Food Science and Technology Project Topics

Antimicrobial Activity of Pawpaw Leaf (Carica Papaya) on Some Selected Test Organisms

Antimicrobial Activity of Pawpaw Leaf (Carica Papaya) on Some Selected Test Organisms

Antimicrobial Activity of Pawpaw Leaf (Carica Papaya) on Some Selected Test Organisms

Chapter One

Objectives of the Study

To subject the leaf of pawpaw (Carica papaya) in powdered form to standard scientific scrutiny in relation to antimicrobial activity spectrum, mode of action as well as toxicological evaluation:

  • To extract the microbial agent of Carica papaya leaf
  • To evaluate the antimicrobial activities of pawpaw leaf (Carica papaya) on selected test organisms.
  • To establish the fact that the activity of the extract is comparable to those of antiobiotics.



Natural History of Herbs and its Importance

In recent years, the growing demand for herbal has led to a quantum jump in volume of plant materials traded across the countries. Therefore, the use and history of herbs dates back to the time of early man, who had the crudest tools as his implements and use stones to start his fire. They used herbs in their raw and cooked forms to keep fit. Since that time, the use of herbs has been known and accepted by all nations and has been known also as the first art of treatment available to man (Kafaru, 1994).

The importance of herbs in the management of human ailments cannot be over emphasized. It is clear that the plant kingdom harbors an inexhaustible source of active ingredients invaluable in the management of many intractable diseases. Furthermore, the active components of herbal remedies have the advantages of being combined with other substances that appear to be inactive. However, these complementary components give the plants as a whole safety and efficiency much superior to that of its isolated and pure active components (Ahmad, 2001).

There is no plant that does not have medicinal value. The active components are normally extracted from all plant structures, but the concentrations of these components vary from structure to structure. However, parts known to contain the highest concentration of the principles are preferred to therapeutic purposes and it can either be the leaves, stems, barks, roots bulks, corms, rhizomes, woods, flowers, fruits or the seeds (Kafaru, 1994).

 Relevance of the Active Components of Medicinal Plant

Some of the active principles singly or in combination inhibit greatly the life processes of microbes, especially the disease causing ones. They do this by binding their protein molecules, acting as chelating agents (selective binding polyvalent metal ions so that the latter loses its biological activities), altering their biochemical systems, preventing utilization of available interests to the microorganisms, other causes inflammation analysis of microbial cells (Garrod et al., 1995).

The bitter taste, pungent and repulsive smell in some plants; have been found to have repressive ability over the metabolic activities of a wide range of microorganisms (Mitscher et al., 1992; Sofowora, 1982; Baladrin et al., 1985) defined medicinal plants as a plant in which one or more of the organs contains substances that can be used for therapeutic purposes or which it precursors for the manufacturing of drugs are useful for disease therapy. The use of medicinal plants predates the introduction of antibiotics and other modern drugs into the African continent. Since medicinal plants do not merely save people from feeling pain but also permit them to emerge unscathed, then they deserve investigation. The active components in these microorganisms especially the disease causing ones e.g. Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Klebsiella pneumonia, Pseudomonas aeruginosa etc. therefore, many studies and researches had been done on the antimicrobial properties of many plants but for this study, the leaf of Carica papaya will be discussed.




Sterilization of Materials

All glass wares were washed with detergent and rinsed with distilled water properly. These were then air dried before wrapping with aluminum foil and sterilized in hot air oven at 170oC for 2hours. Prepared media such as nutrient agar and nutrient broth were sterilized in an autoclave at 121oC for 15minutes. Cork borer, glass rods and forceps were sterilized by dipping in 70% ethanol which was then flamed in Bunsen flame. The inoculating loop was also sterilized by heating in Bunsen flame. The inoculating loop was also sterilized by heating to redness using naked flame before and after each use.

 Collection of Plant Materials

The plant Carica papaya leaf was collected from the Northern part of the country. The plant was identified at Agricultural department (Herbarium Section) in Rufus Giwa Polytechnic, Owo, before it was transferred to the laboratory for analysis.




Table 4.1: Antimicrobial activity of Ethanolic extract of Carica papaya leaf on some test pathogens




Conclusively, the leaf of the plant “Carica papaya” leaves have exhibited grate antimicrobial activities against the bacterium: Lactobacillus, Klebsiella and Pseudomonas and are such are proven to possess good medical properties. The extract of the plant at 1.5g/ml concentration has shown the greatest activities against the bacteria.


            It is therefore recommended that leaf of Carica papaya could be used in the cure of arthritis and more so further should be done on the photochemical of the plant in order to determine the secondary plants metabolites contained in this plant species. It is therefore suggested that further research should be made using the leaves dried at room temperature and not sun drying nor oven drying to see if this had contributed to the impotency of the extracts, it is also suggested that other part of the tree of Carica papaya should be studied as this will enhance more knowledge on the Carica papaya tree.

The results of this study also supports the traditional application of the plant and suggest that the plant extracts possess compounds with antibacterial properties that can be used as antibacterial agents in novel drugs for the treatment of gastroenteritis, urettritis, oitis media and wound infections.


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