SUSCEPTIBILITY PATTERN OF SOME ENTERIC BACTERIA TO AQUEOUS, ETHANOL AND METHANOL EXTRACTS OF ANNONA MURICATA (Linn) LEAF AND BARK

Abstract

Study was carried out to evaluate the susceptibility pattern of some enteric bacteria to aqueous, ethanol and methanol extracts of Annona muricata leaf and bark. Standard methods were employed to determine the bioactive components of the plant, screen for phytochemical, biochemical properties of the bacteria isolates, and carry out minimum inhibitory and minimum bactericidal concentrations (MIC/MBC). The susceptibility pattern of aqueous leaf extracts showed no inhibition on both clinical and typed isolates except for S. typhi (22.00 mm), E coli (12.33 mm) and K. pneumoniae (20.33 mm). Ethanol extract did not inhibit the growth of S. typhi 2 and Shigella sp while methanol inhibited all the test organisms (both clinical and typed). Aqueous bark extract showed no inhibition on both clinical and typed isolates while ethanol and methanol bark extracts inhibited all the clinical and typed bacteria. Methanol leaf extracts has a higher inhibitory effect on the clinical and typed bacteria compared to the bark extracts. The highest concentration of MIC for ethanol leaf extract was 100 mg/ml while that of methanol was 50 mg/ml. The highest concentration of MIC for both ethanol and methanol bark extract was 50 mg/ml. The commercial antibiotics were observed to be effective in inhibiting the test organisms (both clinical and typed) used in this study. Methanol bark and leaf extracts had the highest percentage recovery (42.92% and 55.36%) respectively. Qualitative phytochemical screening of leaf and bark extracts of A. muricata revealed the presence of tannins, saponins, flavonoids, terpenoid and cardiac glycosides. Quantitative phytochemical screening of A. Muricata leaf extracts showed that aqueous extract has the highest quantity of saponin (56.09 mg/100 g) and terpenoids (16.42 mg/100 g) while ethanol extract of the leaf has the least composition (3.34 mg/100 g) of tannin. Quantitative phytochemical screening of bark extracts revealed that glycosides with 7.06 mg/100g, 34.67 mg/100 g and 19.36 mg/100 g was the most abundant phytochemical constituents in aqueous, ethanol and methanol extracts respectively. The GC-MS analysis of ethanol bark extract of A. muricata revealed seventeen chemical compounds while that of methanol leaf extract revealed sixteen chemical compounds. The FTIR result of the ethanol bark extract and methanol leaf extract of A. muricata revealed 17 prominent peaks at various wavelengths ranging from 514.06 to 3904.17 cm-1 and 426.38 cm-1 to 3254.70 cm-1 respectvely. The significant (p≤0.05) increase in the zones of inhibition of the purified extracts of leaf and bark of A. muricata will compete well with standard antibiotics and it may also serve as a substitute for the commercially available antibiotics which can be used for the treatment of infections caused by enteric bacteria. The antibacterial activity demonstrated by both ethanol and methanol extracts of A. muricata leaf and bark against clinical and typed isolates has provided its valuable use for human health management. This study has shown that leaf extracts of A. muricata can be used in the treatment of enteric infection caused by S. typhi.