Nurul Bahiyah Ahmad Khairudin

Green Synthesis of Gold Nanoparticles Using Aqueous Extract of Garcinia mangostana Fruit Peels

The synthesis of gold nanoparticles (Au-NPs) is performed by the reduction of aqueous gold metal ions in contact with the aqueous peel extract of plant, Garcinia mangostana (G. mangostana). An absorption peak of the gold nanoparticles is observed at the range of 540–550źnm using UV-visible spectroscopy. All the diffraction peaks at 2ź = 38.48°, 44.85°, 66.05°, and 78.00° that index to (111), (200), (220), and (311) planes confirm the successful synthesis of Au-NPs. Mostly spherical shape particles with size range of 32.96 ± 5.25źnm are measured using transmission electron microscopy (TEM). From the FTIR results, the peaks obtained are closely related to phenols, flavonoids, benzophenones, and anthocyanins which suggest that they may act as the reducing agent. This method is environmentally safe without the usage of synthetic materials which is highly potential in biomedical applications.

Molecular Docking Study of Beta-Glucosidase with Cellobiose, Cellotetraose and Cellotetriose

Beta-glucosidase (3.2.1.21) plays an essential role in the removal of non-reducing terminal glucosyl residues from glycosides. Recently, beta-glucosidase has been of interest for biomass conversion that acts in synergy with two other enzymes, endoglucanase and exo-glucanase. However, there is not much information available on the catalytic interactions of beta-glucosidase with its substrates. Thus, this study reports on the binding modes between beta-glucosidase from glycoside hydrolase family 1 namely BglB with cellobiose, cellotetraose and cellotetriose via molecular docking simulation. From the results, the binding affinities of BglB-cellobiose, BglB-cellotetraose, and BglB-cellotetriose complexes were reported to be -6.2kJ/mol , -5.68 kJ/mol and -5.63 kJ/mol, respectively. The detail interactions were also been investigated that revealed the key residues involved in forming hydrogen bonds (h-bond) with the substrates. These findings may provide valuable insigths in designing beta-glucosidase with higher cellobiose-hydrolyzing efficiency.

A Green Approach for the Synthesis of Silver Nanoparticles Using Ultrasonic Radiation’s Times in Sodium Alginate Media

The synthesis of silver nanoparticles (Ag-NPs) was achieved by a simple green chemistry procedure using sodium alginate (Na-Alg) under ultrasonic radiation as a stabilizer and physical reducing agent. The effect of radiation time on the synthesis of Ag-NPs was carried out at room temperature until 720 min. The successful formation of Ag-NPs has been confirmed by UV-Vis, XRD, TEM, FESEM-EDX, zeta potential, and FT-IR analyses. The surface plasmon resonance band appeared at the range of 452ź465 nm that is an evidence of formation of Ag-NPs. The XRD study showed that the particles are crystalline structure in nature, with a face-centered cubic (fcc) structure. The TEM study showed the Ag-NPs have average diameters of around 20.16ź22.38 nm with spherical shape. The FESEM-EDX analysis confirmed the spherical shape of Ag-NPs on the surface of Alg and the element of Ag with the high purity. The zeta potential showed high stability of Alg/Ag-NPs especially after 720 min irradiation with value of ź67.56 mV. The FT-IR spectrum confirmed that the Ag-NPs have been capped by the Alg with van der Waals interaction. The Alg/Ag-NPs showed the antibacterial activity against Gram-positive and Gram-negative bacteria. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field.

A molecular dynamics study of Beta-Glucosidase B upon small substrate binding

Paenibacillus polymyxa β-glucosidase B (BglB), belongs to a GH family 1, is a monomeric enzyme that acts as an exo-β-glucosidase hydrolysing cellobiose and cellodextrins of higher degree of polymerization using retaining mechanism. A molecular dynamics (MD) simulation was performed at 300 K under periodic boundary condition for 5 ns using the complexes structure obtained from previous docking study, namely BglB-Beta-d-glucose and BglB-Cellobiose. From the root-mean-square deviation analysis, both enzyme complexes were reported to deviate from the initial structure in the early part of the simulation but it was stable afterwards. The root-mean-square fluctuation analysis revealed that the most flexible regions comprised of the residues from 26 to 29, 43 to 53, 272 to 276, 306 to 325 and 364 to 367. The radius of gyration analysis had shown the structure of BglB without substrate became more compact towards the end of the simulation compare to other two complexes. The residues His122 and Trp410 were observed to form stable hydrogen bond with occupancy higher than 10%. In conclusion, the behaviour of BglB enzyme towards the substrate binding was successfully explored via MD simulation approaches.

In Silico and In Vitro Study of the Bromelain-Phytochemical Complex Inhibition of Phospholipase A2 (Pla2)

Phospholipase A2 (Pla2) is an enzyme that induces inflammation, making Pla2 activity an effective approach to reduce inflammation. Therefore, investigating natural compounds for this Pla2 inhibitory activity has important therapeutic potential. The objective of this study was to investigate the potential in bromelain-phytochemical complex inhibitors via a combination of in silico and in vitro methods. Bromelain-amenthoflavone displays antagonistic effects on Pla2. Bromelian-asiaticoside and bromelain-diosgenin displayed synergistic effects at high concentrations of the combined compounds, with inhibition percentages of more than 70% and 90%, respectively, and antagonistic effects at low concentrations. The synergistic effect of the bromelain-asiaticoside and bromelain-diosgenin combinations represents a new application in treating inflammation. These findings not only provide significant quantitative data, but also provide an insight on valuable implications for the combined use of bromelain with asiaticoside and diosgenin in treating inflammation, and may help researchers develop more natural bioactive compounds in daily foods as anti-inflammatory agent.

Gold Nanoparticles Biosynthesis: A Simple Route for Control Size Using Waste Peel Extract

The production of gold nanoparticles using the aqueous peel extract of Garcinia mangostana plant is presented in this paper. The amount of peels powder and concentration of tetrachloroaurate salt were altered to determine the effect toward the nanoparticles. When the concentration of the starting materials increased, sharper peaks were observed in UV-vis spectroscopy at the region of 530 nm. The nanoparticles produced were spherical in shape with peel extract matrix surrounding them to prevent aggregation. The average size of the nanoparticles was 47.92±4.92 nm. The presence of gold nanoparticles with face centered cubic structure was confirmed by using XRD. The nanoparticles produced were relatively stable with a stability of –18.45 mV. This paper presents a facile and simple way to produce nontoxic nanoparticles that are environmental friendly and cost effective.

Green synthesis of silver nanoparticles in biopolymer stabilizer and their application as antibacterial efficacy

The synthesis of silver nanoparticles (Ag-NPs) has been conducted on the biopolymer media which is sodium alginate (Na-Alg) via the green method. Different times of ultrasound irradiation was used to reduce Ag+ to be Ag seed (Ag0) and produce Ag-NPs. The Ag-NPs was analyzed in their surface plasmon resonance (SPR), morphology, biomolecule responsible, and stability via UV-Vis, TEM, FTIR and Zeta potential, respectively. The application as antibacterial properties was studied against bacteria. Furthermore, this Ag-NPs could be synthesized using the green method and used as antibacterial efficacy for medical vehicles, would dressing, and so on.

Binding Mode Study of β-glucosidase B from P. Polymyxca with Cellobiose and Laminaribiose

Beta-glucosidase (3.2.1.21) plays an essential role in the removal of non-reducing terminal glucosyl residues from sacharides and glycosides. Recently, beta-glucosidase has been of interest for biomass conversion that acts in synergy with two other enzymes, endo-glucanase and exo-glucanase. However, there is not much information regarding the molecular interactions of beta-glucosidase with cellobiose. Thus, this study reports on the binding modes between beta-glucosidase from glycoside hydrolase family 1 namely BglB with cellobiose and laminaribiose via molecular docking method. Further analysis on the hydrophobic interactions revealed the key residues involved in forming hydrogen bonds (h-bond) with the substrates. The important residues were reported to be Gln22, Glu167, Tyr298, Glu356, Glu402, and Trp410. These findings may provide valuable insigths in designing beta-glucosidase with higher cellulose-hydrolyzing efficiency.