AI is absolutely already being applied to scientific discovery. IBM even have an entire product "Waton for Drug Discovery". See also;

https://www.ibm.com/blogs/research/2016/06/artificial-intell...

https://medium.com/@ShaliniAnanda1/ai-and-the-future-of-comp...

http://www.nature.com/news/can-artificial-intelligence-creat...

I can't cite specific instances where it has yielded specific results from the top of my head, but there's no question that AI is already being used in one or more of these areas.