Oral Supplementation of Tocotrienol-Rich Fraction Alleviates Severity of Ulcerative Colitis in Mice.

Ulcerative colitis (UC) is characterized by damaged colonic mucosa and submucosa layers that are caused by excessive inflammatory reactions and oxidative stress. This study aimed to examine the use of tocotrienol-rich fraction (TRF) in mitigating damages caused by UC on the colon epithelium. Dextran sulfate sodium (DSS)-induced UC mice were treated with vehicle control, TRF, alpha-tocopherol (αTP) and 5-aminosalicylic acid (5-ASA). Observable clinical signs, quality of stool, histopathological scoring, inflammatory and oxidative markers were assessed. Vitamin E levels of colons and plasma were quantified. Oral supplementation of TRF significantly reduced the severity of DSS-induced UC by lowering the disease activity index (DAI) and histopathological inflammatory scoring. TRF also attenuated the DSS-induced enlargement of spleen and shortening of the colon. TRF has demonstrated marked anti-inflammatory and antioxidative properties indicated by the attenuation of DSS-induced upregulation of inflammation and oxidative stress markers including interleukin (IL)-6, IL-17, tumor necrosis factor (TNF)-α, myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), nitric oxide (NO), malondialdehyde (MDA) and pNF-κB. These improvements were similar to that of 5-aminosalicylic acid (5-ASA) treatment. In contrast, αTP did not demonstrate evident clinical and histopathological improvements. The superior protective effect of TRF may be ascribed to the preferential absorption of TRF by the gut mucosa. TRF alleviated the signs and symptoms of acute UC in murine model via the reduction of local inflammatory reactions and oxidative stress. These effects suggested that TRF could serve as a gut health supplement for preventive measures for UC condition in patients.

Anti-inflammatory γ- and δ-tocotrienols improve cardiovascular, liver and metabolic function in diet-induced obese rats.

PURPOSE: This study tested the hypothesis that γ- and δ-tocotrienols are more effective than α-tocotrienol and α-tocopherol in attenuating the signs of diet-induced metabolic syndrome in rats. METHODS: Five groups of rats were fed a corn starch-rich (C) diet containing 68 % carbohydrates as polysaccharides, while the other five groups were fed a diet (H) high in simple carbohydrates (fructose and sucrose in food, 25 % fructose in drinking water, total 68 %) and fats (beef tallow, total 24 %) for 16 weeks. Separate groups from each diet were supplemented with either α-, γ-, δ-tocotrienol or α-tocopherol (85 mg/kg/day) for the final 8 of the 16 weeks. RESULTS: H rats developed visceral obesity, hypertension, insulin resistance, cardiovascular remodelling and fatty liver. α-Tocopherol, α-, γ- and δ-tocotrienols reduced collagen deposition and inflammatory cell infiltration in the heart. Only γ- and δ-tocotrienols improved cardiovascular function and normalised systolic blood pressure compared to H rats. Further, δ-tocotrienol improved glucose tolerance, insulin sensitivity, lipid profile and abdominal adiposity. In the liver, these interventions reduced lipid accumulation, inflammatory infiltrates and plasma liver enzyme activities. Tocotrienols were measured in heart, liver and adipose tissue showing that chronic oral dosage delivered tocotrienols to these organs despite low or no detection of tocotrienols in plasma. CONCLUSION: In rats, δ-tocotrienol improved inflammation, heart structure and function, and liver structure and function, while γ-tocotrienol produced more modest improvements, with minimal changes with α-tocotrienol and α-tocopherol. The most important mechanism of action is likely to be reduction in organ inflammation.

Tyrosine phosphorylation of Sprouty2 enhances its interaction with c-Cbl and is crucial for its function.

Mammalian Sprouty (Spry) proteins are now established as receptor tyrosine kinase-induced modulators of the Ras/mitogen-activated protein kinase pathway. Specifically, hSpry2 inhibits the fibroblast growth factor receptor (FGFR)-induced mitogen-activated protein kinase pathway but conversely prolongs activity of the same pathway following epidermal growth factor (EGF) stimulation, where activated EGF receptors are retained on the cell surface. In this study it is demonstrated that hSpry2 is tyrosine-phosphorylated upon stimulation by either FGFR or EGF and subsequently binds endogenous c-Cbl with high affinity. A conserved motif on hSpry2, together with phosphorylation on tyrosine 55, is required for its enhanced interaction with the SH2-like domain of c-Cbl. A hSpry2 mutant (Y55F) that did not exhibit an enhanced binding with c-Cbl failed to retain EGF receptors on the cell surface. Furthermore, individually mutating hSpry2 residues 52-59 to alanine indicated a tight correlation between their affinity for c-Cbl binding and their inhibition of ERK2 activity in the FGFR pathway. We postulate that tyrosine phosphorylation "activates" hSpry2 by enhancing its interaction with c-Cbl and that this interaction is critical for its physiological function in a signal-specific context.