PHYTOCHEMICAL, ANTIMIROBIAL SCREENING AND HUMAN HEALTH RISK ASSESSMENT OF HEAVY METALS OF STEM-BARK AND ROOT EXTRACTS OF NEWBOULDIA LAEVIS (BOUNDARY TREE)

Authors

  • F. C. Orakwue
  • V. N. Okafor
  • F. O. Obumselu
  • J. O. Okoli
  • K. C. Nnamdi

DOI:

https://doi.org/10.46602/jcsn.v46i5.673

Abstract

Increasing awareness of multi-drug resistant strains of microorganisms and the hazards associated with the use of synthetic / orthodox drugs has increased investigations on plant extracts as possible alternative drugs. Extracts of Newbouldia laevis stem-bark and root were subjected to phytochemical and antimicrobial screening as well as heavy metal concentration content. The aim was to investigate the potentiality of using the extracts as alternative to synthetic / orthodox drugs and conduct ecological, and human health risk assessment of heavy metals in the extracts. Phytochemical screening of the extracts was carried out using standard methods. Antimicrobial activities of the aqueous, methanol and n-hexane extracts were carried out using agar well diffusion method. The test organisms were laboratory isolates of Salmolella tyhpi, Staphylococcus aureus, Escherichia coli, Pseudomanas aeruginosa, Aspergellus flavus, Aspergillus niger, and Candida albican. Metal concentration of the extracts was carried out using Atomic Absorption Spectrometry (AAS). Phytochemical screening showed the presence of the following phytochemicals in the stem-back and root extracts: alkaloid (1.00%, 4.00%), flavonoids (7.00%, 0.60%), saponins (10.00%, 11.00%), cardiac glycosides (2.24%, 3.06%), steroids (2.50%,4.87%), terpenoids (1.80%, 1.26%), and tannins (6.00%,10.00%) respectively. The survey of heavy metal concentration was Zn (12.10 mg/kg), Mn (3.45 mg/kg), Cr (4.55) and Zn (10.80 mg/kg), Mn (2.88 mg/kg) and Cr (4.99 mg/kg) in stem bark and root extracts respectively. Cd, Cu and Pb were not detected in both extracts. This showed that the levels of concentrations of the metals determined were generally below the maximum permissible limits established by International regulatory bodies.  All the extracts inhibited growth of the test organisms. The aqueous and ethanol extracts proved more potent than the positive control (tetracycline). The results of ecological risk assessment showed PERI, Cdeg, mCdeg and PLI values of 0.8097, 0.1423, 0.0474 and 0.1222 respectively for the stem bark extract and 0.7015, 0.1332, 0.0444 and 0.1139 respectively for the root extract. Human health risk assessment of the heavy metals gave a total hazard index of 0.0764 and 0.0667 for stem bark and root extracts respectively. These ecological and human health risk assessment results indicated no risk in taking the extracts as alternative medicine.  This study therefore has justified ethno-medical use of the plant for the treatment of diseases caused by these pathogens

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Published

2021-12-31

How to Cite

Orakwue, F. C. ., Okafor, V. N. . ., Obumselu, F. O. ., Okoli, J. O. ., & Nnamdi, K. C. . (2021). PHYTOCHEMICAL, ANTIMIROBIAL SCREENING AND HUMAN HEALTH RISK ASSESSMENT OF HEAVY METALS OF STEM-BARK AND ROOT EXTRACTS OF NEWBOULDIA LAEVIS (BOUNDARY TREE). Journal of Chemical Society of Nigeria, 46(6). https://doi.org/10.46602/jcsn.v46i5.673