International Journal of Chemistry

International Journal of Chemistry | Vol. 1, No. 4, April 2010 | pp. 26–34

DOI: 10.46882/2010/IJC/000004

Article Type: Original Research Paper

Title: Phytochemical Screening, Total Phenolic Content, and In Vitro Antioxidant Activities of Methanolic Extracts from Zingiber officinale Varieties

Names of Authors: Fatima B. Ibrahim¹, Suresh K. Patel²

Authors’ Affiliations:
¹Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria
²Department of Natural Products Chemistry, Indian Institute of Science, Bangalore, India

Abstract: Zingiber officinale (Ginger) is widely utilized globally as both a spice and a traditional medicine. This study evaluates and compares the quantitative phytochemical composition, total phenolic content (TPC), total flavonoid content (TFC), and in vitro antioxidant properties of methanolic extracts from two distinct ginger varieties: yellow ginger and white ginger. Quantitative screening revealed high concentrations of alkaloids, saponins, and terpenoids in both cultivars. TPC was determined using the Folin-Ciocalteu reagent and expressed as gallic acid equivalents (GAE). The TPC of yellow ginger (84.32 ± 1.45 mg GAE/g extract) was significantly higher than that of white ginger (62.15 ± 2.10 mg GAE/g extract). Similarly, the TFC was higher in the yellow variety (34.18 ± 0.85 mg quercetin equivalents [QE]/g) compared to the white variety (21.40 ± 1.12 mg QE/g). The antioxidant capacity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and Ferric Reducing Antioxidant Power (FRAP) assays. Yellow ginger displayed a superior DPPH radical scavenging activity with a lower IC50 value of 42.15 micro-g/mL, compared to white ginger which exhibited an IC50 of 65.80 micro-g/mL. A strong positive correlation (R² = 0.945) was observed between the total phenolic content and the antioxidant performance, validating that phenolic compounds are the primary drivers of antioxidant potential in these ginger varieties.

Keywords: Zingiber officinale, Phytochemicals, Phenolic content, Flavonoids, DPPH assay, Antioxidant activity

Manuscript Timeline: Received: January 10, 2010; Revised: February 18, 2010; Accepted: March 11, 2010; Published: April 02, 2010

International Journal of Chemistry | Vol. 1, No. 8, August 2010 | pp. 61–69

DOI: 10.46882/2010/IJC/000008

Article Type: Original Research Paper

Title: Heterogeneous Transesterification of Waste Cooking Oil into Biodiesel Using a Calcined Eggshell/Zeolite Catalyst Catalyst System

Names of Authors: Tunde J. Alao¹, Yuki Tanaka²

Authors’ Affiliations:
¹Department of Mechanical Engineering, Federal University of Technology, Minna, Nigeria
²Department of Applied Chemistry, Kyushu University, Fukuoka, Japan

Abstract: The high cost of refined vegetable oils limits the commercialization of biodiesel. Utilizing waste cooking oil (WCO) coupled with low-cost heterogeneous catalysts presents an economically attractive option. This study investigates the transesterification of WCO into biodiesel using a composite catalyst synthesized by loading calcined eggshell (CaO) onto a synthetic zeolite support. The catalyst was optimized and characterized using XRD, FTIR, and BET surface area measurements. The calcination of eggshells at 900 degrees Celsius generated highly active CaO particles, and their dispersion on zeolite increased the active surface area to 42.5 m²/g. The effects of molar ratio of methanol to oil (6:1 to 18:1), catalyst loading (2 to 8 wt%), reaction temperature (50 to 70 degrees Celsius), and time (1 to 5 hours) were studied. A maximum biodiesel yield of 96.4% was reached under the optimized conditions of a 12:1 methanol-to-oil molar ratio, 6 wt% catalyst loading, and a reaction temperature of 65 degrees Celsius within 3 hours. Fuel properties of the produced WCO methyl esters, including kinematic viscosity (4.2 mm²/s), flash point (164 degrees Celsius), and acid value (0.32 mg KOH/g), conformed strictly to the ASTM D6751 standards. The catalyst retained high stability and was reused up to five times with less than a 6% drop in yield.

Keywords: Biodiesel, Waste cooking oil, Transesterification, Heterogeneous catalyst, Eggshells, Zeolite

Manuscript Timeline: Received: May 10, 2010; Revised: June 22, 2010; Accepted: July 12, 2010; Published: August 04, 2010

International Journal of Chemistry | Vol. 1, No. 3, March 2010 | pp. 18–25

DOI: 10.46882/2010/IJC/000003

Article Type: Original Research Paper

Title: Electrochemical Evaluation of Mild Steel Corrosion Inhibition in Hydrochloric Acid Solution by Azadirachta indica Leaf Extract

Names of Authors: Chinedu J. Okafor¹, Amara L. Diallo², Jean-Pierre Dupont²

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Nigeria
²Laboratory of Materials Science, Universite de Robert Sorbonne, Paris, France

Abstract: The corrosion inhibition of mild steel in a 1.0 M HCl solution by the crude methanolic extract of Azadirachta indica (Neem) leaves was investigated using weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Weight loss experimental results indicated that inhibition efficiency increased with an increase in the concentration of the extract, reaching a maximum efficiency of 92.6% at an optimum concentration of 1000 mg/L after 24 hours of immersion at 298 K. Potentiodynamic polarization curves revealed that the extract acted primarily as a mixed-type inhibitor, retarding both anodic metal dissolution and cathodic hydrogen evolution reactions, with a slight predominant control over the cathodic reaction. EIS data showed that as the inhibitor concentration increased, the charge transfer resistance increased while the double-layer capacitance decreased, confirming the adsorption of phytochemical constituents onto the metal surface. The adsorption of the extract components on the mild steel surface obeyed the Langmuir adsorption isotherm. The calculated standard Gibbs free energy of adsorption (Delta G°ads) was -21.4 kJ/mol, indicating a spontaneous, physical adsorption mechanism. Scanning electron microscopy (SEM) surface analysis confirmed the formation of a protective organic film on the mild steel specimen, preventing acid attack.

Keywords: Corrosion inhibition, Mild steel, Azadirachta indica, Potentiodynamic polarization, EIS, Adsorption isotherm

Manuscript Timeline: Received: December 01, 2009; Revised: January 15, 2010; Accepted: February 02, 2010; Published: March 05, 2010

International Journal of Chemistry | Vol. 1, No. 2, February 2010 | pp. 9–17

DOI: 10.46882/2010/IJC/000002

Article Type: Original Research Paper

Title: Thermodynamic and Kinetic Studies on the Adsorption of Lead(II) Ions from Aqueous Solutions Using Modified Rice Husk Biochar

Names of Authors: Samuel T. Adebayo¹, Elena P. Vasilyeva²

Authors’ Affiliations:
¹Department of Industrial Chemistry, University of Ibadan, Ibadan, Nigeria
²Department of Environmental Chemistry, Saint Petersburg State University, Saint Petersburg, Russia

Abstract: Heavy metal contamination of water resources poses severe threats to ecological and human health. This study evaluates the efficacy of chemically modified rice husk biochar (MRHB), treated with 0.5 M phosphoric acid, for the removal of toxic Lead(II) [Pb²⁺] ions from synthetic wastewater. Batch adsorption experiments were conducted to optimize variables such as contact time, pH, temperature, and adsorbent dosage. The maximum adsorption capacity of MRHB for Pb²⁺ was determined to be 48.52 mg/g at an optimum pH of 5.5, which represents a three-fold increase compared to unmodified biochar. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models. The data fitted best to the Langmuir model (R² = 0.994), indicating monolayer adsorption on a homogenous surface. Kinetic studies revealed that the adsorption process strictly followed the pseudo-second-order kinetic model, suggesting chemisorption as the rate-limiting step. Thermodynamic parameters, including Gibbs free energy change (Delta G°), enthalpy change (Delta H°), and entropy change (Delta S°), were calculated. The negative values of Delta G° (-4.23 to -6.81 kJ/mol) and positive value of Delta H° (+12.45 kJ/mol) confirmed that the adsorption process was spontaneous and endothermic in nature. Desorption studies using 0.1 M HCl showed a recovery rate of 89.6% of adsorbed Pb²⁺, indicating excellent regenerability.

Keywords: Biochar, Rice husk, Adsorption, Lead removal, Wastewater treatment, Kinetics, Isotherms

Manuscript Timeline: Received: November 05, 2009; Revised: December 14, 2009; Accepted: January 08, 2010; Published: February 04, 2010

International Journal of Chemistry | Vol. 1, No. 6, June 2010 | pp. 43–51

DOI: 10.46882/2010/IJC/000006

Article Type: Original Research Paper

Title: Physicochemical Properties and Fatty Acid Profiles of Seed Oils Extracted from Non-Conventional Oilseeds in Western Nigeria

Names of Authors: Olumide S. Ayodele¹, Khadijah T. Bello¹

Authors’ Affiliations:
¹Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria

Abstract: Exploring underutilized non-conventional oilseeds is critical to reducing reliance on commercial oils for industrial and nutritional applications. This study characterizes the physicochemical properties and fatty acid profiles of crude seed oils extracted from three local species: Citrullus lanatus (Watermelon), Hura crepitans (Sandbox tree), and Blighia sapida (Ackee). Solvent extraction was carried out using n-hexane in a Soxhlet apparatus, yielding oil contents of 41.3%, 36.8%, and 28.5% for C. lanatus, H. crepitans, and B. sapida, respectively. Physicochemical analysis revealed peroxide values ranging between 2.14 and 4.80 meq O2/kg, indicating good oxidative stability. Saponification values were high (188.5 to 204.2 mg KOH/g), pointing toward applicability in soap manufacturing. Iodine values for C. lanatus (118.4 g I2/100g) and H. crepitans (126.8 g I2/100g) classified them as semi-drying oils, whereas B. sapida (74.2 g I2/100g) was classified as a non-drying oil. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of fatty acid methyl esters (FAME) indicated that linoleic acid (61.2%) was the predominant fatty acid in C. lanatus, while H. crepitans was dominated by linolenic acid (44.5%). Conversely, B. sapida was rich in oleic acid (55.4%). These profiles confirm the nutritional viability of C. lanatus oil and the high potential of H. crepitans oil for biodiesel synthesis.

Keywords: Non-conventional seed oil, Physicochemical analysis, Gas chromatography-mass spectrometry, Fatty acid methyl esters, Linoleic acid, Saponification

Manuscript Timeline: Received: March 22, 2010; Revised: April 25, 2010; Accepted: May 18, 2010; Published: June 03, 2010

International Journal of Chemistry | Vol. 1, No. 11, November 2010 | pp. 169–176

DOI: 10.46882/2010/IJC/000021

Article Type: Original Research Paper

Title: Isolation, Structural Elucidation, and Anti-inflammatory Properties of Triterpenoids from the Stem Bark of Khaya senegalensis

Names of Authors: A. A. Yusuf¹, M. T. Garba², S. O. Amupitan¹*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Pharmacology and Therapeutics, Ahmadu Bello University, Zaria, Nigeria.

Abstract: Khaya senegalensis is widely used in West African traditional medicine to manage deep inflammatory conditions, yet specific bioactive compounds responsible for this pathway require isolation. This study reports the extraction, isolation, and structural elucidation of anti-inflammatory triterpenoids from the stem bark of this plant. The dried, powdered bark was extracted using 70% methanol and sequentially fractionated with n-hexane, chloroform, and ethyl acetate. Chromatographic separation of the chloroform fraction over silica gel column chromatography yielded two pure crystalline compounds. Their molecular configurations were determined using mass spectrometry (MS), infrared (IR) spectroscopy, and one-dimensional and two-dimensional nuclear magnetic resonance (¹H-NMR, ¹³C-NMR, COSY, and HSQC) analysis. The isolated compounds were confirmed as methyl angolensate and 7-deacetylkhivorin. In vivo anti-inflammatory screening was conducted using the carrageenan-induced rat paw edema model, benchmarked against indomethacin (10 mg/kg). Oral administration of the isolated triterpenoids at 50 mg/kg significantly suppressed edema volume by 64.2% and 58.8% respectively, after 4 hours. The compounds reduced localized myeloperoxidase activities and lowered systemic tumor necrosis factor-alpha (TNF-alpha) expression, validating that these limonoid-type triterpenoids act as active anti-inflammatory drivers that substantiate the ethnopharmacological use of K. senegalensis.

Keywords: Khaya senegalensis; Limonoids; Triterpenoids; Structural elucidation; Nuclear magnetic resonance; Anti-inflammatory activity

Manuscript Timeline: Received: August 04, 2010; Revised: September 15, 2010; Accepted: October 08, 2010; Published: November 02, 2010.

Citation: Yusuf, A. A., Garba, M. T., & Amupitan, S. O. (2010). Isolation, Structural Elucidation, and Anti-inflammatory Properties of Triterpenoids from the Stem Bark of Khaya senegalensis. International Journal of Chemistry, 1(11), 169–176.