Chemical and Biological Aspects of the Natural 1,4-Benzoquinone Embelin and its (semi-)Synthetic Derivatives

Background: Like the impressive biological properties of embelin, its chemical aspects have raised the interest of scientists in the field as well. A detailed understanding of the chemistry of embelin is necessary to fully exploit it medicinally. Methods: Search for embelin isolation and its chemical modifications was carried out using web-based literature searching tools such as Pubmed and Scifinder. Pertinent literature is covered up to 2016. Structures of bioactive embelin derivatives are provided. Results: Pure embelin, obtained from Embelia ribes berries extraction or by total synthesis, was applied for a number of biological assays. Semi-synthetic and total synthetic approaches led to new high affinity embelin-derived inhibitors of crucial protein targets and to new embelin derivatives with improved pharmacological properties (e.g., with better water-solubility or as applications for drug carrier systems). Conclusion: This review provides a summary of the rich chemistry of embelin and the latest developments in the field of optimized (semi-)synthetic embelin derivatives including their biological activities.