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A. Ocloo (BSc (Ghana), PhD (Cambridge) FCCS (UK))

A. Ocloo (BSc (Ghana), PhD (Cambridge) FCCS (UK))
Associate Professor (Dean)
aocloo@ug.edu.gh
2540

 

AREAS OF SPECIALIZATION /RESEARCH INTEREST

  • Mitochondria in health and diseases and pharmacotoxicologial properties of medicinal plants and herbal extracts

Mitochondria have long been recognized as the generators of energy for the cell. They are generally referred to as the cellular “power houses”. Like any other power source, mitochondrial dysfunction has been linked to a host of diseases. Additionally, the importance of medicinal plants in the discovery of novel pharmaceuticals cannot be overemphasised. The use of natural products with therapeutic properties is as ancient as human civilisation and, for a long time, mineral, plant and animal products were the main sources of drugs. Of the 252 drugs considered as basic and essential by the World Health Organisation (WHO), 11% are exclusively of plant origin and a significant number are synthetic drugs obtained from natural precursors. In deed “nature has provided us with plants for food and medicine”. The overall aim of my research is to understand the pharmacotoxicological effects of a range of medicinal plants and herbal products employing various analytical tools such as mitochondrial oxygen consumption assays and to understand the role of mitochondria in growth and development and study the mitochondrial biogenesis and mitochondrial DNA mutations in both common and rare non-communicable diseases.

  • Bioremediation of Environmental Pollutants

My second research interest is on isolation and characterization of indigenous detoxifying micro-organisms from waste sites with particular interest in cyanide and petroleum hydrocarbon degrading microorganisms

 

Possible research topics

1. Effects of selected herbal products on mitochondrial function

2. Screening for novel anti-malarial compounds from Ghana's medicinal plants

 

Current  research/projects(s)

Alzheimer’s disease (AD) is a neurodegenerative disorder. It is the most common form of age related dementia, characterised by severe memory loss, cognition and motor dysfunctions and currently has no disease-modifying treatments. Despite decades of research, we still don't have an effective treatment against dementia. Many drugs have failed in clinical trials. This is because not much is known about the disease, especially the early mechanism of disease development. The proposed study seeks to investigate the contribution of the interplay between biometal ions and the human gut microbiota, and HHV-1 infection to nucleolar stress induction in a cellular model of AD. This study will reveal the contribution of biometal ions and gut microbiome interplay, and the contribution of HHV-1 to AD pathogenesis and nucleolar stress involvement in a physiologically relevant model and identify new targets from medicinal plants that could be taken forward along the drug development pipeline for the treatment of AD.

 

Past research projects

1. Mitochondrial DNA mutations and male infertility
Mitochondrial involvement in sperm motility and for that matter male infertility has been well established. Mutations in the mitochondrial and nuclear DNAs results in mitochondrial dysfunction leading to dysfunction in sperm motility and fertility. However, data on mtDNA mutations associated with male infertility in Ghana is lacking. The purpose of this study was to ascertain the common mtDNA mutations in Ghanaian infertile men and compared to their fertile counterpart.
2. Studies on the effects of selected medicinal plant extracts on mitochondrial function
The role of mitochondria in pharmacotoxicology has been well established. The interaction between medicinal plant extracts and mitochondrial function could have pharmacological importance and offer opportunity for the discovery of important phytochemicals against several non-communicable diseases. However, plants extracts could cause xenobiotic-induced bioenergetics failure resulting in mitochondrial dysfunction. The purpose of this study was to screen medicinal plant extracts for their effect on mitochondrial respiratory chain activity.
3. Molecular characterization of Pseudomonas spp from selected polluted environments
Pseudomonas spp are ubiquitous organisms which offer opportunity for bioremediation and biosensor development. Molecular characterization is key in identifying microorganisms of biotechnological importance. The purpose of this study was to isolate Pseudomonas spp. From polluted environments and identify their molecular characteristics by sequencing of the 16s RNA gene.
4. A comprehensive study on solvent fractions of Taraxacum officinale (Dandelion)
Taraxacum officinale (Dandelion) is a common vegetable with many purported medicinal benefits many of which are backed by scientific studies. However, the active phytocompounds are not yet known. The aim of this study was to screen solvent fractions of dandelion leaves (the most edible part) for anti-oxidant, antiproliferative and antimicrobial properties. Gold nanoparticles were also synthesized from the crude aqueous extract and the application of the synthesized particles in cosmetics was ascertained by measuring their anti-proliferative, antimicrobial and tyrosinase inhibitory effects.
5. Herb-Drug interaction
As patronage of herbal medicines increase globally, herbs are taken either concurrently or concomitantly with other drugs. This has implication for drug metabolism and consequently could result in either adverse or beneficial effect of herb-drug interactions. The purpose of this study was to investigate the effect of concurrent administration of aqueous extract of Crytolepis sanguinolenta on chloroquine and artesunate. The effect of the extract on pharmacokinetics and metabolism of chloroquine and artesunate was assessed. Its effect on the effectiveness of artesunate was also studied.
6. The role of mitochondrial membrane phospholipid fatty acyl composition on proton leak and ageing
The mitochondria waste about 10% of its energy to fuel a futile cycle of proton pump and leak. Although the mechanism of the inducible proton leak, which is predominant in the brown adipose tissue is known, that of the basal leak, which occurs in all eukaryotic cells is unclear. However, there are indirect pieces of evidence linking the membrane phospholipid bilayer to the basal leak. The purpose of this study was to evaluate extensively the role of the phospholipid fatty acid composition in the leak of protons through the mitochondrial membrane.

 

Awards

• Apr. 2017: West Africa Health Organisation (WAHO). USD50,000.00
• Feb. 2014: Office of Research, Innovation and Development (ORID), University of Ghana, Legon. GH¢24,900.00
• Jun. 2013 – May 2014: Cambridge-Africa Alborada Research Grant, Cambridge, UK. £18,000.00
• May 2013 – Feb. 2014: CAPREx Postdoctoral Research Fellowship, Department of Physiology, Development and Neuroscience, University of Cambridge, UK. £10,200.00
• Jun. 2009 – Sep. 2011: Office of Research, Innovation and Development (ORID), University of Ghana, Legon. GH¢21,000.00
• Oct. 2000: Life Fellow: Cambridge Commonwealth Society, UK (FCCS, UK).
• Oct. 2000- Sept. 2003: Malaysian Commonwealth Scholarship and ORS Equivalent Bursary, University of Cambridge, UK.
• Oct. 2000-Sept. 2003: Scholar: The Perse Scholarship, Gonville and Caius College, University of Cambridge, UK.
• Jun. 1998: NCR Best Graduating Science Student Award, University of Ghana, Legon.

 

SELECTED PUBLICATIONS

  1.  Mensah, E.A., Sarfo, B., Bonney, E.Y., Parbie, P.K., Ocloo, A. Symptoms of Toxicity and Plasma Cytochrome c Levels in Human Immunodeficiency Virus-infected Patients Receiving Anti-retroviral Therapy in Ghana: A Cross-sectional Study. (2020) Infectious disorders drug targets, 20 (1), pp. 88-97.
  2. Ohta, T., Tilkanont, T., Ayertey, F., Nakagawa, M., Tung, N.H., Bolah, P., Blagogee, H., Jnr., Appiah, A.A., Ocloo, A., Ohashi, M., Tanoue, K., Yamaguchi, Y., Ohta, N., Yamaoka, S., Iwanaga, S., Uto, T., Shoyama, Y. Establishment of a quantitative and qualitative analysis and isolation method for tetracyclic iridoids from Morinda lucida Bentham leaves. (2019) Journal of Pharmaceutical and Biomedical Analysis, 164, pp. 475-480.
  3.  Kumatia, E.K., Antwi, S., Brew-Daniels, H., Appiah, A.A., Ocloo, A. In vivo Comparative Anti-Inflammatory and Analgesic Activities of Root Bark, Stem and Leaf Extracts of Capparis erythrocarpus (Capparaceae). (2019) Pharmacognosy Journal, 11 (3), pp. 515-520.
  4. Yeboah, R., Thomford, K.P., Mensah, R., Appiah, A.A., Thomford, A.K., Ocloo, A. A pilot study on the efficacy of an Antiaris toxicaria subsp. Africana (Engl.) C.C. Berg based Ghanaian herbal product in the management of peripheral neuropathy. (2019) Journal of Pharmacy and Pharmacognosy Research, 7 (1), pp. 59-66.
  5.  Antwi, S., Asiedu-Larbi, J., Martey, O.N.K., Quasie, O., Boakye-Yiadom, M., Ayertey, F., Yeboah, R., Sapaty, C.A., Offei-Abrokwa, D., Oduro-Mensah, D., Kumatia, E.K., Ocloo, A. Safety and effectiveness of Mist antiaris, a herbal preparation for treatment of peripheral neuropathy. (2019) BioMed Research International, 2019, art. no. 2607872.
  6. Oduro-Mensah, D., Ocloo, A., Lowor, S.T., Mingle, C., Okine, L.K.N.-A., Adamafio, N.A. Bio-detheobromination of cocoa pod husks: Reduction of ochratoxin A content without change in nutrient profile. (2018) Microbial Cell Factories, 17 (1), art. no. 79.
  7.  Oduro-Mensah, D., Ocloo, A., Lowor, S.T., Bonney, E.Y., Okine, L.K.N.A., Adamafio, N.A. Isolation and characterisation of theobromine-degrading filamentous fungi. (2018) Microbiological Research, 206, pp. 16-24.
  8. Ocloo, A., Kingsford-Adaboh, R. & Murray, A.J. 2017, "Inhibition of mitochondrial respiratory chain activity by O, O-dimethyl- and 4-o- methyl- alpinumisoflavones", Journal of Applied Pharmaceutical Science, vol. 7, no. 3, pp. 95-100.
  9. Ocloo, A., Appiah-Opong, R., Chama, M.A., Appiah, A.A. & Murray, A.J. 2015, "An In Situ Study on the Effects of Extracts of Taraxacum Officinale,Paulliniia Pinnata andThonningia Sanguinea on Mitochondrial Function", Journal of Food Biochemistry, vol. 39, no. 6, pp. 682-688.
  10. Tettey, C.O., Yang, I., Ocloo, A. & Shin, H.M. 2015, "Vasorelaxant and Anti-Inflammatory Activities of the Methylene Chloride Fraction of Foeniculum vulgare Fruit Extract", Journal of Food Biochemistry, vol. 39, no. 1, pp. 55-63.
  11. Tettey, C.O., Ocloo, A., Nagajyothi, P.C.N. & Lee, K.D. 2014, "An in vitro analysis of antiproliferative and antimicrobial activities of solvent fractions of Taraxacum officinale (Dandelion) leaf", Journal of Applied Pharmaceutical Science, vol. 4, no. 3, pp. 41-45.
  12. Tettey, C.O., Ocloo, A., Nagajyothi, P.C. & Lee, K.D. 2014, "Antioxidant activity of solvent fractions of taraxacum officinale (dandelion) leaves", Journal of Herbs, Spices and Medicinal Plants, vol. 20, no. 4, pp. 329-340.
  13. Tettey, C.O., Nagajyothi, P.C., Lee, S.E., Ocloo, A., Minh An, T.N., Sreekanth, T.V.M. & Lee, K.D. 2012, "Anti-melanoma, tyrosinase inhibitory and anti-microbial activities of gold nanoparticles synthesized from aqueous leaf extracts of Teraxacum officinale", International Journal of Cosmetic Science, vol. 34, no. 2, pp. 150-154.
  14. Ocloo, A., Shabalina, I.G., Nedergaard, J. & Brand, M.D. 2007, "Cold-induced alterations of phospholipid fatty acyl composition in brown adipose tissue mitochondria are independent of uncoupling protein-1", American Journal of Physiology - Regulatory Integrative and Comparative Physiology, vol. 293, no. 3.
  15. Ocloo, A., Okpattah, W.E., Quasie, O., Sakyiamah, M.M. & Okine, L.K.N. 2014, "Concurrent administration of aqueous extract of Cryptolepis sanguinolenta reduces the effectiveness of Artesunate against Plasmodium berghei in rats", Journal of Applied Pharmaceutical Science, vol. 4, no. 3, pp. 24-28.
  16. Ocloo, A., Holbech, L.H. & Gbogbo, F. 2013, "Mitochondrial DNA density of peripheral white blood cells as a possible bio-marker of migratory status in partially migrating bird populations", Ecology, Environment and Conservation, vol. 19, no. 3, pp. 891-897.
  17. Ocloo, A. & Dongdem, J.T. 2012, "Mitochondria as pharmacological targets: The discovery of novel antiobesity mitochondrial uncouplers from Africa's medicinal plants", African Journal of Traditional, Complementary and Alternative Medicines, vol. 9, no. 2.
  18. Ocloo, A. & Dongdem, J.T. 2012, "Mitochondria as pharmacological targets: the discovery of novel anti-obesity mitochondrial uncouplers from Africa's medicinal plants.", African journal of traditional, complementary, and alternative medicines : AJTCAM / African Networks on Ethnomedicines, vol. 9, no. 2, pp. 256-259.
  19. Dongdem, J.T., Soyiri, I. & Ocloo, A. 2009, "Public health significance of viral contamination of drinking water", African Journal of Microbiology Research, vol. 3, no. 12, pp. 856-861.
  20. Martey, O.N.K., Ocloo, A., Koomson, E. & Okine, L.K.N. 2009, "Assessent of Tonica, an aqueous herbal haematinic, in the modulation of rat hepatic microsomal CYP-mediated drug metabolizing enzymes: Implications for drug interactions", Journal of Pharmacology and Toxicology, vol. 4, no. 2, pp. 70-78.
  21. Brand, M.D., Pakay, J.L., Ocloo, A., Kokoszka, J., Wallace, D.C., Brookes, P.S. & Cornwall, E.J. 2005, "The basal proton conductance of mitochondria depends on adenine nucleotide translocase content", Biochemical Journal, vol. 392, no. 2, pp. 353-362.
  22. Brand, M.D., Turner, N., Ocloo, A., Else, P.L. & Hulbert, A.J. 2003, "Proton conductance and fatty acyl composition of liver mitochondria correlates with body mass in birds", Biochemical Journal, vol. 376, no. 3, pp. 741-748.
  23. Bishop, T., Ocloo, A. & Brand, M.D. 2002, "Structure and function of mitochondria in hepatopancreas cells from metabolically depressed snails", Physiological and Biochemical Zoology, vol. 75, no. 2, pp. 134-144.

 

Professional menbership(s)

Ghana Science Association, Ghana
International Society for the Study of Xenobiotics, USA
Mitochondrial Physiology Society, Austria