ABSTRACT
The negative consequences of crude oil exploration and exploitation on the health of exposed individuals cannot be overemphasized. The consumption of crude oil-contaminated plant extracts by rural communities in oil-rich regions as traditional medicine for illnesses has raised local and international concerns about their safety. This study was aimed at the evaluation of the physicochemical properties of plant extracts and soils, as well as the biochemical and molecular effects of ingested aqueous stem bark extracts of Mangifera indica obtained from uncontaminated and oil-contaminated environments in Wistar albino rats. In this study, a total of eighty (80) female Wistar albino rats of average weight of 155gm were used. The rats were divided into five groups. Group I was the control, while groups II and III received 250 and 3500 mg/kg b.w. of aqueous extract of contaminated Mangifera indica, respectively. Rats in groups IV and V received 250 and 3500 mg/kg b.w. of aqueous extract of uncontaminated plants. The experiment was for a period of 90 days. Analyses were carried out with the aid of a spectrophotometer. The results showed that the physicochemical properties of the crude oil-contaminated soil decreased or increased significantly (P<0.05). Similarly, the levels of essential elements such as phosphorus, sulfur, calcium, magnesium, iron, and zinc were significantly (P<0.05) reduced in crude oil-contaminated soil and plant samples compared to the normal soil and plant (p < 0.05). Qualitative phytochemical screening revealed significant alteration of important bioactive compounds such as flavonoids, steroids, terpenoids and anthraquinones. The results of biochemical studies revealed a significant elevation and decrease (P<0.05) in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose 6-phosphatase (G6Pase), and the concentrations of creatinine, urea, white blood cells (WBC), monocytes, MDA, as well as lipid profile indices and progesterone in the serum of rats administered the extract of crude oil-contaminated M. indica, as compared to those receiving the aqueous extract of plants from uncontaminated soil (p < 0.05). Histological findings revealed no evident pathology in the heart muscles of both control and treated rats. However, significant damage was observed in the kidneys and livers of rats in Groups II and III, including acute tubular necrosis, parenchymal tissue damage, and morphological alterations in liver structures. In contrast, no pathological changes were noted in the liver and kidney tissues of rats in Groups IV and V. Additionally, molecular investigations showed a significant (p<0.05) increase in the concentrations and gene expression levels of tissue DNA, RNA, protein, KIM-1 (Kidney Injury Molecule-1), MCP-1 (Monocyte Chemoattractant Protein-1), Glutathione Peroxidase-1 (GPx-1), OGA (O-GlcNAcase), and OGT (O-GlcNAc transferase) in rats administered the extract of M. indica from crude oil-contaminated soil, compared to those that received the aqueous extract from plants grown in uncontaminated soil (p < 0.05). In conclusion, this study has showed adverse effects of crude oil contamination on the physicochemical properties of soil and plants, as well as the biochemical and molecular parameters in rats after 90 days of exposure to aqueous extracts of crude oil contaminated plants. These findings highlight the need for strict regulations and measures to minimize the negative impacts of crude oil exploration and exploitation on the environment which could lead to skin cancer, atherosclerosis, diabetes, rashes, ulcer in humans.
