THE PHYTOCHEMICAL CONSTITUENTS AND ANTIMICROBIAL ACTIVITIES OF ABRUS PRECATORIUS METHANOL LEAF AND SEED EXTRACTS

Abstract

Abrus precatorius commonly known as rosary pea in English and Idon Zakara in Hausa; Nigeria, has been used in traditional medicine. The study was carried out to determine the phytochemical constituents and the in vitro antimicrobial activities of Abrus precatorius (A. precatorius) methanol seed and leaf extracts. The quantitative phytochemical contents were determined using standard methods. Different concentrations of the extracts (120mg/ml, 160mg/ml and 200mg/ml) were prepared to determine their antimicrobial activity against Staphylococcus aureus, Salmonella typhi, Klebsiella pneumonia, Penicillum spp., Aspergillus niger and Trychophytom spp. A double fold serial dilution (200 – 12.5 mg/ml) was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extract. The quantitative phytochemical contents of methanol seed extract of A. precatorius showed that phenols had the highest concentration (563.95±0.15 mg/100g) and alkaloid had the least concentration (34.15±0.38 mg/100g), while in methanol leaf extract, Saponins had the highest concentration (2560.64±11.77 mg/100g) and Tannins had the least concentration (35.05±0.14 mg/100g). The bacterial isolates were all susceptible to methanol seed extracts of A. precatorius at a concentration of 200mg/ml, showing the highest zone of inhibition for Klebsiella (26mm) and S. typhi (21mm) exhibiting the least zone of inhibition for the leaf extract, while all the fungi isolates were resistant to the extracts at the concentration tested. The result for MIC methanol seed extract showed highest MIC value for Klebsiella as 200mg/ml and the least 175mg/ml for both S. typhi and S. aureus while 200mg/ml MIC value for Klebsiella, S. typhi and S. aureus in methanol leaf extract. There was no significant difference (at p>0.05) between MIC and MBC of K. pneumonia while significant difference was observed in the treatment with methanol seed and leaf extract for both S. typhi and S. aureus. Based on the result obtained from this study, it can be concluded that the methanol seed and leaf extracts of A. precatorius have inhibitory potential against bacterial isolates. These observed level of activity may be attributed to presence of phytoconstituents in extracts of A. precatorius. Therefore, A. precatorius could serve as antibacterial agents.