Sucrose-induced biosynthesis of pharmaceutically important secondary cell products in cell suspension cultures of Stevia rebaudiana (Bert.)

Abstract

Stevia (Stevia rebaudiana) is well known for production of pharmaceutically important and nontoxic steviol glycosides (SGs) which can be used as alternative sweeteners to regular sugar. The primary focus of this report was to investigate the sweet diterpenes in cell suspension cultures with different growth responses to sucrose. Initially, different concentrations of carbon source (sucrose; 05–50 g l^− 1) were tested for the establishment of cell suspension culture and growth kinetics were determined for 30 days period with three days intervals for each treatment. Cultures collected at late-log phase (day-18) were used for determination of steviosides, rebaudioside-A, dulcoside-A, total phenolic content, total flavonoid content and antioxidant activity. The results showed maximum values for fresh biomass (97.71 g l^− 1-FW), dry biomass (8.57 g l^− 1-DW), rebaudioside-A content (27.64 mg/g-DW) and dulcoside-A content (6.43 mg/g-DW) in response to 20 g l^− 1. The cultures grown with 30 g l^− 1sucrose exhibited maximum stevioside content (42.23 mg/g-DW) and highest antioxidant activity (83.87%). However, the exposure of suspended cells to sucrose (40 g l^− 1) improved total phenolic (139.20 mg/g-DW) and total flavonoid (41.46 mg/g-DW) contents. The correlation studies showed strongly positive correlation of dry biomass and phenolics and flavonoids contents respectively. Furthermore, the antioxidant activity was positively correlated with phenolics and flavonoids contents, but not with steviol glycoside content. This work shows the potential for utilizing liquid suspension cultures of S. rebaudiana for enhanced production of SGs and antioxidant phenolic metabolites.