Increased antioxidant capacity in the plasma of dogs after a single oral dosage of tocotrienols

Abstract

The intestinal absorption of tocotrienols (TCT) in dogs is, to our knowledge, so far unknown. Adult Beagle dogs (n 8) were administered a single oral dosage of a TCT-rich fraction (TRF; 40 mg/kg body weight) containing 32 % a-TCT, 2 % b-TCT, 27 % g-TCT, 14 % d-TCT and 25 % a-tocopherol (a-TCP). Blood was sampled at baseline (fasted), 1, 2, 3, 4, 5, 6, 8 and 12 h after supplementation. Plasma and chylomicron concentrations of TCT and a-TCP were measured at each time point. Plasma TAG were measured enzymatically, and plasma antioxidant capacity was assessed by the Trolox equivalent antioxidant capacity assay. In fasted dogs, levels of TCT were 0·07 (SD 0·03) mmol/l. Following the administration of the TRF, total plasma TCT peaked at 2 h (7·16 (SD 3·88) mmol/l; P, 0·01) and remained above baseline levels (0·67 (SD 0·44) mmol/l; P, 0·01) at 12 h. The TCT response in chylomicrons paralleled the increase in TCT in plasma with a maximum peak (3·49 (SD 2·06) mmol/l; P, 0·01) at 2 h post-dosage. a-TCP was the major vitamin E detected in plasma and unaffected by TRF supplementation. The Trolox equivalent values increased from 2 h (776 (SD 51·2) mmol/l) to a maximum at 12 h (1130 (SD 7·72) mmol/l; P,0·01). The results show that TCT are detected in postprandial plasma of dogs. The increase in antioxidant capacity suggests a potential beneficial role of TCT supplementation in the prevention or treatment of several diseases in dogs.Key words: Dogs: Tocotrienols: Intestinal absorption: Antioxidant capacity Vitamin E is a potent lipid-soluble antioxidant that is only synthesised by plants and cyanobacteria, and therefore it is essential for human and animal nutrition (1) . In nature, compounds with vitamin E activity include a-, b-, g-and d-tocopherols (TCP) as well as a-, b-, g-and d-tocotrienols (TCT). The molecular structure of TCT differs from the corresponding TCP in their aliphatic tail containing an unsaturated isoprenoid chain, whereas the tail of TCP has a saturated phytyl chain (1) . TCT are minor plant constituents especially abundant in palm oil, cereal grains and rice bran, all providing significant sources of vitamin E activity (2) . The antioxidant properties of TCT have been well investigated by several in vitro experiments and seem to be higher than those of a-TCP (3,4) . Recently, TCT have gained increasing scientific interest mainly by the discovery of their non-antioxidant actions, which include neuroprotective, anti-carcinogenic and cholesterol-lowering properties (5,6) . These properties of TCT have also spurred interest in determining their ability to prevent degenerative diseases (7) . However, TCT metabolism in dogs or other companion animals is not known. Therefore, the present study was conducted to measure the intestinal absorption of TCT and antioxidant capacity in the plasma of dogs receiving a single oral dosage of TCT. Experimental methods Animals and experimental designA total of eight adult Beagle dogs, age ranging from 3 to 6 years (average 3·8 years), were enrolled in the present stud...

Tocotrienol-Rich Fraction (TRF) Suppresses the Growth of Human Colon Cancer Xenografts in Balb/C Nude Mice by the Wnt Pathway

“…Thus, palm oil is considered as a mixture of vitamin E, which is known as fractions from palm tocotrienol-rich oil (TRF). TRF has many biological activities, especially tocotrienols reduced atherosclerosis of rabbits, which may be related to the antioxidant activity of the TRF[ 20 ], improving pancreatic inflammation and fibrosis in DBTC-induced CP rats[ 21 ], preventing or treatment of diseases in dogs[ 22 ], neuroprotective effects [ 23 ], and anti-cancer activities[ 2 ]. In our research group, we used high dose of 20 mg/kg of TRF which were equivalent to 1.09 mg vitamin E/mice per day.…”