Investigation of possible heavy metal contaminants of Zingiber officinale rhizomes and Allium sativum bulbs sourced from a market in Enugu State of Nigeria using rat models

Daniel Ikechukwu Oraekei 1, *, Peter Chibueze Ihekwereme 1, Daniel Lotanna Ajaghaku 3, Markben Nnamdi Adione 2 and Onyeka Chinwuba Obidiegwu 2

1 Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
2 Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
3 Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Enugu State University of Science and Technology, Enugu State, Nigeria. 
 
Research Article
World Journal of Biology Pharmacy and Health Sciences, 2023, 16(02), 088–095.
Article DOI: 10.30574/wjbphs.2023.16.2.0465
Publication history: 
Received on 23 September 2023; revised on 05 November 2023; accepted on 08 November 2023
 
Abstract: 
Natural products such as plants, animals, microorganisms, and aquatic organisms have been employed by humans from ancient time for treatment and prophylaxis of diseases. In the last decade, attention is being diverted towards traditional medicine partly due to high cost of synthetic and semi-synthetic drugs, increase in multidrug resistant disease causing microorganisms, and unavailability of certain drugs. A major limitation is heavy metal contamination. This study is aimed at investigating the possible heavy metal contaminants of Zingiber officinale rhizomes and Allium sativum bulbs sourced from a market in Enugu State of Nigeria using rat models. Phytochemical analysis and acute toxicity studies were done according to standard methods with slight modifications. The Atomic Absorption Spectroscopy (AAS) technique was used for extraction and assay of the possible heavy metal contaminants. The phytochemicals in Zingiber officinale were alkaloids, tannins, flavonoids, steroids and terpenoids and those of Allium sativum were alkaloids, saponins, flavonoids, and glycosides. The actual lethal doses (actual LD50) of Zingiber officinale, Allium sativum and combination of the two were 8,660, 4,472, and 5,477 mg/kg body weight respectively. The respective amounts of the tested heavy metals (lead, cadmium, mercury, chromium and arsenic) present in the samples were 0.041, 0.082, 0.084, 0.061 and 0.041 ppm in Zingiber officinale and 0.012, 0.018, 0.039, 0.045 and 0.030 ppm in Allium sativum. These were below the WHO permissible limits. This study therefore concluded that heavy metals contamination of herbal products are inevitable but can be controlled and minimized to WHO acceptable limit.
 
Keywords: 
Allium sativum bulbs; Ethanol extracts; Heavy metal contaminants; Zingiber officinale rhizomes
 
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