IOSR Journal of Pharmacy and Biological Sciences (IOSR-JPBS) e-ISSN:2278-3008, p-ISSN:2319-7676. Volume 11, Issue 6 Ver. VI (Nov. - Dec.2016), PP 38-41 www.iosrjournals.org DOI: 10.9790/3008-1106063841 www.iosrjournals.org 38 | Page Antipseudomonal Activities of Aqueous and Methanolic Peel Extracts of Carica papaya L. (Pawpaw) Unripe Fruits Sulayman Tunde Balogun* 1 , Assumpta Okoro Nwabugwu 2 , Ayodele Oluwasoji Akanmu 1 , Justus Jibrin 1 and Samson Gamache 3 1 (Department of Clinical Pharmacology and Therapeutics) 2 (Department of Medical Laboratory Science) 3 (Department of Medical Microbiology) (College of Medical Sciences) (University of Maiduguri, Nigeria) Abstract: In response to the multi-drug resistance of Pseudomonas aeruginosa, the discovery of new effective agents is important in overcoming the infections resulting from the organisms. The present study assessed the antipseudomonal activities of aqueous and methanolic peel extracts of Carica papaya L. (pawpaw) unripe fruits against ten (10) multi-drug resistant (MDR) P. aeruginosa clinical isolates obtained from patients attending University of Maiduguri Teaching Hospital. The unripe fruit peels were extracted by maceration using distilled water and methanol (99%) and the antipseudomonal activities evaluated by modified diffusion method using concentrations of 20, 40, 80 and 160mg/ml. The activities of both extracts were compared by determining Extract Potency Index (EPI). The mean age ± standard deviation (range) of the patients from whom the isolates were obtained was 34.1 ± 14.3 (21.0 – 72.0) years. Significantly highest proportion (60.0%) of the isolates was obtained from wound swabs (p < 0.05). The aqueous peel extract had percentage yield of 24.6% (35g/145g) as against 21.1% (21. 1g/100g) for methanolic peel extract (χ 2 = 1.2, df = 1, p > 0.05). Both extracts demonstrated a concentration-dependent inhibition of all the 10 isolates with methanolic peel extract having larger zones of inhibition. The mean zone of inhibition produced by methanolic extract at 160mg/ml (17.9 ± 2.3mm) was similar to that of ciprofloxacin (30μg) with 19.7 ± 3.7mm (p > 0.05) but significantly higher than 14.5 ± 2.3mm produced by aqueous extract at 160mg/ml (p < 0.05). In addition, the overall mean ± standard deviation (range ) of EPI was 0.77 ± 0.22 (0.25 – 1.00); this was significantly higher for methanolic peel extract with 0.93 ± 0.12 (0.75 – 1.00) than aqueous peel extract with 0.63 ± 0.32 (0.25 – 1.00) [p < 0.05]. These findings could contribute to effective use of C. papaya L. unripe fruits and may offer alternative treatment strategy for pseudomonal infections. Keywords: Pseudomonas aeruginosa, Carica papaya L., Unripe fruit, Antibacterial activity I. Introduction C. papaya L. (commonly called pawpaw or papaya) is a fast growing, usually unbranched tree or shrub with a single stem growing from 5 – 10m tall with spirally arranged leaves confined to the top of the trunk [1]. It belongs to the family Caricaceae. The fruit varies in shapes (oval, round, cylindrical or club- shaped) and sizes (0.5 – 2.25kg); the greenish unripe fruit contains latex which disappears as the fruit ripens to a light or dark yellow. The thick juicy flesh of the fruit may be yellow, orange or red in colour [2]. C. papaya L. is largely used in traditional medicine for treatment of various diseases, various parts are often used to treat different illnesses. For instance, the root of the male plant is chewed with seven seeds of Melegueta pepper during labour for prompt delivery. The leaves are used in many decoctions for bathing children [3]. The aqueous extract of the unripe fruits is used in southwest Nigeria to relief crises in patients with sickle cell anaemia [4]. The fresh and dried leaves are used in treatment of diarrhoea and typhoid. The roots and unripe fruits are made into concoctions to manage conditions such as asthma, stomach upset, diarrhoea and worm infestation [5,6]. In addition, previous studies have highlighted the pharmacological significance of the plant. For instance, the antibacterial activities of various parts of the plant have been described [7-10]. Other medicinal uses of the plant are treatment of malaria, typhoid fever, diarrhoea, dyspepsis, worm infestation and impotence among others [5,6]. These activities are attributed to presence of some phytoconstituents notably are chymopapain and papain [11]. Pseudomonas aeruginosa, a Gram negative, coccobacillus bacterium with unipolar motility belongs to the family Pseudomonadaceace. It is a major cause of nosocomial infections especially among immuno- compromised individuals [12,13]. It is implicated in several conditions such as cancer, nosocomial pneumonia, urinary tract infections, severe burns etc [14-16]. The multi-drug resistant nature of the bacteria markedly limits