Overview of Medicinally Important Diterpenoids Derived from Plastids

Background: Terpenoids are hydrocarbon compounds derived from common five-carbon isoprene (C5H8) building blocks. They are formed through the condensation and subsequent modification of isoprene units in various ways including – among others – cyclization and/or oxygenation. Their synthesis is localized either to the chloroplast and/or to the cytoplasm/peroxisome/endoplasmic reticulum and mitochondrion. Terpenoids represent a very large and diverse class of metabolites and play important roles in plant growth and development. In addition, they have been intensively used in human health care, disease treatment and in dietary supplements. Approximately 60% of natural products known so far are terpenoids. Results and Discussion: This review briefly summarizes the biosynthetic pathways of major plant terpenoids. Then, five well-known and medicinally important diterpenoids, including paclitaxel, tanshinone, ginkgolide, triptolide and oridonin are discussed in detail. Their structures, occurrence, extraction and identification methods, pharmacological properties and clinical uses are also reviewed. Finally, the prospects of using biotechnology to produce medicinally important terpenoids are also briefly discussed. Keywords: Diterpenoid, ginkgolide, oridonin, paclitaxel, plastid, tanshinone, triptolide.