Regulation of folic acid on phenolic acids production in Salvia miltiorrhiza hairy roots

Salvia miltiorrhiza, a traditional Chinese medicinal herb, contains two groups of bioactive components: lipid-soluble tanshinones and water-soluble phenolic acids. Many researchers have recently focused on elicitation of secondary metabolites to improve their production. In this paper, folic acid was used as an elicitor to stimulate phenolics production in S. miltiorrhiza hairy root cultures. The results showed that folic acid use was effective for eliciting rosmarinic acid (RA), salvianolic acid B (SAB), caffeic acid (CA), and total phenolics from S. miltiorrhiza hairy roots and that 50 μM is the most effective folic acid concentration for elicitation. Roots treated with 50 μM folic acid showed 97.6, 76.7, and 47 % increases in RA, SAB, and CA contents, respectively, relative to the control. The expression of three key genes involved in SAB biosynthesis (i.e., PAL, TAT, and RAS) were upregulated by folic acid. In conclusion, we report for the first time that folic acid is an effective elicitor of phenolics production in S. miltiorrhiza hairy roots. Our results suggest that folic acid is a potential elicitor that may improve phenolic acid production in medicinal plants.