Antioxidant and cytotoxic activity of stems of Smilax zeylanica in vitro

BACKGROUND: Plant-derived phytochemicals consisting of phenols and flavonoids possess antioxidant properties, eventually rendering a lucrative tool to scavenge reactive oxygen species. This study was carried out to evaluate in vitro antioxidant and cytotoxic potential of methanolic extract and petroleum ether extracts of Smilax zeylanica L. stems.

METHODS: Phytochemical screening was done following standard procedures. Antioxidant activity was tested using several in vitro assays, viz., 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, NO assay, H2O2 assay, CUPRAC assay, FRAP assay and total antioxidant capacity assay. Total phenol and flavonoid contents were determined by colorimetric method. Brine shrimp lethality and MTT cell viability assays were used for cytotoxic potential.

RESULTS: Preliminary phytochemical study revealed the presence of flavonoids and glycosides in both extracts. Methanolic extract was found to possess stronger antioxidant potential than petroleum ether extracts in all assays. The IC50 value of methanolic extract was 29.14±0.39 μg/mL, 120.30±3.32 μg/mL and 78.41±5.53 μg/mL in DPPH assay, NO assay and H2O2 assay, respectively. Likewise, total phenol [56.78 mg/g gallic acid (GAE)] and flovonoid [125.69 mg/g quercetin equivalents (QE)] were higher in methanolic extract. In cytotoxicity assays, petroleum ether extract showed stronger activity in both brine shrimp lethality (LC50 2.85±0.13 μg/mL) and MTT cell viability assay (IC50 15.49±1.18 μg/mL).

CONCLUSIONS: These findings demonstrate that methanolic extracts could be considered as potential sources of natural antioxidant, whereas petroleum ether extracts could be explored for promising anticancer molecules.