Effects of tocotrienols supplementation on markers of inflammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials

Insights into the Anticancer Mechanisms Modulated by Gamma and Delta Tocotrienols in Colorectal Cancers

Colorectal cancer (CRC) is a growing concern all over the world. There has been a concerted effort to identify natural bioactive compounds that can be used to prevent or overcome this condition. Tocotrienols (T3s) are a naturally occurring form of vitamin E known for various therapeutic effects, such as anticancer, antioxidant, neuroprotective, and anti-inflammatory activities. The literature evidence suggests that two T3 analogues, ie, gamma (γ)- and delta (δ)-T3, can modulate cancers via several cancer-related signaling pathways. The aim of this review was to compile and analyze the existing literature on the diverse anticancer mechanisms of γT3 and δT3 exhibited in CRC cells, to showcase the anticancer potential of T3s. Medline was searched for research articles on anticancer effects of γT3 and δT3 in CRC published in the past 2 decades. A total of 38 articles (26 cell-based, 9 animal studies, 2 randomized clinical trials, and 1 scoping review) that report anticancer effects of γT3 and δT3 in CRC were identified. The findings reported in those articles indicate that γT3 and δT3 inhibit the proliferation of CRC cells, induce cell cycle arrest and apoptosis, suppress metastasis, and produce synergistic anticancer effects when combined with well-established anticancer agents. There is preliminary evidence that shows that T3s affect telomerase functions and support anticancer immune responses. γT3 and δT3 have the potential for development as anticancer agents.

Health Benefits of Palm Tocotrienol-Rich Fraction: A Systematic Review of Randomized Controlled Trials

CONTEXT

Vitamin E, a well-known antioxidant with numerous positive effects on human health, encompasses tocotrienol-rich fraction (TRF), a natural variant abundant in palm oil.

OBJECTIVE

This systematic review analyzed findings from randomized controlled trials published until 2022 to evaluate the health impacts of palm TRF.

DATA SOURCES

A literature search was performed in Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, OVID Medline, SCOPUS, and Web of Science from inception until December 2022. Thirty studies involving 2646 patients, including both healthy individuals and those with underlying conditions, were identified.

RESULTS

This review shows palm TRF to be a promising natural supplement against inflammation and lipid peroxidation and that can significantly enhance overall health. Additionally, the study underscores the necessity for further research to ascertain the optimal dosage, formulation, and duration of supplementation, maximizing the potential health advantages.

CONCLUSION

This systematic review provides evidence supporting the health benefits associated with palm TRF.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020204070.

The Effects of Tocotrienol on Gut Microbiota: A Scoping Review

Gut dysbiosis has been associated with many chronic diseases, such as obesity, inflammatory bowel disease, and cancer. Gut dysbiosis triggers these diseases through the activation of the immune system by the endotoxins produced by gut microbiota, which leads to systemic inflammation. In addition to pre-/pro-/postbiotics, many natural products can restore healthy gut microbiota composition. Tocotrienol, which is a subfamily of vitamin E, has been demonstrated to have such effects. This scoping review presents an overview of the effects of tocotrienol on gut microbiota according to the existing scientific literature. A literature search to identify relevant studies was conducted using PubMed, Scopus, and Web of Science. Only original research articles which aligned with the review's objective were examined. Six relevant studies investigating the effects of tocotrienol on gut microbiota were included. All of the studies used animal models to demonstrate that tocotrienol altered the gut microbiota composition, but none demonstrated the mechanism by which this occurred. The studies induced diseases known to be associated with gut dysbiosis in rats. Tocotrienol partially restored the gut microbiota compositions of the diseased rats so that they resembled those of the healthy rats. Tocotrienol also demonstrated strong anti-inflammatory effects in these animals. In conclusion, tocotrienol could exert anti-inflammatory effects by suppressing inflammation directly or partially by altering the gut microbiota composition, thus achieving its therapeutic effects.

Effects of Tocotrienol-Rich Fraction Supplementation in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

There are a large number of studies that have reported benefits of tocotrienol-rich fraction (TRF) in various populations with different health status. To date, no systematic reviews have examined randomized controlled trials (RCTs) on the effect of TRF supplementations specifically in patients with type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis aim to examine the changes in HbA1c (glycated hemoglobin), blood pressure, and serum Hs-CRP (C-reactive protein high sensitivity) levels at post-TRF supplementation. Online databases including PubMed, Scopus, OVID Medline, and Cochrane Central Register of Controlled Trials were searched from inception until March 2023 for RCTs supplementing TRF in patients with T2DM. A total of 10 studies were included in the meta-analysis to estimate the pooled effect size. The Cochrane Risk-of-Bias (RoB) Assessment Tool was utilized to evaluate the RoB in individual studies. The meta-analysis revealed that TRF supplementation at a dosage of 250-400 mg significantly decreased HbA1c (-0.23, 95% CI: -0.44, -0.02, P < 0.05, n = 754), particularly where the intervention duration is less than 6 mo (-0.47%, 95% CI: -0.90, -0.05, P < 0.05, n = 126) and where duration of diabetes is less than 10 y (-0.37, 95% CI: -0.68, -0.07, P < 0.05, n = 83). There was no significant reduction in systolic and diastolic blood pressure and serum Hs-CRP (P > 0.05). The present meta-analysis demonstrated that supplementing with TRF in patients with T2DM decreased HbA1c but does not decrease systolic and diastolic blood pressure and serum Hs-CRP.

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.

Role of δ-tocotrienol and resveratrol supplementation in the regulation of micro RNAs in patients with metabolic syndrome: a randomized controlled trial

OBJECTIVE

To determine the effect of δ-tocotrienol and resveratrol mixture (TRM) supplementation in comparison to placebo for 24 weeks, on the relative expression of miRNAs (miRNA-130b-5p, miRNA-221-5p, miR-15b-5p, miRNA-122-5p, and miRNA-376b-5p) in patients with Metabolic syndrome (MetS).

DESIGN

This randomized placebo-controlled trial was conducted at the tertiary care institute of the NUMS, Rawalpindi, Pakistan. A total of 82 adult MetS patients were enrolled and randomly grouped into the TRM group (n=41) and the Placebo group (n=41). Patients in the TRM group were given 400mg capsules (δ-tocotrienol 250mg; Resveratrol 150mg) and placebo received (cellulose 400mg capsule) twice daily for 24 weeks.

RESULTS

The TRM supplementation revealed a significant (p<0.001) upregulation of 3.05-fold in miRNA-130b-5p and 2.45-fold in miRNA-221-5p while miRNA-122-5p was downregulated by 2.22-fold as compared to placebo. No significant difference was observed in miRNA-15b-5p and miRNA-376b-5p. Moreover, TRM group participants with reverted MetS had significantly (p<0.05) upregulated miRNA-130b-5p, miRNA-221-5p, and downregulated miRNA-122-5p relative to non-reverted patients with MetS.

CONCLUSION

Daily TRM supplementation may improve metabolic syndrome by upregulated miR-130b-5p, which is involved in central obesity and inflammation, as well as miR-221-5p, which is involved in insulin resistance. Additionally, TRM downregulate of miRNA 122, which improved dyslipidemia.

δ-Tocotrienol in Combination with Resveratrol Improves the Cardiometabolic Risk Factors and Biomarkers in Patients with Metabolic Syndrome: A Randomized Controlled Trial

Background: Metabolic syndrome (MetS) is a cluster of central obesity, hypertension, hyperglycemia, and dyslipidemia. It is a global health issue with an increased risk of cardiovascular disease. Recently, a few natural products have been reported with promising anti-inflammatory and antioxidative effects. We aimed to evaluate the impact of δ-tocotrienol and resveratrol mixture (TRM) supplementation on cardiometabolic risk factors and biomarkers in patients with MetS. Methods: A randomized controlled trial was conducted at the hospitals of National University of Medical Sciences Rawalpindi, Pakistan. A total of 82 patients with MetS aged 18-60 years were enrolled based on International Diabetes Federation-2005 diagnostic criteria and randomly grouped into TRM (n = 41) and placebo (n = 41). Patients in the TRM group were given a 400 mg capsule (δ-tocotrienol 250 mg; resveratrol 150 mg), and a placebo (cellulose 400 mg) twice daily for 24 weeks. The biochemical tests were analyzed on ADVIA 1800 Chemistry^® analyzer and inflammatory biomarkers by ELISA methods. Results: In the TRM group, a significant reduction in waist circumference, blood pressure, mean (95% confidence interval) of fasting plasma glucose -0.15 mmol/L (-0.22 to -0.08), serum triglyceride -0.32 mmol/L (-0.47 to -0.17), and increment in high-density lipoprotein cholesterol were observed as compared with placebo. TRM supplementation also improved biomarkers: high-sensitive C-reactive protein -0.61 mg/L (-0.89 to -0.33), interleukin-6-1.99 pg/mL (-2.50 to -1.48), tumor necrosis factor-α -2.19 pg/mL (-2.55 to -1.83), malondialdehyde -0.48 μmol/L (-0.65 to -0.30), and total antioxidant capacity 1.71 U/mL (1.29 to 2.13). Conclusion: TRM supplementations improved cardiometabolic risk factors and biomarkers of inflammation and oxidative stress without any significant side effects in the patients with MetS. Clinical Trials Registry: The clinical trial was registered in Sri Lanka Clinical Trials Registry (https://slctr.lk/trials/slctr-2019-021).

Comparison of delta-tocotrienol and alpha-tocopherol effects on hepatic steatosis and inflammatory biomarkers in patients with non-alcoholic fatty liver disease: A randomized double-blind active-controlled trial

OBJECTIVE

We aimed to compare the efficacy of δ-tocotrienol with α-tocopherol in the treatment of patients with non-alcoholic fatty liver disease (NAFLD).

DESIGN AND INTERVENTIONS

This study was a double-blinded, active-controlled trial. The patients with NAFLD were randomly assigned to receive either δ-tocotrienol 300 mg or α-tocopherol 268 mg twice daily for 48 weeks.

ENDPOINTS

The primary endpoints were change from baseline in fatty liver index (FLI), liver-to-spleen attenuation ratio (L/S ratio), and homeostatic model assessment for insulin resistance (HOMA-IR) at 48 weeks. Key secondary endpoints were change in markers of inflammation, oxidative stress, and hepatocyte apoptosis. Clinical assessment, biochemical analysis, and computed tomography scan of the liver were conducted at baseline, 24 and 48 weeks.

RESULTS

A total of 100 patients (δ-tocotrienol = 50, α-tocopherol = 50) were randomized and included in the intention to treat analysis. Compared with baseline, there was a significant improvement (p < .001) in FLI, L/S ratio, HOMA-IR, and serum malondialdehyde in both groups at 48 weeks that was not significant between the two groups. However, there was a significantly greater decrease in body weight, serum interleukin-6, tumor necrosis factor-alpha, leptin, cytokeratin-18, and increase in adiponectin in the δ-tocotrienol group compared to the α-tocopherol group at 48 weeks (p < .05). No adverse events were reported.

CONCLUSION

δ-tocotrienol and α-tocopherol exerted equally beneficial effects in terms of improvement in hepatic steatosis, oxidative stress, and insulin resistance in patients with NAFLD. However, δ-tocotrienol was more potent than α-tocopherol in reducing body weight, inflammation, and apoptosis associated with NAFLD. TRIAL REGISTRATION: Sri Lankan Clinical Trials Registry (https://slctr.lk/SLCTR/2019/038).

The Role of PKC-MAPK Signalling Pathways in the Development of Hyperglycemia-Induced Cardiovascular Complications

Cardiovascular disease is the most common cause of death among diabetic patients worldwide. Hence, cardiovascular wellbeing in diabetic patients requires utmost importance in disease management. Recent studies have demonstrated that protein kinase C activation plays a vital role in the development of cardiovascular complications via its activation of mitogen-activated protein kinase (MAPK) cascades, also known as PKC-MAPK pathways. In fact, persistent hyperglycaemia in diabetic conditions contribute to preserved PKC activation mediated by excessive production of diacylglycerol (DAG) and oxidative stress. PKC-MAPK pathways are involved in several cellular responses, including enhancing oxidative stress and activating signalling pathways that lead to uncontrolled cardiac and vascular remodelling and their subsequent dysfunction. In this review, we discuss the recent discovery on the role of PKC-MAPK pathways, the mechanisms involved in the development and progression of diabetic cardiovascular complications, and their potential as therapeutic targets for cardiovascular management in diabetic patients.

Revisiting the therapeutic potential of tocotrienol

The therapeutic potential of the tocotrienol group stems from its nutraceutical properties as a dietary supplement. It is largely considered to be safe when consumed at low doses for attenuating pathophysiology as shown by animal models, in vitro assays, and ongoing human trials. Medical researchers and the allied sciences have experimented with tocotrienols for many decades, but its therapeutic potential was limited to adjuvant or concurrent treatment regimens. Recent studies have focused on targeted drug delivery by enhancing the bioavailability through carriers, self-sustained emulsions, nanoparticles, and ethosomes. Epigenetic modulation and computer remodeling are other means that will help increase chemosensitivity. This review will focus on the systemic intracellular anti-cancer, antioxidant, and anti-inflammatory mechanisms that are stimulated and/or regulated by tocotrienols while highlighting its potent therapeutic properties in a diverse group of clinical diseases.

Tocotrienol in Pre-Eclampsia Prevention: A Mechanistic Analysis in Relation to the Pathophysiological Framework

The pathophysiology of pre-eclampsia involves two major pathways, namely systemic oxidative stress and subsequent generalised inflammatory response, which eventually culminates in endothelial cell injury and the syndrome of pre-eclampsia with multi-organ dysfunction. Aspirin has been used to reduce the risk of pre-eclampsia, but it only possesses anti-inflammatory properties without any antioxidant effect. Hence, it can only partially alleviate the problem. Tocotrienols are a unique form of vitamin E with strong antioxidant and anti-inflammatory properties that can be exploited as a preventive agent for pre-eclampsia. Many preclinical models showed that tocotrienol can also prevent hypertension and ischaemic/reperfusion injury, which are the two main features in pre-eclampsia. This review explores the mechanism of action of tocotrienol in relation to the pathophysiology of pre-eclampsia. In conclusion, the study provides sufficient justification for the establishment of a large clinical trial to thoroughly assess the capability of tocotrienol in preventing pre-eclampsia.