Chitin is the main structural component of cell walls of fungi, exoskeletons of insects and other arthropods and shells of crustaceans. Chitinase enzyme is capable of degrading chitin, and this enzyme can be used as a biological fungicide against phytopathogenic fungi, as well as an insecticide against insect pests.

In this study, the authors presented synthesis of ceria nanoparticles (NPs) by the bio‐reduction method and their antioxidative activity. Aqueous extract of Euphorbia ( Euphorbia amygdaloides ) was used as reducing and stabilising agents. They used aqueous extract of Euphorbia ( E. amygdaloides ) as reducing and stabilising agent. Ultraviolet–visible (UV–vis) absorption spectroscopy was used to monitor the quantitative formation of ceria NPs. They also addressed the characteristics of the obtained ceria NPs using scanning electron microscopy (SEM), X‐ray diffraction (XRD) and transmitting electron microscope (TEM). The synthesised cerium (III) oxide (Ce ₂ O ₃ ) NPs were initially noted through visual colour change from colourless pale yellow cerium (III) to light yellow cerium (IV) and further confirmed the band at 345 nm employing UV–vis spectroscopy. The average diameter of the prepared NPs was about 8.6–10.5 nm. In addition, the synthesised Ce ₂ O ₃ NPs were tested for antioxidant and anti‐bacterial activities using ferric reducing antioxidant power, cupric reducing antioxidant capacity, ferrous ions chelating activity, superoxide the anion radical scavenging and 2, 2′‐azinobis 3‐ethylbenzothiazol to‐6‐sulphonic acid scavenging activity. It could be concluded that Euphorbia ( E. amygdaloides ) extract can be used efficiently in the production of potential antioxidant and anti‐bacterial Ce ₂ O ₃ NPs for commercial applications.

In this study, it was aimed to obtain copper oxide nanoparticles (CuO NPs) with the method of green synthesis by using peroxidase enzymes which were partly purified from fig ( Ficus carica ). Copper (II) oxide nanoparticles are successfully synthesized with the green synthesis method on the experiments we performed. UV-VIS spectroscopy of the characterization of acquired CuO NPs were performed with Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Optimum activation temperature for green synthesis was observed to be in 30 min, pH:8, at 25 o C and in the concentration of 1mM CuCl 2 . By using peroxidase enzymes with green synthesis, it was found out the results of SEM and XRD measurements that acquired CuO NPs were in the size of 50-120 nm. Afterwards, the antioxidant and antibacterial activities of these nanoparticles were measured and it was understood from the obtained results that CuO NPs had both antioxidant and antimicrobial activities.

Silver nanoparticles are used an increased attention for various biomedical and medical applications. In this study, green synthesis of silver nanoparticles was made with simple method by using peroxidase enzyme partially purified from Euphorbia ( Euphorbia amygdaloides ) plant. Optimum pH, temperature and time period were determined to obtain silver nanoparticles using the peroxidase enzyme. The result shows that higher silver nanoparticle was synthesized for 4 hours and at 20°C and pH 8. Also, optimal concentration of metal ions was found as 0.5 mM. The synthesized silver nanoparticles were characterized by UV spectrum, scanning electron microscope (SEM) and X‐ray diffraction. Antibacterial activity of silver nanoparticles was measured against some microorganisms such as Serratia marcescens, Yersinia pseudotuberculosis, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Pseudomonas aeruginosa, Salmonella typhimurium, Listeria monocytogenes, and Escherichia coli . Synthesized silver nanoparticles have wide spectrum antibacterial activity in low concentration and may be a good alternative therapeutic approach in medicine and pharmaceutical fields in future.