Antimicrobial Activities of Irvingia Gabonesis Leaf and Cyperus Esculentus Extracts on Some Selected Isolates

Bacterial resistance to antibacterial drugs in the treatment of some bacterial infections have become a menace that is causing untold health challenges to patients. The antibacterial activity of ethanolic extract of tiger nut (Cyperus Esculentus) and Bush mango (Irvingia Gabonensis) against candida albicans, Echerichia coli, Pseudomonas sp, Salmonella sp and Staphylococcus aureus was evaluated using agar-well diffusion, Minimum Inhibitory Concentration (M.I.C) and Minimum Bacteriocidal Concentrations (M.B.C) methods. Echerichia coli had the highest total colony count of 1.3 X 1011 Colony forming unit/ml(Cfu/ml) followed by Pseudomonas sp (8.8 X 1010Cfu/ml) and Staphylococcus aureus (6.7 X 1010) at 1.0E-09 dilution, but in the 1.0E-10 dilution, Pseudomonas sp was highest with 9.7 X 1011Cfu/ml followed by E. coli (9.0 X 1011Cfu/ml).The result from the comparative agar well diffusion assay of Tiger nut and Irvingia crude extracts showed that the extracts have antimicrobial activity against some of the test isolates. Pseudomonas spp. were susceptible to the tiger nut extract (10% and 20%) with the diameter of Zone of Inhibition (ZOI) of 18.0±0mm and 18.5±1.5mm. While Echerichia coli, Pseudomonas sp, Salmonella sp and Staphylococcus aureus showed susceptibility to the Irvingia (10%) crude extract with ZOI diameters of 13±2mm, 15.5±0.5mm, 16.5±1.5mm and 16.5±0.5mm respectively. Pseudomonas also exhibited susceptibility to the Tiger nut (20%) crude extract having a ZOI diameter of 18.5±1.5 mm while E.coli, Pseudomonas spp, Salmonella spp and Staphylococcus aureus were susceptible to Irvingia (20%) crude extract, revealing ZOI diameters of 15.5±0.5 mm ,19±0 mm,18±1 mm and 15±0 mm respectively The Minimum Inhibitory Concentration (MIC) of both extracts was 50% for all organisms, while the Minimum Bacteriocidal Concentration (MBC) of both crude extracts was 50% for Staphylococcus aureus only. The dilution factors and total colony counts from 1.0E-09 and 1.0E-10 dilutions of 5 test isolates. where statistically analyzed with ANOVA, and the P. values where 0.13 and 0.4 respectively were significant.


Background
The rise of antibiotic resistant microorganism is one of the severe problems in health care system of the world and infectious diseases are the second most serious causes of death worldwide.
Thus, it is essential to find new compounds that have antimicrobial properties by screening plant species to detect those that can synthesize new drugs [1]. Thus, this study is carried out to determine the antimicrobial activity of bush mango and tiger nut extracts on some selected microorganisms.
Tiger nut (Cyperus esculentus) is a tuber that is consumed widely in Nigeria and in various other parts of West and East Africa [2]. It is eaten raw or roasted, used as hog feed or pressed for its juice to make a beverage [3].Tiger nuts are valued for their highly nutritious starch content, dietary fibre and carbohydrate and are rich in sucrose (17.4-20.0%), fat (25.5%), protein (8.0%). Tiger nut is also rich in mineral elements such as sodium, calcium, potassium, magnesium, zinc and traces of copper [4].
Bush mango (Irvingia gabonensis) belongs to the Irvingiaceae plant family [5]. Bush mango leaf/root extracts have documentary inhibitory activity against several bacteria and fungi. It possesses antimicrobial effects against Escherichia coli and Staphylococcus aureus [6]. Tiger nuts and bush mango have antibacterial activity against Salmonella, Escherichia coli. Candida albicans, Staphylococcus aureus and Pseudomonas [7]. soaked differently in 400ml of 80% absolute ethanol in 500ml conical flasks. The preparation was processed further using the model of [8] with slight modification. Plant extract filtrate of 10%, 20% and 50% v/v of Irvingia gabonesis and Tiger nut was prepared using method by [9] with slight modification.
Bacterial test colonies were introduced into 5mls of tryptic soy broth, incubated overnight at 37°C and centrifuged. Followed by standardization and serial dilution using stardard microbiological procedures. Agar well diffussion assay was done using double at room temperature and incubated at 37% for 18-24hours. The diameter of zones of inhibition was measured after incubation [8].
The model of [8] was adopted with slight modification for minimum inhibitory concentration. Ten milliliter (10ml) volume of double strength molten Mueller Hinton agar after autoclaving at 45°C was dispensed into sterile universal bottle and 10ml of the Irvingia gaboonesis plant extract was added. Equal volume of the test plant extract in graded concentration of 20%, 30%, 50% and 100% was made. These were poured aseptically into sterile petri-dishes and were allowed to solidified at room temperature, for one hour with the lid of the petri-dishes slightly raised.
Twenty microlitre of standardized test bacteria were impregnated/ inoculated aseptically on the sterilized Whatman no 1 filter paper discs, placed on the agar surface at equidistance in duplicate for each concentration of the test plant extracts.
These were incubated at 37°C for 18-24hours. The minimum inhibitory concentration value was taken as the least concentration of the plant extract at 50%, showing no detectable growth.
Augmentin was used as standard antibiotic. The minimum bacteriocidal was determined by transferring inoculated bacterial discs into a sterile 3ml recovery of Luria Bertani broth from the plant extract concentration that showed no visible growth from the M.I.C determination.
These were incubated at 37 oc for 72hours. The least concentration of the plant extracts that showed no bacterial growth in the recovery liquid medium were 50% was taken as the M.B.C.

Results
( Figure 1) shows Total Colony Count of Isolated organisms.
The graph depicts the highest total colony count by E. coli (1.3 X 10 11 Colony forming unit/ml) followed by Pseudomonas spp (8.8 X 10 10 Cfu/ml) and Staphylococcus aureus (6.7 X 10 10 ) at 1.0E-09 dilution, but in the 1.0E-10 dilution, Pseudomonas spp was highest with 9.7 X 10 11 Cfu/ml followed by E. coli (9.0 X 1011Cfu/ml).      The abundance of bush mango and tiger nut plants in Nigeria, and Africa continent should be explored because both plant extracts possess antimicrobial activity and may reduce the drug resistant and cost of treatment diseases. It is therefore recommended.
Pharmaceutical companies should explore it, not only for Antimicrobial activity. But also, food and beverages companies should explore it's for the production of fruit juices because of it nutritional benefits to humans. More research work should be done on Bush mango and Tiger nut.