Biosynthesized Ag nanoparticles on urea-based periodic mesoporous organosilica enhance galegine content in Galega.

The biological approach for synthesizing nanoparticles (NPs) using plant extracts is an efficient alternative to conventional physicochemical methods. Galegine, isolated from Galega (Galega officinalis L.), has anti-diabetic properties. In the present study, silver nanoparticles (AgNPs) loaded onto urea-based periodic mesoporous organosilica (AgNPs/Ur-PMO) were bio-synthesized using G. officinalis leaf extract. The synthesized NPs were characterized and confirmed via analysis methods. Different concentrations of biosynthesized AgNPs/Ur-PMO nanoparticles (0, 1, 5, 10, and 20 mg L -1 ) were used as elicitors in cell suspension culture (CSC) of G. officinalis. The callus cells from hypocotyl explants were treated at their logarithmic growth phase (8 th d) and were collected at time intervals of 24, 72, 120, and 168 h. The viability and growth of cells were reduced (by 17% and 35%, respectively) at higher concentrations and longer treatments of AgNPs/Ur-PMO; however, the contents of hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) were increased (1.23 and 3.01 fold, respectively in comparison with the control average). The highest total phenolic (2.43 mg g -1 dry weight) and flavonoid (2.22 mg g -1 dry weight) contents were obtained 168 h after treatment with 10 mg L -1 AgNPs/Ur-PMO. An increasing tendency in the antioxidant enzyme activities was also observed in all the elicitor concentrations. Treatment with AgNPs/Ur-PMO (in particular 5 mg L -1 for 120 h) significantly enhanced the galegine content (up to 17.42 mg g -1 ) about 1.80 fold compared with the control. The results suggest that AgNPs/Ur-PMO can be used as an effective elicitor for enhancing galegine production in the CSC of G. officinalis. KEY POINTS: • The green biosynthesis of AgNPs/Ur-PMO was done using G. officinalis leaf extract • Its toxicity as an elicitor increased with increasing concentration and treatment time • AgNPs/Ur-PMO significantly increased the antioxidant capacity and galegine content.