Antibacterial Activity of Ethanolic Extracts of InfloreInfructescence and Leaf of Petiveria alliacea L. (Phytolaccaceae)

Petiveria alliacea (Linneaus) is a perennial medicinal plant with record of relevance in folkloric and modern medicine. Its root, stem-bark, and the leaves have been focused upon in many researches. However, little has been documented about the antibacterial effect of the inflore-infructescence part of the plant compared to the leaf which is mostly used. An in vitro antibacterial potential of the leaf and the inflore-infructescence was comparatively assessed by the agar-well diffusion method on eight bacterial isolates namely; Escherichia coli (ECO), Bacillus cereus (BAC), klebsiella aerogens (KLE), Proteus vulgaris (PRO), Staphylococcus aureus (STA), Pseudomonas aeruginosa (PSD), Salmonella typhi (TYP), and Moraxella catarrhalis (MOR). The results showed that the pattern of antibacterial activity of the leaf extract was; BAC > TYP > ECO > KLE (26.67±1.15a , 22.67±2.31b , 20.67±1.15c , and 13.33±1.15d ) while PSD, STA, PRO, and MOR were resistant. The inflore-infructescence presented the order; BAC > MOR > ECO > TYP > KLE (31.33 ± 1.15a, 26.67 ± 1.15b, 25.33 ± 0.58b, 23.33 ± 1.15c, and 21.33 ± 1.15d). PSD, STA and PRO were resistant to both extracts. Inhibition zones from the test isolates were significantly higher in the inflore-infructescence assay than the leaf while the Minimum Inhibition Concentrations (MICs) were lower in the infloreinfructescence assay (0.049 mg/mL – 1.563 mg/mL) than the leaf (0.049 mg/mL – 6.25 mg/mL). The extracts and some of the commercial antibiotics (septrin and amoxicillin) had no inhibitory effect on PSD. ECO was resistant to all the tested antibiotics but highly sensitive to the test extracts while PRO was highly resistant both to the extracts in this study and all the antibiotics in the control experiment. It was concluded that ethanolic extracts of the inflore-infructescence of P. alliacea in this study demonstrated a significant antibacterial activity higher than the leaf while the duo’s activities compared to that of the control commercial antibiotics.