Nothing in this article shall be construed to authorize the board to contract a debt on behalf of, or in any way to obligate, the state of Arizona, or to pledge, assign or encumber in any way, or to permit the pledging, assigning or encumbering in any way, of appropriations made by the legislature or revenue derived from the investment of the proceeds of the sale and from the rental of such lands as have been set aside by the enabling act approved June 20, 1910, or other legislative enactments of the United States, for the use and benefit of the board or the institution.