Evaluation of Saponin Extract from Vitex doniana and Pentaclethra macrophylla for Antibacterial Activity

Abstract

Saponins are pharmacologically active compounds that have been shown to ameliorate abnormal physiological processes and be aptly applied in folklore for the treatment of maladies occasioned by infectious agents. Consequently, saponins from Vitex doniana and Pentaclethra macrophylla were evaluated for antibacterial properties, as these herbs are used in folk medicine. Dried pulverized plant materials were defatted, and solvents with varying polarity were applied at varying ratios for the extraction of saponins. Phyto-chemistry was in accordance with standard methods, while an antibacterial assay was made through the agar well diffusion and micro broth dilution techniques. Phytochemical quantitation showed high concentrations of tannins, 231˘0.6 CE/g, and saponins, 58% from V. doniana. Similarly, P. macrophylla stem bark extract also showed high concentrations of tannins, 309˘2.42 CE/g, alkaloids, 71%˘0.5%, and saponins, 87%˘3.4%. The ethanol extracts of V. doniana inhibited the growth of Staphylococcus aureus (ATCC 11775) and a clinical strain with inhibition zone ranges of 15.5˘2.12 to 7.0˘0.0 (mm) against leaf extracts and 20.0˘1.41 to 7.0˘0.0 (mm) against stem bark extracts. Conversely, saponin extract from V. doniana showed a broad spectrum of activity, as it inhibited both Gram-negative and -positive test strains, E. coli clinical strain (20.0˘1.41 mm), P. aeruginosa clinical strain (18.5˘0.71 mm), E. coli ATCC 11775 (17.0˘0 mm), and S. aureus clinical strain (13.0˘1.41 mm). However, a broad spectrum was similarly achieved with P. macrophylla extracts, as all test bacteria genus was susceptible. Saponin fractions showed a high potency and broad spectrum antibacterial activity and thus a validation of the folklore applications and the potential for use as a drug or drug scaffold.

Ecdysteroids from the Stem Bark of Vitex doniana Sweet (Lamiaceae; ex. Verbenaceae): A Geographically Variable African Medicinal Species

“…Vitex doniana is rich in saponins and authors of antimicrobial studies on the species attribute antibacterial effects to them. Because saponin-enriched extracts have demonstrated non-discriminate activity against Gram-positive [ 17 ] and Gram-negative [ 18 ] bacteria, then it is likely that saponins are important in these antimicrobial outcomes.…”

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“…Then the organic layer was collected, the solvent was evaporated, the residue was dissolved in methanol. Finally, diethyl ether was added to precipitate the saponin 14 .…”