_____________________________________________________________________________________________________ *Corresponding author: Email: fridayata2014@gmail.com; South Asian Research Journal of Natural Products 4(1): 9-15, 2021; Article no.SARJNP.64240 In-vitro Investigation on the Therapeutic Potential of Carica papaya Leaf Extract on Some Pathogenic Bacteria Attah, Friday 1* , E. Moses, Abalaka 1 , Adobu Ugbede Shadrach 2 and OludareTimon Tayo 3 1 Department of Microbiology, Federal University of Technology Minna Niger, State Nigeria. 2 Department of Biology, Kogi State College Education, Ankpa, Kogi State, Ngeria. 3 Department of Plant Biology and Biotechnology, University of Benin, Benin City, Nigeria. Authors’ contributions This work was carried out in collaboration among all authors. Author AF designed the study, performed the statistical analysis, wrote the protocol and wrote the first draft of the manuscript. Authors EMA and AUS managed the analyses of the study. Author AUS managed the literature searches. All authors read and approved the final manuscript. Article Information Editor(s): (1) Dr. Nargis Jamila, Shaheed Benazir Bhutto Women University, Pakistan. Reviewers: (1) J. M. Sasikumar, Haramaya University, Ethiopia. (2) Neetu Rani, Bhagat Phool Singh Mahila Vishwavidyalya, India. Complete Peer review History: http://www.sdiarticle4.com/review-history/64240 Received 20 October 2020 Accepted 25 December 2020 Published 11 January 2021 ABSTRACT Carica papaya is one of the most valuable plants used for various purposes in medicinal field and ethnomedicine. The aim this study was to investigate the therapeutic potential of C. papaya leaf extract using cold maceration method with distilled water, methanol and petroleum-ether. Phytochemical screening of the extracts revealed the presence of the following: alkaloids, saponins flavonoids, steroids, cardiac glycosides and tannins. Antimicrobial activities of the extracts were determined by agar well diffusion method by measuring the diameters of zones of inhibition. In aqueous extract, Klebsiella pneumonia had the highest zone of inhibition (16±0.00 mm) followed by Escherichia coli and Staphylococcus aureus at 14±0.00 mm and 12±0.5 mm respectively. In methanol extracts, E. coli. had the highest zone of inhibition (15±00 mm) followed by Staphylococcusaureus (12±0.00 mm) while K. pneumonia had no inhibition. With Petroleum- ether, Staphylococcusaureus had the highest zone of inhibition (22±0.00 mm) followed by E. coli (0.13±0.00 mm) while K. pneumonia had no inhibition. It was clear that C. papaya had Original Research Article