## 3 Results and Discussion
### Antimicrobial Analysis  
The essential oil was tested against thirteen opportunistic bacteria. The results showed that the plant was active against the growth of all organisms except _Salmonella typhimurium_, _Pseudomonas aeruginosa_ and _Proteus vulgaris_. The essential oil of \(H\). _africana_ showed activity against growth of some pathogenic bacteria that cause infections associated with diarrhoeal diseases (Tables 1 and 2). The antibacterial activity could also be attributed to the presence of some chemical constituents in the essential oil fraction of \(H\). _africana_. For example, Terpinen-4-ol, both in aqueous solutions and vapour form, acts as an antimicrobial agent against bacteria of Legionella genus [19]. \(\beta\)-cymene possesses antibacterial and antifungal activities [20]. Naphthalene has antibacterial and antifungal properties against various human pathogens [21]. Diphenyl ether possesses bactericidal activity against gram-positive and gram negative bacteria [22]. (\(-\))-Spathulenol, an oxygenated sesquiterpene, has antifungal, antibacterial, antiviral and cytotoxic activities [23].The zones of inhibition varied from 10 to 25 mm (Table 1). The HA essential oil showed a significant growth inhibitory effect against the ten organisms (\(p<0.05\)) having IC\({}_{50}\) values ranging from 5 to 0.005 mg/mL (Table 2). The lowest MIC was observed with _Enterococcus faecalis_ (\(p<0.05\)) (Table 2). Of the selected and tested nine fungal isolates, the plant species inhibited only the growth of _Aspergillus niger_ whose MIC activity was significantly similar to the control drug (\(p<0.05\)) (Tables 3 and 4). Figure 5: Hydrogen peroxide scavenging activity of the essential oil of \(H\). _africana_. Lines with different letters within the same concentration are significantly different (\(p<0.05\)). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Organism** & **Essential Oil** & **Positive Control (Amoxicillin)** \\ \hline _Salmonella typhimurium_ – & NA & \(36\pm 1.1\) a \\ _Enterococcus faecalis_ – & 17 \(\pm\) 0.2 a & \(34\pm 1.2\) b \\ _Escherichia coli_ – & 15 \(\pm\) 1.3 a & \(35\pm 0.2\) b \\ _Pseudomonas aeruginosa_ – & NA & NA \\ _Bacillus cereus_ + & 10 \(\pm\) 1.6 a & \(32\pm 1.2\) b \\ _Shigella sontei_ – & 15 \(\pm\) 0.3 a & \(35\pm 2.2\) b \\ _Streptococcus pyogenes_ + & 22 \(\pm\) 0.2 a & \(35\pm 2.1\) b \\ _Bacillus subtilis_ + & 22 \(\pm\) 0.2 a & \(40\pm 0.2\) b \\ _Shigella flexneri_ – & 19 \(\pm\) 0.2 a & \(40\pm 1.1\) b \\ _Kleppneumoniae_ – & 23 \(\pm\) 2.1 a & \(33\pm 2.2\) b \\ _Staphylococcus aureus_ + & 25 \(\pm\) 3.1 a & \(37\pm 0.2\) b \\ _Proteins vulgaris_ – & NA & \(38\pm 1.1\) a \\ _Serretiamercenscens_ – & 25 \(\pm\) 3.1 a & \(35\pm 2.2\) b \\ \hline \end{tabular} The bacteria are denoted thus by: St (_Salmonella typhimurium_), Ef (_Enterococcus faecalis_), Ec (_Escherichia coli_), Pa (_Pseudomonas aeruginosa_), Be (_Bacillus cereus_), Sc (_Shigella somtei_), Sp (_Streptococcus pyogenes_), Bs (_Bacillus subtilis_), Sf (_Shigella flexneri_), Kp (_Kleb pneumoniae_), Sa (_Staphylococcus aureus_), Pv (_Proteins vulgaris_) and Sm (_Serratia marcescens_). Data expressed as means \(\pm\) SD; \(n=3\); values along a row with different subscripts are significantly different (\(p\leq 0.05\)).  
\end{table} 
Table 1: Inhibition zone diameters caused by the essential oil (50 mg/mL) in the tested opportunistic bacteria.