Gravar-mail: Synthesis and Biological Evaluation of Epidithio-, Epitetrathio- and bis-(Methylthio)diketopiperazines. Synthetic Methodology, Enantioselective Total Synthesis of Epicoccin G, 8,8′-epi-ent-Rostratin B, Gliotoxin, Gliotoxin G, Emethallicin E and Haematocin, and Discovery of New Antiviral and Antimalarial Agents