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• Inhibitory Effects of Ludwigia Octovalvis (Jacq.) Raven Extracts on the Growth of Microcystis Aeruginosa

  Nguyen Xuan Hoa, Tran Thi Thuy, Vu Thi Huyen, Phung Thi Vinh, Pham Trung Duc, Doan Thi Thuy Ai

  Received: Jun 12, 2023 / Published: Dec 30, 2023

   Abstract PDF

  This study examined the phytochemical composition and algicidal effectiveness of Ludwigia octovalvis. The powder samples were extracted by ultrasound-assisted extraction with polar solvents (water-diluted ethanol, acetone, methanol, and water). The preliminary phytochemical analyses used standard procedures following Sofowora and Harborne. Total phenolic contents in extracts were determined by the Folin-Ciocalteu method using a calibration curve of gallic acid. The results showed that this plant contains polyphenols, flavonoids, anthraquinones, glycosides, and saponins. The best conditions for the extraction of polyphenol compounds with a total polyphenol content of 149.22 ± 0.96 mg GAE g-1 were acetone/water 70:30 (v/v) and a solvent-to-material ratio of 20 mL g-1. The inhibitory effect of the extracts against M. aeruginosa growth increased from 40.71 to 81.56% on day 7 when exposed to concentrations of the extract from 50-200 μg mL-1 according to the cell counting method. The L. octovalvis extract was identified as an effective inhibitor of the growth of M. aeruginosa.

• Polyphenols from Tropical Almond Leaves (Terminalia catappa L.): Optimized Extraction Conditions and α-Glucosidase Inhibitory Activity

  Nguyen Thi Thu Nga, Nguyen Xuan Bac, Vu Thi Hanh, Lai Thi Ngoc Ha

  Received: Dec 17, 2022 / Published: Mar 29, 2024

   Abstract PDF

  The purpose of this study was to find the optimal conditions for extracting polyphenols from Vietnamese tropical almond leaves (Terminalia catappa L.) and to assess the anti-diabetic activities of the resulting extract. The polyphenol extraction from Vietnamese tropical almond leaves was optimized using the response surface methodology. A rotatable central composite design (RCCD) with three variables (ethanol concentration, temperature, and extraction time), consisting of 21 experimental runs with three replicates at the center, minimal, and maximal factorial points was applied to describe the experimental data. The experimental results properly confirmed the constructed model (R2 = 0.8337). The optimized conditions were as follows: ethanol concentration of 62.76%, a temperature of 62.2°C, and an extraction time of 70 minutes. Five extractions were performed in parallel at the optimized conditions to validate the model. The experimental values highly agreed with the predicted value. The extract powder has powerful effects against the α-glucosidase activity and can develop as a novel natural anti-diabetic agent.

• Green Synthesis and Utility of Nano Fe for Cr(VI) Treatment

  Ngo Thi Thuong, Le Thi Ngoc, Le Thi Thu Huong

  Received: Aug 20, 2018 / Accepted: Aug 20, 2018 / Published: Aug 20, 2018

   Abstract PDF

  Zero valent iron (ZVI) nanoparticles have been considered as effective materials for environmental remediation because of their strong reducing ability, high reaction activity, and excellent absorption properties. In this study, we synthesized iron nanoparticles using an environmentally friendly method in order to treat Cr(VI) ions in an aqueous medium. Polyphenols from green tea leaf extracts were used as both the reducing agent and the stabilizer for ZVI nanoparticles. Modern techniques, including scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and infrared spectroscopy (FTIR), confirmed that ZVI nanoparticles were successfully prepared and surrounded by polyphenol molecules. Cr(VI) ion treatment of the nanoparticles was most favorable at pH 2.0, and 0.04 g ZVI nanoparticles for a 50 mg L-1 Cr(VI) solution. Under some treatment conditions, removal efficiency was 100%, suggesting that the synthesized ZVI nanoparticles can be used as materials for Cr(VI) ion removal.