Potential mevalonate pathway precursors for enhanced production of gymnemic acid

Abstract

Gymnema sylvestre, locally called Gurmar (meaning sugar destroyer), is well known in Indian medicine for treatment of diabetes which is attributed to its triterpenoid saponin content gymnemic acid. Quantity of the gymnemic acid in is influenced by geographical and seasonal variations. Use of precursors enhances production of gymnemic acid in vitro. Here, we explored three different precursors, namely isopentenyl pyrophosphate (IPP), squalene, and 2,3-oxidosqualene for their effect on gymnemic acid production in in vitro cultures of Gymnema sylvestre. Gymnemic acid production in shoot cultures treated with 2,3-oxidosqualene (23.31 mg g^-1 DW) was highest among all three precursors studied, followed by squalene (18.12 mg g^-1 DW) and IPP (15.94 mg g^-1 DW). Addition of these precursors might enhance the activity of respective enzymes, such as IPP isomerase, squalene synthase (SS), squalene epoxidase (SE), and β-amyrin synthase (β-AS) which are the key enzymes in terpenoid production. Higher concentration and higher harvest duration of all three precursors reduced the production of gymnemic acid. Results have shown that addition of these precursors is effective in enhancement of gymnemic acid production and can be successfully utilized for commercial application.