From Plant Extract to a cDNA Encoding a Glucosyltransferase Candidate: Proteomics and Transcriptomics as Tools to Help Elucidate Saponin Biosynthesis in Centella asiatica

Abstract

Centella asiatica (L.) Urban (Apiaceae), a small annual plant that grows in India, Sri Lanka, Malaysia, and other parts of Asia, is well-known as a medicinal herb with a long history of therapeutic uses. The bioactive compounds present in C. asiatica leaves include ursane-type triterpene sapogenins and saponins-asiatic acid, madecassic acid, asiaticoside, and madecassoside. Various bioactivities have been shown for these compounds, although most of the steps in the biosynthesis of triterpene saponins, including glycosylation, remain uncharacterized at the molecular level. This chapter describes an approach that integrates partial enzyme purification, proteomics methods, and transcriptomics, with the aim of reducing the number of cDNA candidates encoding for a glucosyltransferase involved in saponin biosynthesis and facilitating the elucidation of the pathway in this medicinal plant.

Pharmacological Properties, Molecular Mechanisms, and Pharmaceutical Development of Asiatic Acid: A Pentacyclic Triterpenoid of Therapeutic Promise

“…Triterpene saponin contains triterpene aglycones (sapogenins) with one or more sugar moieties connected through acetal or ester glycosidic linkages on one or many sites (Yu et al, 2006 ). Purified recombinant UDP-glucose 28-O-glucosyltransferase was found to exhibit narrow specificity, glucosylating AA at C28 carboxyl, involved in saponin biosynthesis in C. asiatica (de Costa et al, 2016 ). The mRNA of this enzyme was found in the stems, roots, and flowers, with the highest concentration found in the leaves (de Costa et al, 2016 ).…”

“…Purified recombinant UDP-glucose 28-O-glucosyltransferase was found to exhibit narrow specificity, glucosylating AA at C28 carboxyl, involved in saponin biosynthesis in C. asiatica (de Costa et al, 2016 ). The mRNA of this enzyme was found in the stems, roots, and flowers, with the highest concentration found in the leaves (de Costa et al, 2016 ). In Thailand, contents of pentacyclic triterpenoids reported to vary according to the harvesting period and geographical localities.…”