All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Many pharmaceutical products have been reported to be substandard and counterfeit. About 15% of a... more Many pharmaceutical products have been reported to be substandard and counterfeit. About 15% of all drugs circulating in some parts of Africa and Asia are believed to be counterfeit, with figures rising to as high as 50%. This study was therefore carried out to assess the quality of five groups of drugs of different brands manufactured by pharmaceutical companies in Nigeria. Qualitative and quantitative analysis were carried out on the drugs using United States, British and Indian Pharmacopoeias. Qualitative analysis investigated includes: friability test, hardness test, disintegration test, dissolution test, pH, and weight uniformity for tablets; specific gravity, flow rate, pH and weight per ml of syrups. The quantitative analysis includes percentage purity and drug assay determination for different constituents using titrimetric, spectrophotometric and high performance liquid chromatographic (HPLC) methods. From the study, it was established that the Nigeria brands of pharmaceuti...
Conducting and electroactive nanostructured poly(2, 5-dimethoxyaniline), PDMA, doped with anthrac... more Conducting and electroactive nanostructured poly(2, 5-dimethoxyaniline), PDMA, doped with anthracene sulphonic acid, ASA, and phenanthrene sulphonic acid, PSA, respectively, were prepared by oxidative polymerisation of 2, 5-dimethoxyaniline, DMA, with ammonium persulphate as oxidant. Scanning electron microscope, SEM, images of the polymers showed well defined nanotubes and fibrils with diameters of between 50 to 100 nm and 200 to 300 nm for PDMA-ASA and PDMA-PSA, respectively. Evidence of the incorporation of ASA and PSA into the PDMA backbone was provided by UV-Vis and FTIR analyses. Electrochemical interrogation of the sulphonic acid-doped polymers by cyclic voltammetry showed that both PDMA-ASA and PDMA-PSA exhibit quazi-reversible electrochemistry. The standard rate constant, ko, for the charge transfer reactions of PDMA-ASA and PDMA-PSA were 3.81 x 10-4 cm s-1 and 3.27 x 10-5 cm s-1, respectively. There was a relationship between the ko value and the formal potential, E0ʹ, of the polymeric nanomaterial. PDMA-ASA that had larger ko value gave an E0ʹ value of 134 mV which was lower than that of PDMA-PSA by 19 mV, indicating that PDMA-ASA has lower activation energy than PDMA-PSA for the electron transfer process Electrochemical impedance spectroscopy over a range of potentials showed that the polymeric nanotubues exhibited high conductivities, though the SA-doped polymer was more conducting.
Journal of Environmental Science and Health, Part A, 2013
A five-step sequential extraction (SE) procedure was used to investigate the leaching behaviour a... more A five-step sequential extraction (SE) procedure was used to investigate the leaching behaviour and geochemical partitioning of the trace elements As, Zn, Pb, Ni, Mo, Cr and Cu in a 20-year-old fly ash (FA) dump. The weathered FA, which was hydraulically co-disposed with salt laden brine in slurry form (FA: brine ratio of 1:5), was analyzed and compared with fresh FA. The weathered FA samples were collected from three cores, drilled at a coal-fired power station in the Republic of South Africa while the fresh FA sample was collected from the hoppers in the ash collection system at the power station. The FA samples were sequentially leached using: ultrapure water; ammonium acetate buffer solution (pH 7); ammonium acetate buffer solution (pH 5); hydroxylamine hydrochloride in nitric acid (pH 2) and finally the residues were digested using a combination of HClO4: HF: HNO3 acids. Digestion of as received (unleached) FA samples was also done using a combination of HClO4: HF: HNO3 acids in order to determine the total metal content. The trace element analysis was done using ICP-OES (Varian 710-ES). The SE procedure revealed that the trace elements present in the fresh FA and the weathered FA samples obtained from the three cores could leach upon exposure to different environmental conditions. The trace elements showed continuous partitioning between five geochemical phases i.e., water soluble fraction, exchangeable fraction, carbonate fraction, Fe and Mn fraction and residual fraction. Although the highest concentration of the trace elements (ranging 65.51%-86.34%) was contained in the residual fraction, a considerable amount of each trace element (ranging 4.42%-27.43%) was released from the labile phases (water soluble, exchangeable and carbonate fractions), indicating that the trace species readily leach from the dumped FA under environmental conditions thus pose a danger to the receiving environment and to groundwater.
Abstract The polymerization of pyrrole in β-naphthalene sulfonic acid (NSA) gave nanotubules, nan... more Abstract The polymerization of pyrrole in β-naphthalene sulfonic acid (NSA) gave nanotubules, nanomicelles or nanosheets of polypyrrole (PPy) depending on the amount of NSA in the polymer and the temperature of the reaction. Scanning electron microscopy (SEM) ...
The hazardous elements associated with various physicochemical forms in coal fly ash are of envir... more The hazardous elements associated with various physicochemical forms in coal fly ash are of environmental concern due to their leaching potential and subsequent contamination of surface and groundwater in the vicinity of the ash dump. Selective sequential extraction was performed on dry disposed fly ash samples from a coal-fired power station in Mpumalanga province, South Africa. The alteration of the chemical, morphological and mineralogical species of weathered fly ash during the selective sequential extraction was investigated using X-ray fluorescence (XRF), Nano-scan electron microscopy (NANOSEM) and X-ray powder diffraction (XRD). Insoluble residue from the water-soluble fraction is composed of amorphous alumino-silicate. The residues from exchangeable carbonate and Fe and Mn fractions consisted mostly of amorphous alumino-silicate spheres with a lesser quantity of iron-rich spheres. The iron-rich spheres are surrounded by amorphous alumino-silicate spheres. The leaching behav...
The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-W... more The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-West Nigeria were evaluated and compared using ion exchange chromatography. The vegetables studied were: Talinium triangulare (gbure), Basella alba (amunututu), Telfaria occidentalis (ugwu), Occium gratissimum (efinrin), Corchorus olitorius (ewedu), Solanum macrocarpon (igbagba), Vernonia amyldalina (ewuro), Amaranthus cruenthus (arowojeja), Solanecio biafrae (worowo), and Cnidoscolus aconitifolius (iyana ipaja).Amongst the seventeen amino acids investigated in the vegetables, aspartic acid was highest in concentration with an average concentration of 10.91 g/100g of crude protein (cp) while cysteine was lowest (with an average of 0.602 g/100g (cp) on a dry weight basis, the leaves that contained the highest total amino acids (TAA) was Telfaria occidentalis (72.55 g/100g) of crude protein (cp) followed by Solanecio biafrae (72.47 g/100g)cp with Vernonia amygdalina being the lowest (63.59g...
The bark of some medicinal trees (Alstonia boonei, Pycnanthus angolensis, Anacardium occidentale,... more The bark of some medicinal trees (Alstonia boonei, Pycnanthus angolensis, Anacardium occidentale, Mangifera indica, Khaya iroresis, Nauclea diderichii, Morinda lucida and Bridelia micrantha) found in Nigeria were analysed for mineral composition and phytochemical screening. The mineral composition were determined and found to contain some elements such as sodium, potassium, calcium, magnesium, zinc, iron, copper, manganese, lead and phosphorous in high concentrations. The result of the phytochemical study revealed presence of alkaloids, saponins, tannins, steroids, phlobatanin, terpenoids, flavonoids and cardiac glycoside in most of the samples. The percentages of tannin (1.75 to 3.32); saponin (2.58 to 4.11) and flavonoid (1.86 to 4.13) were generally high in all the samples studied with M. lucida having the highest value for tannin (3.32%) and flavonoid (4.13%). The presence of these phytochemicals in the result is an attestation that the trees are potentially medicinal. The data ...
The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-W... more The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-West Nigeria were evaluated and compared using ion exchange chromatography. The vegetables studied were: Talinium triangulare (gbure), Basella alba (amunututu), Telfaria occidentalis (ugwu), Occium gratissimum (efinrin), Corchorus olitorius (ewedu), Solanum macrocarpon (igbagba), Vernonia amyldalina (ewuro), Amaranthus cruenthus (arowojeja), Solanecio biafrae (worowo), and Cnidoscolus aconitifolius (iyana ipaja).Amongst the seventeen amino acids investigated in the vegetables, aspartic acid was highest in concentration with an average concentration of 10.91 g/100g of crude protein (cp) while cysteine was lowest (with an average of 0.602 g/100g (cp) on a dry weight basis, the leaves that contained the highest total amino acids (TAA) was Telfaria occidentalis (72.55 g/100g) of crude protein (cp) followed by Solanecio biafrae (72.47 g/100g)cp with Vernonia amygdalina being the lowest (63.59g...
As an innovative therapeutic strategy, drug repurposing affords old, approved, and already establ... more As an innovative therapeutic strategy, drug repurposing affords old, approved, and already established drugs a chance at new indications. In the wake of the COVID-19 pandemic and the accompanied urgency for a lasting treatment, drug repurposing has come in handy to stem the debilitating effects of the disease. Among other therapeutic options currently in clinical trials, chloroquine (CQ) and the hydroxylated analogue, hydroxychloroquine (HCQ) have been frontline therapeutic options in most formal and informal clinical settings with varying degrees of efficacy against this life-threatening disease. Their status in randomized clinical trials is related to the biochemical and pharmacological profiles as validated by in vitro, in vivo and case studies. With the aim to bear a balance for their use in the long run, this review not only synopsizes findings from recent studies on the degrees of efficacy and roles of CQ/HCQ as potential anti-COVID-19 agents but also highlights our perspectiv...
Introduction: The World Health Organization (WHO) has recently declared the outbreak and spread o... more Introduction: The World Health Organization (WHO) has recently declared the outbreak and spread of the new strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) a global pandemic. In this regard, a lot of scientific investigations and clinical trials on some existing antiviral and antibiotic drugs have been ongoing to combat this menace. Methods: In the past, conventional drug therapy has shown irregular drug distribution, poor solubility, and low permeability to target cells, organs, and tissues. However, Chloroquine, Hydroxychloroquine Remdesivir, Lopinavir/Ritonavir, etc. have attracted several investigations in mono-therapeutic approaches and a combination of therapy have shown promising effects in reducing viral loading in some SARS-CoV-2 infected patients. Never the less, the advent of nanomedicine has triggered serious attention on drug-loaded nanoparticle as nanocarriers to deliver bioactive drug molecules to target organs with increased circulation and cont...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Many pharmaceutical products have been reported to be substandard and counterfeit. About 15% of a... more Many pharmaceutical products have been reported to be substandard and counterfeit. About 15% of all drugs circulating in some parts of Africa and Asia are believed to be counterfeit, with figures rising to as high as 50%. This study was therefore carried out to assess the quality of five groups of drugs of different brands manufactured by pharmaceutical companies in Nigeria. Qualitative and quantitative analysis were carried out on the drugs using United States, British and Indian Pharmacopoeias. Qualitative analysis investigated includes: friability test, hardness test, disintegration test, dissolution test, pH, and weight uniformity for tablets; specific gravity, flow rate, pH and weight per ml of syrups. The quantitative analysis includes percentage purity and drug assay determination for different constituents using titrimetric, spectrophotometric and high performance liquid chromatographic (HPLC) methods. From the study, it was established that the Nigeria brands of pharmaceuti...
Conducting and electroactive nanostructured poly(2, 5-dimethoxyaniline), PDMA, doped with anthrac... more Conducting and electroactive nanostructured poly(2, 5-dimethoxyaniline), PDMA, doped with anthracene sulphonic acid, ASA, and phenanthrene sulphonic acid, PSA, respectively, were prepared by oxidative polymerisation of 2, 5-dimethoxyaniline, DMA, with ammonium persulphate as oxidant. Scanning electron microscope, SEM, images of the polymers showed well defined nanotubes and fibrils with diameters of between 50 to 100 nm and 200 to 300 nm for PDMA-ASA and PDMA-PSA, respectively. Evidence of the incorporation of ASA and PSA into the PDMA backbone was provided by UV-Vis and FTIR analyses. Electrochemical interrogation of the sulphonic acid-doped polymers by cyclic voltammetry showed that both PDMA-ASA and PDMA-PSA exhibit quazi-reversible electrochemistry. The standard rate constant, ko, for the charge transfer reactions of PDMA-ASA and PDMA-PSA were 3.81 x 10-4 cm s-1 and 3.27 x 10-5 cm s-1, respectively. There was a relationship between the ko value and the formal potential, E0ʹ, of the polymeric nanomaterial. PDMA-ASA that had larger ko value gave an E0ʹ value of 134 mV which was lower than that of PDMA-PSA by 19 mV, indicating that PDMA-ASA has lower activation energy than PDMA-PSA for the electron transfer process Electrochemical impedance spectroscopy over a range of potentials showed that the polymeric nanotubues exhibited high conductivities, though the SA-doped polymer was more conducting.
Journal of Environmental Science and Health, Part A, 2013
A five-step sequential extraction (SE) procedure was used to investigate the leaching behaviour a... more A five-step sequential extraction (SE) procedure was used to investigate the leaching behaviour and geochemical partitioning of the trace elements As, Zn, Pb, Ni, Mo, Cr and Cu in a 20-year-old fly ash (FA) dump. The weathered FA, which was hydraulically co-disposed with salt laden brine in slurry form (FA: brine ratio of 1:5), was analyzed and compared with fresh FA. The weathered FA samples were collected from three cores, drilled at a coal-fired power station in the Republic of South Africa while the fresh FA sample was collected from the hoppers in the ash collection system at the power station. The FA samples were sequentially leached using: ultrapure water; ammonium acetate buffer solution (pH 7); ammonium acetate buffer solution (pH 5); hydroxylamine hydrochloride in nitric acid (pH 2) and finally the residues were digested using a combination of HClO4: HF: HNO3 acids. Digestion of as received (unleached) FA samples was also done using a combination of HClO4: HF: HNO3 acids in order to determine the total metal content. The trace element analysis was done using ICP-OES (Varian 710-ES). The SE procedure revealed that the trace elements present in the fresh FA and the weathered FA samples obtained from the three cores could leach upon exposure to different environmental conditions. The trace elements showed continuous partitioning between five geochemical phases i.e., water soluble fraction, exchangeable fraction, carbonate fraction, Fe and Mn fraction and residual fraction. Although the highest concentration of the trace elements (ranging 65.51%-86.34%) was contained in the residual fraction, a considerable amount of each trace element (ranging 4.42%-27.43%) was released from the labile phases (water soluble, exchangeable and carbonate fractions), indicating that the trace species readily leach from the dumped FA under environmental conditions thus pose a danger to the receiving environment and to groundwater.
Abstract The polymerization of pyrrole in β-naphthalene sulfonic acid (NSA) gave nanotubules, nan... more Abstract The polymerization of pyrrole in β-naphthalene sulfonic acid (NSA) gave nanotubules, nanomicelles or nanosheets of polypyrrole (PPy) depending on the amount of NSA in the polymer and the temperature of the reaction. Scanning electron microscopy (SEM) ...
The hazardous elements associated with various physicochemical forms in coal fly ash are of envir... more The hazardous elements associated with various physicochemical forms in coal fly ash are of environmental concern due to their leaching potential and subsequent contamination of surface and groundwater in the vicinity of the ash dump. Selective sequential extraction was performed on dry disposed fly ash samples from a coal-fired power station in Mpumalanga province, South Africa. The alteration of the chemical, morphological and mineralogical species of weathered fly ash during the selective sequential extraction was investigated using X-ray fluorescence (XRF), Nano-scan electron microscopy (NANOSEM) and X-ray powder diffraction (XRD). Insoluble residue from the water-soluble fraction is composed of amorphous alumino-silicate. The residues from exchangeable carbonate and Fe and Mn fractions consisted mostly of amorphous alumino-silicate spheres with a lesser quantity of iron-rich spheres. The iron-rich spheres are surrounded by amorphous alumino-silicate spheres. The leaching behav...
The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-W... more The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-West Nigeria were evaluated and compared using ion exchange chromatography. The vegetables studied were: Talinium triangulare (gbure), Basella alba (amunututu), Telfaria occidentalis (ugwu), Occium gratissimum (efinrin), Corchorus olitorius (ewedu), Solanum macrocarpon (igbagba), Vernonia amyldalina (ewuro), Amaranthus cruenthus (arowojeja), Solanecio biafrae (worowo), and Cnidoscolus aconitifolius (iyana ipaja).Amongst the seventeen amino acids investigated in the vegetables, aspartic acid was highest in concentration with an average concentration of 10.91 g/100g of crude protein (cp) while cysteine was lowest (with an average of 0.602 g/100g (cp) on a dry weight basis, the leaves that contained the highest total amino acids (TAA) was Telfaria occidentalis (72.55 g/100g) of crude protein (cp) followed by Solanecio biafrae (72.47 g/100g)cp with Vernonia amygdalina being the lowest (63.59g...
The bark of some medicinal trees (Alstonia boonei, Pycnanthus angolensis, Anacardium occidentale,... more The bark of some medicinal trees (Alstonia boonei, Pycnanthus angolensis, Anacardium occidentale, Mangifera indica, Khaya iroresis, Nauclea diderichii, Morinda lucida and Bridelia micrantha) found in Nigeria were analysed for mineral composition and phytochemical screening. The mineral composition were determined and found to contain some elements such as sodium, potassium, calcium, magnesium, zinc, iron, copper, manganese, lead and phosphorous in high concentrations. The result of the phytochemical study revealed presence of alkaloids, saponins, tannins, steroids, phlobatanin, terpenoids, flavonoids and cardiac glycoside in most of the samples. The percentages of tannin (1.75 to 3.32); saponin (2.58 to 4.11) and flavonoid (1.86 to 4.13) were generally high in all the samples studied with M. lucida having the highest value for tannin (3.32%) and flavonoid (4.13%). The presence of these phytochemicals in the result is an attestation that the trees are potentially medicinal. The data ...
The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-W... more The amino acid distribution patterns of ten indigenous leafy vegetables commonly eaten in South-West Nigeria were evaluated and compared using ion exchange chromatography. The vegetables studied were: Talinium triangulare (gbure), Basella alba (amunututu), Telfaria occidentalis (ugwu), Occium gratissimum (efinrin), Corchorus olitorius (ewedu), Solanum macrocarpon (igbagba), Vernonia amyldalina (ewuro), Amaranthus cruenthus (arowojeja), Solanecio biafrae (worowo), and Cnidoscolus aconitifolius (iyana ipaja).Amongst the seventeen amino acids investigated in the vegetables, aspartic acid was highest in concentration with an average concentration of 10.91 g/100g of crude protein (cp) while cysteine was lowest (with an average of 0.602 g/100g (cp) on a dry weight basis, the leaves that contained the highest total amino acids (TAA) was Telfaria occidentalis (72.55 g/100g) of crude protein (cp) followed by Solanecio biafrae (72.47 g/100g)cp with Vernonia amygdalina being the lowest (63.59g...
As an innovative therapeutic strategy, drug repurposing affords old, approved, and already establ... more As an innovative therapeutic strategy, drug repurposing affords old, approved, and already established drugs a chance at new indications. In the wake of the COVID-19 pandemic and the accompanied urgency for a lasting treatment, drug repurposing has come in handy to stem the debilitating effects of the disease. Among other therapeutic options currently in clinical trials, chloroquine (CQ) and the hydroxylated analogue, hydroxychloroquine (HCQ) have been frontline therapeutic options in most formal and informal clinical settings with varying degrees of efficacy against this life-threatening disease. Their status in randomized clinical trials is related to the biochemical and pharmacological profiles as validated by in vitro, in vivo and case studies. With the aim to bear a balance for their use in the long run, this review not only synopsizes findings from recent studies on the degrees of efficacy and roles of CQ/HCQ as potential anti-COVID-19 agents but also highlights our perspectiv...
Introduction: The World Health Organization (WHO) has recently declared the outbreak and spread o... more Introduction: The World Health Organization (WHO) has recently declared the outbreak and spread of the new strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) a global pandemic. In this regard, a lot of scientific investigations and clinical trials on some existing antiviral and antibiotic drugs have been ongoing to combat this menace. Methods: In the past, conventional drug therapy has shown irregular drug distribution, poor solubility, and low permeability to target cells, organs, and tissues. However, Chloroquine, Hydroxychloroquine Remdesivir, Lopinavir/Ritonavir, etc. have attracted several investigations in mono-therapeutic approaches and a combination of therapy have shown promising effects in reducing viral loading in some SARS-CoV-2 infected patients. Never the less, the advent of nanomedicine has triggered serious attention on drug-loaded nanoparticle as nanocarriers to deliver bioactive drug molecules to target organs with increased circulation and cont...
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Papers by Dr Richard Akinyeye