INCI Name: D Alpha Tocopherol

Vitamin E is a fat soluble vitamin found in many different plant oils and throughout the body where it acts as an antioxidant to prevent the oxidation of lipids.

Alpha tocopherols are chiefly used in the supplement industry where they are taken internally for their antioxidant effects in the body. Research also shows that these results can be achieved through trans-dermal application so topical use of Alpha-tocopherol is a legitimate method to counter oxidation in the skin and subcutaneous tissues.
There are two commonly available forms of Alpha tocopherol:

d-alpha tocopherol- Natural, typically derived from Soy Bean Oil
dl-alpha tocopherol- Synthetic, petrochemical based

Both forms offer antioxidant activity when taken internally but the efficacy of synthetic Alpha-tocopherol is much lower than its natural counterpart. This is because the liver only recognises the natural version and synthetic versions are preferentially excreted. This happens to such an extent that natural Alpha-tocopherol is twice as bioavailable as synthetic when taken internally.
At this stage there is no clear evidence as to how this applies to the topical use of Alpha-tocopherol though it is likely that the natural version will also be more effective as well.