Plumbago zeylanica L. Root Fraction Mitigates Oxidative Stress-Induced DNA Damage in Human Blood Lymphocytes and Exhibits Cytotoxicity against MCF-7 Cells

Abstract

Background: Plumbago zeylanica L. (P. zeylanica L.), an ethnomedicinal plant species, is known for its diverse therapeutic benefits, such as anti-malarial, anti-inflammatory, anti-microbial, memory enhancing, and wound-healing properties. This study aimed to investigate the antioxidant, genoprotective, and cytotoxic activities of different root fractions of P. zeylanica L., namely PzMH (hexane fraction), PzMC (chloroform fraction), PzME (ethyl acetate fraction) and PzMM (methanol fraction). Methods: The present study involved the investigation of the free radical scavenging potential of all the fractions. Antioxidant activity was assessed through superoxide radical scavenging, nitric oxide radical scavenging, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assays. Genoprotective efficacy was determined using the alkaline comet assay to evaluate the protective effects against DNA damage induced by hydrogen peroxide (H₂O₂) in human blood lymphocytes. Additionally, cytotoxicity was investigated against three different cancer cell lines: MCF-7, MDA-MD231 (breast cancer cell lines), and A498 (kidney carcinoma cell line) to examine the suppression of cell proliferation. Results: Among all the fractions, PzME exhibited the highest antioxidant activity with IC₅₀ values of 80.94 μg/mL, 79.63 μg/mL, and 98.3 μg/mL in superoxide radical scavenging, nitric oxide radical scavenging, and DPPH assays, respectively. In terms of genoprotective effects, the PzME fraction demonstrated the highest protection against H₂O₂-induced DNA damage in human blood lymphocytes, reducing the percentage tail DNA content from 29.6% to 7.34% at the highest tested concentration (400 μg/mL). Additionally, the PzME fraction showed potent cytotoxicity against MCF-7 cells, followed by MDA-MB-231 and A498 cells, with 50% growth inhibition at concentrations of 147.95 μg/mL, 225.37 μg/mL, and 226.13 μg/mL, respectively. Phytochemical screening revealed the highest total phenolic, total flavonoid, and total tannin contents in the PzME fraction. GC-MS analysis of the PzME fraction identified trans-cinnamic acid, 2,4-Di-tert-butylphenol, and 2-Methoxy-4-vinylphenol as potential compounds responsible for the observed genoprotective and cytotoxic activities. Conclusions: The study highlights the antioxidant, genoprotective, and cytotoxic properties of PzME fraction from Plumbago zeylanica L. root. The fraction exhibited robust antioxidant potential and protected human blood lymphocytes from DNA damage. Additionally, it exhibited notable cytotoxic effects against breast cancer and kidney carcinoma cell lines.