Sidra Hussan Saeed¹, Ghulam Mujtaba Shah Gillani¹, Uneb Gazder², Shahida Shaheen³, Alia Gul¹,

Md.  Arifuzzaman^4*, Afzal Haq Asif⁵, Alifa Nasrin⁶, Md. Asaduzzaman⁷, Qaisar Mahmood^{8, 9*}

¹Department of Botany, Hazara University, Mansehra, Pakistan

²Department of Civil Engineering, University of Bahrain, Isa Town 32038, Bahrain

³Department of Environmental Sciences, Kohsar University, Murree, Pakistan

⁴Department of Civil and Environmental Engineering, College of Engineering, King Faisal University, Al-Ahsa 31982, Saudi Arabia

⁵Pharmacy Practice Department, College of Clinical Pharmacy, King Faisal University, Al-Ahsa 31982, Saudi Arabia

⁶Combined Military Hospital, Dhaka, Bangladesh

⁷National Heart Foundation Hospital & Research Institute, Dhaka, Bangladesh

⁸Department of Environmental Sciences, COMSATS University, Abbottabad Camps 22060, Pakistan

⁹Department of Biology, College of Science, University of Bahrain, Sakhir 32038, Bahrain

Abstract

Phenolic and flavonoid content in plants are important abiotic stress biomarkers. The individual and combined impacts of toxiferous metals Arsenic (As), Cadmium (Cd) and (Copper) Cu were employed in recent studies to investigate their effect on Total flavonoids content (TFC) and total phenolic content (TPC) in various parts of Hydrocotyle umbellata L., to explore the role of plant in abating metal contamination. Folin-Ciocalteu and AlCl₃ methods were used to study TPC and TFC, respectively. Two-way analysis of variance (ANOVA) and a classification and regression tree (CART) model was employed for statistical analysis. Highest TPC was observed in decreasing order as leaf > stem > root for all the metals stress. Whereas, highest TFC was found in all plant parts when subjected to As toxicity, and the lowest TFC was found in stem of the plant under Cu toxicity. There was significant effect on TPC when subjected to Cu and As stress; in addition, significant effects of Cd and combined metal stress were also evident. Treatment concentration had non-significant effect on TPC under single metal but had significant effect in case of combined metal stress. Similarly, in case of TFC no significant effect was recorded under all the stress types. Metal type had significant effect on TPC and TFC. Whereas plant part had significant impact on TPC but non-significant values were observed on TFC. This study epitomized TPC and TFC in H. umbellata L. as effective and viable tool to pertain its role in phytoremediation against contamination of Cd, Cu and As.

Keywords: Metal toxicity, Phytoremediation, Secondary plant metabolites, Water pennywort