Asian Journal of Applied Chemistry Research

Structural Characterization, Computational Investigation and Electrochemical Properties of 1-(2′-Hydroxy-3-methoxybenzylidene)-5-(1′-pyridylethylidene)-carbonohydrazide

Moussa Ndiaye — 2026-06-12

Asymmetric carbonohydrazide-derived Schiff bases have attracted increasing attention owing to their versatile coordination behaviour, tunable electronic properties, and potential applications in catalysis and bioactive metal-complex design. In this work, 1-(2'-hydroxy-3-methoxybenzylidene) -5-(1'-pyridylethylidene) -carbonohydrazide (H₃L²), an asymmetric Schiff base obtained by the condensation of carbohydrazide with o-vanillin and 2-acetylpyridine, was synthesised and comprehensively characterised. The crystal structure, determined by X-ray diffraction analysis, reveals a triclinic system (P-1) stabilised by a network of intra- and intermolecular hydrogen bonds. DFT calculations performed using the 6-31+G(d,p) basis set accurately reproduce the experimental geometric parameters and confirm the conjugated planarity of the molecule. Mulliken population analysis highlights the nucleophilic sites (O, N) as well as the polarisation of hydrogen bonds. The investigation of the frontier molecular orbitals HOMO and LUMO reveals an energy gap of 3.93 eV and a pronounced electrophilic character (ω = 25.55 eV). Global reactivity descriptors, particularly chemical hardness (η = 0.95 eV) and the high dipole moment (13.14 D), indicate moderate reactivity and strong electronic polarization favoring intermolecular interactions. FTIR spectroscopic characterisation is in good agreement with the calculated vibrational frequencies. Electrochemical studies performed by cyclic voltammetry reveal quasi-reversible electron transfer processes involving oxygen and nitrogen atoms, accompanied by remarkable stability in solution. Altogether, these structural, electronic, and electrochemical properties confer particular interest to this ligand as a promising candidate for the synthesis of metal complexes with potential biological or catalytic applications.

Production of Mosquito Repellent Cream with Extract from Lemon Grass (Cymbopogon citratus), Clove (Syzygium aromaticum) and Neem (Azadirachta indica)

Treasure, O. Akpomere — 2026-06-15

The increasing health and environmental concerns associated with synthetic mosquito repellents have necessitated the development of safer, plant-based alternatives. This study produced and evaluated mosquito repellent creams formulated from lemon grass (Cymbopogon citratus), clove (Syzygium aromaticum), and neem (Azadirachta indica) extracts, including their combinations. Fixed oils were extracted using n-hexane and incorporated into seven oil-in-water cream formulations. Physicochemical properties, chemical composition (GC-MS), antimicrobial activity (agar well diffusion against Salmonella sp., Escherichia coli, Candida albicans, and Aspergillus sp.) were determined. Repellency efficacy (modified Arm-in-Cage method) was evaluated using anopheles mosquito (Anopheles gambiae). The experiments were performed in triplicates. Statistical analysis of the results was done by one –way analysis of variance (ANOVA) and post hoc test. GC-MS revealed that lemon grass extraction with n-hexane altered its composition, yielding mainly 9-Octadecenoic acid (42.52%) instead of volatile citral, reducing its repellency. Significant difference was observed in the density, refractive index and viscosities of the extracted oils. There was significant difference in the oxidative properties of the extracted oils except in thiobarbituric acid (TBA) levels. ANOVA revealed distinct concentration – dependent behaviors for Salmonella sp., Candida albicans, and Aspergillus sp., whereas E. coli showed no statistically significant sensitivity to concentration variance. The extracted oils provided better antioxidant, antimicrobial and mosquito repellent efficiency while standing alone. Formulations combining the extracts yielded antagonistic rather than synergistic effects in most cases.

Biological Activities and Isolation of Bioactive Compounds from Zanthoxylum thouvenotii H. Perr. (Rutaceae) Bark

Sandratra Ramaroson Rakotonomenjanahary — 2026-06-23

Background: Zanthoxylum thouvenotii H. Perr. (Rutaceae) is used in Malagasy traditional medicine for toothache, malaria and metabolic disorders, but information on the biological activities and chemical constituents of its bark remains limited. Aim: This study evaluated the anti-hyperglycaemic, antimicrobial, antioxidant and anti-inflammatory activities of bark extracts and isolated bioactive constituents. Methods: Air-dried bark was extracted with ethanol/water and cyclohexane to obtain EE1, CE and EE2. Phytochemical screening was performed on EE1. Acute oral toxicity, antimicrobial activity by disc diffusion, hypoglycaemic activity in glucose-induced transient and high-fat diet-induced chronic hyperglycaemia, antioxidant activity by DPPH bioautography and anti-inflammatory activity using carrageenan-induced paw oedema were assessed. The active cyclohexane extract was fractionated by silica gel column chromatography, and isolated compounds were identified using NMR data. Results: EE1 contained steroids, alkaloids and triterpenoids, showed no mortality or clinical signs of acute toxicity up to 5 g/kg, and produced inhibition zones below 7 mm against the tested microorganisms. In the transient hyperglycaemia model, EE1 reduced blood glucose to 7.0 ± 0.8 mmol/L at 200 mg/kg after glucose administration, but did not restore glycaemia in obese mice. CE and EE2 were positive in the DPPH assay and inhibited carrageenan-induced oedema by 66.63% and 45.12%, respectively, at 250 mg/kg after 2 h. Fractionation of CE yielded lupeol and a mixture of β-sitosterol and stigmasterol. Lupeol inhibited paw oedema by 83.76% at 25 mg/kg. Conclusion: The findings indicate that Z. thouvenotii bark contains compounds associated with antioxidant and anti-inflammatory activity, with lupeol contributing to the observed anti-inflammatory effect.

Mining Activities and the Risks Associated with Fish Consumption

A. I. Yaradua — 2026-06-23

Freshwater fish may accumulate heavy metals from contaminated aquatic environments, thereby creating potential health concerns for populations that depend on fish as a dietary protein source. This study assessed selected heavy metals and associated health risks in edible fish samples from Jibia Dam, Jibia Local Government Area, Katsina State, Nigeria, an area affected by illegal mining activities. Eight samples each of Clarias gariepinus, Ameiurus nebulosus and Tilapia zilli were obtained from commercial anglers and analysed for Fe, Pb, Cd, Cu, Mn, Zn and Ni using spectrophotometric procedures after ashing and acid digestion. The daily intake of metals, target hazard quotient (THQ), health risk index (HRI), incremental lifetime cancer risk (ILCR) and cumulative incremental lifetime cancer risk (ΣILCR) were calculated for children and adults using the stated exposure assumptions. The results showed that mean Pb concentrations in Ameiurus nebulosus and Tilapia zilli exceeded the maximum allowable concentration, whereas the Pb concentration in Clarias gariepinus and the concentrations of the other assessed metals in all three species were within the stated safety limits. The THQ values for individual metals were below 1 in both children and adults, suggesting no appreciable non-carcinogenic risk from single-metal exposure under the adopted assumptions. However, the HRI values for Ameiurus nebulosus and Tilapia zilli exceeded 1 in children, indicating potential concern from combined metal exposure in this group. The ILCR values for Ni, and the corresponding ΣILCR values, exceeded the acceptable cancer risk range in both children and adults. These findings indicate that fish consumption from Jibia Dam may present health concerns, particularly in relation to Pb exposure and Ni-related carcinogenic risk, and support the need for periodic monitoring of fish from the area.

Recent Advances in Flavonoid Extraction Technology and its Nitrite-Scavenging Activity

Zhiqin Xiong — 2026-06-25

This review examines recent advances in flavonoid extraction technologies and their relevance to nitrite scavenging in pickled vegetable systems. Nitrite accumulation during vegetable fermentation is associated with raw-material nitrate content and microbial nitrate reduction, and it may pose health risks through acute toxicity and potential nitrosamine formation. The manuscript summarises current nitrite detection and control strategies, with emphasis on plant-derived flavonoids as natural scavenging agents. Three mechanisms are considered: direct electron-transfer-based nitrite scavenging, inhibition of nitrosation reactions, and regulation of nitric oxide metabolism. Extraction technology is identified as a key factor influencing flavonoid yield, structural retention, and nitrite-scavenging performance. Conventional methods, including reflux extraction, water extraction, and ethanol maceration, are discussed alongside advanced approaches such as semi-bionic extraction, ultrasound-assisted aqueous two-phase extraction, ultrasound-assisted extraction, microwave-assisted extraction, and supercritical fluid extraction. Green extraction using deep eutectic solvents and natural deep eutectic solvents is further reviewed because of its potential to improve extraction efficiency and preserve bioactivity. Evidence from pickled food and in vitro systems suggests that flavonoid extracts can reduce nitrite levels, although efficacy depends on plant source, extraction method, pH, temperature, reaction time, and dosage. The review highlights the need to connect extraction optimisation with practical food-system validation and to assess flavonoid stability in complex fermentation matrices.