Investigation of in-vitro antioxidant and cytotoxic potential of Crotalaria pallida leaves

Abstract

Crotalaria pallida (C. pallida) is a locally known as Kudug Jhunjhuni, and it is traditionally used for treating urinary problems, swelling of joints, the extract of the leaves is used as vermifuge. Since the antioxidant potential using methanolic leaf extract and cytotoxic activity on HeLa cell line have not been investigated before with C. pallida leaves, this study was aimed to screen these activities. In this study, the phytochemical screening of methanolic leaf extract of C. pallida showed the presence of flavonoids, phenolic compounds, alkaloids, tannins, phytosterols and carbohydrates. Various in-vitro antioxidant studies were performed to determine its antioxidant potential. In DPPH free radical scavenging assay, the IC50 value for C. pallida and reference standard ascorbic acid was found to be 157.01μg/mL and 276.6μg/mL respectively, which infers that, C. pallida has higher free radical scavenging power than the standard ascorbic acid. Whilst the total phenolic content was found to be 141.00mg of gallic acid equivalent (GAE)/g, the total flavonoid content was found to be 144.00mg of quercetin equivalent (QE)/g and the total antioxidant capacity was determined to be 90.7mg of ascorbic acid equivalent (AAE)/g of crude extract for a concentration of 1200μg/mL of methanolic extract of C. pallida. Other antioxidant studies conducted previously on the leaf extract with ethanol, ethyl acetate, chloroform, petroleum ether solvent showed that free radical scavenging activity of C. pallida reached above 80% with ethanolic extract and 60% with other extracts, whereas the study conducted with methanolic leaf extract showed 96.55% scavenging activity. The cytotoxicity of leaf extract was examined on HeLa cell line that was performed by MTT assay. The study indicated that, with the highest 2.0mg/mL concentration of leaf extract the IC50 value was found to be 1.25mg/mL and that inferred about 90% cancerous cell population was dead; which was the highest percentage of mortality of HeLa cells compared to 1.5, 1.0 and 0.5 mg/mL concentrations of leaf extract. Thus the study inferred that C. pallida leaf extract has strong antioxidant and cytotoxic potential. The presence of flavonoid provides a notion to the possibility of antioxidant activity, whereas the strong cytotoxic property attributes to the presence of tannins. The findings of this study pave the way for using this medicinal plant as antioxidant agent and possible anticancer agent. Further research and tests may confirm its’ possibilities and effectiveness for treating oxidative stress degenerative diseases like Alzheimer’s disease, Parkinson’s disease etc. and in the treatment of cervical cancer in future.