Enhanced biosynthesis of triterpenoids in Centella asiatica hairy root culture by precursor feeding and elicitation

Abstract

Centella asiatica contains various triterpenoids, including madecassoside, asiaticoside, madecassic acid, and asiatic acid. Among them, they are mainly contained in leaf, and among them asiaticoside is known as tissue-specific compound that are mainly accumulated in the leaves. Therefore, in the present study, C. asiatica hairy root cultures were established from petiole and leaf explants using Agrobacterium rhizogenes-mediated transformation. To promote the biosynthesis of these triterpenoids, hairy root cultures were treated with precursors (squalene and pyruvic acid) and elicitors [methyl jasmonate (MeJA) and salicylic acid (SA)] at various concentrations. No significant difference was detected in the growth index of hairy root cultures between precursor feeding and elicitation, except pyruvic acid feeding, suggesting that elicitors do not affect the growth of hairy roots. Treatment with 2.5 mM squalene and 5 mM pyruvic acid enhanced the biosynthesis of target triterpenoids (57.53 and 29.13 mg g−1 DW, respectively) compared with other treatments. However, compared to squalene, MeJA showed a greater effect on the triterpene saponin content in C. asiatica. The highest quantity of triterpenoids (60.25 mg g−1 DW) was produced in hairy root cultures treated with 400 μM MeJA. These results indicate that precursor- and elicitor-treated C. asiatica hairy root cultures rapidly accumulate biomass and could be used to enhance the production of triterpenoids for industrial purposes.