Production of plant bioactive triterpenoid saponins: from metabolites to genes and back

Saponins are specialized plant terpenoids derived from the mevalonic acid pathway. Triterpenoid saponin cores are decorated with sugar residues, conferring a highly amphipathic nature to these molecules, which show hypocholesterolemic, immunoadjuvant and anti-inflammatory activities, among others. Natural sources of bioactive saponins are relevant in light of the technical challenges of chemical synthesis of these compounds. Current supply of high quality, homogeneous and renewable plant material falls short of industrial demand. Research regarding molecular regulation of saponin metabolism has advanced considerably in recent years. Recent studies have focused on transcriptome analysis and identification of key transcription factors regulating gene expression patterns related to saponin biosynthesis. Biotechnological approaches to engineer saponin production in plants, organ and cell cultures, as well as development of heterologous expression systems, are being actively pursued as alternative sources of these high value plant terpenoids. It is expected that these efforts will impact industrial scale sustainable production systems in the coming years.