The Antibacterial, Antioxidant and Phytochemical Composition of Combretum tanaense (J. Clark) Root Extracts

Aims: To evaluate the antibacterial, antioxidant and phytochemical composition of Combretum tanaense extracts.

Study Design: Laboratory-experimental design was used in this study.

Place and Duration of Study: Fresh roots of Combretum tanaense were obtained from Mount Kenya University botanical garden in Thika (Kiambu County-Kenya). The study was carried out between November 2017 and February 2018 at Mount Kenya University Biochemistry and Pharmacognosy laboratories.

Methodology: Duplicate voucher specimens were prepared and deposited at the East Africa herbarium housed at the National Museums of Kenya and Mount Kenya University herbarium. Extraction of total extracts of C. tanaense roots was conducted according to standard procedures. Agar well diffusion and 2-2-diphenyl picryl hydrazyl (DPPH) assay methods were used to evaluate antibacterial and free radical scavenging activities of the extracts. All assays were performed in triplicate. Antibacterial data was presented as a mean zone of inhibition ± SEM while free radical scavenging activities were expressed regarding IC50. Phytochemical screening was carried out using standard procedures to ascertain the presence or absence of various phytochemical groups in the test plant.

Results: The current study indicated that Combretum tanaense root extracts had antibacterial activities against the selected gram-positive and gram-negative bacterial strains. The highest activity was recorded against gram-negative bacteria (Haemophilus influenza) by exhibiting inhibition zones of 13.32±0.15 mm and 12.82±0.36 mm for methanol and water extracts respectively. Antioxidant activities for both methanol and water extracts were ten times higher compared to that of standard (L-ascorbic acid). The extracts were found to have saponins, phenols including tannins and glycosides.

Conclusion: Extracts of Combretum tanaense have compounds that exhibit antibacterial and antioxidant activities. From the results obtained, the ability of the extracts to inhibit bacterial growth and scavenge for free radicals was due to the presence of phenolic compounds and will be attributed to the healing properties of this plant. This study recommends further studies including toxicity and isolation of active compounds for the development of products with pharmaceutical value.