Effect of nano-delivery systems on the bioavailability and tissue biodistribution of vitamin E tocotrienols.

Vitamin E is one of the most important essential vitamins to support the regulation of oxidative stress in human body. Tocotrienols are part of the vitamin E family. The potentials of tocotrienols as nutraceutical ingredient are largely understated due to low oral bioavailability, which is a common problem associated with fat-soluble bioactive compounds. Nanoencapsulation technology offers innovative solutions to enhance the delivery mechanisms of these compounds. In this study, the effect of nanoencapsulation on the oral bioavailability and tissue distribution of tocotrienols were investigated using two types of formulations, i.e. nanovesicles (NV-T3) and solid lipid nanoparticles (NP-T3). At least 5-fold increment in maximum plasma concentrations, evident with dual-peak pharmacokinetic profiles, were observed after oral administration of nano-encapsulated tocotrienols. Plasma tocotrienol composition showed a shift from α-tocotrienol dominant in control group (Control-T3) to γ-tocotrienol dominant after nanoencapsulation. Tissue distribution of tocotrienols was found to be strongly influenced by the type of nanoformulation. Both nanovesicles (NV-T3) and nanoparticles (NP-T3) showed elevated accumulation in the kidneys and liver (5-fold) compared to control group while selectivity for α-tocotrienol was evident for NP-T3. In brain and liver of rats given NP-T3, α-tocotrienol emerged as the dominant congener (>80%). Acute oral administration of nanoencapsulated tocotrienols did not show signs of toxicity. The study concluded enhanced bioavailability and selective tissue accumulation of tocotrienol congeners when delivered via nanoencapsulation.

Chitosan-based drug delivery systems for skin atopic dermatitis: recent advancements and patent trends.

Atopic dermatitis (AD) is a complex, relapsing inflammatory skin disease with a considerable social and economic burden globally. AD is primarily characterized by its chronic pattern and it can have important modifications in the quality of life of the patients and caretakers. One of the fastest-growing topics in translational medicine today is the exploration of new or repurposed functional biomaterials into drug delivery therapeutic applications. This area has gained a considerable amount of research which produced many innovative drug delivery systems for inflammatory skin diseases like AD. Chitosan, a polysaccharide, has attracted attention as a functional biopolymer for diverse applications, especially in pharmaceutics and medicine, and has been considered a promising candidate for AD treatment due to its antimicrobial, antioxidative, and inflammatory response modulation properties. The current pharmacological treatment for AD involves prescribing topical corticosteroid and calcineurin inhibitors. However, the adverse reactions associated with the long-term usage of these drugs such as itching, burning, or stinging sensation are also well documented. Innovative formulation strategies, including the use of micro- and nanoparticulate systems, biopolymer hydrogel composites, nanofibers, and textile fabrication are being extensively researched with an aim to produce a safe and effective delivery system for AD treatment with minimal side effects. This review outlines the recent development of various chitosan-based drug delivery systems for the treatment of AD published in the past 10 years (2012-2022). These chitosan-based delivery systems include hydrogels, films, micro-, and nanoparticulate systems as well as chitosan textile. The global patent trends on chitosan-based formulations for the AD are also discussed.

Tocotrienols protect differentiated SH-SY5Y human neuroblastoma cells against 6-hydroxydopamine-induced cytotoxicity by ameliorating dopamine biosynthesis and dopamine receptor D2 gene expression.

Oxidative stress is a critical factor that triggers a "domino" cascade of events leading to the degeneration of dopaminergic neurons in Parkinson disease. Tocotrienols (T3) have antioxidant effects and can protect neuronal cells against oxidative damage. In the present study, we investigated the neuroprotective effects of different forms of T3 (alpha, delta, gamma) or tocotrienol-rich fraction (TRF) against 6-hydroxydopamine (6-OHDA)-induced oxidative damage in differentiated SH-SY5Y human neural cells. Differentiating the SH-SY5Y cells with retinoic acid and a low-serum culture medium for 6 days allowed development of human dopamine-like neural cells. Subsequently, the differentiated SH-SY5Y neural cells were pretreated with different forms of T3 for 24 hours before these cells were exposed to 6-OHDA. The T3 analogues and TRF displayed neuroprotective effects (P < .05) via restoration of cell viability and activation of antioxidant enzymes (e.g., superoxide dismutase, catalase). Notably, TRF was highly efficient in scavenging reactive oxygen species and upregulating dopamine and tyrosine hydroxylase levels in the differentiated SH-SY5Y cells. Gamma-T3 exhibited the most potent effects in attenuating apoptosis, whereas alpha-T3 was most effective in preventing 6-OHDA-induced leakage of α-Synuclein. Delta-T3 displayed a noticeable effect in upregulating the dopamine receptor D2 gene expression compared with controls. These findings suggest T3 isoforms and TRF demonstrate significant neuroprotective effects in protecting differentiated neural cells against 6-OHDA-mediated oxidative stress.

Co-encapsulation of gemcitabine and tocotrienols in nanovesicles enhanced efficacy in pancreatic cancer.

Aim: To synthesize niosomes co-encapsulating gemcitabine (GEM) and tocotrienols, and physicochemically characterize and evaluate the antipancreatic effects of the nanoformulation on Panc 10.05, SW 1990, AsPC-1 and BxPC-3 cells. Materials & methods: Niosomes-entrapping GEM and tocotrienols composed of Span 60, cholesterol and D-α-tocopheryl polyethylene glycol 1000 succinate were produced by Handjani-Vila and film hydration methods. Results: The film hydration produced vesicles measuring 161.9 ± 0.5 nm, approximately 50% smaller in size than Handjani-Vila method, with maximum entrapment efficiencies of 20.07 ± 0.22% for GEM and 34.52 ± 0.10% for tocotrienols. In Panc 10.05 cells, GEM's antiproliferative effect was enhanced 2.78-fold in combination with tocotrienols. Niosomes produced a significant ninefold enhancement in cytotoxicity of the combination, supported by significantly higher cellular uptake of GEM in the cells. Conclusion: This study is a proof of concept on the synthesis of dual-drug niosomes and their efficacy on pancreatic cancer cells in vitro.

Biodistribution Study of Niosomes in Tumor-Implanted BALB/C Mice Using Scintigraphic Imaging.

The purpose of this work was to study the biodistribution of niosomes in tumor-implanted BALB/c mice using gamma scintigraphy. Niosomes were first formulated and characterized, then radiolabeled with Technetium-99 m (99mTc). The biodistribution of 99mTc-labeled niosomes was evaluated in tumor-bearing mice through intravenous injection and imaged with gamma scintigraphy. The labeled complexes possessed high radiolabeling efficiency (98.08%) and were stable in vitro (>80% after 8 h). Scintigraphic imaging showed negligible accumulation in the stomach and thyroid, indicating minimal leaching of the radiolabel in vivo. Radioactivity was found mainly in the liver, spleen and kidneys. Tumor-to-muscle ratio indicated a higher specificity of the formulation for the tumor area. Overall, the formulated niosomes are stable both in vitro and in vivo, and show preferential tumor accumulation.

Characterization, optimization, and in vitro evaluation of Technetium-99m-labeled niosomes.

BACKGROUND AND PURPOSE: Niosomes are nonionic surfactant-based vesicles that exhibit certain unique features which make them favorable nanocarriers for sustained drug delivery in cancer therapy. Biodistribution studies are critical in assessing if a nanocarrier system has preferential accumulation in a tumor by enhanced permeability and retention effect. Radiolabeling of nanocarriers with radioisotopes such as Technetium-99m (99mTc) will allow for the tracking of the nanocarrier noninvasively via nuclear imaging. The purpose of this study was to formulate, characterize, and optimize 99mTc-labeled niosomes. METHODS: Niosomes were prepared from a mixture of sorbitan monostearate 60, cholesterol, and synthesized D-α-tocopherol polyethylene glycol 1000 succinate-diethylenetriaminepentaacetic acid (synthesis confirmed by 1H and 13C nuclear magnetic resonance spectroscopy). Niosomes were radiolabeled by surface chelation with reduced 99mTc. Parameters affecting the radiolabeling efficiency such as concentration of stannous chloride (SnCl2·H2O), pH, and incubation time were evaluated. In vitro stability of radiolabeled niosomes was studied in 0.9% saline and human serum at 37°C for up to 8 hours. RESULTS: Niosomes had an average particle size of 110.2±0.7 nm, polydispersity index of 0.229±0.008, and zeta potential of -64.8±1.2 mV. Experimental data revealed that 30 µg/mL of SnCl2·H2O was the optimal concentration of reducing agent required for the radiolabeling process. The pH and incubation time required to obtain high radiolabeling efficiency was pH 5 and 15 minutes, respectively. 99mTc-labeled niosomes exhibited high radiolabeling efficiency (>90%) and showed good in vitro stability for up to 8 hours. CONCLUSION: To our knowledge, this is the first study published on the surface chelation of niosomes with 99mTc. The formulated 99mTc-labeled niosomes possessed high radiolabeling efficacy, good stability in vitro, and show good promise for potential use in nuclear imaging in the future.

Tocotrienols Modulate a Life or Death Decision in Cancers.

Malignancy often arises from sophisticated defects in the intricate molecular mechanisms of cells, rendering a complicated molecular ground to effectively target cancers. Resistance toward cell death and enhancement of cell survival are the common adaptations in cancer due to its infinite proliferative capacity. Existing cancer treatment strategies that target a single molecular pathway or cancer hallmark fail to fully resolve the problem. Hence, multitargeted anticancer agents that can concurrently target cell death and survival pathways are seen as a promising alternative to treat cancer. Tocotrienols, a minor constituent of the vitamin E family that have previously been reported to induce various cell death mechanisms and target several key survival pathways, could be an effective anticancer agent. This review puts forward the potential application of tocotrienols as an anticancer treatment from a perspective of influencing the life or death decision of cancer cells. The cell death mechanisms elicited by tocotrienols, particularly apoptosis and autophagy, are highlighted. The influences of several cell survival signaling pathways in shaping cancer cell death, particularly NF-κB, PI3K/Akt, MAPK, and Wnt, are also reviewed. This review may stimulate further mechanistic researches and foster clinical applications of tocotrienols via rational drug designs.

Challenges and Opportunities of Nanotechnology as Delivery Platform for Tocotrienols in Cancer Therapy.

Plant-derived phytonutrients have emerged as health enhancers. Tocotrienols from the vitamin E family gained high attention in recent years due to their multi-targeted biological properties, including lipid-lowering, neuroprotection, anti-inflammatory, antioxidant, and anticancer effects. Despite well-defined mechanism of action as an anti-cancer agent, their clinical use is hampered by poor pharmacokinetic profile and low oral bioavailability. Delivery systems based on nanotechnology were proven to be advantageous in elevating the delivery of tocotrienols to tumor sites for enhanced efficacy. To date, preclinical development of nanocarriers for tocotrienols include niosomes, lipid nanoemulsions, nanostructured lipid carriers (NLCs) and polymeric nanoparticles. Active targeting was explored via the use of transferrin as targeting ligand in niosomes. In vitro, nanocarriers were shown to enhance the anti-proliferative efficacy and cellular uptake of tocotrienols in cancer cells. In vivo, improved bioavailability of tocotrienols were reported with NLCs while marked tumor regression was observed with transferrin-targeted niosomes. In this review, the advantages and limitations of each nanocarriers were critically analyzed. Furthermore, a number of key challenges were identified including scale-up production, biological barriers, and toxicity profiles. To overcome these challenges, three research opportunities were highlighted based on rapid advancements in the field of nanomedicine. This review aims to provide a wholesome perspective for tocotrienol nanoformulations in cancer therapy directed toward effective clinical translation.

Tumor regression and modulation of gene expression via tumor-targeted tocotrienol niosomes.

AIM: To develop 6-O-palmitoyl-ascorbic acid-based niosomes targeted to transferrin receptor for intravenous administration of tocotrienols (T3) in breast cancer. MATERIALS & METHODS: Niosomes were prepared using film hydration and ultrasonication methods. Transferrin was coupled to the surface of niosomes via chemical linker. Nanovesicles were characterized for size, zeta potential, morphology, stability and biological efficacy. RESULTS: When evaluated in MDA-MB-231 cells, entrapment of T3 in niosomes caused 1.5-fold reduction in IC50 value compared with nonformulated T3. In vivo, the average tumor volume of mice treated with tumor-targeted niosomes was 12-fold lower than that of untreated group, accompanied by marked downregulation of three genes involved in metastasis. CONCLUSION: Findings suggested that tumor-targeted niosomes served as promising delivery system for T3 in cancer therapy.

Effect of palm-based tocotrienols and tocopherol mixture supplementation on platelet aggregation in subjects with metabolic syndrome: a randomised controlled trial.

Tocotrienols, the unsaturated form of vitamin E, were reported to modulate platelet aggregation and thrombotic mechanisms in pre-clinical studies. Using a Food and Drug Administration (FDA)-approved cartridge-based measurement system, a randomised, double-blind, crossover and placebo-controlled trial involving 32 metabolic syndrome adults was conducted to investigate the effect of palm-based tocotrienols and tocopherol (PTT) mixture supplementation on platelet aggregation reactivity. The participants were supplemented with 200 mg (69% tocotrienols and 31% α-tocopherol) twice daily of PTT mixture or placebo capsules for 14 days in a random order. After 14 days, each intervention was accompanied by a postprandial study, in which participants consumed 200 mg PTT mixture or placebo capsule after a meal. Blood samples were collected on day 0, day 14 and during postprandial for the measurement of platelet aggregation reactivity. Subjects went through a 15-day washout period before commencement of subsequent intervention. Fasting platelet aggregation reactivity stimulated with adenosine diphosphate (ADP) did not show substantial changes after supplementation with PTT mixture compared to placebo (p = 0.393). Concomitantly, changes in postprandial platelet aggregation reactivity remained similar between PTT mixture and placebo interventions (p = 0.408). The results of this study highlight the lack of inhibitory effect on platelet aggregation after short-term supplementation of PTT mixture in participants with metabolic syndrome.

Chromatographic Separation of Vitamin E Enantiomers.

Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.

Biological Properties of Tocotrienols: Evidence in Human Studies.

Vitamin E has been recognized as an essential vitamin since their discovery in 1922. Although the functions of tocopherols are well established, tocotrienols have been the unsung heroes of vitamin E. Due to their structural differences, tocotrienols were reported to exert distinctive properties compared to tocopherols. While most vegetable oils contain higher amount of tocopherols, tocotrienols were found abundantly in palm oil. Nature has made palm vitamin E to contain up to 70% of total tocotrienols, among which alpha-, gamma- and delta-tocotrienols are the major constituents. Recent advancements have shown their biological properties in conferring protection against cancer, cardiovascular diseases, neurodegeneration, oxidative stress and immune regulation. Preclinical results of these physiological functions were translated into clinical trials gaining global attention. This review will discuss in detail the evidence in human studies to date in terms of efficacy, population, disease state and bioavailability. The review will serve as a platform to pave the future direction for tocotrienols in clinical settings.

Tocotrienol and cancer metastasis.

Tumor metastasis involves some of the most complex and dynamic processes in cancer, often leading to poor quality of life and inevitable death. The search for therapeutic compounds and treatment strategies to prevent and/or manage metastasis is the ultimate challenge to fight cancer. In the past two decades, research focus on vitamin E has had a shift from saturated tocopherols to unsaturated tocotrienols (T3). Despite sharing structural similarities with tocopherols, T3 strive to gain scientific prominence due to their anti-cancer effects. Recent studies have shed some light on the anti-metastatic properties of T3. In this review, the roles of T3 in each step of the metastatic process are discussed. During the invasion process, signaling pathways that regulate the extracellular matrix and tumor cell motility have been reported to be modulated by T3. Although studies on T3 and tumor cell migration are fairly limited, they were shown to play a vital role in the suppression of angiogenesis. Furthermore, the anti-inflammatory effect of T3 could be highly promising in the regulation of tumor microenvironment, which is crucial in supporting tumor growth in distant organs.

Validation of a HPLC/FLD Method for Quantification of Tocotrienols in Human Plasma.

Quantification of tocotrienols in human plasma is critical when the attention towards tocotrienols on its distinctive properties is arising. We aim to develop a simple and practical normal-phase high performance liquid chromatography method to quantify the amount of four tocotrienol homologues in human plasma. Using both the external and internal standards, tocotrienol homologues were quantified via a normal-phase high performance liquid chromatography with fluorescence detector maintained at the excitation wavelength of 295 nm and the emission wavelength of 325 nm. The four tocotrienol homologues were well separated within 30 minutes. A large interindividual variation between subjects was observed as the absorption of tocotrienols is dependent on food matrix and gut lipolysis. The accuracies of lower and upper limit of quantification ranged between 92% and 109% for intraday assays and 90% and 112% for interday assays. This method was successfully applied to quantify the total amount of four tocotrienol homologues in human plasma.

Bioavailability of tocotrienols: evidence in human studies.

As a minor component of vitamin E, tocotrienols were evident in exhibiting biological activities such as neuroprotection, radio-protection, anti-cancer, anti-inflammatory and lipid lowering properties which are not shared by tocopherols. However, available data on the therapeutic window of tocotrienols remains controversial. It is important to understand the absorption and bioavailability mechanisms before conducting in-depth investigations into the therapeutic efficacy of tocotrienols in humans. In this review, we updated current evidence on the bioavailability of tocotrienols from human studies. Available data from five studies suggested that tocotrienols may reach its target destination through an alternative pathway despite its low affinity for α-tocopherol transfer protein. This was evident when studies reported considerable amount of tocotrienols detected in HDL particles and adipose tissues after oral consumption. Besides, plasma concentrations of tocotrienols were shown to be higher when administered with food while self-emulsifying preparation of tocotrienols was shown to enhance the absorption of tocotrienols. Nevertheless, mixed results were observed based on the outcome from 24 clinical studies, focusing on the dosages, study populations and formulations used. This may be due to the variation of compositions and dosages of tocotrienols used, suggesting a need to understand the formulation of tocotrienols in the study design. Essentially, implementation of a control diet such as AHA Step 1 diet may influence the study outcomes, especially in hypercholesterolemic subjects when lipid profile might be modified due to synergistic interaction between tocotrienols and control diet. We also found that the bioavailability of tocotrienols were inconsistent in different target populations, from healthy subjects to smokers and diseased patients. In this review, the effect of dosage, composition and formulation of tocotrienols as well as study populations on the bioavailability of tocotrienols will be discussed.

Novel tocotrienol-entrapping vesicles can eradicate solid tumors after intravenous administration.

The therapeutic potential of tocotrienol, a vitamin E extract with anti-cancer properties, is hampered by its failure to specifically reach tumors after intravenous administration. In this work, we demonstrated that novel transferrin-bearing, tocopheryl-based multilamellar vesicles entrapping tocotrienol significantly improved tocotrienol uptake by cancer cells overexpressing transferrin receptors. This led to a dramatically improved therapeutic efficacy in vitro, ranging from 17-fold to 72-fold improvement depending on the cell lines, compared to the free drug. In vivo, the intravenous administration of this novel tocotrienol formulation led to complete tumor eradication for 40% of B16-F10 murine melanoma tumors and 20% of A431 human epidermoid carcinoma tumors. Animal survival was improved by more than 20 days compared to controls, for the two tumor models tested. These therapeutic effects, together with the lack of toxicity, potentially make transferrin-bearing vesicles entrapping tocotrienol a highly promising therapeutic system as part as an anti-cancer therapeutic strategy.

Tumor regression after systemic administration of tocotrienol entrapped in tumor-targeted vesicles.

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.