Biotechnological production of silymarin in Silybum marianum L.: A review

Abstract

Abstract Biotechnology approaches applied through plant tissue culture of milk thistle (Silybum marianum L. Gaertn.) can contribute to the production of biologically active substances, micropropagation and the study of genes involved in the biosynthetic pathway of silymarin. The fruits (achenes) of S. marianum contain a mixture of flavonolignans, collectively known as silymarin, a high value hepatoprotectant. Because of its high biological activities, the increasing pharmaceutical demand for silymarin has made it an important target to study its production through biotechnological systems. In vitro cell, tissue and organ cultures of medicinal plants provide an appropriate solution for the problems correlated to conventional production in the open field. However, the productivity of silymarin through different biotechnological systems is low in comparison to field production, which requires more efforts and attempts in this regard. Elicitation strategy has substantially enhanced the accumulation of silymarin substances in callus, cell and hairy root cultures, providing a continuous and promising production of such high value natural derived compounds in large-scale through bioreactor system. Few investigations have focused on studying the bioengineering of key genes involved in the biosynthetic pathway of silymarin in S. marianum plant. These studies have provided a rational approach and new insights into the regulation of silymarin biosynthetic pathway to improve the biotechnological production of silymarin and flavonoids through plant tissue culture system. This review comprehensively summarizes the recent advances on various approaches of biotechnology of S. marianum plant and discusses the advantages and possible challenges, which will provide useful clues and strategies to overcome the problems correlated to each. A brief description of the phytochemistry of milk thistle, biosynthesis of silymarin components and biological activity of in vitro cultures was also reviewed.