Progress in the chemistry of organic natural products ; Volume 115 Total Synthesis of Decanolides (Nonanolides) with a Special Focus on Olefin Metathesis From Plant to Patient: Thapsigargin Antileishmanial Activity of Lignans and Neolignans Cryptolepine as a Lead to new Antiprotozoal Agents Biologically Active Constituents from Plants of the Genus Xanthium. This book describes current understandings and recent progress into a varied group of natural products. In the first chapter the role that total synthesis may play in revising the structures proposed for decanolides which are ten membered lactones found primarily in fungi frogs and termites is presented. The following chapter presents the development of the intriguing plant derived sesquiterpene lactone thapsigargin a potent inhibitor of the enzyme SERCA (sarco endoplasmic Ca2+ ATPase) which has potential as a lead compound to treat cancer. The third chapter covers the potential of various plant phenolic compounds for treating the tropical and sub tropical infectious disease leishmaniasis. In addition the volume presents recent advances related to the plant alkaloid cryptolepine which is of particular interest as a lead for the treatment of malaria trypanosomiasis and cancer.