Influence of Plant Growth Regulators on Callus Induction, Silymarin Production and Antioxidant Activity in Silybum marianum L. Gaertn. by Tissue Culture

Silybum marianum (L.) is a medicinally important herb known for producing the liver-protecting compound silymarin, an isomeric mixture of flavonolignans and taxifolin. In this study, a protocol (plant growth regulators in various concentrations and combinations of coconut water) for the initiation of callus and silymarin production using different types of explantes (root, hypocotyls, cotyledonary leaf) of S. marianum L. was established. The free radical scavenging activity of silymarin extracted from callus cultures of these explants was investigated. In comparison to other plant growth regulators and explants studied, root explants cultured on MS medium enriched with 5.0 M NAA + 2.5 M BAP + 10% coconut water produced the most friable callus and had the highest possible level of silymarin and free radical scavenging activity. NAA + BAP + coconut water was found to be the best hormonal combination for callus initiation and mass production. This research will aid in understanding the influence of plant growth regulators and different types of explantes on the production of valuable secondary metabolites in S. marianum L. in vitro cultures.