Common bean is an important source of protein in sub-Saharan Africa but its production is constrained by various factors especially bacterial diseases. The aim of this study was to evaluate compounds from Juniperus procera for bioactivity against common bean pathogens, Pseudomonas savastanoi pv. phaseolicola and Xanthomonas axonopodis pv. phaseoli. Solvent extraction method was used to obtain crude extracts from the stem bark and leaf of J. procera that underwent fractionation and purification using various chromatographic techniques, leading to the isolation of three compounds, namely: epicatechin (1), podocarpusflavone A (2) and juniperolide (3). Structures of the compounds were elucidated based on NMR and HRESIMS analyses. The bioactivity of the compounds was determined by disc diffusion assay. The compound epicatechin showed the highest activity against P. savastanoi pv. phaseolicola (21.7±1.2 mm). On the other hand, podocarpusflavone A and juniperolide showed weaker activity of 8.0±1.7 and 8.0±2.0 mm, respectively against the same pathogen. The three compounds showed weak or no activity against X. axonopodis pv. phaseoli of 6.0±0.0, 7.0±0.0 and 6.0±0.0 mm, respectively. Therefore, epicatechin can be used for the development of biopesticides for the control of P. savastanoi pv. phaseolicola.
Key words: Antibacterial compounds, Juniperus procera, Pseudomonas savastanoi pv. phaseolicola, Xanthomonas axonopodis pv. phaseoli.
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