Laser Seed Pretreatment Alters the Silybin Content and Anti-Dictyostelium discoideum Cell Growth Activity of Silybum marianum (L.) Fruit

Abstract

Silybum marianum is a medicinal plant that produces silybins A and B, which exhibit liver-protective activities. The He–Ne laser pre-sowing seed treatment has been used as a physical biostimulator in numerous plants to promote seed germination, plant growth, and secondary metabolite production. Thus, in this study, a He–Ne laser at 632.8 nm was used to irradiate S. marianum seeds with the aim of promoting plant growth as well as enhancing the production of silybin (A + B). The seeds were irradiated with a He–Ne laser for 2, 4, 6, 8, and 10 min. The growth attributes of the plants, as well as the silybin (A + B) content and bioactivities of fruit extracts from various treatment groups, were compared. The results indicated that all laser seed treatments resulted in a subsequent increase in plant growth, with the highest yield observed in the 10 min laser treatment. An increase in fruit silybin (A + B) content and in chalcone synthase gene expressions were observed in plants from the 6-, 8-, and 10-min laser-irradiated seeds. The highest silybin (A + B) contents were observed in plants from the 6-min-irradiated seeds. Furthermore, the corresponding fruit extract also exhibited elevated cell growth inhibition in the Dictyostelium discoideum cell model.