Synthesis and characterization of Sophora alopecuroides L. green synthesized of Ag nanoparticles for the antioxidant, antimicrobial and DNA damage prevention activity

Abstract In this study, it was aimed to investigate the amount of antioxidant, protective properties against DNA damage and antibacterial properties against various pathogens after the interaction of Ag metal (Ag NPs/Sa) of Sophora alopecuroides L. (S. alopecuroides L) plant seed, which is grown in Igdir and used in the treatment of many diseases. The DPPH radical quenching activity of Ag NPs/Sa was performed by using Blois method, DNA damage prevention activity by gel electrophoresis and antibacterial property by disk diffusion method. With the green synthesis method, AgNPs obtained as a result of the reaction of the plant and Ag metal are UV visible spectrophotometer (UV-vis), fourier-transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). DPPH radical quenching activity of Ag NPs/Sa was investigated in the concentration range of 25-250 µg/ml. The radical quenching activity at a concentration of 250 µg/ml was 85,215 ± 0,101%, while this value was 93,018% for the positive control BHA. It has been observed that the protective property of pBR322 plasmid DNA damage against OH radicals originating from H2O2 increases with concentration. It has been observed that Ag NPs/Sa has significant antimicrobial properties against some pathogens (B. subtilis ATCC 6633 E. coli ATCC 25952, B. cereus ATCC 10876, P. aeruginosa ATCC 27853, E. faecalis ATCC 29212, S. aureus ATTC 29213 and C. albicans ATTC 90028) that cause disease and even some pathogens are more effective than antibiotics

N-terminal truncation of prenyltransferase enhances the biosynthesis of prenylnaringenin / 生物工程学报

8-prenylnaringenin (8-PN) is a potent estrogen with high medicinal values. It also serves as an important precursor for many prenylated flavonoids. Microbial synthesis of 8-PN is mainly hindered by the low catalytic activity of prenyltransferases (PTS) and insufficient supply of precursors. In this work, a SfN8DT-1 from Sophora flavescens was used to improve the efficiency of (2S)-naringenin prenylation. The predicted structure of SfN8DT-1 showed that its main body is comprised of 9 α-helices and 8 loops, along with a long side chain formed by nearly 120 amino acids. SfN8DT-1 mutants with different side-chain truncated were tested in Saccharomyces cerevisiae. A mutant expressing the truncated enzyme at K62 site, designated as SfND8T-1-t62, produced the highest 8-PN titer. Molecular docking of SfN8DT-1-t62 with (2S)-naringenin and dimethylallyl diphosphate (DMAPP) showed that K185 was a potentially crucial residue. Alanine scanning within a range of 0.5 nm around these two substrates showed that the mutant K185A may decrease its affinity to substrates, which also indicated K185 was a potentially critical residue. Besides, the mutant K185W enhanced the affinity to ligands implied by the simulated saturation mutation, while the saturated mutation of K185 showed a great decrease in 8-PN production, indicating K185 is vital for the activity of SfN8DT-1. Subsequently, overexpressing the key genes of Mevalonate (MVA) pathway further improved the titer of 8-PN to 31.31 mg/L, which indicated that DMAPP supply is also a limiting factor for 8-PN synthesis. Finally, 44.92 mg/L of 8-PN was produced in a 5 L bioreactor after 120 h, which is the highest 8-PN titer reported to date.