that tocotrienol-rich fractions lowers the blood glucose level and improves dyslipidemia. Levels of oxidative stressmarkers were also reduced by administration of tocotrienol-rich fractions. Vessel wall integrity was maintained due to the positive effects mediated bytocotrienol-rich fractions.
Attenuation of diabetic nephropathy by tocotrienol: Involvement of NFkB signaling pathway
Kuhad, A.,Chopra, K.
Life Sci, 2009;84(9-10);296-301.
Aim: Diabetic nephropathy is a serious complication for patients with diabetes mellitus. Approximately 30-40% of patients with type I and 15% with type II diabetes mellitus develop end stage renal disease. The study was designed to evaluate the impact of tocotrienol on renal function and reno-inflammatory cascade in streptozotocin-induced diabetes.
Main Methods: Streptozotocin (STZ)-induced diabetic rats were treated with tocotrienol (25, 50 and 100 mg/kg), alpha-tocopherol (100 mg/kg) or with vehicle form 5th to 8th weeks. After 8 weeks, urine albumin excretion, urine output, serum creatinine, blood urea nitrogen, creatinine and urea clearance were measured. Cytoplasmic and nuclear fractions of kidney was prepared for the quantification of oxidative-nitrosative stress (lipid peroxidation, superoxide dismutase, catalase, non protein thiols, total nitric oxide), tumor necrosis factor-alpha (TNF-alpha), tissue growth factor-1beta (TGF-beta1), p65 subunit of NFkappabeta and caspase-3.
Key Findings: After 8 weeks of STZ injection, the rats produced significant alteration in renal function, increased oxidative-nitrosative stress, TNF-alpha, TGF-beta1, caspase-3 activity in cytoplasmic lysate and active p65 subunit of NFkappabeta in nuclear lysate of kidney of diabetic rats. Interestingly, co-administration of tocotrienol significantly and dose-dependently prevented biochemical and molecular changes associated with diabetes. Tocotrienol (100 mg/kg) was demonstrated to be more effective than alpha-tocopherol (100 mg/kg). Moreover, diabetic rats treated with insulin-tocotrienol combination produced more pronounced effect on molecular parameters as compared to their respective groups.
Significance: Taken together, the data reveal that tocotrienol modulates the release of profibrotic cytokines, oxidative stress, ongoing chronic inflammation and apoptosis and thus exerts a marked renoprotective effect.
Tocotrienol attenuates oxidative-nitrosative stress and inflammatory cascade in experimental model of diabetic neuropathy
Kuhad, A.,Chopra, K.
Pharmacol Biochem Behav, 2009. 92(2):251-9.
Diabetic neuropathic pain, an important microvascular complication in diabetes mellitus, is recognised as one of the most difficult types of pain to treat. The development of tolerance, inadequate relief and potential toxicity of classical antinociceptives warrant the investigation of the newer agents to relieve this pain. Reactive oxygen/nitrogen species, cytokines and apoptosis are implicated in the pathogenesis of diabetic neuropathy. The aim of the present study was to explore the effect of tocotrienol on thermal and mechanical hyperalgesia, allodynia, oxidative-nitrosative stress, inflammation and apoptosis in streptozotocin-induced experimental diabetes. Diabetic rats developed neuropathy which was evident from a marked hyperalgesia and allodynia associated with enhanced nitrosative stress, release of inflammatory mediators (TNF-alpha, IL-1beta, TGF-1beta) and caspase-3. Chronic treatment with tocotrienol (25, 50 and 100 mg/kg body weight; p.o.) for 4 weeks starting from the 4th week of streptozotocin injection significantly attenuated behavioral, biochemical and molecular changes associated with diabetic neuropathy. Moreover, diabetic rats treated with insulin-tocotrienol combination produced more pronounced beneficial effect as compared to their per se groups. The major finding of the study is that insulin alone corrected the hyperglycemia and partially reversed the pain response in diabetic rats. However, combination with tocotrienol not only attenuated the diabetic condition but also reversed neuropathic pain through modulation of oxidative-nitrosative stress, inflammatory cytokine release and caspase-3 in the diabetic rats and thus it may find clinical application to treat neuropathic pain in the diabetic patients.
Evidence of gamma-tocotrienol as an apoptosis-inducing, invasion-suppressing, and chemotherapy drug-sensitizing agent in human melanoma cells
Chang PN, Yap WN, Lee DT, Ling MT, Wong YC, Yap YL.
Nutr Cancer. 2009;61(3):357-66.
To date, the most effective cure for metastatic melanoma remains the surgical resection of the primary tumor. Recently, tocotrienol-rich-fraction has shown antiproliferative effect on cancer cells. To elucidate this anticancer property in malignant melanoma, this study aimed, first, to identify the most potent isomer for eliminating melanoma cells and second to decipher the molecular pathway responsible for its activity. Results showed that the inhibitory effect of gamma-tocotrienol was most potent, which resulted in induction of apoptosis as evidenced by activation of procaspases and the accumulation of sub-G1 cell population. Examination of the prosurvival genes revealed that the gamma-tocotrienol-induced cell death was associated with suppression of NF-kappaB, EGF-R, and Id family proteins. Meanwhile, gamma-tocotrienol treatment also resulted in induction of JNK signaling pathway, and inhibition of JNK activity by selective inhibitor was able to partially block the effect of gamma-tocotrienol. Interestingly, gamma-tocotrienol treatment led to suppression of mesenchymal markers and the restoration of E-cadherin and gamma-catenin expression, which was associated with suppression of cell invasion capability. Furthermore, synergistic effect was observed when cells were cotreated with gamma-tocotrienol and chemotherapy drugs. Together, our results demonstrated for the first time the anti-invasion and chemonsensitization effect of gamma-tocotrienol against human malignant melanoma cells.
Suppression of tumor growth by palm tocotrienols via the attenuation of angiogenesis
Weng-Yew W, Selvaduray KR, Ming CH, Nesaretnam K.
Nutr Cancer. 2009;61(3):367-73.
Previous studies have revealed that tocotrienol-rich fractions (TRF) from palm oil inhibit the proliferation and the growth of solid tumors. The anticancer activity of TRF is said to be caused by several mechanisms, one of which is antiangiogenesis. In this study, we looked at the antiangiogenic effects of TRF. In vitro investigations of the antiangiogenic activities of TRF, delta-tocotrienol (deltaT3), and alpha-tocopherol (alphaToc) were carried out in human umbilical vein endothelial cells (HUVEC). TRF and deltaT3 significantly inhibited cell proliferation from 4 microg/ml onward (P < 0.05). Cell migration was inhibited the most by deltaT3 at 12 microg/ml. Anti-angiogenic properties of TRF were carried out further in vivo using the chick embryo chorioallantoic membrane (CAM) assay and BALB/c mice model. TRF at 200 microg/ml reduced the vascular network on CAM. TRF treatment of 1 mg/mouse significantly reduced 4T1 tumor volume in BALB/c mice. TRF significantly reduced serum vascular endothelial growth factor (VEGF) level in BALB/c mice. In conclusion, this study showed that palm tocotrienols exhibit anti-angiogenic properties that may assist in tumor regression.
Simultaneous induction of non-neoplastic and neoplastic lesions with highly proliferative hepatocytes following dietary exposure of rats to tocotrienol for 2 years
Tasaki M, Umemura T, Kijima A, Inoue T, Okamura T, Kuroiwa Y, Ishii Y, Nishikawa A.
Arch Toxicol. 2009 Nov;83(11):1021-30. Epub 2009 Aug 11.
It was recently shown that 1-year chronic exposure of rats to tocotrienol (TT) induced highly proliferative liver lesions, nodular hepatocellular hyperplasia (NHH), and independently increased the number of glutathione S-transferase placental form (GST-P)-positive hepatocytes. Focusing attention on the pathological intrinsic property of NHH, a 104-week carcinogenicity study was performed in male and female Wistar Hannover rats given TT at concentrations of 0, 0.4 or 2% in the diet. The high-dose level was adjusted to 1% in both sexes from week 51 because the survival rate of the high-dose males dropped to 42% by week 50. At necropsy, multiple cyst-like nodules were observed, as in the chronic study, but were further enlarged in size, which consequently formed a protuberant surface with a partly pedunculated shape in the liver at the high dose in both sexes. Unlike the chronic study, NHH was not always accompanied by spongiosis, and instead angiectasis was prominent in some nodules. However, several findings in the affected hepatocytes such as minimal atypia, no GST-P immunoreactivity and heterogeneous proliferation, implied that NHH did not harbor neoplastic characteristics from increased exposure despite sustained high cell proliferation. On the other hand, in the high-dose females, the incidence of hepatocellular adenomas was significantly higher than in the control. There was no TT treatment-related tumor induction in any other organs besides the liver. Thus, the overall data clearly suggested that NHH is successively enlarged by further long-term exposure to TT, but does not become neoplastic. In contrast, TT induces low levels of hepatocellular adenomas in female rats.
Effects of tocotrienol-rich fraction on exercise endurance capacity and oxidative stress in forced swimming rats
Lee SP, Mar GY, Ng LT.
Eur J Appl Physiol. 2009 Nov;107(5):587-95. Epub 2009 Aug 25.
The present study aimed to examine the effects of tocotrienol-rich fraction (TRF) on exercise endurance and oxidative stress in forced swimming rats. Rats fed on isocaloric diet were orally given 25 (TRF-25) and 50 (TRF-50) mg/kg of TRF, or 25 mg/kg D-alpha-tocopherol (T-25) whilst the control group received only the vehicle for 28 days, followed by being forced to undergo swimming endurance tests, with measurements taken of various biochemical parameters, including blood glucose, lactate and urea nitrogen, glycogen, total antioxidant capacity, antioxidant enzymes, thiobarbituric acid-reactive substances (TBARS), and protein carbonyl. Results showed that the TRF-treated animals (268.0 +/- 24.1 min for TRF-25 and 332.5 +/- 24.3 min for TRF-50) swam significantly longer than the control (135.5 +/- 32.9 min) and T-25-treated (154.1 +/- 36.4 min) animals, whereas there was no difference in the performance between the T-25 and control groups. The TRF-treated rats also showed significantly higher concentrations of liver glycogen, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as of muscle glycogen and SOD than the control and the T-25-treated animals, but lower levels in blood lactate, plasma and liver TBARS, and liver and muscle protein carbonyl. Taken together, these results suggest that TRF is able to improve the physiological condition and reduce the exercise-induced oxidative stress in forced swimming rats.
Assessing the neuroprotective effect of antioxidative food factors by application of lipid-derived dopamine modification adducts
Liu X, Yamada N, Osawa T.
Methods Mol Biol. 2009;580:143-52.
Advances in understanding the neurodegenerative pathologies are creating new opportunities for the development of neuroprotective therapies, such as antioxidant food factors, lifestyle modification, and drugs. However, the biomarker by which to determine the effect of the agent on neurodegeneration is limited. We here address hexanoyl dopamine (HED), one of novel dopamine adducts derived from brain polyunsaturated acid, referring to its in vitro formation, potent toxicity to SH-SY5Y cells, and application to assess the neuroprotective effect of antioxidative food factors. Dopamine is a neurotransmitter and its deficiency is a characterized feature in Parkinson’s disease (PD), thereby HED represents a new addition to understanding of dopamine biology and pathophysiology of PD and a novel biomarker for the assessment of neuroprotective therapies. We have established an analytical system using for the detection of HED and its toxicity to the neuroblstoma cell line, SH-SY5Y cells. Here, we discuss the characteristics of the system and its applications to investigate the neuroprotective effect of several antioxidants that originate from food.