Antimicrobial Activity of Methanolic Leaf Extract of Terminalia brownii on Streptococcus pneumoniae Isolates

Abstract

Streptococcus pneumoniae is a gram-positive facultative anaerobic bacterium that is responsible for causing pneumonia, otitis, sinusitis, bacteremia, and meningitis. Pneumococcal infections are treated using antibiotics and can be prevented through vaccination. Alternatively, ethnobotanical studies have elucidated that specific plant species including Terminalia brownii were used for treating pneumococcal infections. Terminalia brownii (Combretaceae) is a leafy deciduous tree that can grow up to 15m high and is widely distributed within semi-arid areas and bushy grasslands. Traditionally, infusions from the wood part were used to treat cough while decoctions from the bark are used to manage gonorrhea, tuberculosis, and fungal infections. In this study, we sought to investigate the antimicrobial activity of Terminalia brownii toward pneumococcus bacteria.

Method; In vitro antimicrobial susceptibility testing was carried out. Green leaves of Terminalia brownii were obtained from the botanical garden at Kabarak University. The disk diffusion method was used to assess antimicrobial susceptibility and therefore activity. The percentage yield of extract obtained after preparation was 7%. Phytochemical analysis showed flavonoids and Terpenoids were in the highest concentration while tannins and saponins in moderated concentration. Alkaloids and cardiac glycosides were undetected in the extract. Four concentrations of leaf extract were used: 7, 3.5, 1.75, and 0.875mg/ml. correspondingly, their zones of inhibition were 9.12mm, 8.03mm, 7.32mm, and 6.52mm respectively which was lower than that of amoxicillin (10.26mm). Notably, a decrease in concentration was associated with a decrease in antistreptococcal activity. The methanolic leaf extract of Terminalia brownii showed antistreptococcal activity against pneumococcus but was less potent than amoxicillin.