Distribution of tocopherols and tocotrienols to rat ocular tissues after topical ophthalmic administration

Abstract

With increasing evidence suggesting the involvement of oxidative stress in various disorders and diseases, the role of antioxidants in vivo has received much attention. Chemically, tocopherols and tocotrienols are closely related; however, it has been observed that they have widely varying degrees of biological effectiveness. The present study has been carried out in an attempt to deepen our understanding of whether there is a significant difference in distribution between tocopherol and tocotrienol homologs to rat eye tissues. Rats were administered 5 microL of pure tocopherol or tocotrienol to each eye once a day for 4 d. Various tissues of the eyes were separated and analyzed for tocopherol and tocotrienol concentrations. The concentration of alpha-to-cotrienol increased markedly in every tissue to which it was administered; however, no significant increase was observed in the case of alpha-tocopherol. The intraocular penetration of gamma-tocopherol and gamma-tocotrienol did not differ significantly. Additionally, a significant increase in total vitamin E concentration was observed in ocular tissues, including crystalline lens, neural retina, and eye cup, with topical administration using a relatively small amount (5 microL) of vitamin E, whereas no significant increase was observed when the same amount of vitamin E was administered orally. Topical administration of tocotrienols is thus an effective way to increase ocular tissue vitamin E concentration.

Acceleration of Age-Related Changes in the Retina in α-Tocopherol Transfer Protein Null Mice Fed a Vitamin E–Deficient Diet

“…The preparation of ocular tissue samples has been described previously. 15,27 Briefly, after a deep anesthesia was induced by an intraperitoneal injection of pentobarbital sodium (30 mg/kg), the mice were perfused with ice-cold phosphate-buffered saline (PBS; pH 7.4) from the left ventricle to wash out the blood; subsequently, the eyes were rapidly enucleated. For morphologic analyses, the enucleated eyes were immersed in fixatives, as described in later sections.…”

“…S1, online at http://www.iovs.org/ cgi/content/full/48/1/396/DC1). 14 ␣-Toc is the most abundant VE in vivo, 15 although plants and normal diets often contain a nearly equal or a higher amount of ␥-Toc. ␣-Toc transfer protein (␣-TTP), a cytosolic liver protein with a highly specific binding affinity for ␣-Toc, selectively transports ␣-Toc from the liver to the blood stream 16 ; thus, the presence of ␣-TTP is thought to be the reason for such a high bioavailability of ␣-Toc in vivo.…”

Tocotrienol alleviates inflammation and oxidative stress in a rat model of spinal cord injury via suppression of transforming growth factor-β

“…Tocotrienols are isomers of vitamin E, located primarily in plants, with antioxidative (9), anti-tumor (10) and neuroprotective functions (11). Tocotrienols inhibit proliferation of breast cancer cells, show G1 phase retardation and can promote cell apoptosis (12,13). However, to the best of our knowledge, the potential protective effect and underlying molecular mechanism of tocotrienol on SCI has not been investigated.…”

Rat Optik Sinir Ezme Modelinde Topikal ve Sistemik Alfa Tokoferol Uygulaması Yoluyla Retina Gangliyon Hücre Korunması

“…Tanito et al 18 also demonstrated increased concentration of α-tocopherol and α-tocopherol-3 in ocular tissues including neural retina after a 4-day application of 5μL pure α-tocopherol and α-tocopherol-3 (2.23±0.14 mg). However, topical α-tocopherol-3 was reported to reach much more drug concentration in ocular tissues than those detected with topical α-tocopherol.…”