Cuk Imawan

KOMPOSISI KIMIA, AKTIVITAS ANTIBAKTERI, DAN POTENSI SEBAGAI KEMASAN AKTIF BEBERAPA MINYAK ATSIRI DARI TANAMAN REMPAH INDONESIA

The single-step green synthesis has been successfully established to prepare a bi-phase structure of Zn/ZnO nanoparticles using laser ablation in a liquid medium. Nd: YAG laser with the wavelength of 1064 nm was employed to perform the laser ablation in pure water and Pometia pinnata (P. pinnata) leaf extract, with the leaf, were extracted in pure water and some concentration of ethanol. ZnO nanoparticles can be obtained via laser ablation in pure water, while the usage of P. pinnata leaf extract as the solution has caused the appearance of the bi-phase Zn/ZnO nanostructure. X-ray diffraction (XRD) pattern indicates the appearance of Zn peaks alongside with ZnO peaks with the inclusion of P. pinnata leaf extract. Transmission electron microscope (TEM) images show the change of shape from the rod-like shape into a spherical shape and smaller size spherical shape of Zn/ZnO nanoparticles in comparison with ZnO. Noticeable change of UV–visible spectrum emerges as the water was substituted by P. pinnata leaf extract. The zeta potential of Zn/ZnO prepared with P. pinnata extracted in water, with the value of − 18.9 V, reduces down to − 43.5 and − 41.1 for 20–40% of ethanol concentration, respectively. The as-prepared ZnO and Zn/ZnO colloidal samples were evaluated for their antibacterial activities against two strains Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Zn/ZnO sample shows a more substantial antibacterial effect in comparison with pure ZnO, no bacteria alive after 12 and 24 h’ treatment for E. coli and S. aureus, respectively.

Biodegradable and non-toxic plastic as food packaging is used instead of conventional plastic. One of biodegradable and non-toxic plastic can be made from cassava starch and PVA. This paper reports the results of a study of the effect of glycerol content on the mechanical and water barrier properties of cassava starch/Polyvinyl alcohol (PVA) composite films. The composite films of cassava starch/PVA were prepared with a solution casting method by the addition of glycerol or not. Glycerol concentrations in composite films varied from 10, 20 and 30% by weight of the polymer in the mixture. Mechanical and water barrier properties of cassava starch/PVA were analyzed. Film transparency was analyzed using a UV-Vis spectrophotometer. Changes in the functional groups on the FTIR spectra of composite films were also observed. Tensile strength decreased with increasing glycerol concentration on composite films but increased the elongation. The addition of glycerol decreased the water barrier properties by increasing the rate of transmission of water vapor from cassava starch/PVA composite films. Film transparency increased with the addition of 10% and 20% glycerol then decreases when the addition of 30% glycerol. Mechanical and water barrier properties of the composite films indicated that the addition of glycerol modified their properties significantly.

Pometia pinnata (Matoa) is widely known for its use in traditional medicines and as fruit sources in Indonesia. Stem bark and leaves of Matoa are the most used parts. Each part contains secondary metabolites, including flavonoids, tannins, triterpenoids, glycosides, and saponins. These compounds could act as reducing agents in the biosynthesis of silver nanoparticles. Our research attempts to compare the efficacy of aqueous extracts of Matoa leaf and stem bark in the biosynthesis of silver nanoparticles. We characterized products of silver nanoparticles using UV-Vis spectrophotometer, transmission electron microscope, and particle size analyzer to compare the biosynthesis between the two parts based on ratios of various concentrations of plant extract to silver nitrate (AgNO3). We found that the solution (extract and AgNO3) became darker as the concentration and reaction time increased. Increasing reaction time also caused an increase in absorption peak intensity due to the reduction process of silver ions. The use of leaf and stem bark for biosynthesis resulted in different shapes and sizes of silver nanoparticles; the use of leaves and stem bark resulted in sphere-shaped silver nanoparticles, whereas the use of aqueous leaf extracts triangle-shaped silver nanoparticles formed.

Silver nanoparticles (AgNPs) have a specific property for antibacterial agents. This research aims to explore the antibacterial activity from the AgNPs synthesized using Diospyros discolor Willd. extract. We determined that the leaf extract solution of D. discolor can provide reducing properties for AgNPs synthesis. The result showed a maximum absorbance peak wavelength between 420–450 nm in the produced AgNPs. The Transmission Electron Microscope (TEM) image supported the presence of AgNPs, with size between 10–50 nm. Antimicrobial assays using E. coli produced an inhibition zone of 7.4 ± 0.7 mm from the centrifuged AgNPs, whereas those using S. aureus produced an inhibition zone of 7.66 ± 0.9 mm. An antimicrobial activity index (AI) assay against E. coli resulted in 0.2 ± 0.1 mm, whereas the activity against S. aureus resulted in an activity index of 0.40 ± 0.19 mm. AI values that were lower than 1.0 was considered had less significant activity. We also tested the growth of bacteria in the medium added with AgNPs using the dilution method. The growth of bacteria colony from the streak line showed a decline in growth for the bacteria that had been exposed to biosynthesized AgNPs with the increasing of time exposure for 5, 10 and 15 minutes, respectively.

Plant extracts have been recognized as a substitute for chemical reducing agents in the synthesis of nanoparticles. Plants with antioxidants, including phenols and flavonoids, are expected to be reducing agents. Preliminary research has shown thatPometia pinnata(Matoa) stem bark aqueous extract can be used for silver nanoparticle (AgNP) biosynthesis. However, the compounds that serve as reducing agents in this process are still unknown. In this study, we studied antioxidant strength using DPPH radical reduction method. AgNP biosynthesis was performed by mixing powdered Matoa stem bark aqueous extract (2 %) with 1 mM AgNO3 (1:2). Further, pH of the Matoa stem bark aqueous extract was varied (pH 4, 7, 9 and 11), and one sample without pH adjustment was used as the control. Additionally, we synthesized AgNPs using the standard antioxidants gallic acid and rutin trihydrate. Our results showed that with increasing pH, changes in the color of solutions and escalation of UV–Vis spectrum absorbance were observed. The sizes and shapes of the AgNPs were further characterized using TEM and PSA, which revealed spherical and short rod-shaped particles. Our findings about the strength of the antioxidant activity of the Matoa stem bark aqueous extract under different pH conditions provide relevant information on the processes that can affect silver nanoparticle biosynthesis.