Enhanced gymnemic acids production in cell suspension cultures of Gymnema sylvestre (Retz.) R.Br. ex Sm. through elicitation

Gymnemic Acids (GAs) belong to the class of triterpenoid saponins present majorly in the leaves of Gymnema sylvestre. These bioactive compounds are responsible for hypoglycemic activity. Therefore, it is expansively used in Ayurveda treatment for diabetes. This study is aimed to develop an effective method for suspension culture and to investigate the effect of sodium nitroprusside (SNP), salicylic acid (SA) and methyl jasmonate (MeJA) on the enhancement of deacylgymnemic acid, gymnemagenin, gymnemic acid IV and gymnemic acid XVII in G. sylvestre cell suspension culture. To induce callus, in vitro-derived leaf explants were cultivated on Murashige and Skoog's (MS) medium supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) or α-naphthalene-acetic acid (NAA) either alone or in combination with 6-benzylaminopurine (BAP) or kinetin (Kin) at 1.0 to 5.0 mg/L. The highest callus initiation frequency (95.30 ± 1.40%) and better friable callus observed on MS medium supplemented with 3.0 mg/L (2,4-D) + 1.0 mg/L (Kin). Optimized callus induction medium was used to develop cell suspension culture, growth kinetic study, elicitors treatment and quantify the production of major bioactive compounds. At 40 days, the highest fresh cell suspension culture biomass was 339.08 g/L fresh weight (FW). Biomass production, 366.68 g/L FW and 30.30 g/L DW were the highest in the treatment of 20 μM SNP among the tested elicitors. The highest accumulation of deacylgymnemic acid (2936.90 μg/g DW, 96 h treatment) and gymnemic acid XVII (2414.20 μg/g dry weight (DW), 48 h treatment) were obtained in 20 μM SNP treatments which were 6.1 and 5.2 fold higher than the control. Furthermore, the highest values of gymnemagenin (1179.77 μg/g DW at 50 μM treatment) and gymnemic acid IV (731.04 μg/g DW at 10 μM treatment) were obtained in SA treatment which was 4.12 and 5.11 fold greater than the control was studied through our newly developed HPLC method. The findings of the present study showed that the SNP could be a good strategy for large-scale industrial production of triterpenoid saponins in G. sylvestre cell suspension cultures.