Modulation of Triterpene Saponin Production: In Vitro Cultures, Elicitation, and Metabolic Engineering

Abstract

Saponins are secondary metabolites that are widely distributed in the plant kingdom and are often the active components in medicinal herbs. Hence, saponins have a potential for the pharmaceutical industry as antibacterial, virucidal, anti-inflammatory, and anti-leishmanial drugs. However, their commercial application is often hindered because of practical problems, such as low and variable yields and limited availability of natural resources. In vitro cultures provide an alternative to avoid problems associated with field production; they offer a system in which plants are clonally propagated and yield is not affected by environmental changes. Additionally, treatment of in vitro cultures with elicitors such as methyl jasmonate may increase the production of saponins up to six times. In vitro cultures are amenable to metabolic engineering by targeting specific genes to enhance saponin production or drive production towards one specific class of saponins. Hitherto, this approach is not yet fully explored because only a limited number of saponin biosynthesis genes are identified. In this paper, we review recent studies on in vitro cultures of saponin-producing plants. The effect of elicitation on saponin production and saponin biosynthesis genes is discussed. Finally, recent research efforts on metabolic engineering of saponins will also be presented.

Studies on saponin production in tropical medicinal plants Maesa argentea and Maesa lanceolata

“…Another important method to enhance saponin production is via treatment with elicitors [16]. The elicitation process is generally regarded as the expression of defense-related genes and activating defense-related secondary metabolic pathways.…”

Cloning and Expression Analysis of a Squalene Epoxidase Gene from Ginkgo biloba

“…Triterpenoid saponins skeleton are synthesized by the isoprenoid pathway (Lambert et al, 2011). Oxidosqualene (also named as squalene-2,3-epoxide), the precursor of the triterpenoid saponins in plants, is synthesized by mevalonate (MVA) pathway in the cytoplasm and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway in plastids.…”

Proteomic signature of fenugreek treated by methyl jasmonate and cholesterol

“…Receptors, which are situated in plasma membrane, recognized an elicitor and activated signal transduction pathway. Next, the secondary messengers, e.g., jasmonates, ethylene, and salicylic acid, activated the expression of defense genes including the genes which are involved in synthesis of secondary metabolites (Lambert et al 2011). Methyl jasmonate was used to induce production of diosgenin in the seedlings of fenugreek (De and De 2011).…”