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Publication

A molecular docking simulation study on potent inhibitors against Rhizoctonia solani and Magnaporthe oryzae in rice: silver-tetrylene and bis-silver-tetrylene complexes vs. validamycin and tricyclazole pesticides

( 2020)

Bui Thi Phuong Thuy

;

Tran Thi Ai My

;

Nguyen Thi Thanh Hai

;

Huynh Thi Phuong Loan

;

Le Trung Hieu

;

Tran Thai Hoa

;

Thanh Q. Bui

;

Ho Nhat Tuong

;

Nguyen Thi Thu Thuy

;

Doan Kim Dung

;

Pham Van Tat

;

Phan Tu Quy

;

Nguyen Thi Ai Nhung

Rice, well known as the most important staple food source worldwide, is highly susceptible to many infectious diseases, especially rice sheath blight caused by fungus Rhizoctonia solani and rice blast caused by fungus Magnaporthe oryzae. The inhibitory ability of silver- and bis-silver-tetrylene complexes, including Ag-E and bis-Ag-E with E = C, Si, Ge, onto protein 4G9M in Rhizoctonia solani and protein 6JBR in Magnaporthe oryzae was theoretically investigated using molecular docking simulation methodology. Two commercial pesticides selected as inhibitory references are validamycin for 4G9M and tricyclazole for 6JBR. The results reveal that bis-silver-tetrylene complexes perform the strongest inhibitory effects towards both proteins. The structures of the complexes exhibit good site–site binding to both proteins given the observations on the hydrogen bond interactions, cation–π bonds, π–π bonds, and ionic interactions, interaction distance between amino acids and ligands, and van der Waals interactions. The inhibitory capacity onto protein 4G9M decreases in the following order: bis-Ag-C > bis-Ag-Si > bis-Ag-Ge > validamycin > Ag-C ≈ Ag-Si ≈ Ag-Ge. The corresponding order observed from the study for protein 6JBR is bis- Ag-C > bis-Ag-Si ≈ bis-Ag-Ge > tricyclazole ≈ Ag-C ≈ Ag-Si ≈ Ag-Ge. The study opens a promising approach to tackle rice blast and rice sheath blight based on a family of silver-tetrylene organometallic chemicals given the theoretical proof of environment-advanced properties and molecule-scaled effectiveness.

Publication

Alpha-Glucosidase Inhibitory Diterpenes from Euphorbia antiquorum Growing in Vietnam

( 2021)

Cong-Luan Tran

;

Thi-Bich-Ngoc Dao

;

Thanh-Nha Tran

;

Dinh-Tri Mai

;

Thi-Minh-Dinh Tran

;

Nguyen-Minh-An Tran

;

Van-Son Dang

;

Thi-Xuyen Vo

;

Thuc-Huy Duong

;

Jirapast Sichaem

Bioactive-guided phytochemical investigation of Euphorbia antiquorum L. growing in Vietnam led to the isolation of five ent-atisanes, one seco-ent-atisane, and one lathyrane (ingol-type). The structures were elucidated as ent-1α,3α,16β,17-tetrahydroxyatisane (1), ethyl ent-3,4-seco-4,16β,17-trihydroxyatisane-3-carboxylate (2), ent-atisane-3-oxo-16β,17-acetonide (3), ent-3α-acetoxy-16β,17-dihydroxyatisane (4), ent-16β,17-dihydroxyatisane-3-one (5), calliterpenone (6), and ingol 12-acetate (7). Their chemical structures were unambiguously determined by analysis of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry, as well as by comparison with literature data. Among them, 1 is a new compound while 2 is an ethylated artifact of ent-3,4-seco-4,16β,17-trihydroxyatisane-3-carboxylic acid, a new compound. Isolates were evaluated for alpha-glucosidase inhibition. Compound 3 showed the most significant inhibitory activity against alpha-glucosidase with an IC50 value of 69.62 µM. Further study on mechanism underlying yeast alpha-glucosidase inhibition indicated that 3 could retard the enzyme function by noncompetitive.

Publication

Applying SiO2 nano-particles for improving optical properties of WLED conformal and in-cup structures

( 2021)

Phan Xuan Le

;

Pham Quang Minh

This article is the analysis of SiO2 nano-particles’ influences on the luminous efficiency and the color temperature uniformity of a remote phosphor structure in a WLED. The purpose of integrating SiO2 into the silicone layer in the remote phosphor structure is to significantly promote the scattering occurrences. Particularly, with an appropriate proportion of SiO2, there could be more blue lights generated at large angles, leading to reducing the angular-dependent color temperature deviation. The luminous flux also can get benefits from SiO2 addition owing to a proper air-phosphor layer refractive index ratio provided by this SiO2/silicone compound. The attained experimental results were compared with optical values of a non-SiO2 remote phosphor configuration and showed a notable enhancement. The color deviation was reduced by approximately 600 K in the angles from -700 to 700. Additionally, the lumen efficiency was improved by 2.25% at 120 mA driving current. Hence, SiO2 can be used to boost both color uniformity and luminous efficacy for remote-phosphor WLED.

Publication

Ảnh hưởng của phân bón hữu cơ tạo từ thân chuối đến sinh trưởng và năng suất cây ngải cứu

( 2021)

Vũ Thị Quyền

;

Lê Quốc Bảo

Nghiên cứu nhằm đánh giá ảnh hưởng của phân hữu cơ từ thân chuối (gọi tắt là phân chuối) đến sinh trưởng và năng suất cây ngải cứu trồng theo phương thức hữu cơ tại vùng đất xám thuộc xã Phước Hiệp, huyện Củ Chi, thành phố Hồ Chí Minh. Kết quả sau hơn 2 tháng thử nghiệm đã chỉ ra rằng: (i) bón phân chuối với liều lượng 15 tấn/ha cho chiều cao cây đạt 44,11 cm, tổng số lá/cây 150 lá, năng suất sinh khối binh quân 18 tấn/ha, hệ số giữa sinh khối khô và sinh khối tươi của cây ngải cứu dao động ở mức 23 - 27%; (ii) việc bón lót phân chuối đé trồng ngải cứu có ý nghĩa rất lớn trong việc cải thiện pH và độ dẫn điện của đất (EC) đối vói khu vực đất xám thuộc huyện Củ Chi. Chỉ sau 70 ngày thí nghiệm, độ pHH20 từ 5,26 (chua) tăng lên 6,77 (trung tính) và độ dẫn điện của đất (EC) từ 124 pS/cm tăng lên 252,25 pS/cm, thể hiện đất được tăng cường ion hòa tan sau khi bón lót phân chuối và thực hiện canh tác hữu cơ cho cây ngải cứu; giúp tăng khả năng cung cấp dinh dưỡng cho cây từ đất. Điều này ghi nhận vai trò to lớn của phân bón hữu cơ từ thân chuối đến năng suất cây ngải cứu, cũng như việc cải thiện tính chất lý, hóa của đất canh tác.

Publication

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

( 2021)

Nguyen Kim Uyen

;

Kyung Yuk Chae

;

Nguyen Ngoc Duy

;

Nguyen Duy Ly

The β−-decay half-lives of extremely neutron-rich nuclei are important for understanding nucleosynthesis in the rapid neutron capture process (r-process). However, most of their half-lives are unknown or very uncertain, leading to the need for reliable calculations. In this study, we updated the coefficients in recent semi-empirical formulae using the newly updated mass (AME2020) and half-life (NUBASE2020) databases to improve the accuracy of the half-life prediction. In particular, we developed a new empirical model for better calculations of the β−-decay half-lives of isotopes ranging in Z = 10–80 and N = 15–130. We examined the β−-decay half-lives of the extremely neutron-rich isotopes at and around the neutron magic numbers of N = 50, 82, and 126 using either five different semi-empirical models or finite-range droplet model and quasi-particle random phase approximation method. The β−-decay rates derived from the estimated half-lives were used in calculations to evaluate the impact of the half-life uncertainties of the investigated nuclei on the abundance of the r-process. The results show that the half-lives mostly range in 0.001 < T1/2 < 100 s for the nuclei with a ratio of N/Z < 1.9; however, they differ significantly for those with the ratio of N/Z > 1.9. The half-life differences among the models were found to range from a few factors (for N/Z < 1.9 nuclei) to four orders of magnitude (for N/Z > 1.9). These discrepancies lead to a large uncertainty, which is up to four orders of magnitude, in the r-process abundance of isotopes. We also found that the multiple-reflection time-of-flight technique is preferable for precise mass measurements because its measuring timescale applies to the half-lives of the investigated nuclei. Finally, the results of this study are useful for studies on the β-decay of unstable isotopes and astrophysical simulations.

Publication

Chemical Constituents of Cordyceps neovolkiana DL0004

( 2021)

Chi-Dung Nguyen

;

Thi-My-Ninh Pham

;

Thi-Bich-Hang Ha

;

Thi-Phuong Nguyen

;

Huu-Hung Nguyen

;

Hoang-Vinh-Truong Phan

;

Thuc-Huy Duong

;

Minh-Hiep Dinh

Publication

Development of polyvinyl (alcohol)/D-glucose/agar/silver nanoparticles nanocomposite film as potential food packaging material

( 2021)

Bao-Tran Tran Pham

;

Thuy-Hang Thi Duong

;

Thuong Thi Nguyen

;

Dai Van Nguyen

;

Chinh Dung Trinh

;

Long Giang Bach

The functional nanocomposite films from polyvinyl (alcohol) (PVA), D-glucose, agar, and silver nanoparticles (AgNPs) components were synthesized through the facile casting method. Results from the evaluation of antimicrobial activity and composite film properties showed that the combination of PVA/D-glucose/agar with AgNPs significantly enhanced bactericidal activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, as well as mechanical property. Furthermore, the coating from the combination of PVA/D-glucose/agar with AgNPs was also applied in Areca banana preservation for 7 days at 25 ℃. Appearance, physiological weight loss, total soluble sugars, and titratable acidity were daily evaluated during storage period. The obtained results of this study show the promising potential of PVA/D-glucose/agar nanocomposite film incorporated with AgNPs for food packaging applications in the near future.

Publication

Different Transfer Functions for Binary Particle Swarm Optimization with a New Encoding Scheme for Discounted {0-1} Knapsack Problem

( 2021)

Tung Khac Truong

;

Luigi Rodino

The discounted {0-1} knapsack problem (DKP01) is a kind of knapsack problem with group structure and discount relationships among items. It is more challenging than the classical 0-1 knapsack problem. In this paper, we study binary particle swarm optimization (PSO) algorithms with different transfer functions and a new encoding scheme for DKP01. An effective binary vector with shorter length is used to represent a solution for new binary PSO algorithms. Eight transfer functions are used to design binary PSO algorithms for DKP01. A new repair operator is developed to handle isolation solution while improving its quality. Finally, we conducted extensive experiments on four groups of 40 instances using our proposed approaches. The experience results show that the proposed algorithms outperform the previous algorithms named FirEGA and SecEGA . Overall, the proposed algorithms with a new encoding scheme represent a potential approach for solving the DKP01.

Publication

Effects of air temperature and blanching pre-treatment on phytochemical content, antioxidant activity and enzyme inhibition activities of Thai basil leaves (Ocimum basilicum var. thyrsiflorum)

( 2021)

N.L. Le

;

T.T.H. Le

;

N.B. Ma

Thai basil leaves (Ocimum basilicum var. thyrsiflorum) have been used in food flavoring and traditional medicine. Hot-air drying is a convenient and low-cost method to preserve them for long-term use but causes the loss of their bioactive compounds during the process. In this work, the effect of pre-blanching on preserving these characteristics of Thai basil leaves dried at different air temperatures was studied. The antioxidant characteristics were evaluated by the contents of total phenolics, total flavonoids and total chlorophylls and the scavenging capacity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. In addition, the inhibitory activities against starch-digesting enzymes were assessed with α-amylase and amyloglucosidase. At the air temperature of 50oC, antioxidant characteristics of dried leaves with pre-blanching were proven better than those without blanching and came close to those of the fresh sample. The drying temperature had more evident effects on inhibitory activities against starch-digesting enzymes than blanching. These activities of hot-air dried leaves were comparable to those of the fresh one. This study could provide insights into the integration of blanching and hot-air drying to preserve medicinal plants.

Publication

Effects of NaB2O4:Mn2+ and Ba2Li2Si2O7:Sn3+,Mn2+ phosphors and remote structure organizations on the white light-emitting diodes with quantum dots and phosphors

( 2021)

Phan Xuan Le

;

Le Nguyen Hoa Binh

In order to increase the optical features of white light-emitting diodes (WLEDs), quantum dots (QDs) and phosphor materials have been proposed because of outstanding performance. The configuration of WLEDs with QDs layer and phosphor-silicone layer suggested placing these components separately to limit light loss, and enhance consistency at contact surface of QDs. In this research, the effects of QDs and phosphor on the performance of WLEDs are concluded through experiments. The emitted light and PL spectra were examined thoroughly, and infrared thermal imagers were applied to simulate the heat generation of an actual WLED device. The results show that with the configuration of 60 mA energy source, WLEDs which has the QDs-on-phosphor form attained luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra=92 and R9=80, whereas the WLEDs which has the phosphor-on-QDs form only has 68 lm/W in LE, Ra=57 and R9=24. Furthermore, WLEDs which has the QDs-on-phosphor form has less high temperature generated at the components’ conjunction in comparison to the counterpart, the peak generated heat in QDs-on-phosphor WLEDs is also lower and the heating capacity gap between 2 structures can go up to 12.3°C.

Publication

Electrochemical Determination of Diclofenac by Using ZIF-67/g-C3N4 Modified Electrode

( 2021)

Dang Thi Ngoc Hoa

;

Nguyen Thi Thanh Tu

;

Le Van Thanh Son

;

Le Vu Truong Son

;

Tran Thanh Tam Toan

;

Pham Le Minh Thong

;

Dao Ngoc Nhiem

;

Pham Khac Lieu

;

Dinh Quang Khieu

;

Thanh Son Le

A facial differential pulse voltammetric procedure using a glassy carbon electrode modified with zeolite imidazolate framework-67/graphitic carbon nitride (ZIF-67/g-C3N4) for the diclofenac (DCF) determination is demonstrated. ZIF-67/g-C3N4 with different mass ratios of the components was synthesized in a self-assembly process. The obtained materials were characterized by using X-ray diffraction, scanning electron microscopy (SEM), EDX-mapping, and nitrogen adsorption/desorption isotherms. The peak current varies linearly with the DCF concentration in the range of 0.2–2.2 μmol·L−1 and has a detection limit of 0.071 μmol·L−1. The modified electrode exhibits acceptable repeatability, reproducibility, and selectivity towards DCF. The proposed electrode allows determining DCF in human urine without pretreatment, and the results are comparable with those determined with HPLC.

Publication

Electrochemical Determination of Uric Acid in Urine by Using Zeolite Imidazolate Framework-11 Modified Electrode

( 2021)

Tran Si Thanh

;

Phan Tu Qui

;

Nguyen Thi Thanh Tu

;

Tran Thanh Tam Toan

;

Tran Thi Bich Hoa

;

Le Van Thanh Son

;

Do Mai Nguyen

;

Tran Ngoc Tuyen

;

Dinh Quang Khieu

;

Thanh-Danh Nguyen

In the present article, the synthesis of zeolite imidazole framework-11 (ZIF-11) by ultrasonic-assisted hydrothermal process and its application as an electrode modifier for electrochemical determination of uric acid in urine are demonstrated. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms. It was found that the ZIF-11 with rhombic dodecahedron topology and high surface area (1066m2.g-1) was synthesized in a certain temperature and found in around 25–40°C, and other crystalline phases of zinc benzimidazolate deferring from ZIF-11 phase were found in less 25°C or higher than 40 ° C. The ZIF-11 is stable in the pH range 6-10. The modification of glassy carbon electrode was performed with ZIF-67 using the drop-casting procedure. The present ZIF-11 modified electrode was employed to study the electrochemical behavior of uric acid (UA). UA oxidation is catalyzed by this electrode in aqueous buffer solution (pH7) with a decrease of 70mV in overpotential compared to glassy carbon electrode. With the differential pulse–anodic stripping voltammetry (DP-ASV) method, the oxidation current of UA versus its concentration shows good linearity in the range 20– 540μM (R = 0:998) with a detection limit of 0.48 μM (S/N = 3). The obtained ZIF-11 modified electrode was applied in the detection of UA content in urine samples, and satisfied results were obtained.

Publication

Evaluation of fatty acids, phenolics and bioactivities of spent coffee grounds prepared from Vietnamese coffee

( 2021)

Danh C. Vu

;

Quyen T. Vu

;

Long Huynh

;

Chung-Ho Lin

;

Sophie Alvarez

;

Xuyen T. Vo

;

Trang H. D. Nguyen

Spent coffee ground (SCG) is a residue released during coffee brewing. Disposal of SCG is able to lead to a loss of bioactive constituents and have a negative impact upon the environment. This study aimed to explore fatty acids, bioactive phenolics, antioxidant and anti-aging potentials of SCG samples obtained from coffee shops in Ho Chi Minh city, Vietnam. The oil content of the SCG samples ranged from 6.3 to 10.5%, and linoleic (43%), palmitic (33.4%) and oleic (11%) acids were identified as major constituents of the oil. Chlorogenic acid was the most abundant phenolic acid examined (832.9–7657.7 μg/g of dry weight), followed by ferulic acid (40.5–1041.7 μg/ g). Through anti-collagenase and anti-elastase assays, SCG showed a promising anti-aging activity, with IC50 values comparable with those of epigallocatechin gallate. The correlation analysis revealed gallic acid positively correlated with the free radical scavenging potential evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and the inhibitory effect on elastase. The results demonstrated that utilization of SCG prepared from Vietnamese coffee could open new avenues for food and cosmeceutical industry.

Publication

Fluoride and Arsenite Removal by Adsorption on La2O3-CeO2/Laterite

( 2021)

Duong Thi Lim

;

Trinh Ngoc Tuyen

;

Dao Ngoc Nhiem

;

Dao Hong Duc

;

Pham Ngoc Chuc

;

Nguyen Quang Bac

;

Dang Xuan Tung

;

Ngo Nghia Pham

;

Luu Thi Viet Ha

;

Nguyen Thi Thanh Tu

;

Vo Thang Nguyen

;

Dinh Quang Khieu

;

Dong kee Yi

In the present article, the adsorbent prepared from laterite with lanthanum and cerium oxides (La2O3-CeO2/laterite (LCL)) was efficiently employed for the removal of arsenite and fluoride from an aqueous environment. The obtained materials were characterized by XRD, SEM, and nitrogen adsorption/desorption. The synthesized LCL exhibited a high adsorption capacity towards arsenite (As(III)) and fluoride. The adsorption of both analytes on LCL, which was well-fitted to a pseudo-second-order equation, was found to be kinetically fast in the first 20 minutes and reached equilibrium at around 180 minutes. Weber’s intraparticle diffusion model in multilinearity using the piecewise linear regression combined with Akaike’s criteria was addressed. The adsorption capacities of LCL calculated from Langmuir’s isotherm model were found to be 67.08 mg·g-1 for arsenite and 58.02 mg·g-1 for fluoride. Thermodynamic parameters presented an endothermic nature of arsenite adsorption but an exothermic nature for fluoride and a negative Gibbs free energy for the spontaneous process of arsenite or fluoride adsorption at the studied temperature range. The excellent adsorption performance and stability make the composite of laterite and La-Ce binary oxides an alternative efficient and cheap adsorbent for the removal of arsenite and fluoride in an aqueous solution.

Publication

Health risk assessment of volatile organic compounds at daycare facilities

( 2021)

Mohamed Bayati

;

Danh C. Vu

;

Phuc H. Vo

;

Elizabeth Rogers

;

Jihyun Park

;

Thi L. Ho

;

Alexandra N. Davis

;

Zehra Gulseven

;

Gustavo Carlo

;

Francisco Palermo

;

Jane A. McElroy

;

Susan C. Nagel

;

Chung‐Ho Lin

Children are particularly vulnerable to many classes of the volatile organic compounds (VOCs) detected in indoor environments. The negative health impacts associated with chronic and acute exposures of the VOCs might lead to health issues such as genetic damage, cancer, and disorder of nervous systems. In this study, 40 VOCs including aldehydes and ketones, aliphatic hydrocarbons, esters, aromatic hydrocarbons, cyclic terpenes, alcohols, and glycol ethers were identified and qualified in different locations at the University of Missouri (MU) Child Development Laboratory (CDL) in Columbia, Missouri. Our results suggested that the concentrations of the VOCs varied significantly among classrooms, hallways, and playground. The VOCs emitted from personal care and cleaning products had the highest indoor levels (2-ethylhexanol-1, 3-carene, homomenthyl salicylate with mean concentration of 5.15 µg/m3, 1.57 µg/m3, and 1.47 µg/m3, respectively). A cancer risk assessment was conducted, and none of the 95th percentile dose estimates exceeded the age-specific no significant risk levels (NSRL) in all classrooms. Dimensionless toxicity index scores were calculated for all VOCs using a novel web-based framework called Toxicological Prioritization Index (ToxPi), which integrates multiple sources of toxicity data. According to the method, homomenthyl salicylate, benzothiazole, 2-ethylhexyl salicylate, hexadecane, and tridecane exhibited diverse toxicity profiles and ranked as the five most toxic indoor VOCs. The findings of this study provide critical information for policy makers and early education professionals to mitigate the potentially negative health impacts of indoor VOCs in the childcare facilities.

Publication

Isolation and Plant Growth Promoting Characterization of Potassium Solubilizing Bacteria in Rhizosphere of Some Crops in Vietnam

( 2021)

Võ Thị Xuyến

Many soil microorganisms are able to dissolvethese types of potassium and have been applied in agriculture. These potassium solubilizing bacteria (KSB) have also been shown to have by many other direct or indirect plant growth-promoting activities. This study's aim was isolation, screening and plant growth-promoting characterization of KSB from rhizospheric soil of some crops in Vietnam. The results were that thirty-four KSB isolates were collected on Aleksandrov agar medium from ten soil samples from the rhizospheres of banana, pitaya, and mango. By the spot streak technique on this medium, three KSB isolates including BE204, BE208 and BE220 were screened with the potassium solubility indexes 10.87, 10.97, and 10.72, respectively. All of three selected isolates were identified as belong to Burkholderia genus by the specific protein springers, in which, BE208 had the best match with B. gladiola. The two strains BE204 and BE208 showed a higher potential because of the capility to antagonize to most of thirteen surveyed phytopathogens including Phomopsis longicolla, Neoscytalidium dimidiatum, and Phyllosticta cavendishii, based on the dual culture technique, causing significant damage on many crops in Vietnam. In addition, the two strains were also able to dissolve phosphate and zinc and produce enzymes hydrolyzing protein, starch and cellulose by also the spot streak technique. The results contributed the potential bacterial collection for the research and development of products from indigenous KSB in Vietnam. However, additional classifications as well as the safety of these selected strains need to be further investigated.

Publication

Nghiên cứu tổng hợp vật liệu oxit hỗn hợp sắt mangan trên nền diatomite Phú Yên và khả năng ứng dụng làm chất hấp phụ loại bỏ Asen trong môi trường nước

( 2021)

Nguyễn Thị Thanh Tú

The paper presents the modification of Phu Yen diatomite by oxidationreduction reaction between Fe (II) and KMnO4 salts in solution pH = 6 on the diatomite surface. Characteristics of modified materials and the influence of research factors on these characteristics were investigated using techniques XRD, EDX, XPS, SEM, TEM, BET. Arsenic adsorption capacity of modified materials, the influence of environmental factors on the adsorption capacity were also investigated and evaluated. The results showed that mixed oxide-modified diatomite has higher arsenic adsorption capacity than natural diatomite and modified diatomite by individual oxides.

Publication

Nickel ferrite: synthesis and application for voltammetric determination of uric acid

( 2021)

Nguyen Thi Vuong Hoan

;

Nguyen Ngoc Minh

;

Nguyen Thi Lieu

;

Nguyen Van Thang

;

Vo Thang Nguyen

;

Nguyen Thi Thanh Tu

;

Tran Thanh Tam Toan

;

Nguyen Hoang Tuan

;

Duong Quang Nhan

;

Ho Van Minh Hai

;

Tran Ngoc Tuyen

;

Dinh Quang Khieu

In this paper, the synthesis of nickel ferrite and its use for voltammetric determination of uric acid (UA) are presented. Nickel ferrite was synthesized via a hydrothermal process using spherical carbons as hard template followed by calcination at 500 °C. It was found that iron and nickel compositions in nickel ferrite can be controlled by the initial Fe/Ni molar ratio. The stoichiometric nickel ferrite (NiFe2O4) with hollow spherical morphology was obtained from a reaction mixture with Fe/Ni molar ratio of around 1.2–1.5. Glassy carbon electrode modified with nickel ferrite was employed to quantitatively determine UA by different pulse voltammetric method. Under the optimum conditions, the anodic peak current was linearly proportional to UA concentration in the range of 0.398 to 6.761 μM. The detection limit (3σ) was found to be 0.15 μM. The proposed method has been employed to determine UA in human urine samples with acceptable recoveries of 95.15–104.8%. On the other hand, the results obtained from this method were also compared with that from standard HPLC method, showing no statistical difference.

Publication

Norquandrangularic acid D, a new trinorcycloartane isolated from the leaves of Combretum quadrangulare

( 2021)

Huu-Hung Nguyen

;

Xuan-Hao Bui

;

Thi-Minh-Dinh Tran

;

Jirapast Sichaem

;

Thi-Kim-Dung Le

;

Ngoc-Hong Nguyen

;

Thuc-Huy Duong

Phytochemical investigation on the leaves of Combretum quadrangulare growing in Vietnam afforded a new trinorcycloartane triterpenoid, norquandrangularic acid D (1), along with three known compounds, betulinic acid (2), luteolin (3), and apigenin (4). Their structures were elucidated using spectroscopic methods and comparison was made with reports in the literature. Compounds 1 and 3 were evaluated for α-glucosidase inhibition. Compound 3 showed significant activity, with an IC50 value of 11.39 µM, (acarbose, used as a positive control, had an IC50 of 367 µM).

Publication

On the Inhibitability of Natural Products Isolated from Tetradium ruticarpum towards Tyrosine Phosphatase 1B (PTP1B) and α-Glucosidase (3W37): An In Vitro and In Silico Study

( 2021)

Dao-Cuong To

;

Thanh Q. Bui

;

Nguyen Thi Ai Nhung

;

Quoc-Toan Tran

;

Thi-Thuy Do

;

Manh-Hung Tran

;

Phan-Phuoc Hien

;

Truong-Nhan Ngu

;

Phan-Tu Quy

;

The-Hung Nguyen

;

Huu-Tho Nguyen

;

Tien-Dung Nguyen

;

Phi-Hung Nguyen

Folk experiences suggest natural products in Tetradium ruticarpum can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (1) and 3-[4-(4-methylhydroxy-2-butenyloxy)-phenyl]-2-propenol (2). In vitro study shows that the compounds (1 and 2) possess high potentiality for the inhibition of PTP1B (IC50 values of 24.3 ± 0.8, and 47.7 ± 1.1 μM) and α-glucosidase (IC50 values of 92.1 ± 0.8, and 167.4 ± 0.4 μM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure–activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.

Journal Articles - Natural Science - 2021

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