A new galactomannan extracted from the seeds of Astragalus gombiformis Pomel (Fabaceae) and its utilization in the biosynthesis of silver nanoparticles

Finding novel sources of polysaccharides with suitable properties for desired uses in numerous sectors, such as nanotechnology, is becoming a more active area of research. Galactomannan (AGFPG) from the seeds of Astragalus gombiformis Pomel (Fabaceae) was extracted and characterized, and its potential application in the biosynthesis of silver nanoparticles (AgNPs) was investigated. The yield after hot water extraction was 10.4% (w/w), and the total carbohydrate content was 83.09±0.03% (w/w). High-performance liquid chromatography and nuclear magnetic resonance revealed that AGFPG was composed of β-D-mannose (60.05%) and α-D-galactose (39.95%), with a Man/Gal ratio of 1.51. Biosynthesis was confirmed by the absorption peak of AgNPs at 423nm. Scanning electron microscopy images and X-ray diffractogram revealed the spherical shape and the crystalline structure of AgNPs. A Zeta potential value of AgNPs -48.6mV showed their high stability. The hydrodynamic diameter of AgNPs by Dynamic light scattering is 144.4nm. The AgNPs showed significant antimicrobial activity and antioxidant activity (DPPH and Ferric reducing power). AGFPG, as a new galactomannan, can be used as a reducing and capping agent. Biosynthesized AgNPs exhibit good antimicrobial and antioxidant activities, which has led to their use in a variety of fields.