Antimicrobial Activity of Moringa oleifera Leaf Extracts against Streptococcus pneumoniae Isolates

Pneumococcal diseases (PD) constitute a major threat to the global public health stability especially in the developing world. The risk is greater for children under 5 years, the elderly and persons living with compromised immune systems. Antibiotic agents, conjugate as well as polysaccharide vaccines have been available for several decades and have saved many lives. However, the burden of PD has consistently remained high resulting in poor quality of life and strained economic tenets. Constant resistance to available antibiotic agents and low access to vaccines constitute major setbacks to efforts meant to scale down the burden of PD. The need to explore more viable and promising options is not only urgent but also untenable. We profiled the pharmacological credentials of Moringa oleifera extracts as a possible efficacious alternative to conventional prophylactic and therapeutic interventions.  Methanol and ethanol extracts of air-dried leaves of Moringa oleifera plant were subjected to phytochemical screening to identify the presence of carbohydrates, proteins, saponins, alkaloids, tannins, flavonoids, phyto-sterols, oils, and fats. A working solution of the two extracts was prepared by dissolving 20 mg & 40 mg of the extracts in 1ml of 99.9% dimethyl sulfoxide solvent. Sterilized 6 mm blank discs were loaded with 20ul of the final extract concentrations and incubated at 45 oC for 20 hours. Dimethyl sulfoxide (100% DMSO) impregnated discs and 30 mcg ceftriaxone antibiotics were used as negative and positive controls respectively. Colon morphology on gentamicin blood agar (GBA) and blood agar (BA), gram staining and optochin assay were leveraged to identify Streptococcus pneumoniae. Disk diffusion method on Muller Hinton agar was used to evaluate sensitivity of Streptococcus pneumoniae to the subject extracts. Methanol and ethanol extracts were found to contain carbohydrates, proteins, saponins, tannins, flavonoids, steroids, fixed oils, alkaloids, and cardiac glycosides. Both extracts were found to contain flavonoids, tannins, and phenolic compounds. Ethanol & methanol extracts had lower anti-bacterial activity as compared to the 30 mcg positive control. Further exploration to reveal the anti-bacterial activity of aqueous based extracts on Streptococcus pneumoniae is strongly recommended