There's a whole area of algebraic graph theory, but without any information on a the graph, I can't remember anything graph specific right now
What is relevant is Gershgorin circle theorem
Which for example would mean that a undirected graph without loops, the adjacency matrix would have eigenvalues smaller than the maximum linksdegree of a vertex, that is |M||M-1|. And for the Laplacian we should get something like 2|M|.