Study on the Phytochemistry and Antibacterial Activity of the Whole Root of Rothmania whitfieldii

Abstract

Plants as sources of medicinal compounds have continued to play dominant roles in the maintenance of human health since ancient times. Rothmannia whitfieldii an evergreen shrub which is known for its height of 15 meters, is also gathered from the wild for a number of local medical applications. Whole dried root specimen of Rothmania whitfieldii was extracted by maceration and then screened for antibacterial activity using the agar well-diffusion technique. Five typed bacterial strains namely, Staphylococcus aureus (ATCC 12600), Pseudomanas aeruginosa (ATCC 10145), Escherichia coli (ATCC 11775), Salmonella kintambo (SSRL 113) and Bacillus subtilis (ATCC 6051), and six locally isolated clinical strains (E. coli, S. typhi, P. aeruginosa, S. aureus and two Proteus species designated as Proteus I and Proteus II), were tested for susceptibility to the plant extract. Phytochemistry revealed the presence of flavonoids, saponnins, tannins, carbohydrates and steroidal aglycone. Alkaloid is present in trace amount only in the ethanolic extract. Ethanolic extract exhibited a wider spectrum of activity, being effective against 81.8% of the test organisms compared with the cold-water extract (54.5%) or hot water extract (27.3%). The minimum inhibitory concentrations (MICs) varied not only with the test organisms but also with the various extracts of the plant. All the extracts had bacteriostatic activity on the susceptible organisms with the exception of ethanolic extract, which had a cidal activity against Sal. Kintambo (SSRL 113). These experimental findings endorse the folkloric claims that the plant is medicinal against gastrointestinal diseases.