Endale Teju

In this study, the root of Carissa spinarum (Apocynaceae) was investigated for compound isolation and assessment of antimicrobial and antioxidant activities. The methanol extract was found to have a better yield (7.65%) and growth‐inhibitory effect on all microbes, with the lowest inhibitory concentrations observed against Escherichia coli , Staphylococcus aureus , and Streptococcus pyogenes bacteria (MIC = 12.5 mg/mL) and Aspergillus niger fungus (MIC = 25 mg/mL). The methanol extract also demonstrated the strongest antioxidative effect (IC ₅₀ = 12.25 ± 0.32 µg/mL) on the DPPH radical, though it was weaker than that of ascorbic acid (IC50 = 6.39 ± 0.59 µg/mL). Chromatographic fractionation of the methanol extract furnished tetradecanal ( CS1 ), α ‐amyrin ( CS2 ), and O ‐methyl inositol ( CS3 ). In silico drug‐likeness, ADME, and toxicity evaluation revealed that tetradecanal obeys Lipinski's rule of five and indicates blood‐brain barrier permeability, CYP1A2 inhibitory effect, high gastrointestinal absorption, and no organ toxicity. This study supports the ethnomedicinal uses of Carissa spinarum root and highlights the presence of polar antimicrobial and antioxidant agents in it. Further studies are needed to assess the cytotoxicity and in vivo bio‐efficacy of the plant. The tentatively proposed structures of the isolated compounds should also be further confirmed by NMR spectroscopy.

This study was conducted to determine the concentrations of some physicochemical parameters of water and sediment in Lake Tinike during dry and wet seasons as well as some heavy metals in water, sediment, and fish. A laboratory-based study was carried out between January and June 2017, with samples collected from three purposively selected sites. Heavy metal concentrations were determined using Atomic Absorption Spectrophotometry (AAS), while physicochemical parameters, including temperature, pH, total dissolved solids (TDS), and electrical conductivity, were measured using standard procedures. The mean concentrations of copper (Cu), cadmium (Cd), lead (Pb), and manganese (Mn) in water were 0.96 ± 0.02, 0.05 ± 0.003, 0.13 ± 0.07, and 1.00 ± 0.01 mg/L, respectively, while in sediments—2.00 ± 0.041, 0.80 ± 0.008, 1.70 ± 0.10, and 1.22 ± 0.10 mg/kg; and in fish—2.78 ± 0.034, 0.07 ± 0.001, 1.72 ± 0.02, and 3.46 ± 0.08 mg/kg. Fish samples recorded the highest levels of Cu, Pb, and Mn compared to sediments and water. Cd, Pb, and Mn in water slightly exceeded the maximum permissible concentration limits for drinking water, while Cd and Mn in sediments were above permissible levels of concentration. In fish, Pb exceeded permissible limits of concentration, whereas Cu, Cd, and Mn remained within acceptable ranges. Generally, some heavy metal concentrations (Cd, Pb, and Mn) in Lake Tinike were above international safety standards, indicating potential ecological risks and public health concerns for surrounding communities that rely on the lake for water and fish consumption. Therefore, continuous monitoring, strict regulation of pollutant discharges, and public awareness initiatives are strongly recommended to safeguard both environmental and human health in the region.

Herein, we report a green synthesized gold nanoparticle (AuNPs) based colorimetric detection of bisphenol A (BPA). The AuNPs were synthesized using khat leaf extract as a reducing agent by optimizing factors affecting the AuNPs synthesis, including gold precursor concentration (1 mM), and reaction temperature (60 °C). The AuNPs characterization was carried out using ultraviolet–visible spectrophotometry and transmission electron microscopy, and it was found spherical with an average particle size of 17.3 ± 3.7 nm. A colorimetric nanosensor was developed by conjugation of bio-inspired AuNPs with BPA-specific aptamer for a quick and easy detection of BPA in plastic bottled water. The colorimetric assay relies on the strong affinity of BPA for aptamer, which causes detachment of the aptamer from the AuNPs surface in the presence of BPA inducing AuNPs aggregation. To achieve the colorimetric detection of BPA, the concentrations of NaCl and aptamer were optimized. The detection of BPA was monitored visually using a naked eye, as well as quantitatively using an ultraviolet–visible spectrophotometer. The method visual limit of detection (LOD) was determined to be 0.1 ng/mL and reached 0.09 ng/mL using ultraviolet–visible spectrophotometer. The method demonstrated very good linearity (R² = 0.9986) in the range of 0.1–100 ng/mL. The proposed method showed high sensitivity to BPA detection in plastic bottled water with 86.7–98.0%, recovery. Therefore, the proposed colorimetric nanosensor can be used for determination of BPA in plastic bottled waters with reliable performance at lower concentrations. Graphical abstract

This study addresses the limited understanding of factors affecting the efficiency of water treatment plants in reducing trihalomethane (THM) formation through total organic carbon (TOC) removal, highlighting significant challenges in improving treatment effectiveness. The aim of this study was to examine the influence of water quality on the efficiency of water treatment plants to remove TOC and reduce THM formation. Linear regression and correlation analyses were conducted to examine the relationship between water quality parameters and THM concentrations. The results showed that there was a negative relationship between turbidity, metals, and TOC concentration with TOC removal efficiency. Positive correlations were found between parameters and the formation of THMs in water. Of these parameters, water temperature was observed to have relatively less influence on THM formation. It was observed that seasonal variations in water quality affect the efficiency of TOC removal and THM content in treated water. THM levels in chlorinated water were found to be within the permissible range of the World Health Organization's drinking water quality guidelines. However, it is still important to maintain continuous monitoring and take measures to reduce THMs. The model demonstrated a strong correlation (R2 = 0.906) between predicted and measured THM values.

The discharge of inorganic pollutants like phosphate and fluoride is a cause of mounting concern to the world due to the substantial environmental and human health risk. Adsorption is one of the most common and affordable technologies widely utilized for removing inorganic pollutants such as phosphate and fluoride anions. Investigating efficient sorbents for the adsorption of these pollutants is extremely important and challenging. This work aimed at studying the adsorption efficiency of the Ce(III)-BDC metal-organic framework (MOF) for the removal of these anions from an aqueous solution using a batch mode. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) techniques evidenced the successful synthesis of Ce(III)-BDC MOF in water as a solvent without any energy input within a short reaction time. The outstanding removal efficiency of phosphate and fluoride was exhibited at an optimized pH (3, 4), adsorbent dose (0.20, 0.35 g), contact time (3, 6 h), agitation speed (120, 100 rpm), and concentration (10, 15 ppm) for each ion, respectively. The experiment on the effect of coexisting ions demonstrated that SO₄^2- and PO₄^3- ions are the primary interfering ions in phosphate and fluoride adsorption, respectively, while the HCO₃^- and Cl^- ions were found to have interfered less. Furthermore, the isotherm experiment showed that the equilibrium data fitted well with the Langmuir isotherm model and the kinetic data correlated well with the pseudo-second-order model for both ions. The results of thermodynamic parameters such as ΔH°, ΔG°, and ΔS° evidenced an endothermic and spontaneous process. The regeneration of the adsorbent made using water and NaOH solution showed the easy regeneration of the sorbent Ce(III)-BDC MOF, which can be reused four times, revealing its potential application for the removal of these anions from aqueous environment.