**2.7 Discussion**

#### **2.7.1 Crude extracts of root, stem barks and leaves of** *Erythrina abyssinica*

#### **Yields of the plants extracts**

The results show that the yields of root barks perform better than the stem barks and leaf extracts detailed in Table 1 and Figure 3. There is an average 8.6%, 5.5% and 2.9% yield for the root barks, stem barks and leaves respectively in the districts of Ntungamo, Mbarara, Bushenyi and Rakai. The information gained on the percent yields of crude extracts were used for standardizing dosage rates of fine powder preparations of the plant materials. For example, the amount of crude extract contained in a known weight of fine powder of plant materials can then be calculated. This agrees with findings by (Ejobi F and Olila D 2004; Olila *et al*., 2007).

#### **Antibacterial activities of the plant extracts**

The antimicrobial activity of crude extracts of root barks and stem barks of *Erythrina abyssinica* had activity against *Staphylococus aureus in* Ntungamo, Bushenyi, Mbarara and Rakai districts except stem bark from Rakai. There was activity against *Pseudomonas aeuroginosa* in Mbarara and Bushenyi respectively as detailed in table 2 and figure 4. Generally, leaves extracts showed no microbial activity except for leaf extracts from Bushenyi district. No antibacterial activities were noted against *Salmonella species* and *E.coli*.

*Staphylococcus aureus* 

Ntungamo 1 0 0 0 0

Bushenyi 1 0 0 0 0

Mbarara 1 0 0 0 0

Leaves Ca Rakai 1 0 0 0 0

Ntungamo 0.328 0 0 0 0

Bushenyi 1 0 0 1 0

Mbarara 1 0 0 0 0

Fruits of Capsicum annum exhibited minimum inhibitory concentration against *Salmonella* 

The results show that the yields of root barks perform better than the stem barks and leaf extracts detailed in Table 1 and Figure 3. There is an average 8.6%, 5.5% and 2.9% yield for the root barks, stem barks and leaves respectively in the districts of Ntungamo, Mbarara, Bushenyi and Rakai. The information gained on the percent yields of crude extracts were used for standardizing dosage rates of fine powder preparations of the plant materials. For example, the amount of crude extract contained in a known weight of fine powder of plant materials can then be calculated. This agrees with findings by (Ejobi F and Olila D 2004;

The antimicrobial activity of crude extracts of root barks and stem barks of *Erythrina abyssinica* had activity against *Staphylococus aureus in* Ntungamo, Bushenyi, Mbarara and Rakai districts except stem bark from Rakai. There was activity against *Pseudomonas aeuroginosa* in Mbarara and Bushenyi respectively as detailed in table 2 and figure 4. Generally, leaves extracts showed no microbial activity except for leaf extracts from Bushenyi district. No antibacterial activities were noted against *Salmonella species* and *E.coli*.

Fruits Ca Rakai 1 0 1 0 0

Table 6. Minimum inhibitory concentration of different micro-organism

**2.7.1 Crude extracts of root, stem barks and leaves of** *Erythrina abyssinica*

*species* and *Pseudomonas aeruginosa* detailed in table 6.

**Antibacterial activities of the plant extracts** 

MICs of Extracts to different microorganisms (g/ml)

*aeruginosa Salmonella E.coli* 

*Pseudomonas* 

Sample ID

Leaves Ca

Leaves Ca

Leaves Ca

Fruits Ca

Fruits Ca

Fruits Ca

**2.7 Discussion** 

Olila *et al*., 2007).

**Yields of the plants extracts** 

Original sample concentration (g/ml)

The attributing factor for anti bacterial activity of the crude fruit extracts could be due to presence of bioactive constituents' in the extracts. This agrees with findings by Masola *et al*., 2009 and Ogundare *et al.,* (2006).

Moriyasu et al., (1998) collected stem bark E.abyssinica from Meru district of Kenya. They carried structural elucidation of new flavanones isolated from E.abyssinica and found presence of prenylated flavanones (abyssinin I(**1**), II (**2**), III(**3**), along with abyssinone V, sigmoidin A, B, C and F, and sigmoidin B 4´-(methyl ether). These compounds exhibited antimicrobial activities.

Further still, the presence of bioactive compounds viz; abyssinoflavanone IV, V and VI posses some antimicrobial activities as reported by (Ichimaru *et al*., 1996).

The stem woods of *Erythrina latissima* another species of Erythrina have two isoflavones and a flavanone with isolates Isoflavone (erylatissin A, B, C) in addition to 10 known flavonoids. These compounds exhibited antimicrobial activity against *Escherichia coli*, *Staphylococcus aureus*, *Bacillus subtilis* and *Candida mycoderma* (Chacha *et al*., 2004). This study found that *Erythrina abyssinica* was effective against *Staphyloccus aureus* and *Pseudomonas aeuroginosa*.

The root and stem extracts of *Erythrina abyssinica* however did not show any microbial activity against Salmonella species and *Escherichia coli.*

A study by Masola *et al*.,(2009) in Mpwapwa, in the semi arid central zone of Tanzania found out that bioactive constituents of terpenoids, tannins, phlobotannins, saponins and cardiac glycosides were found to be present in the stem barks of the plant *Adansonia digitata* (Bombacaceae) (African baobab). It would therefore mean similar bioactive compounds were present in the plant *Erythrina abysinnica*.

Ikigai et al., (1993) indicated that purified tannins, saponins and terpenoids have anti microbial activity. These bioactive compounds were reported to be effective against gram positive and gram negative bacteria. They exert bactericidal and bacteriostatic effects. This explained why there were activities on bacteria by the *Erythrina abyssinica* plant extracts.

Understanding the spectrum of antibacterial activity indicated that bioactive substances had broad spectrum or narrow spectrum of activity. The degree of susceptibility (diameter of inhibition zone) showed that gram positive bacteria were more susceptible compared to gram negative bacteria. There was urgent need to undertake phytochemical analysis of *Erythrina abyssinica* extracts to determine the chemical bioactive substances present in the extracts.

#### **Minimum inhibitory concentration (MICs)**

The root and stem barks of *Erythrina abyssinica* had activity against *Staphylococcus aureus* in all districts except stem bark for Rakai. The root barks, stem barks and leaves of Mbarara, Bushenyi respectively were effective against *Pseudomonas aeruginosa* demonstrated in Table 3. This demonstrated that the leaves extracts do not have antimicrobial activities.

Traditionally, the results from in vitro antimicrobial tests are written as qualitative or quantitative. Qualitative results are reported as susceptible, intermediate or resistant,

*In Vitro* Antimicrobial Activity of Crude Extracts of Erythrina abyssinica and Capsicum

bacteriostatic effects.

leaves of *Capsicum annum*.

g/ml or mg/l (Walker, 2006).

Bushenyi, Ntungamo and Rakai districts

**2.7.2.3 Minimum inhibitory concentration (MICs)** 

extracts.

correctly. **Plant Sample** 

annum in Poultry Diseases Control in the South Western Agro-Ecological Zone of Uganda 611

Further still, studies by Ikigai et al., 1993 indicate that purified tannins, saponins and terpenoids have anti microbial activity. These bioactive compounds were reported to be effective against gram positive and gram negative bacteria. They exert bactericidal and

Understanding the spectrum of antibacterial activity will indicate if given bioactive substance had broad spectrum or narrow spectrum of activity. The degree of susceptibility (diameter of inhibition zone) will show that gram positive bacteria are more susceptible compared to gram negative bacteria. The need to undertake phytochemical analysis of fruit extracts of *Capsicum annum* to know the chemical bioactive substances present in these

The fruit extracts of *Capsicum annum* from Bushenyi and Rakai exhibited minimum inhibitory concentration against *Salmonella species* and *Pseudomonas aeruginosa* respectively as detailed in table 4. There was no minimum inhibitory concentration noted for the case of

Traditionally, qualitative and quantitative results from in vitro antimicrobial tests are reported. Qualitative results are reported as susceptible, intermediate or resistant, whereas quantitative results are reported as minimum inhibitory concentration (MIC) in µg/ml or

Walker,(2006), noted that in-vitro antimicrobial susceptibility tests are predictive of in vivo therapeutic efficacy. However the ability of an in-vitro test to predict the clinical effectiveness of an antimicrobial agent is dependent on that test being performed

**sample (g)** 

Bushenyi Leaves 62.4 53.9 86.4 Ntungamo Leaves 162.5 84.2 51.8 Rakai Leaves 253.0 174.0 68.8 Mbarara Fruits 85.3 8.8 10.3 Bushenyi Fruits 127.1 11.6 9.1 Ntungamo Fruits 61.3 4.9 8.0 Rakai Fruits 248.9 37.0 14.9

**Dry weight of concentrate (g)**  **% yield** 

**Location Plant part Weight of** 

*C. annum* Mbarara Leaves 146.8 37.1 25.3

Table 4. Percentage yield extracts of the leaves and fruits of *Capsicum annum* from Mbarara,

In vitro tests cannot always predict the efficacy of an antibacterial agent in vivo (Walker, 2006). In vitro tests involve the continuous exposure of a relatively small concentration of bacteria to a constant level of antimicrobial agent under standardized testing conditions. The selection of an appropriate dose can be driven by the result of quantitative susceptibility tests (Ambrose, 2005). Despite these considerable differences, studies in human medicine

have demonstrated the clinical value of in vitro susceptibility tests (Ambrose, 2005).

whereas quantitative results are reported as minimum inhibitory concentration (MIC) in µg/ml or g/ml or mg/l (Walker, 2006).

Walker,(2006), indicated that in-vitro antimicrobial susceptibility tests were predictive of in vivo therapeutic efficacy. However the ability of an in-vitro test to predict the clinical effectiveness of an antimicrobial agent is dependent on that test being performed correctly.

In vitro tests involve the continuous exposure of a relatively small concentration of bacteria to a constant level of antimicrobial agent under standardized testing conditions (Walker, 2006).

The selection of an appropriate dose can be driven by the result of quantitative susceptibility tests (Ambrose, 2005). Studies in human medicine have demonstrated the clinical value of in vitro susceptibility tests.

The interpretation of susceptibility testing depended on the relationship between in vitro susceptibility and factors involved in relation to tissue drug concentration (which depended on factors such as dose and pharmacokinetic and pharmaco-dynamic properties of the drug or drug class.
