Department of Chemistry and Industrial Chemistry

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A cocrystallised Cobalt(II) Cluster of Pyridinedicarboxylic Acid (PDC) as a Luminescent Material for Selective Sensing of Methanol
(2021)
A rapid reversed-phase thin layer chromatographic detection protocol for adulteration in some edible fats and oils food formulation
(Federal University of Technology, Minna, 2021-05-24) Mustapha A.O, Adepoju, R.A, Fadipe V.O
The problems of adulteration in the vegetable oil and fat have been the major draw backs in the food products formulation, in spite of the various adulteration detection methods in different applications that have been reported. However, the detection tools that can be fast and reliable for the routine analysis necessitated the current work. The two groups of three different samples: vegetable fat containing sample (Blue Band, Golden Penny, La Prairie Classic) and animal fat containing samples (Kell Salad Cream, Crosse & Blackwell and Nola) was used for the purity check using the reversed phased - thin layer chromatographic (RPTLC) method of analysis were developed. The average Rf ratio of 0.95 and 0.92, found for the vegetable and animal fat groups were reported, respectively. The Rf = 0.03 difference between the two groups indicated the presence of sistosterol (plant sterol) and cholesterol (animal sterol), an improvement over color detection methods to screen oils and fats to ascertain purity.
A zinc-based coordination polymer as adsorbent for removal of trichlorophenol from aqueous solution: Synthesis, sorption and DFT studies
(2022) Adetola C. Oladipo, Adedibu C. Tella, Hadley S. Clayton, Victoria T. Olayemi, Oghenerobor B. Akpor, Tendai O. Dembaremba, Adeniyi S. Ogunlaja, Guy J. Clarkson, Richard I. Walton
[Z n ( hba ) 2 ( tmdp )] n ( 1 ), a Zn-coordination polymer (CP), prepared by the reaction of Zn(NO 3 )2 •6H 2 O, 4- hydroxybenzoic acid (Hhba) and 4,4 - trimethylenedipyridine (tmdp) was reported. The compound was characterised, using CHN, single crystal and powder X-ray diffraction analysis, FT-IR, and TGA techniques. It exhibits a square pyramidal geometry, with the zinc (II) atom coordinated to two nitrogen atoms from two tmdp ligand molecules and to three oxygen atoms from two hba molecules. The zinc (II) carboxy- late units are bridged through the N-donor spacer ligand, thereby giving rise to a one-dimensional CP. PXRD analysis confirmed the purity of the bulk of ( 1 ) . Compound ( 1 ) presented an adsorption capac- ity of 207.8 mg/g for the removal of 2,4,6-trichlorophenol (TCP) from aqueous solution. The adsorption mechanism is governed by π- πstacking and electrostatic interactions, as obtained from DFT studies. The feasibility and exothermic nature of the adsorption process is indicated by the negative binding energy obtained.
ACIDIC LEACHING OF IRON FROM KAOJE GOETHITE ORE BY HYDROCHLORIC ACID: KINETICS MODELLING
(Nigerian Journal of Technology (NIJOTECH), 2020) K. I. Ayinla*, A. A. Baba, S. Girigisu, O. S. Bamigboye, B. C. Tripathy, A. S. Ibrahim and S. O. Azeez
Considering the recent focus of the Nigeria Government to grow and develop the nation’s economy through the solid minerals sector reform, this study has been devoted to the kinetics of a Nigerian goethite ore by hydrochloric acid leaching for improved iron and steel industries applications. This study was performed in three different phases. In the first phase, acidic leaching of iron from a goethite ore was examined and the influence of the operating variables including: HCl concentration, leaching temperature, stirring speed and particle sizes was examined experimentally. The optimum condition was found to be HCl concentration of 1.81M, temperature of 80°C, 200 rpm stirring speed and particle size 0.09 µm for iron in the range of investigated parameters. Under those conditions, the highest iron recovery was obtained to be 95.67 %. In the second phase, the dissolution kinetics of iron was evaluated by the shrinking core models. The finding reveals that diffusion through the fluid was the leaching kinetics rate-controlling step of the iron. The activation energy (Ea) was found to be 14.54 kJmol-1 for iron. Equation representing the leaching kinetic of iron was achieved to be 1−2/3α - (1 − x)2/3 = 0.7272 × e−38.29/8.314×T × t. The final stage of the experiment was carried out by characterizing the leached residues by X-ray diffractometer (XRD) and scanning electron microscopy (SEM), the result showed majorly the presence of rutile (TiO2), anglesite (PbSO4), and traces of iron-silicate face like pyrite (FeS), quartz (SiO2)
Adsorption of Cr (VI) ion from Aqueous Solution Using Unmodified Desert Date Peels (Balanites aegyptiaca) Composite with MWCNTs: Isotherm and Kinetic Studies
(Arid Zone Journal of Basic and Applied Research, 2022-12-26) Alkali, M.I., Abdus-Salam, N., Bello, M.O., Musa, M.O., Jimoh, A.A., Dikwa, M.K. and Abdullahi, M.M
Continuous Changing of human lifestyles has consistently added different notorious anthropogenic pollutants into aquatic matrices. Exterminating these toxic pollutants is feasible using adsorption studies instead of the traditional water purification methods. The purpose of this study was to investigate the adsorption of Cr (VI) ion from aqueous using Unmodified Desert Date (UDD) Peels as a low-cost adsorbent and composite with multi-walled carbon nanotubes (UDDC). A batch adsorption experiment was conducted to evaluate the maximum quantity adsorbed of Cr (VI) ions from an aqueous medium under various conditions. The Fourier-Transform Infrared Spectroscopy (FTIR) revealed 3448.84 cm-1 and 3441.12 cm-1 which corresponds to O-H stretching vibration modes for UDD and UDDC and 1620.26 cm-1 relates to C=O stretching vibrations for both UDD and UDDC respectively. The maximum adsorption capacity (qe ) is found to be 114.11 and 741.14 (mg/g) for UDD and UDDC respectively. The results showed that UDDC has a large adsorption capacity due to its higher surface area. The adsorption data were fitted well into Langmuir with correlation coefficient (R2 ) values close to unity 0.9076 and 0.9069 for UDD and UDDC respectively. Kinetic studies showed a good correlation coefficient pseudo-second-order kinetic model fitted very well into UDD and UDDC with (R2 ) values 0.9173 and 0.9943 respectively. The results indicated that UDDC could be used as a potential adsorbent for the adsorption of Cr (VI) ions from an aqueous solution
Adsorption of Mn(II) and Co(II) ions from aqueous solution using Maize cob activated carbon: Kinetics and Thermodynamics Studies
(2015-12-28) ADEBAYO, GB; ADEGOKE, HI; JAMIU, W; BALOGUN, BB; JIMOH AA
The adsorption of Mn(II) and Co(II) ions from aqueous solution was investigated using batch adsorption experiment at room temperature. The effect of pH, contact time, metal ion concentration and temperature were evaluated. The residual concentrations of the metal ions were determined by atomic absorption spectrophotometer. The results showed that maximum removal of Mn(II) and Co(II) ions occurred at pH 9. Some physico-chemical and spectroscopic characterization of the adsorbents were done such as moisture content, ash content, bulk density, volatile matter, iodine number, point of zero charge (PZC), XRF, and FTIR. The moisture and ash content of MCAC adsorbent were found to be 9.85±0.06 and 5.5±0.1% respectively. The bulk density was found to be 0.37±0.01g/m3, iodine number of 367.66±30 mg/g and PZC of 6.8. The SEM micrograph shows particle grains and jelly like rough surfaces, FTIR analysis results show different functional group in the MCAB adsorbent such as O-H, C=O, and C=C stretching. Kinetic study shows that the pseudo-second order kinetic model best described the adsorption of metal ions. The equilibrium data fitted Langmuir, Freundlich and Temkin adsorption isotherms, in each case, the Langmuir model appears to have better regression coefficients than the Freundlich and Temkin. Thermodynamics investigation showed that Gibb’s free energy change ( ) was negative indicating that the adsorption of Mn(II) and Co(II) ions by maize cob activated carbon were feasible and spontaneous. The positive value of enthalpy change ( ) implies that the reaction was endothermic while positive value of entropy change ( ) implies an irregular increase in the randomness at the solid/solution interface of the adsorbent during the adsorption process.
Adsorption of p-Phenylenediamine onto Activated Carbon Prepared from Jatropha curcas and Terminalia catappa Seed Coats
(2016)
This research work is concerned with the applicability of sodium hydroxide-activated carbon prepared from Jatropha curcas seed coats and Terminalia catappa seed coats in the removal of p-phenylenediamine (PPD), a component of hair dye industrial effluent. The surface characteristics of the prepared activated carbons were examined using Scanning Electron Microscopy (SEM), Brunauer- Emmett-Teller (BET) surface area analysis and Fourier Transform Infrared Spectroscopy (FTIR). The influence of various factors such as initial concentration, pH, contact time, adsorbent dose and temperature were studied and the p-phenylenediamine adsorption capacity was found to be 32.4 mg/g and 45.5 mg/g for Jatropha activated carbon (JAC) and Terminalia activated carbon (TAC), respectively. The experimental data were analysed using Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The data could be fitted successfully for both systems by the Langmuir and Freundlich isotherms. The data show also that the sorption process is exothermic and that it follows pseudo second order kinetics.
Adsorption of p-Phenylenediamine onto Activated Carbon Prepared from Jatropha curcas and Terminalia catappa Seed Coats
(2016) Saheed, Ismaila Olalekan; Adekola, Folahan Amoo; Olatunji, Gabriel Ademola
This research work is concerned with the applicability of sodium hydroxide-activated carbon prepared from Jatropha curcas seed coats and Terminalia catappa seed coats in the removal of p-phenylenediamine (PPD), a component of hair dye industrial effluent. The surface characteristics of the prepared activated carbons were examined using Scanning Electron Microscopy (SEM), Brunauer- Emmett-Teller (BET) surface area analysis and Fourier Transform Infrared Spectroscopy (FTIR). The influence of various factors such as initial concentration, pH, contact time, adsorbent dose and temperature were studied and the p-phenylenediamine adsorption capacity was found to be 32.4 mg/g and 45.5 mg/g for Jatropha activated carbon (JAC) and Terminalia activated carbon (TAC), respectively. The experimental data were analysed using Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The data could be fitted successfully for both systems by the Langmuir and Freundlich isotherms. The data show also that the sorption process is exothermic and that it follows pseudo second order kinetics.
Adsorption of Pb (II) ion onto Modified Doum Palm (Hyphaene thebaica) Shells: Isotherm, Kinetic and Thermodynamic Studies
(Arid Zone Journal of Basic and Applied Research, 2022-12-25) Alkali, M.I., Abdus-Salam, N., Dikwa, M.K., Oyewumi-Musa, R.T., Jimoh, A.A., Ojo, I. and John, G
The negative impact of high concentrations of lead in the analytical environment on humans and aquatic plants prompted this research. The adsorption of hazardous lead from an aqueous medium using a Modified Doum Palm (MDP) shell was investigated. The modification of the Doum palm shell was supported via 2 M 1: 2 ZnCl2 as activating agent. The batch equilibrium technique was employed to study the effect of initial concentration (800 mg/L), contact time (90 min) and temperature (313 K) on the adsorption capacity of the prepared adsorbent. Experimental data were analyzed using four kinetic models: pseudo-first-order, pseudo-second order, intra-particle diffusion and Elovich models and it was found that the pseudo-second-order model fitted the adsorption data most with the highest correlation (R2 = 0.9875). The studies of thermodynamic behaviour revealed negative values for ∆Go (-26.7036 to -28.1252 kJ/mol), and negative values for ∆Ho (-15.5796 kJ/mol) and ∆So (0.03554 kJ/mol/k) respectively. These indicated the adsorption process was exothermic, feasible and spontaneous in the removal of the Pb (II) ion. The findings demonstrated that the adsorbent could be exploited in the removal of Pb (II) ion from an aqueous solution
Aflatoxin - control, analysis, detection and health risks
(InTech Open, 2017-09-01) Abdulrauf, L. B.
Aflatoxins are a group of highly toxic and carcinogenic substances, which occur naturally, and can be found in food substances. Aflatoxins are secondary metabolites of certain strains of the fungi Aspergillus flavus and A. parasiticus and the less common A. nomius. Aflatoxins B1, B2, G1, and G2 are the most important members, which can be categorized into two groups according to the chemical structure, namely, difurocoumarocyclopentenone series and ifurocoumarolactone. Of the 20 aflatoxins identified so far, only aflatoxins B1, B2, G1, and G2 are known to occur naturally and B and G classes refer to the blue and green fluorescence emitted by their metabolites under ultraviolet (UV) light, and the subtype 1 and subtype 2 imply the major and minor compounds, respectively. Aflatoxins fluoresce strongly under UV radiation (ca. 365 nm). The most common food commodities affected by aflatoxins are cereals (corn, wheat, barley, maize, oats, and rye), nuts (hazelnut, peanut, and pistachio nut), dried fruits (fig), and spices (chili powder). Aflatoxins pose a potential threat to human and animal health through the consumption, contact, or inhalation of foodstuffs and feedstuffs prepared from these commodities. As a result of the adverse health effects of mycotoxins, their levels have been strictly regulated especially in food and feed samples. Therefore, their accurate identification and determination remain a Herculean task due to their presence in complex food matrices. The great public concern and the strict legislation incited the development of reliable, specific, selective, and sensitive analytical methods for mycotoxins monitoring that are discussed in this book. The book comprises 12 chapters. Chapters 1 to 4 discuss the control and prevention of aflatoxin contaminations in foods, and Chapters 5 to 10 discuss the health risk posed by aflatoxin contaminations in food, while Chapters 11 and 12 discuss the new development in the analysis and detection of aflatoxins in food samples. The book contains up-to-date publications of leading experts, and, therefore, it is hoped that the reference cited by various authors will be a starting point to acquire a deeper knowledge on the prevention, control, identification, and determination of aflatoxins in foods and feedstuffs. I gratefully acknowledge the efforts and expertise of the contributing authors for their time and efforts in preparing the chapters and for their interest in the book project. I am indebted to the vice chancellor of Kwara State University, Malete, Ilorin, Nigeria, Prof. Abdul Rasheed Na’Allah and all the academic staff of the Department of Chemistry for the support and encouragement. I also acknowledge the support of my wife (Mrs. Rihanat Abdulra’uf), my children, and my colleagues at the School of Basic and Remedial Studies, Kwara State College of Education, Ilorin, Nigeria, for their unwavering support and encouragement during the chapter review process. My special appreciation and thanks go to the editorial team and publishing manager of InTechOpen Publisher for their promptness, encouragement, and patience during the review and publication process. Dr. Lukman Bola Abdulra’uf Department of Chemistry, College of Pure and Applied Sciences, Kwara State University, Malete, Nigeria
Aflatoxins - Occurrence, Detoxification, Determination and Health Risks
(2022-06-05) Abdulra’uf, Lukman Bola
Alternative method of reducing sugars determination in some selected fizzy drinks and fruits by chromic acid reagent
(Alternative method of reducing sugars determination in some selected fizzy drinks and fruits by chromic acid reagent, 2020-04-30) Mustapha, Aliru Olajide
Chromic acid reagent as an alternative colorimetric method for the quantitative determination of reducing sugars and ascorbic acid in some selected fizzy drinks: Seven Up, Limca, Mirinda, Cocoa-Cola, Fanta, Pepsi Cola, Maltina, Guinness Malt, Hi-Malt and Maltonic) and fruits: pineapple (Ananas cosmoses), sweet orange (Cimifi sinensis), grape fruit (Dints paradise) and tangerine (Citrus reticulate) has been studied. Chromic method involves sugar solution of about 1% concentration. treated with an equal volume of concentrated nitric acid and a few drops of a 5% solution of potassium dichromate was added, a blue colour develops in less than a minute in the cold and the absorbance taken in a Spectronic 20D Spectrophotometer at 560 um. Results obtained from the simple chromic acid as test method compares well with those obtained from the titrimetric methods of Association of Official Analytical Chemists (AOAC, 2012) and Pearson (1991) as control, with negligible variations. Apart from being a very powerful oxidizing agent, its reaction with monosaccharide, disaccharides and ascorbic acid are less-time consuming, showed distinct colour development and its easy preparation, made chromic acid reagent a faster, better and suitable alternative method for the quantitative determination of reducing sugars and ascorbic acid in routine analyses of foods.
Amphetamines analysis in wastewaters – method performance of solid phase extraction-higher performance liquid chromatography mass spectrometry techniques (SPE-HPLC MS/MS).
(Leibniz Research Centre for Working Environment and Human Factors., 2011-08-19) Mustapha, A.O. and Usman L.A
Recently, many articles have reported different levels and distribution of amphetamine hither-to detected in biological fluids now appreciably found in aquatic environment at ng/L levels. Identification and measurement of amphetamine and its metabolites in surface and sewage waters using higher performance liquid chromatographic methodologies in the literatures now on current trend have provided information that are of scientific interest and effectively re-placed immunological methods which only suggest the presence of these substances. Active research on both distribution and impacts of this important drug of abuse and related metabo-lites in the wastewaters are on-going.
Analysis of some illicit drugs and abused pharmaceuticals in municipal wastewaters (effluents).
(Federal University of Technology, Lafia, 2019-06-20) Mustapha, Aliru Olajide
A study of myriads of chemical pollutants in aquatic environment was carried out from the effluent of Nottingham Sewage Treatment Works (STWs) in United Kingdom. Using a solid phase extraction - gas chromatography technique (SPE-GCMS), fifteen compounds detected in sampled STW effluents ranged between 1.1 - 33.5 ng L-1 with percentage recoveries of 78.6 – 97.8%. The most abundant compounds found in the final effluent were nicotine, ibuprofen, codeine, ephedrine, procaine, benzoylecgonine, lidocaine, and caffeine, with mean concentrations of 21.4 ± 6.4, 16.7± 4.8, 15.1 ± 6.3, 10.1 ± 3.9, 9.1 ± 3.4, 5.6 ± 3.1, 5.3 ± 5.2 and 5.2 ± 1.9 ng L-1, respectively. The instrumental limits of detection (LODs) from 0.1 – 1.7 ng L-1, with standard deviations (STDs) of 1.1– 21.4% for all the compounds were also observed. The levels of illicit drugs and abused pharmaceuticals detected from the effluents showed the occurrence of these drugs and the Nottingham STW as one of the main transport routes to the receiving environment. These findings have further shown that chemicals in effluent get to the environment due to their incomplete removal from the STW. Persistence influx of these pollutants into the aquatic environment may have implication on ecosystems.
Anti-Diabetic Efficacy and Phytochemical Screening of Methanolic Leaf Extract of Pawpaw (Carica papaya) Grown in North Central Nigeria
(Turkish Chemical Society, 2017) Ayorinde Victor Ogundele, Kabir Opeyemi Otun, Abdulfatai Ajiboye, Bolatito E. Olanipekun and Rasheed Bolaji Ibrahim,
Carica papaya leaf samples (Green) were freshly harvested and dried for six consecutive days. The leaves were extracted with methanol; the resulting extracts were screened for the phytochemical constituents using a standard procedure. Phytochemical screening revealed the presence of bioactive compounds such as tannins, saponins, terpenoids, glycosides, and alkaloids. The in vitro anti-diabetic potential of the plant was also determined so as to justify the traditional usage of the plant in treating diabetes. The result of the present study confirmed that the methanolic extract of C. papaya leaves possess significant anti-diabetic activity in vitro, this shows that the leaves has the potential for the development of drugs in combating diabetes.
Anti-Diabetic Efficacy and Phytochemical Screening of Methanolic Leaf Extract of Pawpaw (Carica papaya) Grown in North Central Nigeria
(Turkish Chemical Society, 2017-10-14) Ogundele A, Otun K, Ajiboye A, Olanipekun B, Ibrahim R.
Carica papaya leaf samples (Green) were freshly harvested and dried for six consecutive days. The leaves were extracted with methanol; the resulting extracts were screened for the phytochemical constituents using a standard procedure. Phytochemical screening revealed the presence of bioactive compounds such as tannins, saponins, terpenoids, glycosides, and alkaloids. The in vitro anti-diabetic potential of the plant was also determined so as to justify the traditional usage of the plant in treating diabetes. The result of the present study confirmed that the methanolic extract of C. papaya leaves possess significant anti-diabetic activity in vitro, this shows that the leaves has the potential for the development of drugs in combating diabetes.
ANTI-HYPERGLYCEMIC AND ANTIOXIDANT POTENTIALS OF SOME BIOACTIVE COMPOUNDS IDENTIFIED FROM THE METHANOLIC KERNEL EXTRACT OF Anacadium ocidentale in vitro and in silico INVESTIGATIONS
(African journal online, 2022-07-27) S. A. Ahmed, A. T. Ajiboye, Y. A. Ibrahim, A. T. Olagunju, S. Salau & O. Adetunji
The phytochemical components of roasted kernel of cashew nut (Anacadium ocidentale), its antioxidant and anti-hyperglycemic potentials were investigated via in vitro and in silico. The roasted kernel of cashew nut was extracted in 95 % methanol. Using boron trifloride (10 % in 1 butanol), the extract was derivatized and the derivatized sample was analyzed using a Gas Chromatographic–Mass Spectrometry (GC-MS) method to establish its chemical constituents. Antioxidant potential was evaluated through 2, 2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2′ azino-bis-(3-ethyl benzothiazoline-6-sulphonic acid) (ABTS•+) radical scavenging assays. The anti-hyperglycemic potential of the crude methanol extract was investigated through α glucosidase assay. The results of phytochemical screening revealed the presence of phytochemicals such as phenols, glycosides, alkaloids, steroids, carbohydrate, flavonoids and terpenoids. Total numbers of 20 phytochemicals belonging to different classes of natural products were identified by GC-MS analysis. Carbonic acid, dodecyl vinyl ester (45.9 %) was found to be the major compound. Other compounds like N- serylserine, D- fructose, 3-0-methyl, β- Amyrone, β- Amyrin, Lupeol and 9- octadecenoic acid were also identified. The methanol extract of roasted cashew kernel showed highest DPPH scavenging activity (IC50 10 ± 0.001 µg/mL) which is statistically similar to positive controls, vitamin C and rutin (IC50 = 4 ± 0.001 and 1 ± 0.0001 µg/mL) and also exhibited moderate ABTS scavenging activity (IC50 = 14 ± 0.001 µg/mL) which is statistically significant as compared to positive controls, vitamin C (IC50 = 13 ± 0.01 µg/mL) and rutin (IC50 = 16 ± 0.001 µg/mL) respectively. The result of enzyme inhibition assay showed that the extract possesses highest anti-hyperglycemic potential against α-glucosidase with IC50 value (0.00024 ± 0.00002 µg/mL) compared to standard drug acarbose (IC50 = 0.417 ±0.021 µg/mL). The in silico techniques comprising the molecular docking, bioactivity and toxicity studies provides insight into the inhibitory properties, structure-activity-relationship predictions and drug-likeliness activities of the identified compounds. The research reveals the bioactive components present in the roasted kernel of cashew nut that can be utilized for its antioxidant and anti-hyperglycemic properties. Hence consumption of roasted cashew kernel could be beneficial for the treatment of diabetes mellitus and prevention of oxidative stress-related degenerative disorders.
ANTI-HYPERGLYCEMIC AND ANTIOXIDANT POTENTIALS OF SOME BIOACTIVE COMPOUNDS IDENTIFIED FROM THE METHANOLIC KERNEL EXTRACT OF Anacadium ocidentale in vitro and in silico INVESTIGATIONS
(2022) S. A. Ahmed, A. T. Ajiboye, Y. A. Ibrahim, A. T. Olagunju, S. Salau & O. Adetunji
Antioxidant and α-Glucosidase Inhibitory Activities of Phenolic Compounds Isolated from the Aerial Parts of Ampelocissus africanus
(Natural Product Research Group, Department of Pharmaceutical Chemistry Faculty of Pharmacy, University of Benin, Nigeria., 2021) 1. Lukman Mustapha, Ezekiel Garba, Umar U. Pateh, Bilqis A. Lawal, Bolatito E. Olanipekun, Florence Tarfa, Augustine A. Ahmadu
Ampelocissus africanus is an important medicinal plant with diverse ethnomedicinal uses. The purpose of this study was to investigate the antioxidant and α-glucosidase inhibitory activities of phenolic compounds isolated from the aerial parts of Ampelocissus africanus.Two known compounds were isolated using a combination ofcolumn and thin layer chromatography. The structures were elucidated usingUV and NMR spectroscopy. The antioxidant activity of the compounds was evaluated using 2,21-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays, while the antidiabetic potential was investigated using the α-glucosidase inhibition assay. Ascorbic acid and acarbose were used as standard and data obtained were expressed as mean ± SEM.The IC50 of the two compounds were calculated using a suitable regression analysis and graph pad prism software 6.0 using t-test.Compounds 1 and 2 were isolated as a yellow solids and identified as methyl gallate and quercetin, respectively. Result of the antioxidant assay using ABTS revealed that compound 1 gave a percentage inhibition of 98.22±0.79, while compound 2 gave 99.04±0.39% inhibition. The DPPH assay revealed inhibition at 59.38±3.23% and 63.45±2.56% for compounds I and 2, respectively. The values for DPPH assay were significantly different at p value <0.05 when compared to ascorbic acid. Compound 2 exhibited α-glucosidase inhibitory activity (IC50 4.02±0.37 μg/mL) though lower than acarbose (IC50 0.98± 0.57 μg/mL). Compound 1 however, showed weak α-glucosidase inhibitory activity with IC50>100μg/mL. These results might justify the ethnomedicinal uses of this plant in ameliorating metabolic disorder such as diabetes.
Antioxidant Capacity of Fractionated Extract and Structural Elucidation of Isolated Compounds from Leaf Extract of Hydrocotyl bonariensis Com. Exlam
(Taylor and Francis, 2017) 12. Emmanuel O Ajani, Saheed Sabiu, Mariam Zakari, Bolatito E. Olanipekun, Jacob K. Akintunde & Fisayo A Bamisaye
Hydrocotyl bonariensis is a plant which anticataractogenic potentials have been reported. In the present study an attempt was made to evaluate the in vitro antioxidant activity of the fractionates of the leaves extract and also characterize some of its chemical constituents. DPPH, H2O2, OH and NO free radical scavenging, metal chelating and reducing power activity was used to evaluate the antioxidant activity of the crude extract fractionates. Fresh leaves of H. bonariensis leaves were extracted in 70 % methanol. The extract was partitioned with different solvent system of increasing polarity (n-hexane, chloroform, ethyl acetate methanol and water). Compounds were isolated from the aqueous practitionate using accelerated gradient chromatography, vacuum liquid chromatography, preparative TLC and conventional column chromatography. The presence of the chemical groups was established with HPLC and Fourier Transform Infra Red. The structures of isolated compounds were elucidated by spectroscopic study and chemical shifts. Data from the study indicates that all the fractionates contain compounds with free radical scavenging activity. This activity was more pronounced in the aqueous fractionate (DPPH IC50, 0025 ± 0.011 mg/ml, metal chelating capacity 27.5 %, OH scavenging IC50, 0.846 ± 0.037 mg/ml, H2O2 scavenging IC50 0.521 ± 0.015 mg/ml, reducing power IC50 0.248 ± 0.025 mg/ml and NO scavenging IC50 0.537 ± 0.038 mg/ml). Two compounds were isolated and when compared with data from the literature; the structures were suggestive of polyphenolic flavonoid, quercetin and 3-O-β-D-glucopyranosyl-sitosterol. The result indicates that H. bonariensis leaves contain bioactive compounds with antioxidant activity.

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