Abstract
Sennoside A (dianthrone glycoside) shows laxative properties and used as a folk traditional medicine. Sennoside A capped silver nanoparticles (Ag/sennoside A) were synthesized at room temperature for the first time by using sennoside A as reducing and capping agent. UV-visible spectroscopic data reveals that the absorption peaks of pure sennoside A was appeared at 266, and 340 nm, which red shifted to 304, and 354 nm at higher sennoside A concentration. Upon addition of the Ag(+) ions, an additional peak also observed at 398 nm, indicating the formation of spherical sennoside A capped silver nanoparticles (Ag/sennoside A). Cetyltrimethylammonium bromide (CTAB) was used a stabilizing agent to determine the role of cationic micelles on the nucleation and growth processes of Ag/sennoside A NPs formation. The 2,2-diphenyl-1-picrylhydrazyl nitrogen radical (DPPH (·) ), two bacteria strains (Staphylococcus aureus and Escherichia coli) and two yeast strains (Candida albicans ATCC 10231 and Candida parapsilosis ATCC 22019) were used to determine the antioxidant and antimicrobial properties of Ag/sennoside A NPs. In addition, Rhein-9-anthrone (4,5-dihydroxy-10-oxo-9H-anthracene-2-carboxylate) was isolated from the acidic hydrolysis of glycoside linkage of sennoside A and characterized. The antioxidant and antimicrobial activities of rhein-9-anthrone were also determined against DPPH radical, antibacterial and antifungal strains. The minimum inhibitory concentration was determined and discussed.