1. Introduction

According to the World Health Organization (WHO) a medicinal plant is any plant which in one or more of its organ contains substances that can be used for the synthesis of useful drugs (World Health Organization, WHO, 1977). Medicinal plants contain biologically active chemical substances such as saponins, tannins, essential oils, flavonoids, alkaloids and other chemical compounds (Sofowora, 1996) which have curative properties. These complex chemical substances of different compositions are found as secondary plant metabolites in one or more of these plants (Kayode and Kayode 2011).

Telfairia occidentalis commonly called fluted pumpkin occurs in the forest zone of West and Central Africa, most frequently in Benin, Nigeria and Cameroon (Kayode and Kayode 2011). It is a popular vegetable all over Nigeria. It has been suggested that it originated in south-east Nigeria and was distributed by the Igbos, who have cultivated this crop since time immemorial. It is, however, equally possible that fluted pumpkin was originally wild throughout its current range, but that wild plants have been harvested to local extinction and are now replaced by cultivated forms (Badifu and Ogunsina, 1991, Kayode and Kayode 2011).

The medicinal activities of Telfairia occidentalis has been reported by many investigators. In Nigeria, the herbal preparation of the plant has been employed in the treatment of anaemia, chronic fatigue and diabetes (Alada, 2000; Dina et al., 2006; Kayode and Kayode 2011). The leaves contain essential oils, vitamins; root contains cucubitacine, sesquiterpene, lactones (Iwu, 1983). The young leaves sliced and mixed with coconut water and salt are stored in a bottle and used for the treatment of convulsion in ethno medicine (Gbile, 1986). The leaf extract is useful in the management of cholesterolemia, liver problems and impaired defense immune systems (Eseyin et al., 2005). Telfairia occidentalis is popularly used in soup and folk medicine preparation in the management of various diseases such as diabetics, anaemia and gastrointestinal disorder (Oboh et al., 2006). A study has shown that the ethanol root extract of T. occidentalis possess antiplasmodial potential (Okokon et al., 2007) and inhibitory effects on some enterobacteriacae Odoemena and Onyeneke (1998) while Oluwole et al. (2003) reported Telfairia occidentalis anti-inflammatory activities (Kayode and Kayode 2011).

The aims and objectives of this research are to identify the phytochemical components of the leaf of Telfairia occidentalis, to determine the antimicrobial activities of the leaf extract of Telfairia occidentalis, to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Telfairia occidentalis on S. typhi, E. coli and Strept. faecalis, to compare the antibacterial activities of the leaf extract of Telfairia occidentalis-with antibiotics commonly used to treat infections of the test organisms.

2. Materials and Methods

Collection and preparation of Samples

Fresh leaves of T. occidentalis were purchased in Bosso market in Minna, Niger State, Nigeria and brought to the microbiology laboratory of Federal University of Technology, Minna. The leaves were air-dried at room temperature over a period of one week. The dried leaves were pulverized to dry powder using a wooden mortar. Fifty grams (50mg) of dried leaves were extracted in a succession using 250ml of 75% ethanol in a separate conical flask for 72 hours with regular agitation. The extract was evaporated to dryness using steam bath and stored in sterile universal bottle as described by Sliver et al. (1997).

Pure culture of the organisms were obtained from stock culture of microbiology laboratory, Federal University of Technology, Minna

Extraction of the extract

One hundred grams (100g) of the blended leaf was soaked in 500ml of 75% ethanol in a flask It was shaken daily for 72hours at regular intervals, after which it was filtered suing Whatman’s (No II) filter paper. The filtrate was evaporated to dryness using steam water bath at 100^oC. The extract was then stored at 4^oC in a refrigerator.

Phytochemical screening of the extracts

Phytochemical screening of the extracts was carried out according to methods described by Odebiyi and Sofowora (1978) and Trease and Evans (1989). The components analyzed for were alkaloids, tannins, phenolics, glycosides, saponins, flavonoids, steroids. Phylobatanins and triterpenes.

Determination of Minimum Inhibitory Concentration (MIC)

The MIC of the plant extract was determined by serially diluting extract from 10¹ to 10¹⁰. One millilitre (1ml) of each of the dilutions representing a known concentration of the extract was introduced into 9ml of sterile nutrient broth in a test tube. The mixture was then inoculated with 0.1ml of the test organisms previously standardized at 10⁶. It was then incubated at 37^oC for 24 hours. The least concentration of the plant extract in the test tube with no turbidity was taken as the MIC (Hugo and Russsel 1983).

Determination of Minimum Bactericidal Concentration (MBC)

The plant extract was serially diluted from 10 to 10¹⁰. One millilitre (1ml) of each of the dilutions representing a known .concentration of the extract was introduced into 9ml of sterile nutrient broth in test tubes. The mixture was then inoculated with 0.1ml culture of the test organisms previously standardized to 10⁶. It was then incubated at 37^oC for 24hours. The least concentration of plant extract in the test tube with no turbidity was taken as the MIC. Subsequently, tubes that indicated no turbidity was plated out on nutrient agar plates and absence of growth after incubation for 24hours confirms the MBC as described by Hugo and Russell (1983).

3. Results

Phytochemical Screening of extract

Table 1 shows the phytochemical components of extract of Telfairia occidentalis. The result indicated the presence of saponins, alkaloids, tannins, phenolics, and absence of glycosides, steroids, phylobatanins, triterpenes

Table 1. Phytochemical components of Telfairia occidentalis Plant phytochemicals Extract alkaloides + Tannins + Phenolics + Glycosides - Saponins + Flavonoids + Steroids - Phylobatanins - triterpenes -

Sensitivity test

The leaf extract of T. occidentalis showed varying antimicrobial; activities against the test organisms (Table 2). E. coli showed the highest activity on the extract. The zone of inhibitions were 20± 0.58 at 500mg/ml, 14± 2.52 at 50mg/ml and 10± 1.00 at 5.0mg/ml of extract followed by S. typhi with zones of inhibitions of 19± 2.31 at 500mg/ml and 11± 0.70 at 50mg/ml but no activity at 5.0mg/ml while Strept. faecalis had zones of inhibitions of 16± 0.58 at 500mg/ml, 6.0±1.10 at 5.0mg/ml but no activity at 50mg/ml.

Table 2. Mean diameter of zone of inhibition (mm) Concentration of extract (mg/ml) E.coli S.typhi Strept. faecalis 500 20 ±0.58 19±2.31 16±0.58 50 14 ±2.52 11±0.70 - 5 10±1.00 - 6±1.10

Minimum inhibitory concentration and minimum bactericidal concentration of T. occidentalis

Table 3 shows the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of extract of T. occidentalis. The MIC and MBC of T. occidentalis on E.coli and S. typhi were 0.5mg/ml and 5.0 mg/ml respectively. The MIC of T. occidentalis on Strept. faecalis was 500mg/ml while T. occidentalis had no MBC activity against Strept. faecalis.

Table 3. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) Test organisms MIC MBC E. coli 0.5 0.5 S. typhi 5.0 5.0 Strept. faecalis 500 -

Susceptibility testing using standard antibiotics

Table 4 shows the susceptibility testing using standard antibiotics (positive control). S typhi was susceptible to the entire tested antibiotic except Norfloxacin (NB), E.coli was only susceptible to CPX- Ciproflox, GN –Gentamycin and LC-Lincocin while Strept. faecalis was susceptible to all the tested antibiotic except CPX- Ciproflox and LC-Lincocin.

Table 4. Susceptibility testing using standard antibiotics (positive control)

4. Discussion

The preliminary phytochemical analysis showed that the leaf of T. occidentalis contains tannins, saponins, alkaloids and flavonoids. These compounds have been found to inhibit bacterial growth and are capable of protecting certain plant against bacterial infections (Clark, 1981; Gonzales and Mather, 1982).

At concentrations of 500mg/ml, 50mg/ml and 5.0mg/ml, E. coli had the highest zones of inhibitions (20±0.58mm) whereas, at concentrations of 50mg/ml, Strept. faecalis was tolerant to the extract of T. ocicidentalis and at 5.0mg/ml S. typhi was also tolerant (Table 2). This indicated that E.coli was the most susceptible to the leaf extract of T. occidentalis at the various concentrations used. At concentration of 500mg/ml, all the test microorganisms had higher zones of inhibition when compared to the commonly used antibiotic (Table 4 and Table 5).

The minimum inhibition concentration of the test organisms were 0.5mg/ml for E. coli, 5.0mg/ml for S.typhi and 500mg/ml for Strept. faecalis (Table 3). This is similar to the finding of Oboh et al. (2006) who reported inhibitory effects of ethanolic extract of T. occidentalis on , Pseudomonas aeruginosa and Proteus sp. but no inhibitory effect on Salmonella typhi. The minimum bactericidal concentration (MBC) of 0.5mg/ml and 50mg/ml appeared to be bactericidal on S. typhi and E. coli respectively but Strept. faecalis had no bactericidal activity on extracts of T. occidentalis at 500mg/ml, 50mg/ml and 5.0mg/ml. This could be due to its ability to develop resistance to the extracts of T. occidentalis at concentrations considered and also because of the presence of peptodoglycan cell wall component.

5. Conclusions

The results of the study indicates that the ethanolic extract of T. occidentalis has an antibacterial activity on S. typhi, E. coli and Strept. faecalis. E.coli was most susceptible (MIC and MBC values of 0.5mg/ml) followed by S.typhi (MIC and MBC values of 5.0mgml) while S. faecalis was the least susceptible.