Natural and synthetic biologically active dimeric molecules: anticancer agents, anti-HIV agents, steroid derivatives and opioid antagonists.

Symmetry plays a crucial role in a variety of biological processes. For instance, many protein receptors, upon activation, dimerize to its active form and subsequently produce its biological action. Hence, there is a renewal of curiosity for the synthesis of dimeric molecules (or bivalent ligands) capable, not only to interact with specific biologic receptors, but also to induce greater biological responses than the corresponding monomeric counterpart. This is a vast and diverse theme of research. Hence, this review will discuss recent developments into this flourishing research field and will focus mainly into four specific topics namely dimeric 1) anticancer agents, 2) anti-HIV, 3) steroid derivatives and 4) opioid antagonists.