Unfortunately it's currently not possible to map relations between assets and AD Groups, I'll add this to our customer wishlist. I've moved this topic to the wishlist section of our forum in this context. Do note that at this moment in time we cannot yet guarantee that this feature will be implemented and we cannot provide you with an estimated release date.
For now if you wish to associate an asset with an AD group this would have to be done through one of the Asset comment fields or an Asset Custom Field for instance.