A CuO-loaded SrTiO₃ catalyst showed highly photocatalytic activity for H₂ evolution. This catalyst was prepared by an impregnation method and characterized by XRD, TEM, BET, XPS, Uv-vis DRS and PL techniques. Under optimum conditions, the best rate of H₂ evolution of the CuO-loaded SrTiO₃ catalyst is 5811 µmol h⁻¹g⁻¹, whereas it is a mere 34 µmol h⁻¹g⁻¹ for the pure SrTiO₃. High efficiency, low cost and good stability are some of the merits that underline the promising potential of CuO-loaded SrTiO₃ in the photocatalytic hydrogen.

Cinnamomum verum (Cinnamomum genus) essential oil is commonly used in food preparation and traditional medicines, with a broad spectrum of biological activities. However, research on the extraction of essential oils (EOs) from C. verum cultivated locally in Vietnam is currently limited. Therefore, in this study, the chemical compositions and bioactivities of EOs from the bark and leaves of C. verum collected from the Thai Nguyen and Yen Bai provinces of Vietnam were investigated. The EOs samples were extracted by using water distillation, organic solvent (n-hexane) and ultrasound-assisted (in n-hexane solvent) extraction methods. The chemical composition of the obtained EOs were analyzed by GC-FID and GC/MS analyses. Results showed that the major chemical compositions of C. verum EOs were: (E)-cinnamaldehyde, trans-cinnamic acid, cinnamyl acetate, and benzaldehyde. Furthermore, C. verum EOs exhibited inhibitory activities against two tested cancer cell lines and four bacterial strains. These findings provide essential knowledge about the potential application of C. verum EOs cultivated in Vietnam for the pharmaceutical industry.

In this study, we report on the preparation of copper oxide/strontium titanate/multi-walled carbon nanotube (CuO/STO/MWCNTs) nanocomposites and their photocatalytic activity for degradation of dye under visible light. The crystalline structures of the nanocomposites were investigated by an X-ray diffraction (XRD) technique, which explored the successful fabrication of CuO/STO/MWCNTs nanocomposites, and the cubic STO phase was formed in all samples. For the morphological study, the transmission electron microscope (TEM) technique was used, which had proved the successful preparation of CuO and STO nanoparticles. The energy dispersive X-ray spectroscopy (EDX), dark field scanning transmission electron microscope (DF-STEM-EDX mapping), and X-ray photoelectron spectra (XPS) analysis were performed to evidence the elemental composition of CuO/STO/MWCNTs nanocomposites. The optical characteristics were explored via UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) techniques. These studies clearly indicate the effect of the presence of CuO and MWCNTs on the visible absorption of the CuO/STO/MWCNTs nanocomposites. The photocatalytic activity of CuO/STO/MWCNTs nanocomposites was evaluated by the degradation of methylene blue (MB) dye under visible light irradiation, following first-order kinetics. Among the different x% CuO/STO/MWCNTs nanocomposites, the 5 wt.% CuO/STO/MWCNTs nanocomposites showed the highest photocatalytic efficiency for the degradation of MB dye. Moreover, the 5% CuO/STO/MWCNTs showed good stability and recyclability after three consecutive photocatalytic cycles. These results verified that the optimized nanocomposites can be used for photocatalytic applications, especially for dye degradation under visible light.

Litsea umbellata (Lour.) Merr. is a plant commonly grown in Vietnam and some Asian countries. The plant is used in traditional medicines and exhibits significant biological activities. However, the sesquiterpenes’ extraction in the essential oil (EO) of L. umbellata harvested from the northern region of Vietnam has been limitedly known. Therefore, in the present study, the L. umbellata leaves and stem EOs were obtained by hydrodistillation method, then determined for the phytochemical profile by using gas chromatography–mass spectrometry system, and investigated the cytotoxicity activities against five cancer cell lines. Results have identified a total of 21 and 26 compounds in the EOs of L. umbellata leaves and stem, respectively, with the main sesquiterpene compounds being β-caryophyllene (16.87–11.04%), (+)-spathulenol (9.74–6.57%), β-caryophyllene oxide (26.12–18.34%), and (−)-spatulenol (11.08–8.8%). L. umbellata leaves exhibit significant anti-cancer activity with IC₅₀ values ranging from 29.58 to 62.96 µg/ml. Otherwise, L. umbellata EOs also exhibited the good inhibition activities against DPPH free radical and three bacteria strains. The chemical constituents and cytotoxicity activity of L. umbellata EO stems have been reported for the first time and provided the future applications of this plant.

Phytochemical investigation of a new plant, Capparis dongvanensis (Sy, B. H. Quang & D. V. Hai) of the Capparaceae family was carried out and identified two new polycyclic compounds and twelve known compounds. Among them, compounds 3 and 7 are two new polycyclic compounds, while twelve known compounds are stigmasterol (1), β-sitosterol (2), nonadecan-1-ol (4), nonacosan-1-ol (5), nonadecyl nonadecanoate (6), tetracontane (8), benzoic acid (9), salicylic acid (10), tryptophan (11), glycine (12), berberine (13), and β-sitosterol 3-O-β-D-glucopyranoside (14). The chemical structures of the isolated compounds were confirmed based on NMR spectral and mass spectrometry (MS) data. Moreover, we also elucidated the chemotaxonomic significance of these isolated compounds. In the end, preliminary bioactivity assessment of ethanolic and ethyl acetate extracts of Capparis dongvanensis leaves indicated that both extracts exhibited inhibitory activities on five cancer cell lines and alpha-glucosidase enzyme.