I don't think you can find any scientific information on the interactions. But from what I can gather two things can happen. Both substances irritate the stomach especially if you have a sensitive stomach that can be a problem so you might want to avoid taking them simultaneously or on an empty stomach. Ginkgo activates the immune system and speeds up the cardiovascular system; where basil slows down blood clotting which can be beneficial to the metabolism in short time use but that can be a problem if you have any cardiovascular problems like a heart condition. I don't know if these interactions are a real concern or not, that just out of the top of my head.