Analysis of phytochemicals in watercress leaves using chromatographic, spectroscopic and in-vitro approaches

Watercress (WC, Nasturtium officinale ) is an aquatic leafy, perennial vegetable which belongs to the Brassicaceae family and is popularly used in salads and soups. Literature provides evidence on therapeutic importance of WC in treating wide spectrum of heath disorders, which include hypertension, cardiac and hepatic diseases, cancer, arthritis, bronchitis, diuresis, scurvy hypercholesterolemia, and hyperglycemia. The beneficial properties of watercress are due to the presence of phytochemicals including polyphenols, flavonoids, and terpenoids in WC leaves. The present study aims to explore the effect of a combination of polar solvents as mobile phase in HPLC to investigate the inherent phytochemical components in the WC-leaves methanol, ethanol, ethyl acetate and water extracts. Each WC leaf extract possessed a concentration of 0.105 g/mL of watercress leaf. Three different mobile phases were used in this study: i. 50 % acetonitrile, 30 % methanol, and 20 % water containing 0.04 % HCl; ii. 20 % acetonitrile, 30 % methanol, and 50 % water containing 0.04 % HCl; iii. 65 % acetonitrile, and 35 % water containing 0.04 % HCl. Our goal was to find the best solvent for extracting phytochemicals from WC leaves and to identify some of the chemicals that may be responsible for watercress's therapeutic properties. Total flavonoid content (TFC), total antioxidant capacity (TAC), and total phenolic acid content (TPAC) were determined using various colorimetric methods. Chemical structural analysis was conducted through attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectroscopy. Some preliminary investigations in ovarian cancer cells showed important oxidative effects of WC against ovarian cancer.