Qualitative and quantitative analysis of pawpaw (Carica papaya) leaf extract and its antimicrobial effect in animal production

Abstract

In order to improve livestock production and curb the losses from diseases occurrence in livestock, producers resort to the use of antimicrobials as growth promoters to inhibit the growth of disease-causing organisms.  Freshly harvested pawpaw leaves were extracted using three solvents:  ethanol, methanol and n-hexane and their phytochemicals determined using standard procedure. The inhibitory activities of the extracts at low (200ppm) and high (1000ppm) concentrations against Aspergillus niger and Escherichia coli were also determined. Results obtained showed that alkaloid, flavonoid, saponin, tannin and cardiac glycosides were present while anthraquinone was absent. The percentage yield of phenols using methanol (0.115%) and ethanol (0.214%) solvents were similar but lower than nhexane yield (0.450%). Also the yield of flavonoid using methanol (0.700%) is significantly (p<0.05) higher than the yield using other solvents. The yield of phenols using methanol (0.480%) and ethanol (0.470%) solvents were identical but higher than n-hexane yield (0.400%). At low concentration, it was observed that the inhibitory concentrations of
pawpaw leaf extract against bacteria by control, streptomycin (1.2cm) was significantly (p<0.05) higher but similar to the extract from methanol  solvent (1.1cm). Methanol extract inhibition was also similar to ethanol (1.0cm) but higher than n-hexane (0.0cm). At high concentration, the inhibitory activity of the ethanol extract (1.2cm) was significantly (p<0.05) higher than the control (0.7cm) and the least observed in n-hexane  (0.0cm) extract. The inhibitory concentrations of pawpaw leaf extract against fungi Aspergillus niger at low (2.2cm) and high (2.2cm)  concentrations, the methanol extract was observed to be significantly (p<0.05) higher than other extracts including control. The results suggest that using methanol-extracted pawpaw leaf as alternatives to synthetic
antibiotic in animal production is effective against microbial organisms. Thus the occurrence of resistance to antibiotic or its residues on animal products will be reduced.

Keywords: Pawpaw; microbes; extraction solvents; phytochemicals; phytobiotics