UV-VIS spectroscopy and heavy metals analysis for toxicological assessment of some selected Nigerian medicinal plants

Abstract

This study assessed the concentrations of heavy metals and the UV-Vis spectroscopic properties of five medicinal plants (Chevala bolli, Blighia unijugata, Carica papaya, Hippocrate sp., Cananga odorata). The result of heavy metals analysis showed that content of copper (Cu) content varied between (0.5258 mg/kg) and (0.6262 mg/kg) in Blighia unijugata and Chevala bolli, respectively. Chromium (Cr) was the maximum in Hippocrate sp. indicating potential toxicological concerns with cadmium (Cd), which was observed at a peak concentration of 0.438 mg/kg, and arsenic (As), which was detected at a concentration of 1.146 mg/kg. Hippocrate sp. were especially worrisome in terms of lead (Pb) concentrations per organism, and Carica papaya levels exceeded recommended safety limits, both at 2.919 mg/kg and 2.99 mg/kg, respectively. UV-Vis spectroscopic analysis revealed significant absorbance changes that signify the presence of important phytochemicals, such as flavonoids and phenolic compounds. Reduced absorbance values may be indicative of possible reduction in medicinal efficacy due to the accumulation of heavy metals in these plants. Correlation analysis also revealed the strongest positive correlations between the plants, especially the Chevala bolli and Cananga odorata (correlation coefficient is 0.996), indicating that these plants share similar phytochemical profiles. These findings underscore the importance of regular monitoring as well as stricter regulation of heavy metals and medicinal plant products to protect public health. Continuous heavy metal screening, phytochemical characterization and improved consumer awareness with respect to the origin and consumption of these plants are recommended to mitigate the contamination risk. The information from this study may be valuable for the safety and therapeutic reliability of medicinal plants used in traditional or modern medicine.