Rapid determination of total flavonoid content, xanthine oxidase inhibitory activities, and antioxidant activity in Prunus mume by near-infrared spectroscopy.

Evaluating the quality of herbal medicine based on the content and activity of its main components is highly beneficial. Developing an eco-friendly determination method has significant application potential. In this study, we propose a new method to simultaneously predict the total flavonoid content (TFC), xanthine oxidase inhibitory (XO) activity, and antioxidant activity (AA) of Prunus mume using near-infrared spectroscopy (NIR). Using the sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric method, uric acid colorimetric method, and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) free radical scavenging activity as reference methods, we analyzed TFC, XO, and AA in 90 P. mume samples collected from different locations in China. The solid samples were subjected to NIR. By employing spectral preprocessing and optimizing spectral bands, we established a rapid prediction model for TFC, XO, and AA using partial least squares regression (PLS). To improve the model's performance and eliminate irrelevant variables, competitive adaptive reweighted sampling (CARS) was used to calculate the pretreated full spectrum. Evaluation model indicators included the root mean square error of cross-validation (RMSECV) and determination coefficient (R2) values. The TFC, XO, and AA model, combining optimal spectral preprocessing and spectral bands, had RMSECV values of 0.139, 0.117, and 0.121, with RCV2 values exceeding 0.92. The root mean square error of prediction (RMSEP) for the TFC, XO, and AA model on the prediction set was 0.301, 0.213, and 0.149, with determination coefficient (RP2) values of 0.915, 0.933, and 0.926. The results showed a strong correlation between NIR with TFC, XO, and AA in P. mume. Therefore, the established model was effective, suitable for the rapid quantification of TFC, XO, and AA. The prediction method is simple and rapid, and can be extended to the study of medicinal plant content and activity.

Efficient Fabrication of Quartz Glass Using Laser Coaxial Powder-Fed Additive Manufacturing Approach.

This article investigates a laser-directed energy deposition additive manufacturing (AM) method, based on coaxial powder feeding, for preparing quartz glass. Through synergistic optimization of line deposition and plane deposition experiments, key parameters of laser coaxial powder feeding AM were identified. The corresponding mechanical properties, thermal properties, and microstructure of the bulk parts were analyzed. The maximum mechanical strength of the obtained quartz glass element reached 72.36 ± 5.98 MPa, which is ca. 95% that of quartz glass prepared by traditional methods. The thermal properties of the obtained quartz glass element were also close to those prepared by traditional methods. The present research indicates that one can use laser AM technology that is based on coaxial powder feeding to form quartz glass with high density and good thermodynamic properties. Such quartz glass has substantial potential in, for example, optics and biomedicine.

Epigenetic modifiers alter the secondary metabolite composition of a plant endophytic fungus, Pestalotiopsis crassiuscula obtained from the leaves of Fragaria chiloensis.

The addition of the DNA methyltransferase inhibitor 500 µM 5-azacytidine to the culture medium of a plant endophytic fungus, Pestalotiopsis crassiuscula, obtained from the leaves of Fragaria chiloensis, dramatically altered the profiles of its metabolites and resulted in the isolation of one new coumarin (1), along with six known compounds (2-7). HPLC profiles revealed that only compounds 3, 4, and 7 belonged to the new induced secondary metabolites. The structures of all isolated compounds were elucidated on the basis of extensive analysis of NMR spectra.