Sirtuins, Nicotinamide and Aging: A Critical Review

Sirtuins are enzymes that deacetylate proteins at the expense of NAD. The nuclear forms of sirtuins have generated an enormous amount of interest due to their putative regulation of lifespan. Yeast sirtuins and human sirtuins are involved in very different biochemical processes that make extrapolation of yeast results to the human situation difficult. This review critically examines the issues of NAD biochemistry in relation to nuclear sirtuin activity. Putative sirtuin inhibitors and activators are discussed, especially in terms of lifespan extension by sirtuin activators.