VNUHCM Journal of Advanced Research in Natural Sciences

Characteristics of material composition and formation age of felsic dyke in Dak Ruong, Kon Ray, Kon Tum and its geological significance

Khoi Van Lu — 2026-03-26

The felsic dykes in the Dak Ruong, Kon Ray, Kon Tum areas were 0.5 m to 15 m wide. The observed length was from a few tens of meters to over 1,000 m in the sub−longitude direction and northeast−southwest. The felsic dykes cut through the small−grained biotite granite of the Hai Van complex and the Proterozoic metamorphic formations of the Tac Po formation. The characteristics of the felsic dykes were phenocryst architecture with phenocrysts (5−20%) on a microcrystalline background (95−80%). The common phenocrysts were K−feldspar (35−40%), plagioclase (10−15%) and quartz (35−40%). They included plagioclase, K−feldspar, quartz, biotite, muscovite, sericite and ore. The main accessory minerals included zircon and apatite. The average SiO₂ content was about 75.53 wt%, the total potassium (K₂O and Na₂O) was about 6.66−7.22 wt% belonging to the lime−alkali series, high potassium, corresponding to the S−type granite. In the rare earth element group composition of the felsic dykes, the content of heavy rare earth (HREE) was hihger than that of the light rare earth (LREE). The rare earth elements were normalized with chondrites, giving a negative slope and a strong negative Eu anomaly. The ²⁰⁶Pb/²³⁸U zircon isotopic age results had an average age of 240 ± 2.1 Ma, corresponding to the middle Triassic age, Permian−Triassic period (Indosinian orogen). Their formation could be relaled to the internal extension between the Indochina and South China continental block.

Synthesis of magnetic CuFe2O4 materials by a sol-gel method using dragon fruit peel extract: Comparison of synthesis methods and evaluation of catalytic activity in benzyl alcohol oxidation

Thi Trinh Thi Tran — 2026-03-26

This paper presents the synthesis and evaluation of the catalytic activity of magnetic CuFe₂O₄ powders for the selective oxidation of benzyl alcohol to benzaldehyde under mild and environmentally friendly conditions, in an aqueous medium at room temperature. Three simple preparation routes, including ceramic, co-precipitation, and sol-gel methods, were employed to investigate the influence of synthesis methodology on material characteristics and catalytic behavior. More specifically, the sol-gel method was assisted by a dragon fruit peel extract, which served as a natural gelling agent to facilitate gel formation and enhance the dispersion of metal ions within CuFe₂O₄ lattice. The experimental results showed that the choice of synthetic method significantly impacts several key physicochemical properties, including phase composition, particle size, and importantly, the surface distribution of Cu²⁺ and Fe³⁺ ions. These structural and surface features played a decisive role in governing the catalytic activity during persulfate activation. While all CuFe₂O₄ samples effectively activated persulfate to drive the oxidation of benzyl alcohol following pseudo-second-order kinetics, the sol-gel-derived sample exhibited superior catalytic activity, with benzyl alcohol conversion and benzaldehyde selectivity both exceeding 85% after 24 hours of reaction. This enhanced performance was attributed to the more homogeneous dispersion and optimal surface arrangement of metal ions, which facilitated electron transfer processes and the generation of reactive species during persulfate activation. In addition to high catalytic activity, this prepared CuFe₂O₄ sample exhibited strong magnetic properties, enabling rapid and efficient separation from the solution after reactions. The catalyst also retained its activity over repeated reaction cycles, demonstrating its high stability and reusability. Overall, the CuFe₂O₄ materials could promise magnetically recoverable catalysts for green, selective oxidation processes in aqueous systems, with the bio-assisted sol–gel method emerging as the most effective synthesis route.

Nitric oxide radical scavenging activity of compounds isolated from Plantago major

Tho Huu Le — 2026-03-27

Plantago major, a perennial herbaceous plant found across various provinces in Vietnam, is known for its short stem, growing 15-45 cm tall, with fibrous roots forming clusters. A study investigating the nitric oxide (NO) radical scavenging activity of several Vietnamese medicinal plants revealed that the methanol extract of P. major exhibited significant inhibitory activity with an IC₅₀ value of 75,8 μg/mL. Utilizing column chromatography combined with preparative thin-layer chromatography on both normal and reverse phases, fractions PMA and PMC of this species led to the isolation of eight compounds. These include two iridoids: 3β-methoxyartselawnin C (1) and iridolactone (2); three alkaloids: uridine (3), caffeine (4), and paraxanthine (5); and three phenolics: 4-hydroxybenzoic acid (6), vanillin (7), and 3,5-dihydroxyfuran-2(5H)-one (8). Their structures were identified by analyzing nuclear magnetic resonance (1D- and 2D-NMR) data, high-resolution mass spectrometry (HRMS) data, and comparing them with literature references. Compounds 1-5 and 8 are reported for the first time in this species. NO radical scavenging activity assays indicated that compounds 2, 3, and 7 displayed IC₅₀ values of 99,6, 77,9, and 34,2 µM, respectively, while the remaining compounds exhibited weak biological activity.

Triterpenoids and a sterol from the bark of Entandrophragma angolense

Dũng Ngọc Bùi — 2026-03-27

Entandrophragma angolense (Welw) C. DC. is a large tree belonging to the family Meliaceae, distributed mainly in Africa. The wood is highly valued for exterior and interior joinery and ship building. The tree is used in folk medicine for the treatment of colds, fever, malaria, stomach pain, peptic ulcers, swellings, earache, arthritic or rheumatic pain and ophthalmia. Limonoids, triterpenoids, steroids and fatty acids have been found in the species. In this study, we report the results of the isolation and structure determination of four compounds from an n-hexane extract of the bark of the species collected in Trang Bom Botanical Garden, Dong Nai Province. Extraction was carried out using a Soxhlet extractor with n-hexane and ethyl acetate, respectively, as the solvents. Recovery of the solvents produced an n-hexane extract and an ethyl acetate extract. Repeated column chromatography over silica gel, RP-18 and Sephadex LH-20 on the n-hexane extract produced four compounds. Analysis of NMR spectra (¹H and ¹³C NMR, DEPT 90, DEPT 135, HSQC and HMBC) and comparison of the spectral data with those in literature revealed that the compounds comprising three triterpenoids, 3-oxoolean-12-en-30-oic acid (1), 3-oxoolean-12-en-29-oic acid (2) and 20-epibryonolic acid (3), together with a steroid, stigmas-4-en-3-one (4). This is the first time that all the compounds have been isolated from this species.

Anthraquinones from the ethyl acetate extract from the stem of Gnetum montanum Markgr

Truong Nhat Van Do — 2026-03-28

Gnetum montanum, called “Dây gắm” in Vietnam, is a perennial plant belonging to the family Gnetaceae. Gnetum montanum is traditionally used in folk medicine to treat conditions such as rheumatism, chronic bronchitis, menstrual disorders, and as an antidote. Studies on the chemical composition of this species have revealed that it contains various valuable compounds, including flavonoids, stilbenoids, lignans and alkaloids. However, no research has been conducted on the presence of anthraquinone compounds in Gnetum montanum. Through applying column chromatography and thin-layer chromatography, six compounds were isolated. Their chemical structures were elucidated by analyzing nuclear magnetic resonance spectroscopy (1D and 2D-NMR) and comparison with reference data. These compounds were identified as chrysophanol (1), emodin (2), physcion (3), questin (4), aloe-emodin (5) and acetyl-aloe-emodin (6). All isolated compounds were reported for the first time in the genus Gnetum. The DPPH free radical scavenging, α-glucosidase inhibition, and xanthine oxidase inhibition assays were performed on all isolated compounds. The results of the α-glucosidase inhibition assay showed that all compounds exhibited activity at the tested concentration of 100 µM, with compounds 2, 3, 5, and 6 have the α-glucosidase inhibitory activity with IC₅₀ values of 73.6, 97.1, 72.2, and 73.5 µM, respectively, that is more potent than acarbose (IC₅₀ = 190.6 µM). The results of the DPPH free radical scavenging assay showed that 3 out of 6 compounds exhibited activity at the tested concentration of 100 µM, while compounds 1, 2, and 3 did not show DPPH free radical scavenging activity at this concentration. All six compounds exhibited relatively weak xanthine oxidase inhibitory activity at the tested concentration of 100 µM. The findings of this study provide the national database on the phytochemical profile of medicinal plants in Vietnam, especially Gnetum montanum.